Journal articles on the topic 'Geology stratigraphic – Champlain, Lake'
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1
Rayburn, John A., Thomas M. Cronin, David A. Franzi, Peter L. K. Knuepfer, and Debra A. Willard. "Timing and duration of North American glacial lake discharges and the Younger Dryas climate reversal." Quaternary Research 75, no. 3 (May 2011): 541–51. http://dx.doi.org/10.1016/j.yqres.2011.02.004.
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AbstractRadiocarbon-dated sediment cores from the Champlain Valley (northeastern USA) contain stratigraphic and micropaleontologic evidence for multiple, high-magnitude, freshwater discharges from North American proglacial lakes to the North Atlantic. Of particular interest are two large, closely spaced outflows that entered the North Atlantic Ocean via the St. Lawrence estuary about 13,200–12,900 cal yr BP, near the beginning of the Younger Dryas cold event. We estimate from varve chronology, sedimentation rates and proglacial lake volumes that the duration of the first outflow was less than 1 yr and its discharge was approximately 0.1 Sv (1 Sverdrup = 106 m3 s−1). The second outflow lasted about a century with a sustained discharge sufficient to keep the Champlain Sea relatively fresh for its duration. According to climate models, both outflows may have had sufficient discharge, duration and timing to affect meridional ocean circulation and climate. In this report we compare the proglacial lake discharge record in the Champlain and St. Lawrence valleys to paleoclimate records from Greenland Ice cores and Cariaco Basin and discuss the two-step nature of the inception of the Younger Dryas.
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Pair, Donald L., Ernest H. Muller, and Peter W. Plumley. "Correlation of Late Pleistocene Glaciolacustrine and Marine Deposits by Means of Geomagnetic Secular Variation, with Examples from Northern New York and Southern Ontario." Quaternary Research 42, no. 3 (November 1994): 277–87. http://dx.doi.org/10.1006/qres.1994.1078.
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AbstractThe geomagnetic secular variation record retained by glaciolacustrine and marine sediments at nine sites in northern New York and southern Ontario provides a means for stratigraphic correlation of glacial deposits for the time period between about 12,600 to 9900 14C yr B.P. Measurement of the depositional remanent magnetism of sediments deposited in Glacial Lake Iroquois and the Champlain Sea has produced a geomagnetic secular variation curve that represents the time period immediately following deglaciation about 12,600 14 C yr B.P. The curve varies from about 358° to 344° declination and 51° to 61° inclination over approximately 180 valve years. Marine sediments of the Champlain Sea have preserved a record approximately 1500 yr long that varies from about 2° to 29° declination and 47° to 60° inclination. These combined glacial-paleomagnetic records may also correlate with those from glacial sequences beyond our study area. The shape and amplitude of the secular variation record in glaciolacustrine and marine sediments from the western Adirondack borderland show agreement with other glacial varve secular variation records and suggest possible correlations with secular variation curves from lake cores.
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Ross, Martin, Michel Parent, Beatriz Benjumea, and James Hunter. "The late Quaternary stratigraphic record northwest of Montréal: regional ice-sheet dynamics, ice-stream activity, and early deglacial events." Canadian Journal of Earth Sciences 43, no. 4 (April 1, 2006): 461–85. http://dx.doi.org/10.1139/e05-118.
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The Quaternary sediments of previously unstudied buried valleys and sections near Montréal are analyzed and other sites are revisited to further develop the stratigraphic framework of the St. Lawrence Lowland and to establish regional glacial and deglacial models. The southwest-trending buried valleys were investigated by stratigraphic drilling and high-resolution seismic profiling. The Quaternary succession consists, from base to top, of proximal glaciolacustrine sediments, two superposed till sheets (Argenteuil and Oka tills) of inferred Late Wisconsinan age, and Champlain Sea sediments. The glacial sediments of this sequence record an ice advance toward south (Argenteuil Till) followed by an abrupt ice-flow shift toward the southwest (Oka Till). Compositional and geomorphic data indicate that Oka Till is ubiquitous and is associated with a regional set of glacial landforms. The analysis of a regional digital elevation model in combination with published ice-flow indicators shows convergent flow patterns from the OttawaMontréalAdirondack regions toward the Lake Ontario basin. Landforms produced by the inferred ice stream are locally crosscut by southward-trending ice-flow features. Hence southward flow in the upper St. Lawrence Valley seemingly took place in two distinct contexts: (1) during full glacial conditions, as ice margins stood at or near the late glacial maximum limits, and (2) during late deglaciation, as a post-ice stream reequilibration mechanism. Early deglacial events in the study area were also characterized by subglacial meltwater channelling and erosion along the valleys, subaquatic outwash deposition in glacial Lake Candona, and rapid infill of the valleys during the early stages of the ensuing Champlain Sea.
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Wood, Douglas A., and Christopher A. Scholz. "Stratigraphic framework and lake level history of Lake Kivu, East African Rift." Journal of African Earth Sciences 134 (October 2017): 904–16. http://dx.doi.org/10.1016/j.jafrearsci.2016.06.014.
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Birgenheier, L. P., M. D. Vanden Berg, P. Plink-Björklund, R. D. Gall, E. Rosencrans, M. J. Rosenberg, L. C. Toms, and J. Morris. "Climate impact on fluvial-lake system evolution, Eocene Green River Formation, Uinta Basin, Utah, USA." GSA Bulletin 132, no. 3-4 (June 19, 2019): 562–87. http://dx.doi.org/10.1130/b31808.1.
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Abstract In light of a modern understanding of early Eocene greenhouse climate fluctuations and new highly seasonal fluvial system faces models, the role of climate in the evolution of one classically-cited continental, terminal lake system is re-examined. Detailed stratigraphic description and elemental abundance data from fifteen cores and seven outcrop regions of the Green River Formation were used to construct a ∼150 km cross section across the Uinta Basin, Utah, USA. Lake Uinta in the Uinta Basin is divided into five lake phases: (1) post-Paleocene Eocene Thermal Maximum, (2) peak Eocene hyperthermal, (3) waning hyperthermal, Early Eocene Climatic Optimum (EECO), (4) post-hyperthermal, and (5) post-EECO regimes, based primarily on climatically driven changes in fluvial style in combination with sedimentary indicators of lacustrine carbonate deposition, organic matter preservation, salinity, and lake depth. Basinwide siliciclastic dominated intervals were deposited by highly seasonal fluvial systems and record negative organic carbon isotope excursions associated with early Eocene abrupt, transient global warming (hyperthermal) events. Carbonate dominated or organic rich intervals record stable, less seasonal climate periods between hyperthermals, with lower siliciclastic sediment supply allowing the development of carbonate and organic matter preservation. The stratigraphic progression from alternating organic rich and lean zones to the overlying organic rich Mahogany and R8 zones represents the global transition out of the pulsed early Eocene hyperthermal climate regime to a time of sediment starvation and lake stratification, sequestering sedimentary organic carbon. This study provides a novel approach to terrestrial paleoclimate reconstruction that relies largely on unique sedimentary indicators and secondarily on isotopic proxy records within the context of a large basin-wide sedimentologic and stratigraphic data set, thus setting the stage for future detailed geochemical terrestrial paleoclimate proxy development.
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Magyar, Imre, István Cziczer, Orsolya Sztanó, Árpád Dávid, and Michael Johnson. "Palaeobiology, palaeoecology and stratigraphic significance of the Late Miocene cockle Lymnocardium soproniense from Lake Pannon." Geologica Carpathica 67, no. 6 (December 1, 2016): 561–71. http://dx.doi.org/10.1515/geoca-2016-0035.
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Abstract Stratigraphic subdivision of the Upper Miocene deposits in the Pannonian Basin has been traditionally based on the endemic mollusc species of Lake Pannon. The cockle species Lymnocardium soproniense Vitális, apparently evolving through a sympatric speciation event in the sublittoral zone of Lake Pannon about 10.2-10.3 Ma, attained wide geographical distribution in the Pannonian basin and thus may serve as a good stratigraphic marker. Lymnocardium soproniense was one of the few large-sized cockles in Lake Pannon, most closely related to its ancestor, L. schedelianum (Fuchs), and to another descendant of the latter, L. variocostatum Vitális. According to the δ18O stable isotope record of its shells, the large size of L. soproniense was coupled with an extended life time of more than 10 years, probably reflecting a stable lake environment with increased resource availability and decreased predation. The species lived in quiet offshore conditions, below the storm wave base, where clay was deposited from suspension and the influence of currents was negligible. The base of the Lymnocardium soproniense Zone in the sublittoral deposits of Lake Pannon is defined by the first occurrence of the species, whereas the top of the zone is marked with the base of the overlying Congeria praerhomboidea Zone, defined by the FAD of C. praerhomboidea.
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Palzer-Khomenko, Markus, Michael Wagreich, Wolfgang Knierzinger, Maria Meszar, Susanne Gier, Mădălina-Elena Kallanxhi, and Ali Soliman. "A calcite crisis unravelling Early Miocene (Ottnangian) stratigraphy in the North Alpine–Carpathian Foreland Basin: a litho- and chemostratigraphic marker for the Rzehakia Lake System." Geologica Carpathica 69, no. 4 (August 1, 2018): 315–34. http://dx.doi.org/10.1515/geoca-2018-0019.
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Abstract Within the Lower Austrian part of the North Alpine Foreland Basin (NAFB), up to 1000 m of sediments were deposited throughout the Ottnangian (Early Miocene, Burdigalian). According to homogeneous compositions and sparse biostratigraphic resolution, a consistent stratigraphic concept from the basin margins into the foreland depocenter was still lacking. New investigations on several deep drill cores throughout the basin provide comprehensive sedimentological, mineralogical, chemical and micropaleontological data. A calcite poor, fossil- and pyrite-free, smectite-rich, up to 800 m thick interval was identified and correlated to the time interval of the late Ottnangian brackish Rzehakia Lake System. For this section, we introduce the term Calcite Minimum Interval (CMI). We define the onset of the CMI by a sharp decrease of calcite contents and the disappearance of autochthonous (and reworked) calcareous nannofossils. We define the termination of the CMI by the permanent increase of pyrite contents and the reappearance of calcareous nannofossils. The CMI as a litho- and chemostratigraphical marker for the Rzehakia Lake System constitutes a stratigraphic key horizon. Within the NAFB in Lower Austria, its onset corresponds to the middle/upper Ottnangian transition while its termination correlates roughly to the Ottnangian / Karpatian boundary. This allows a precise definition, identification and correlation of (upper) Ottnangian stratigraphic units of the NAFB. For the central basinal parts of the Rzehakia Lake System, we introduce the new lithostratigraphic term Wildendürnbach Formation which correlates to the marginal Traisen Formation.
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Normandeau, Alexandre, Patrick Lajeunesse, Annie-Pier Trottier, Antoine G. Poiré, and Reinhard Pienitz. "Sedimentation in isolated glaciomarine embayments during glacio-isostatically induced relative sea level fall (northern Champlain Sea basin)." Canadian Journal of Earth Sciences 54, no. 10 (October 2017): 1049–62. http://dx.doi.org/10.1139/cjes-2017-0002.
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The nature of glaciomarine sediments deposited during ice margin retreat can vary according to physiographic setting and relative sea level fluctuations. To understand the effects of these two parameters on sedimentation, we analyzed the sediment records of four lakes located within former isolated glaciomarine embayments of the northern Champlain Sea basin. These lakes were initially inundated by marine water of the Champlain Sea, following deglaciation, and have subsequently experienced basin isolation owing to glacio-isostatic rebound. Three of these lakes reveal a common litho- and acoustic stratigraphic succession, characterized by an IRD-free glaciomarine to marine facies consisting of homogeneous to faintly laminated clayey silts grading into well-laminated silts with rapidly deposited layers. These two units recorded the transitional environment from glaciomarine sedimentation below multiyear shorefast ice to increased terrestrial runoff and rapid glacio-isostatic rebound once the ice margin retreated inland. During ice margin retreat, relative sea level fell concomitantly resulting in the deposition of coarser sediments in marine embayments. Upon the complete retreat of the ice margin, the supply of terrestrial sediments diminished and lake isolation, driven by relative sea level fall, led to higher biogenic content and increased bioturbation. This study provides a framework for sedimentation in isolated glaciomarine embayments which differs from deep-water sedimentation owing to the presence of shorefast sea-ice and their protected location from major ice-stream outlets.
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Rigueti, Ariely L., Patrick Führ Dal' Bó, Leonardo Borghi, and Marcelo Mendes. "Bioclastic accumulation in a lake rift basin: The Early Cretaceous coquinas of the Sergipe–Alagoas Basin, Brazil." Journal of Sedimentary Research 90, no. 2 (February 27, 2020): 228–49. http://dx.doi.org/10.2110/jsr.2020.11.
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ABSTRACT Coquinas constitute widespread deposits in lacustrine, estuarine, and shallow marine settings, where they are a valuable source of information on environmental conditions. Thick coquina successions were deposited in a series of lacustrine rift basins that formed along the Brazilian Continental Margin during the early stages of the opening of the South Atlantic Ocean, in the Early Cretaceous. In the Sergipe–Alagoas Basin, the coquina sequence, equivalent to the Morro do Chaves Formation, crops out in the Atol Quarry, and is considered a relevant analog for the economically important hydrocarbon reservoirs in the Pre-salt strata (Barremian to Aptian) of the Campos Basin (Pampo, Badejo, and Linguado oil fields), which occur only in the subsurface. The aim of this study is to generate a depositional and stratigraphic model through facies and stratigraphic analyses of a well core. These analyses allowed the geological characterization of the Morro do Chaves Formation and of its transition to the adjacent stratigraphic units, the Coqueiro Seco Formation above and the Penedo Formation below, contributing to the growing knowledge of sedimentation in rift basins and exploratory models in hydrocarbon-producing reservoirs. Facies analysis consists of sedimentological, taphonomic, and stratigraphic features of the rocks. Fourteen depositional facies were recognized, stacked into low-frequency and high-frequency, deepening-upward and shallowing-upward cycles driven by the interaction between climate and tectonism. A depositional model is presented, based on the correlation between well-core and outcrop data described in previous studies, providing insights into the spatial distribution of facies. The detailed analysis of facies and stacking patterns sheds light on depositional processes, paleoenvironmental conditions, and the evolution of the system through time, so we may better understand analogous deposits in the geological record.
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Johnson, Ronald, Justin Birdwell, and Paul Lillis. "Stratigraphic Intervals for Oil and Tar Sand Deposits in the Uinta Basin, Utah." Mountain Geologist 54, no. 4 (November 2017): 227–64. http://dx.doi.org/10.31582/rmag.mg.54.4.227.
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To better understand oil and bitumen generation and migration in the Paleogene lacustrine source rocks of the Uinta Basin, Utah, analyses of 182 oil samples and tar-impregnated intervals from 82 core holes were incorporated into a well-established stratigraphic framework for the basin. The oil samples are from the U.S. Geological Survey Energy Resources Program Geochemistry Laboratory Database; the tar-impregnated intervals are from core holes drilled at the Sunnyside and P.R. Spring-Hill Creek tar sands deposits. The stratigraphic framework includes transgressive and regressive phases of the early freshwater to near freshwater lacustrine interval of Lake Uinta and the rich and lean zone architecture developed for the later brackish-to-hypersaline stages of the lake. Two types of lacustrine-sourced oil are currently recognized in the Uinta Basin: (1) Green River A oils, with high wax and low β-carotane contents thought to be generated by source rocks in the fresh-to-brackish water lacustrine interval, and (2) much less common Green River B oils, an immature asphaltic oil with high β-carotane content thought to be generated by marginally mature to mature source rocks in the hypersaline lacustrine interval. Almost all oil samples from reservoir rocks in the fresh-to-brackish water interval are Green River A oils; however four samples of Green River A oils were present in the hypersaline interval, which likely indicates vertical migration. In addition, two samples of Green River B oil are from intervals that were assumed to contain only Green River A oil. Tar sand at the P.R. Spring-Hill Creek deposit are restricted to marginal lacustrine and fluvial sandstones deposited during the hypersaline phase of Lake Uinta, suggesting a genetic relationship to Green River B oils. Tar sand at the Sunnyside deposit, in contrast, occur in marginal lacustrine and alluvial sandstones deposited from the early fresh to nearly freshwater phase of Lake Uinta through the hypersaline phase. The Sunnyside deposit occurs in an area with structural dips that range from 7 to 14 degrees, and it is possible that some tar migrated stratigraphically down section.
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Wang, Hongliang, Zehua Zhang, Jintong Liang, Huimin Liu, and Shige Shi. "Application of Elemental Geochemistry in High-Frequency Sequence—Stratigraphic Analysis of Lacustrine Shale." Minerals 11, no. 6 (June 21, 2021): 657. http://dx.doi.org/10.3390/min11060657.
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The successful development of shale gas and oil in North America has created considerable interest in shale. The analysis of genetic types, the sedimentary environment, and the mudstone development mechanism within sequences is critical for evaluating shale gas and oil exploration prospects, exploration favorable zones, and resource potential. This study focused on the shale of Shahejie Formation in Dongying Depression of Bohai Bay Basin. Shale lithofacies division, geochemical analysis, and well-log analysis were performed for a sedimentary environment and its related elemental response characteristics’ identification. Based on the results, we concluded that the sedimentary environment of the lake basin evolved from the saltwater lake to the ambiguous lake and then the open lake to the delta. In response, we observed gradually decreasing Sr/Ba and Ca/Mg ratios and increasing Rb/Ca and Fe/Mn ratios during the whole process during the reduction of the salinity and the decrease in PH value and sediments’ transport distance. The relationship between ratio elements and high-frequency sequences was initially established within the shale strata. Our results show that ratios of Sr/Ba and Ca/Mg ratios near the sequence boundary are relatively low, and ratios of Fe/Mn and Rb/Ca are relatively high, while ratios of Sr/Ba and Ca/Mg near the flooding surface are relatively high, and ratios of Fe/Mn and Rb/Ca are relatively low. Those features can be used as a marker for high-frequency sequence division of shale strata. Our results provided a new theoretical basis and technical method for shale gas and oil exploration and development.
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Benison, Kathleen, Jonathan Knapp, Adam Difrisco, and Troy Rasbury. "The Permian Minnekahta Limestone: a Saline Lake Gypsum Replaced by Calcite." Mountain Geologist 55, no. 2 (April 2018): 59–73. http://dx.doi.org/10.31582/rmag.mg.55.2.59.
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The late Permian Minnekahta Limestone of the Black Hills of South Dakota is not a typical limestone. Sandwiched stratigraphically between continental redbed siliciclastics, it is distinct in its gray-pink appearance and carbonate mineralogy and is considered a local and regional marker bed. Based on its calcite composition and stromatolites, it has previously been interpreted as a tidal flat deposit, leading to speculation of a regional late Permian marine transgression. Here, we show observations that question the original composition, reexamine and refine the sedimentary and stratigraphic characteristics, and suggest an alternate depositional environment. Petrography and x-ray diffraction indicate that the Minnekahta Limestone is dominated by an interlocking crystal mosaic of calcite and gypsum. We have documented pseudomorphs after bottom-growth gypsum crystals, alternating laminae of mm-scale bottom growth gypsum crystal shapes and mud drapes, as well as mudcracks, raindrop imprints, and stromatolites. No carbonate grains, fossils, or tidal rhythmites were noted. These observations suggest that the carbonate phase is a replacement of gypsum. In addition to the sedimentology and petrography, close stratigraphic association with overlying and underlying continental redbeds indicates that this was likely a shallow saline-lake deposit. Other Permo-Triassic carbonate strata in continental redbed sequences throughout the midcontinent of North America, such as those in the Goose Egg, Chugwater, Nippewalla, and Spearfish strata, may have similar continental origin. This study serves as a lesson that paired petrographic observations and mineral identifications are important data necessary for the best interpretation of depositional environments and diagenetic histories.
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Sharpe, David R., and Peter J. Barnett. "Significance of Sedimentological Studies on the Wisconsinan Stratigraphy of Southern Ontario." Géographie physique et Quaternaire 39, no. 3 (December 4, 2007): 255–73. http://dx.doi.org/10.7202/032607ar.
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ABSTRACTDetailed facies mapping along Lake Erie and Lake Ontario Bluffs, plus other studies illustrate that sedimentological studies, especially those with geomorphic or landform control, have had three main effects on the Wisconsinan stratigraphy of Ontario: (1) improved understanding of depositional processes and environments of several major rock stratigraphic units, without altering the stratigraphic framework, (2) aided correlation of drift sequences, and (3) questioned previous interpretations and stratigraphic correlations of drift sequences. Thus sedimentological analysis can not be separated from stratigraphy because the interpretation of depositional environnments of many mapped strata relies on their geometry and the inclusion of regional data. The geomorphic control provided by sedimentological study of surface landforms is also important because assessment of older buried sediments such as those at the Scarborough Bluffs has been hampered by the failure to determine landform control. The Late Wisconsinan stratigraphy of Southern Ontario generally remains unchanged, except for questions on the role of climate versus ice margin dynamics. The pre-Late Wisconsinan stratigraphy is scarce and not well defined, yet sedimentary studies support the presence of glacial ice in the Ontario Lake basin for all of the Middle Wisconsinan and possibly earlier, including the formation of the Scarborough delta. Large channel cut and fill sequences in the Toronto area (Pottery Road Formation), initially interpreted as resulting from subaerial erosion, were probably formed by subaqueous or subglacial meltwater erosion. If so, the pre-Late Wisconsinan stratigraphy in southern Ontario changes because the Pottery Road Formation may not be an Early Wisconsinan correlative of the St. Pierre beds. The channel example illustrates that stratigraphie correlation without sedimentological investigations may be misleading.
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Hersi, Osman Salad, and George R. Dix. "Hog's Back Formation: a new (Middle Ordovician) stratigraphic unit, Ottawa Embayment, eastern Ontario, Canada." Canadian Journal of Earth Sciences 34, no. 5 (May 1, 1997): 588–97. http://dx.doi.org/10.1139/e17-047.
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The Hog's Back Formation, exposed in Ottawa, Ontario, is a new stratigraphic unit that disconformably overlies the Rockcliffe Formation and underlies, with apparent conformity, the Pamelia Formation of the Ottawa Group. The Hog's Back Formation is 14.3 m thick at its type section (Prince of Wales Falls, Ottawa) and thickens eastward to 27 m in Russell County, about 40 km southeast of Ottawa. It consists of lower, dark green shales with thin lime-mudstone and sandstone interbeds, and upper thin to thick beds of fine crystalline greenish grey sandy and calcareous dolostones with thin to medium (10–30 cm) pinkish grey, bioclastic packstone and grainstone interbeds. The latter thicken eastward and correlate with the "St. Martin calcarenites" of the Beaconsfield Member, Laval Formation, in the Montréal area. Together, these beds correlate with the Valcour Formation, Chazy Group, in the Lake Champlain area of New York. Conodonts and macrofossils indicate a Chazyan (Llandeilian) age for the Hog's Back Formation. The lower sandstone–shale–carbonate assemblage of the formation indicates sedimentation in peritidal environments, and documents initial regional flooding of nearshore sandy facies of the Rockcliffe Formation. The overlying carbonate facies represent sabkha environments punctuated by storm deposition. The gross shallowing-upward succession of the formation was terminated by renewed flooding associated with another regional transgressive event heralding deposition of the Ottawa Group.
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Corfu, Fernando, and Shoufa Lin. "Geology and U-Pb geochronology of the Island Lake greenstone belt, northwestern Superior Province, Manitoba." Canadian Journal of Earth Sciences 37, no. 9 (September 1, 2000): 1275–86. http://dx.doi.org/10.1139/e00-043.
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Mapping and U-Pb geochronology have been used to examine the tectonic and depositional history of the Archean Island Lake greenstone belt in the northwestern Superior Province. The Island Lake greenstone belt comprises two main supracrustal successions, the older Hayes River Group and the younger Island Lake Group. Zircon data for two volcanic units from the Hayes River Group provide identical ages of 2852 ± 1.5 Ma, whereas a turbidite of this group contains a detrital zircon population with ages between 2858 and 2847 Ma. Younger intrusive events include the emplacement of tonalite in the southern batholith at 2825 ± 2 Ma and the Whiteway Island gabbro at 2807 ± 1 Ma. A wacke at the base of the Island Lake Group is dominated by detrital zircon grains yielding ages between 2830 and 2821 Ma, the latter defining a maximum age of sedimentation. A relatively early time of deposition of the lower stratigraphic sections of the Island Lake Group is also supported by an age of 2744 ± 2 Ma obtained for a crosscutting tonalite. By contrast, two turbidite horizons from higher stratigraphic levels of the Island Lake Group contain detrital zircon populations with ages mostly younger than 2730 Ma, the youngest zircon grains providing maximum ages of sedimentation at 2722 and 2712 Ma, respectively. Our results confirm the protracted evolution of the greenstone belt and show in particular that major sedimentary processes were active throughout the main stages of volcanism of the belt. This pattern of protracted sedimentation is comparable to that observed in other greenstone belts of the northwestern Superior Province, all of which developed on pre-Kenoran crust.
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Gearon, James H., Cornel Olariu, and Ronald J. Steel. "The supply-generated sequence: A unified sequence-stratigraphic model for closed lacustrine sedimentary basins with evidence from the Green River Formation, Uinta Basin, Utah, U.S.A." Journal of Sedimentary Research 92, no. 9 (September 20, 2022): 813–35. http://dx.doi.org/10.2110/jsr.2021.096.
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Abstract Closed lakes and oceans are stratigraphically distinct systems. However, closed-lake stratigraphy is often interpreted using conventional sequence stratigraphic concepts which were generated for marine settings. As a consequence, lacustrine stratigraphy has long been vexing and applied on an ad-hoc basis. To remedy this, we present a novel, unified sequence stratigraphic model for hydrologically closed (endorheic) basins: the Supply-Generated Sequence (SGS) Model. This model was generated to interpret our outcrop-based correlation—the largest to date at ∼ 30 km—across the Sunnyside Interval member of the middle Green River Formation in Nine Mile Canyon near Price, Utah, USA. The SGS model is based on the fundamental sedimentological and hydrodynamic differences between closed lakes and marine settings wherein the relationship between water discharge and sediment discharge is highly correlated. The SGS model divides packages of genetic lacustrine strata by bounding correlative surfaces, conformable or unconformable, separating facies and surfaces associated with low clastic supply (e.g., carbonates, mudstones, or exposure surfaces) from facies characteristic of relatively higher amounts of clastic supply (subaerial channelized sandstones, subaqueous siltstones, and pedogenic mudstones). We use the SGS model to correlate regional sequences at a higher resolution than previous interpretations and find the greatest amount of clastic deposition occurs during periods of lake-level rise, indicating that the SGSs are characteristically transgressive. Additionally, this model removes the implicit and explicit base-level assumptions of previous sequence stratigraphic models while being agnostic to the source of increased sediment discharge and therefore generalizable to other closed lacustrine settings. We use the high-resolution supply-generated sequences (meters thick) to argue for a climatic origin of the cyclic Sunnyside interval deposits based on sequence durations (40–50 kyr), and aligning sequences with recognized early Eocene transitory hyperthermal event timing and their associated climatic shifts across the region, increasing riverine discharge of sediment and water.
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Trottier, Annie-Pier, Patrick Lajeunesse, Alexandre Normandeau, and Antoine Gagnon-Poiré. "Deglacial and postglacial paleoseismological archives in mass movement deposits of lakes of south-central Québec." Canadian Journal of Earth Sciences 56, no. 1 (January 2019): 60–76. http://dx.doi.org/10.1139/cjes-2018-0167.
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Investigation of seismic activity in eastern Canada is important for natural hazard management as two major active seismic zones with many historical records are located in the region: the Western Québec seismic zone (WQSZ) and the Charlevoix–Kamouraska seismic zone (CKSZ), with the latter being the most active in northeastern America. This paper describes and analyses a dataset of high-resolution swath bathymetric imagery, sub-bottom profiles, and sediments cores collected in three lakes (Maskinongé, Aux-Sables, and St-Joseph) located between two active seismic zones. The geomorphology observed on high-resolution swath bathymetric imagery, the acoustic sub-bottom profiles, and the sediment analysis indicate that the lakes were disturbed by three phases of seismically induced mass movements since deglaciation: (i) during the deglacial Champlain Sea transgression and the rapid initial glacio-isostatic rebound between ∼13 and 10.5 ka cal BP; (ii) around 1180 AD; and (iii) the well-documented CKSZ 1663 AD M >7 historical earthquake. The second phase of earthquake events (1180 AD) corresponds chronologically to a previously documented large landslide in western Québec, dated at ∼1020 years BP. This earthquake is responsible for remobilizing the largest volume of sediments in the entire stratigraphic sequence of Lake Maskinongé, the westernmost lake. This earthquake was not recorded in Lake Aux-Sables and St-Joseph, which are located eastward from Maskinongé, but the largest mass movement deposits are associated with the well-known 1663 AD event of eastern Québec. Therefore, both earthquake events are interpreted to have different epicenters and the lakes of southeastern Québec recorded earthquakes from both seismic zones.
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Onnis, Luciano, Roberto Antonio Violante, Ana Osella, Matías De la Vega, Alejandro Tassone, and Ernesto López. "Neogene-Quaternary seismic stratigraphy of the Llancanelo Lake Basin, Mendoza, Argentina." Andean Geology 45, no. 1 (November 14, 2017): 35. http://dx.doi.org/10.5027/andgeov45n1-3026.
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A new shallow multichannel seismic survey was carried out in the Llancanelo Lake region (Southern Mendoza Province, Argentina), in order to complete and extend previously surveyed seismic sections. The new seismic data allowed to double the already existing data. The obtained information was correlated with seismic and stratigraphic data from the industry. In this way it was possible to depict the major Neogene-Quaternary sedimentary-volcanic sequences and the regional evolution of a tectonic-volcanic basin located in a key region at the eastern foot of the Andes cordillera. This research is settled on early studies that comprised seismic works reaching depths of 600-700 m as well as geoelectric and electromagnetic surveys reaching the uppermost 80-100 m of the sequences. The obtained results indicate the presence of three major sedimentary units separated by conspicuous seismic horizons SR1, SR2 and SR3, respectively considered as representing the late Mesozoic transition from marine to continental deposition, the beginning of the Cenozoic basaltic volcanism, and the change from dominantly sedimentary to dominantly volcanic processes at the base of the Quaternary. The resulting stratigraphic scheme reveals increasing volcanic (basaltic layers) intercalations with depth that accommodate to the geometry of the depocenter.
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Rundić, Ljupko, Meri Ganić, Slobodan Knežević, and Ali Soliman. "Upper Miocene Pannonian sediments from Belgrade (Serbia): new evidence and paleoenvironmental considerations." Geologica Carpathica 62, no. 3 (June 1, 2011): 267–78. http://dx.doi.org/10.2478/v10096-011-0021-z.
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Upper Miocene Pannonian sediments from Belgrade (Serbia): new evidence and paleoenvironmental considerationsThe Late Miocene sublittoral marls of the Pannonian Stage (the long-lived Lake Pannon) were studied. From neotectonic point of view, the investigated area represents a natural border between two different morphostructural domains: the Pannonian Basin to the north and the Peri-Pannonian Realm to the south. More than 20 mollusc and 34 ostracod species were identified which indicate the upper part of the Lower Pannonian and the lower part of the Middle Pannonian ("Serbian") predominantly. The identified dinoflagellate cyst assemblage (21 taxa) hinders assignment of the studied samples to a Pannonian substage but supports the high endemism of the Pannonian flora. The lithostratigraphical, paleontological, and paleoecological analyses indicate a mesohaline (8-16 ‰), sublittoral (<90 m deep) environment of the early Lake Pannon. The estimated stratigraphic range for the investigated deposits is 9.8-11.4 Ma.
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Crow, Ryan S., Keith A. Howard, L. Sue Beard, Philip A. Pearthree, P. Kyle House, Karl E. Karlstrom, Lisa Peters, et al. "Insights into post-Miocene uplift of the western margin of the Colorado Plateau from the stratigraphic record of the lower Colorado River." Geosphere 15, no. 6 (October 16, 2019): 1826–45. http://dx.doi.org/10.1130/ges02020.1.
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Abstract The spatial and temporal distribution of Pliocene to Holocene Colorado River deposits (southwestern USA and northwestern Mexico) form a primary data set that records the evolution of a continental-scale river system and helps to delineate and quantify the magnitude of regional deformation. We focus in particular on the age and distribution of ancestral Colorado River deposits from field observations, geologic mapping, and subsurface studies in the area downstream from Grand Canyon (Arizona, USA). A new 4.73 ± 0.17 Ma age is reported for a basalt that flowed down Grand Wash to near its confluence with the Colorado River at the eastern end of what is now Lake Mead (Arizona and Nevada). That basalt flow, which caps tributary gravels, another previously dated 4.49 ± 0.46 Ma basalt flow that caps Colorado River gravel nearby, and previously dated speleothems (2.17 ± 0.34 and 3.87 ± 0.1 Ma) in western Grand Canyon allow for the calculation of long-term incision rates. Those rates are ∼90 m/Ma in western Grand Canyon and ∼18–64 m/Ma in the eastern Lake Mead area. In western Lake Mead and downstream, the base of 4.5–3.5 Ma ancestral Colorado River deposits, called the Bullhead Alluvium, is generally preserved below river level, suggesting little if any bedrock incision since deposition. Paleoprofiles reconstructed using ancestral river deposits indicate that the lower Colorado River established a smooth profile that has been graded to near sea level since ca. 4.5 Ma. Steady incision rates in western Grand Canyon over the past 0.6–4 Ma also suggest that the lower Colorado River has remained in a quasi–steady state for millions of years with respect to bedrock incision. Differential incision between the lower Colorado River corridor and western Grand Canyon is best explained by differential uplift across the Lake Mead region, as the overall 4.5 Ma profile of the Colorado River remains graded to Pliocene sea level, suggesting little regional subsidence or uplift. Cumulative estimates of ca. 4 Ma offsets across faults in the Lake Mead region are similar in magnitude to the differential incision across the area during the same approximate time frame. This suggests that in the past ∼4 Ma, vertical deformation in the Lake Mead area has been localized along faults, which may be a surficial response to more deep-seated processes. Together these data sets suggest ∼140–370 m of uplift in the past 2–4 Ma across the Lake Mead region.
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Browning, C., and M. Reid. "Lithostratigraphy of the Kweekvlei Formation (Witteberg Group), Cape Supergroup." South African Journal of Geology 120, no. 3 (September 1, 2017): 421–32. http://dx.doi.org/10.25131/gssajg.120.3.421.
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AbstractThe Lower Carboniferous, probably Tournaisian, Kweekvlei Formation is part of the Witteberg Group (Cape Supergroup) of South Africa. Together with the overlying Floriskraal Formation, it forms an upward-coarsening succession within the Lake Mentz Subgroup. Sedimentary features of the Kweekvlei Formation suggest deposition in a storm-wave dominated marine setting, within the storm-influenced, distal part of an offshore transition zone environment. This predominantly argillaceous formation preserves a low diversity trace fossil assemblage. Reworked vascular plant debris (including the problematic genus Praeramunculus sp.) and a shark spine have been reported for the Kweekvlei Formation. There are no known stratigraphic equivalents in South Africa.
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Birdwell, Justin, Ronald C. Johnson, and Michael E. Brownfield. "Distribution of mineral phases in the Eocene Green River Formation, Piceance Basin, Colorado—Implications for the evolution of Lake Uinta." Mountain Geologist 56, no. 2 (May 1, 2019): 73–141. http://dx.doi.org/10.31582/rmag.mg.56.2.73.
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The mineralogy of the Eocene Green River Formation in the Piceance Basin, Colorado, has been the subject of numerous studies since the 1920s. Most previous work has focused on the resource potential of these lacustrine mudrocks, which in addition to substantial oil shale potential (in-place resources of 353 billion barrels of synthetic crude oil for rocks yielding at least 25 gallons per ton, GPT), includes nahcolite, a currently utilized soda ash resource, and dawsonite, a potential alternative source of aluminum. Another reason to study the mineralogy in this system is that the geographic and stratigraphic distribution of various authigenic minerals may provide insights into the geochemistry and depositional environment of the long-lived Eocene Lake Uinta. In this study, legacy non-quantitative (presence/absence) X-ray diffraction (XRD) data recently published by the U.S. Geological Survey (USGS) for more than 9,000 samples collected from 30 coreholes in the Green River Formation, Piceance Basin were examined. These data were used to better define the stratigraphic and paleogeographic extent of a set of indicator minerals (illite, analcime, albite, dawsonite, and nahcolite) within the Piceance Basin lacustrine strata. This set of minerals was selected based on observations from previous work and variability in their occurrence and co-occurrence within the Piceance Basin. The USGS database has been used to (1) construct maps showing geographic variations in mineral occurrences for 14 stratigraphically defined rich and lean oil shale zones; (2) assess co-occurrences of indicator minerals; and (3) compare occurrence results with quantitative XRD datasets collected on Piceance Basin oil shales. Occurrences of many authigenic minerals (analcime, dawsonite, and nahcolite) varied in the lacustrine strata near and around the depocenter, but others, like quartz, dolomite, and feldspar (potassium + undifferentiated), were widely and consistently present (>90% of samples) across the basin. Shifts in the distribution of indicator mineral occurrences generally coincide with changes identified in previous lake history descriptions and indicate that the water chemistry of Lake Uinta varied significantly going from near-shore to the depocenter and through time.
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Cross, Timothy, and Yohan Kusumanegara. "Stratigraphic Controls on Petrophysical Attributes and Fluid-Flow Pathways in an Exhumed Fluvial Reservoir." Mountain Geologist 54, no. 3 (July 2017): 129–45. http://dx.doi.org/10.31582/rmag.mg.54.3.129.
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Fluvial, floodplain and lake strata of the Green River Formation (Eocene) occur within an exhumed oil reservoir exposed in a quarry near Sunnyside, Utah. Strata in the quarry highwalls define three, asymmetrical, 15- to 20-m thick, base-level-rise genetic sequences arranged in a long-term base-level-rise (landward stepping) stacking pattern. Variable intensity of oil stain on rock surfaces is a qualitative measure of pore volumes, as all permeable facies are fully saturated with oil. Visual estimates of oil-stain intensity, combined with petrophysical measurements and petrographic analysis of the different facies, were used to define fluid-flow compartments and their boundaries. Strata and facies that functioned as fluid-flow conduits, retardants and barriers were mapped on photomosaics of the quarry highwall. Three separate fluid-flow compartments coincide with the three genetic sequences. Amalgamated fluvial sandstones at the base of each genetic sequence functioned as flow units of varying permeability and degree of interconnectedness. Laterally continuous floodplain and/or lacustrine mudstones, which cap each genetic sequence, entirely lack oil in matrix porosity and functioned as fluid-flow barriers and compartment boundaries. Petrophysical properties of specific sedimentary facies are sensitive to stratigraphic position at three spatial scales, even though the sedimentary facies appear nearly identical. At the long-term scale, porosity and permeability of the same facies (trough cross-stratified sandstone is the most common) in channel sandstones of the three genetic sequences decrease in stratigraphic succession. Within each genetic sequence, porosity and permeability are highest at the base and decrease quasilinearly to the top. Using oil-stain intensity as a proxy, porosity and permeability generally decrease from base to top of each scour-based channel macroform. Petrophysical variations coincide with subtle variations in grain size and trough cross-stratification set thickness within otherwise indistinguishable sedimentary facies. These results demonstrate that conventional crossplots of porosity/permeability versus sedimentary facies are unnecessarily broad and imprecise. When such petrophysical data are plotted in a stratigraphic context, porosity and permeability values have significantly reduced scatter. Porosity and permeability measurements and predictions of each sedimentary facies should be made from a stratigraphic perspective. From our observations of variations in intensity of oil stain, homogeneity of fluid flow may not be equated directly with facies homogeneity. At one extreme of an apparent continuum, fluid-flow pathways are tortuous and extremely variable within homogeneous, high permeability, amalgamated channel sandstones. Sweep efficiencies may be low in these cases. At an intermediate position in the continuum, increased diversity of sedimentary facies and stratigraphic variability usually cause sufficient stratigraphic separation of permeable and impermeable strata such that fluid-flow pathways are more confined and have a reduced tortuosity. Sweep efficiencies may be high in these cases. At the other extreme of the continuum, where diversity of sedimentary facies and stratigraphic variability is very high, stratigraphic units are discontinuous and restricted in area. In such cases, fluid-flow pathways are not laterally connected, and sweep efficiencies would be low.
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Tian, Shaobing, Ping Zhang, Tongxiao Shang, Huogen Chen, Yongxiang Li, and Shugang Xu. "Application of resistivity sounding in Quaternary stratigraphic division in Yixing, Eastern China." Journal of Geophysics and Engineering 19, no. 3 (June 1, 2022): 362–75. http://dx.doi.org/10.1093/jge/gxac025.
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Abstract Stratigraphic classification and correlation are fundamental for the study of regional geology, tectonic structures and paleogeographic evolution. Geological structures have undergone a dramatic change since the Quaternary. However, the division of the Quaternary stratigraphic boundary in southeastern China is debated. In this study, we used a direct current vertical electric sounding method to study the Quaternary strata in Yixing, Jiangsu, China. Using one-dimensional resistivity inversion and analyzing the regional geology and geological core data, the electrical features of the study area were evaluated. We found good agreement between the geological core data and lithological data, and we were able to identify two stratigraphic groups: the hilly sedimentary area in the southwest and the Tai Lake plain sedimentary area in the northeast. The latter can further subdivided into two parts. Division and classification of the Quaternary strata in the study area provide a basis for locating areas likely to have a high pore-confined water content (such as Gaoteng, Heqiao and Wanshi town), whereby useful information is provided for groundwater exploitation for emergency use.
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Lyon, Eva C., Michael M. McGlue, Edward W. Woolery, Sora L. Kim, Jeffery R. Stone, and Susan R. H. Zimmerman. "Sublacustrine geomorphology and modern sedimentation in a glacial scour basin, June Lake, eastern Sierra Nevada, U.S.A." Journal of Sedimentary Research 89, no. 10 (October 21, 2019): 919–34. http://dx.doi.org/10.2110/jsr.2019.52.
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ABSTRACT Small sub-alpine glacial lakes are often targeted as Holocene paleoclimate archives, but their evolution as landforms and depositional basins is understudied. At June Lake in the eastern Sierra Nevada of California (USA), bathymetry, surface sediment composition, and seismic stratigraphy are studied to assess the modern sedimentary system and gain insight into the basin's origins. A basin-wide seismic survey reveals sublacustrine morphological features that attest to the role of ice in scouring the June Lake basin, including a prominent abraded bedrock shoal and an adjacent overdeepened depression. The seismic survey reveals four acoustically distinct stratigraphic units that reflect the history of sedimentation following glacial scouring. The youngest of these is represented in the recovered lacustrine core records as hemipelagically deposited, organic-rich, laminated diatomaceous oozes alternating with coarse tephra beds. The organic-rich oozes are characterized by low carbon and nitrogen stable-isotope values and occur in profundal areas of the modern lake floor. These sediments suggest an algae-dominated productivity regime and preservation of organic matter at depth. With no perennial streams entering June Lake, surface-sediment grain-size distribution and geochemistry are controlled by water depth and basin morphology. Additional modern facies types include poorly sorted coarse detrital landslide deposits below steep basin walls and volcaniclastic sandy gravel in windward littoral areas. These data provide a modern facies model for sedimentation in ice-scoured, hydrologically closed sub-alpine lakes and a baseline for future paleoclimate studies using June Lake sediment cores.
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Lowe, J. John, and Peter Cairns. "New pollen-stratigraphic evidence for the deglaciation and lake drainage chronology of the Glen Roy-Glen Spean area." Scottish Journal of Geology 27, no. 1 (September 1991): 41–56. http://dx.doi.org/10.1144/sjg27010041.
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Borer, James. "High-Resolution Stratigraphy of the lower portion of the Green River Formation at Raven Ridge and Red Wash Field, NE Uinta Basin, Utah, Colorado, USA: Facies and Stratigraphic Patterns in a High-Gradient, High-Energy Lacustrine System." Mountain Geologist 53, no. 3 (July 2016): 119–223. http://dx.doi.org/10.31582/rmag.mg.53.3.119.
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Lacustrine strata of a portion of the Green River Formation studied in outcrops along Raven Ridge and in the subsurface around Red Wash Field in the northeastern Uinta Basin represent cyclic storm-dominated shoreface to deep lake deposition within a syntectonic embayment on the margin of Eocene Lake Uinta. The study interval consists of the lower Green River Formation, including the Douglas Creek, Garden Gulch, and lower Parachute Creek members, from the top of the underlying Wasatch to the Mahogany Zone of the Parachute Creek Member. Data consists of 11,900 ft (3627 m) of section measured at 23 locations across Raven Ridge, including 7,800 ft (2377 m) of hand-held gamma-ray scintillometer measurements, and over 500 wells in the greater Red Wash Field area, including pay zone analysis correlated to stratigraphy in the field. Facies analysis, as the basis for an integrated stratigraphic approach, reveals a seven-fold hierarchy of stratigraphic cycles ranging from two orders of large-scale cycles to five orders of progressively higher-frequency (smaller scale) shoreface-lake cycles across an 18-mile (29 km) long and 1900-ft (579 m) thick dip-oriented stratigraphic transect. This study recognized twenty-two facies grouped into eight facies tracts using Walther’s Law for two composite shoreface successions: one for a siliciclastic storm-graded shoreface profile that was dominant during times of regression and one for a carbonate profile that dominated in times of transgression. Two important regional facies trends across Raven Ridge include: 1) greater proportions of mudstone facies present in the southern, upper portion of the Green River Formation; and 2) significantly higher proportion of bioturbated sandstone in the northern, lower portion of the formation. The long-term 2nd-order transgression of Lake Uinta from base to top of the study interval results in an evolution from a low-gradient shoreline with marshes, ponds, and sand/mud flats to a high-gradient high-energy profile composed of spits and shorefaces that grew southward away from the emergent highlands. A composite storm-graded shelf profile shows how trough, hummocky, and swaley cross stratification type and amalgamation style change offshore proportionally to contain mud-dominated tempestites, erosional storm furrows, and oil shale. In the most offshore positions, diastasis cracks caused by differential loading are common. The lacustrine shoreface profile is compressed in the Green River Fm. in the study area with narrow facies tracts and large local gradient changes as a result of different responses to sediment supply. As a lake grows and shorelines migrate, the increase in accommodation is balanced, or in-phase, by a corresponding increase in sediment supply resulting in shoreface progradation keeping up with lake-level rise. As the shoreface stacks vertically during the rise, over steepening and failure of the profile generates gravity-flow sandstone facies. Little reworking of hummocky cross stratification high on the profile was observed, probably because wave power was limited by a shallow fair-weather wave-base. These differences also result in more symmetrical lacustrine shoreface cycles, with a large proportion of sediment partitioned into rise hemicycles, as opposed to the classical fall-asymmetric marine para-sequence which tends to have little to no strata preserved in the rise hemicycle along most of the shoreface profile. Landward-stepping lacustrine shoreface cycles are more common during the early rise portions of larger-scale 3rd-order megacycles for similar reasons. Strata at Raven Ridge support the concept that Eocene Lake Uinta was chemically stratified, or meromictic, at least during certain periods. The equable subtropical Eocene paleoclimate is interpreted to be the most important control on meromixis. Chemical stratification played a critical role in the development and preservation of organic matter, as evidenced by oil shale facies. The equable climate, however, might also have made the lake prone to thermal stratification. A paradox exists in the storm dominance of the lacustrine shorefaces and the coeval lake stratification: wave energy apparently was insufficient to break through the strong chemocline. Red Wash Field, directly downdip from the Raven Ridge outcrop belt, is an example of an oil field in a setting where the lake margin is not coincident with a structural feature: a “non-coincident” margin. Reservoirs mostly are present in the 6th-order aggradational shoreface cycles that are interpreted to have accumulated in the rise portions of 3rd-order megacycles. The best reservoir facies are trough, hummocky, and swaley cross-stratified sandstone deposited by storm processes and structureless sandstone probably derived from over steepening and failure of the shoreface during transgression. A petroleum accumulation model encompassing the Red Wash-Raven Ridge area proposes that lacustrine-sourced petroleum originated from an over-pressured mature cell in the Altamont-Bluebell field region. Oil migrated updip through leaky seals and became trapped in reservoirs within the non-coincident lake margin strata. An irregular shoreline configuration and compaction folds at Red Wash Field trapped petroleum. After reaching spill point at Red Wash Field, oil migrated farther updip to Raven Ridge and Asphalt Ridge, forming tar sand accumulations.
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Sauer, E. Karl, and E. A. Christiansen. "Preconsolidation pressures in intertill glaciolacustrine clay near Blaine Lake, Saskatchewan." Canadian Geotechnical Journal 25, no. 4 (November 1, 1988): 831–39. http://dx.doi.org/10.1139/t88-091.
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Soft, intertill, glaciolacustrine clays are of concern for stability of slopes and foundations. An intertill clay deposit between 32 and 54 m below the surface was continuously cored. Index properties were determined for 46 samples and 10 samples were tested on the oedometer. Stratigraphic evidence indicates that the glaciolacustrine clay (Blaine Lake Member), lying between the till of the Sutherland and Saskatoon groups, was glaciated three times. However, preconsolidation pressures of this intertill clay show the degree of consolidation is less than 20% based on a total stress from an estimated ice thickness extrapolated from the Cypress Hills. This low preconsolidation pressure suggests there was insufficient time for dissipation of excess pore-water pressure created by thickening of the advancing glacier. Key words: preconsolidation pressure, excess pore-water pressure, glaciers, intertill clay.
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Ortega-Guerrero, Beatriz, Sandra García, Guadalupe Cruz, Claudio Salinas, Margarita Caballero, Ismerai Reyes, and Lizeth Caballero. "Holocene and Upper Pleistocene stratigraphy of Xochimilco lake, central Mexico." Revista Mexicana de Ciencias Geológicas 39, no. 2 (July 26, 2022): 167–78. http://dx.doi.org/10.22201/cgeo.20072902e.2022.2.1687.
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The lacustrine system developed in the basin of Mexico has been of great interest in studies of various geological and social disciplines. Its sediments preserve the history of the environmental changes that occurred during the late Quaternary. Between 2016 and 2018, a set of lacustrine sediment cores were collected in the Xochimilco sub-basin, located south of the basin of Mexico. From these sedimentary sequences, a master sequence was constructed that represents the upper 66.5 m of the lacustrine deposits. For the establishment of its stratigraphic column, 15 lithotypes were defined from their sedimentary components in which the clastic components made up of silicates dominate, mostly silt and clay in size. The most abundant biogenic fraction is diatoms that frequently form oozes, and ostracods are a common component in most of the sequence, which locally form hashes. Interbedded with the clastic and biogenic lithotypes are volcaniclastic deposits. Eight lithological units were defined based on their dominant lithotypes. The time scale of the sequence is still uncertain for the oldest sediments; however, it is estimated that it covers the last 300000 to 350000 years. From this temporality, environmental oscillations of millennial scales are inferred. Diatom-rich laminated sediments represent the deepest phases in the lake. The deposits with higher biogenic and authigenic calcareous components indicate the phases of higher ionic concentration during which the lake was shallower. The detailed analysis of the stratigraphy and the description of the sedimentary components in Xochimilco allows to establish an initial interpretation of the variations in the depositional environments, and provides the base from which the detailed studies of paleoclimatic indicators will be supported.
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Eljalafi, Abdulah, and J. Frederick Sarg. "Depositional system and lake-stage control on microbialite morphology, Green River Formation, eastern Uinta Basin, Colorado and Utah, U.S.A." Journal of Sedimentary Research 91, no. 6 (June 18, 2021): 636–61. http://dx.doi.org/10.2110/jsr.2020.073.
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ABSTRACT Lake-margin lacustrine carbonates of the Green River Formation, in the eastern Uinta basin of Colorado and Utah, occur interbedded with fluvial and shoreline-parallel sandstone and shale. Microbial bindstones were deposited in a saline-alkaline lake during and after the Early Eocene Climate Optimum (EECO) (52–50 million years ago) that is characterized by global hot-house conditions, elevated atmospheric CO2, and highly fluctuating climate conditions. The stratigraphic architecture, chemostratigraphy, and morphology of the microbialites and other associated carbonate beds can be related to these climatic conditions. Three facies associations are recognized in the carbonate units across the lake margin from upper littoral to lower sublittoral environments: facies association 1, delta proximal non-microbial carbonates, characterized by quartzose bioclastic, peloidal, intraclastic packstones and grainstones–rudstones, quartose peloid wackestones and sandy oil shale; facies association 2, microbialite associated non-microbial carbonates, composed of ostracod, ooilitic, peloidal packstones–grainstones and intraclastic packstones, grainstones and rudstones; and facies association 3, microbial carbonates, consisting of diverse forms of stromatolitic and thrombolitic lithofacies. Multiple scales of carbonate cyclicity are suggested by shifts of δ18O and δ13C stable isotopes and deepening-upward microbialite facies. High-frequency cycles, on the order of 1 to 5 m thickness, are characterized by positive shifts in stable isotopes and interpreted deepening trends from littoral to lower sublittoral conditions. Large-scale trends, on the order of tens to hundreds of meters thickness record long-term lake changes, including: 1) sparse microbialite deposition during initial fresh conditions in lake stage 1, with low macro-structure diversity and light δ18O and δ13C isotope values; 2) transitional lake stage 2 corresponding to moderate macro-structural diversity, large meter-scale biostromal and biohermal buildups, and a positive shift in δ18O and δ13C isotope values that suggest increasing saline and alkaline conditions; 3) a highly fluctuating lake stage 3 that contains the highest microbialite macro-structural diversity and marks the interval of heaviest δ18O and δ13C isotope values, suggesting the greatest lake restriction, and the highest salinity and alkalinity conditions; and 4) a rising lake stage 4 that marks the lowest microbialite macro-structure diversity and a reversal in trend of δ18O and δ13C isotope values, that indicate deepening and freshening conditions.
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Huang, Xiu, Keyu Liu, Caineng Zou, Xuanjun Yuan, and Lili Gui. "Forward stratigraphic modelling of the shallow-water delta system in the Poyang Lake, southern China." Journal of Geochemical Exploration 144 (September 2014): 74–83. http://dx.doi.org/10.1016/j.gexplo.2014.01.019.
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Rodrigues, Cyril G., and Gustavs Vilks. "The impact of glacial lake runoff on the goldthwait and champlain seas: The relationship between glacial lake agassiz runoff and the younger dryas." Quaternary Science Reviews 13, no. 9-10 (January 1994): 923–44. http://dx.doi.org/10.1016/0277-3791(94)90009-4.
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Zhu, Ji-Chang, Cai-Neng Zou, You-Liang Feng, Shu Jiang, Wei-An Wu, Ri-xiang Zhu, and Miao Yuan. "Distribution and controls of petroliferous plays in subtle traps within a Paleogene lacustrine sequence stratigraphic framework, Dongying Depression, Bohai Bay Basin, Eastern China." Petroleum Science 17, no. 1 (November 29, 2019): 1–22. http://dx.doi.org/10.1007/s12182-019-00387-z.
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AbstractThe characteristics of petroliferous plays in subtle traps within a sequence stratigraphic framework in the Dongying Depression are investigated in this study. Sand bodies within lowstand systems tracts (LSTs) of sequences, comprising incised-channel fills, sublacustrine fans, deltas in LSTs, controlled by syndepositional normal faults, and sand bodies within transgressive systems tracts (TSTs) to early highstand systems tracts (HSTs), consisting of beach bars, and turbidites, controlled by the prodelta slope, paleorelief, and syndepositional normal faults, are good subtle reservoirs. Mudstones and shale of deep lake subfacies in TSTs to early HSTs of sequences are source and cap rocks. Abnormal overpressure is the dominant dynamic factor for hydrocarbon migration from source rock to the subtle traps. Normal faults, sand bodies, and unconformities function as conduit systems. Sand bodies distributed in the abnormal overpressure source rocks within LSTs to early HSTs are petroliferous plays in lithologic traps. The petroliferous plays in stratigraphic traps are controlled by unconformities at margins of the Depression.
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KRÖGER, BJÖRN, and ED LANDING. "Onset of the Ordovician cephalopod radiation – evidence from the Rochdale Formation (middle Early Ordovician, Stairsian) in eastern New York." Geological Magazine 145, no. 4 (May 9, 2008): 490–520. http://dx.doi.org/10.1017/s0016756808004585.
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AbstractThe Rochdale Formation of eastern New York (= Fort Ann and lower Bascom formations, designations abandoned) is now recognized to record the earliest stages of the Great Ordovician Radiation of cephalopods. The earliest Bassleroceratidae, Tarphyceratidae and endoceridans on the east Laurentian shallow carbonate platform occur in the upper, thrombolite-bearing member of the Rochdale. This fauna demonstrates that the earliest radiation of Ordovician nautiloids took place in the late Tremadocian and is best recorded in tropical platform facies. Revision of this cephalopod fauna based on approximately 190 specimens collected along a 200 km, N–S belt in easternmost New York has provided new information on inter- and intraspecific variation of earlier described species. The ellesmerocerid Vassaroceras and the endocerids Mcqueenoceras and Paraendoceras are emended. New taxa include Bassleroceras champlainense sp. nov. and B. triangulum sp. nov., Mccluskiceras comstockense gen. et sp. nov., Exoclitendoceras rochdalense gen. et sp. nov. and Paraendoceras depressum sp. nov. A rank abundance plot of 146 specimens from a locality in the Lake Champlain lowlands provides information on the community structure of a nautiloid fauna in which the longiconic cyrtoconic Bassleroceras is shown to dominate strongly. The nautiloid community structure of the Rochdale Formation is similar to that of the underlying Tribes Hill Formation (late early Tremadocian) with respect to the depositional setting, diversity and evenness but displays a remarkably increased taxonomic distinctness.
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Kneller, B. C., L. M. King, and A. M. Bell. "Foreland basin development and tectonics on the northwest margin of eastern Avalonia." Geological Magazine 130, no. 5 (September 1993): 691–97. http://dx.doi.org/10.1017/s0016756800021002.
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AbstractThe early Palaeozoic convergence of Avalonia and Laurentia created a foreland basin at the suture zone of the former lapetus Ocean. Sedimentological and stratigraphic evidence of shallowing and contemporaneous shortening suggests that the southern part of the basin (the Windermere Group) became detached from its basement in the late Ludlow, and began to invert. The detachment beneath the basin rooted into a northwest-dipping mid-crustal thrust system. Contemporaneous uplift to the north of the late Silurian basin involved shortening of the Avalonian foreland basement by thrusting. Basin inversion occurred ahead of a southeastward-advancing mountain front. We postulate a foreland (southeast) prograding sequence of thrusting through the Ludlow in the Lake District. The basin continued to migrate onto the Avalonian foreland through the early Devonian, ahead of an advancing orogenic wedge, finally coming to a stop in the Emsian.
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Netto, Paulo R. A., Manuel Pozo, Maurício Dias da Silva, Márcia Elisa Boscato Gomes, André Mexias, Camila Wense Ramnani, Yaro Parizek-Silva, Leonardo Borghi, and Aristóteles de Moraes Rios-Netto. "Paleoenvironmental Implications of Authigenic Magnesian Clay Formation Sequences in the Barra Velha Formation (Santos Basin, Brazil)." Minerals 12, no. 2 (February 4, 2022): 200. http://dx.doi.org/10.3390/min12020200.
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The characterization of Mg-clays in rock samples (well P1) from the Barra Velha Formation (Early Cretaceous) allowed the establishment of mineral assemblages on the basis of their kerolite and Mg-smectite (stevensite and saponite) content. Kerolite-rich assemblages (A and B) rarely contain saponite. Assemblage B is composed of kerolite-stevensite mixed layers, while assemblage A consists of more than 95% kerolite. Mg-smectite-rich assemblages (C and CB) are made up of both Mg-smectites. The predominance of stevensite in the lower interval of the stratigraphic succession suggests evaporative conditions, higher salinity and pH, which would favor its authigenesis by neoformation. In the upper portion, the occurrence of thick kerolite-rich intervals suggests regular water inputs, contributing with a decreasing in salinity and pH, favoring the neoformation of kerolite and later kerolite-stevensite mixed layering. The saponite would be the result of the transformation from Al-smectite into Mg-smectite in a Mg2+ rich medium. The results indicate that lake hydrochemical processes would have allowed the establishment of a basic depositional sequence, from base to top, as follows: (i) initial lake expansion stage marked by the occurrence of saponite, (ii) later kerolite neoformation, (iii) formation of kerolite-stevensite mixed layer with increasing salinity, and (iv) neoformation of stevensite, marking a final stage of maximum salinity (evaporation) and alkalinity of the lake.
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Fahad Al-Ajmi, Hussain, Martin Keller, Matthias Hinderer, and Claudio Miro Filomena. "Lithofacies, depositional environments and stratigraphic architecture of the Wajid Group outcrops in southern Saudi Arabia." GeoArabia 20, no. 1 (January 1, 2015): 49–94. http://dx.doi.org/10.2113/geoarabia200149.
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ABSTRACT The Wajid Group is a Palaeozoic siliciclastic succession of southern Saudi Arabia. In the outcrop belt it is ca. 500 m thick, whereas in the subsurface, the thickness increases to more than 4,500 m. The siliciclastic sediments have great reservoir potential for hydrocarbons and for groundwater. Although they represent one of the most important aquifers of the Arabian Peninsula, neither their sedimentologic, lithostratigraphic, nor their reservoir characteristics are satisfactorily known. In this study, a detailed description of lithology and sedimentology is given and the Wajid Group sediments are interpreted in terms of depositional environment and facies architecture. Thirteen lithofacies (LF 1 to LF 13) have been recognised, most of them composed of different subfacies. These lithofacies are grouped into 9 lithofacies associations (LF-A1 through LF-A9). LF-A1 through LF-A3 and LF-A7 represent shallow-marine siliciclastic environments. The remaining lithofacies associations describe periglacial environments of the Hirnantian (Late Ordovician) and Permian Gondwana glaciations. Except for a few pro-glacial fluvial deposits, fluvial successions and aeolian sediments are absent in the outcrops of the Wajid Sandstone. Five formations are recognised in the Wajid Group: the Dibsiyah, Sanamah, Qalibah, Khusayyayn, and Juwayl formations. They are all separated by major unconformities. The Dibsiyah Formation represents a vast sand-sheet complex with core and margin facies formed under shallow-marine conditions. These marine conditions enabled an abundant fauna to proliferate and leave its traces in the form of Skolithos piperock and Cruziana sp. A late Cambrian to Early Ordovician age is inferred for these deposits from regional considerations. The Sanamah Formation records the Late Ordovician Hirnantian glaciation with coarse sandstones and conglomerates. A variety of glacier-induced sedimentary structures are present. The internal succession is composed of three major sediment packages reflecting three ice advance-retreat cycles. The latest of these cycles is overlain by a few metres of marginal-marine sediments of the Qalibah Formation. The Khusayyayn Formation was deposited probably during Early Devonian times. It also represents a sand-sheet environment characterised by the dominance of mega-scale and giant cross beds and bed sets. A marine depositional environment is assumed from scarce Skolithos sp., and because nearly all indicators of a braided river system are absent. The Juwayl Formation of Permian age was deposited at the interface of the Late Palaeozoic Gondwana ice shield with a large lake that may have covered most of southern Arabia and adjacent areas. Proglacial sandstones and conglomerates were deposited close to the glaciers, whereas fine-grained sediment with dropstones, boulder pavements and a wide spectrum of soft-sediment deformation are characteristic of the lake environment. While the two glacial successions and the Khusayyayn Formation can rather confidently be attributed to the geological time scale, either through seismic correlation or biostratigraphically, the Dibsiyah Formation has not yet been biostratigraphically well dated.
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Melvin, John, Brian P. Wallick, and Christian J. Heine. "Advances in Arabian stratigraphy: Allostratigraphic layering related to paleo-water table fluctuations in eolian sandstones of the Permian Unayzah A reservoir, South Haradh, Saudi Arabia." GeoArabia 15, no. 2 (April 1, 2010): 55–86. http://dx.doi.org/10.2113/geoarabia150255.
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ABSTRACT In the early stages of development of the Permian Unayzah A gas reservoir at South Haradh, difficulties in intra-reservoir wireline log correlation, poor seismic character, and the recognition of multiple gas-water contacts, necessitated a detailed (core- and image log-based) geological study of the reservoir. This study revealed that the Unayzah A can be divided into two stratal units. The lower unit has poor reservoir quality. It consists of a thin, discontinuous basal eolian dune sandstone that is abruptly overlain by up to 70 ft (21 m) of very fine-grained and silty, irregularly laminated sandstones. These sediments were deposited in a very shallow ephemeral (playa) lake setting. They terminate upwards in a thin but widespread upward-fining interval that represents the Maximum Extent of the Lake (MEL horizon). In the upper unit several facies of varying reservoir quality are recognized, representing deposits that were laid down in a “mixed” eolian depositional system. Although these facies are generally common to all of the studied wells, they vary significantly in their proportions and associations from well to well. Thus a number of depositional settings are identified, which pass southwards across the study area from erg-center, eolian dune cross-bedded sandstones in the north (“dry” eolian system) through erg margin, interbedded dune and interdune deposits to very finegrained sandstones representing ephemeral lake sediments in the south (“wet” eolian system). Depositional cycles in the upper Unayzah A interval are recognized among the facies in each well, and in every case these can be related to fluctuations in the paleo-water table. When the wells are displayed in a stratigraphic section using the MEL horizon as a datum, several of these cycles are seen to be correlatable across the study area. Significantly, these sub-regional correlations are maintained both within and between the various facies tracts. They are allostratigraphic in nature with facies distribution controlled by a number of extrinsic factors including position of the paleo-water table relative to the depositional surface, rates of fluctuation of the water table, sediment availability for eolian transportation, transporting capability of the wind and rates of subsidence. Proximity to local ephemeral stream sedimentation was probably also a factor. It may be that in the long term the pulsed nature of the rising water table in South Haradh reflects the onset of a distant, pulsed rise in sea level, possibly related to the creation of the Neo-Tethys Ocean in the southern and eastern part of the Arabian Plate. Recognition of this allostratigraphic reservoir layering clearly identifies significant stratigraphic compartmentalization within the reservoir. This permits a clearer understanding of the distribution of reservoir bodies within the Unayzah A, and explains the variable gas-water contacts in the area. This conceptual stratigraphic model has been incorporated in object-based geocellular modeling for reservoir simulation at South Haradh and also at other Unayzah A gas fields in the area. Integration with geophysical (impedance) data leads to significantly improved success rates in relation to the strategic location of wells, yielding enhanced results in reservoir development.
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Neubauer, Thomas A., Mathias Harzhauser, and Radovan Pipík. "Upper Miocene endemic lacustrine gastropod fauna of the Turiec Basin: addressing taxonomic, paleobiogeographic and stratigraphic issues." Geologica Carpathica 66, no. 2 (April 1, 2015): 139–56. http://dx.doi.org/10.1515/geoca-2015-0016.
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Abstract The present work displays the first detailed taxonomic study on the freshwater gastropod fauna of the Upper Miocene Lake Turiec. Apart from several mentions of species and genus names in the literature, the mollusc fauna has been poorly studied up to now. Some of the cited genera implied peculiar paleobiogeographic relationships, urging a taxonomic investigation to either prove or revise such arising claims. Variable degrees of preservation, however, limited the possibility to identify all the fossils at species level. The fauna includes at least ten species, of which five turned out to be new to science. Four of those were sufficiently well preserved to be described as new species, namely Viviparus pipiki Neubauer & Harzhauser nov. sp., Melanopsis glaubrechti Neubauer & Harzhauser nov. sp., Tournouerina turiecensis Neubauer & Harzhauser nov. sp., and Radix kovaci Neubauer & Harzhauser nov. sp. Additionally, the new genus Popovicia Neubauer & Harzhauser nov. gen. is introduced for the primary homonym Metohia Popović, 1964 non Absolon, 1927. Most importantly, this taxonomic study revises many of the names cited in the literature and proves most of the alleged paleobiogeographic relationships wrong. The only biogeographic and stratigraphic surprise is the record of Popovicia cf. compressa, a species described from lower Pliocene deposits of the Metohia Basin in Kosovo. The majority of the fauna, however, has only been documented for the Turiec Basin, once more confirming the high degree of its endemicity. The faunal relationships indicate a latest Middle to early Late Pannonian (Middle to Late Tortonian) age, which is in agreement with available age models.
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Manor, Matthew J., Stephen J. Piercey, Corey J. Wall, and Nikola Denisová. "High-Precision CA-ID-TIMS U-Pb Zircon Geochronology of Felsic Rocks in the Finlayson Lake VMS District, Yukon: Linking Paleozoic Basin-Scale Accumulation Rates to the Occurrence of Subseafloor Replacement-Style Mineralization." Economic Geology 117, no. 5 (August 1, 2022): 1173–201. http://dx.doi.org/10.5382/econgeo.4910.
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Abstract Felsic igneous complexes and associated volcano-sedimentary rocks in continental back-arc environments host large-tonnage and/or high-grade volcanogenic massive sulfide (VMS) deposits. The emplacement mechanisms, style, and preservation of these deposits is thought to be partially dependent on depositional rates of the host lithofacies (i.e., discrete volcanic eruptions) relative to the setting of massive sulfide genesis on the seafloor as mounds and/or via subseafloor replacement of existing strata. The localization and occurrence of subseafloor replacement-style VMS deposits is therefore strongly influenced by the characteristics of the volcano-sedimentary facies in the hosting basin and the rates of their emplacement; the latter are poorly constrained in the literature due to the difficulty of obtaining high-precision dates that make this possible in Phanerozoic and older rocks. New high-resolution U-Pb geochronology and detailed regional stratigraphic investigation indicate that Devonian-Mississippian volcanic rocks and associated VMS mineralization in the Yukon-Tanana terrane in the Finlayson Lake district, Yukon, Canada, were erupted or emplaced during distinct time periods (ca. 363.3, 362.8, and 355.2 Ma) in two discrete submarine basins: the Kudz Ze Kayah formation and the Wolverine Lake group. The VMS deposits in both settings are contained within intrabasinal rocks that accumulated at rapid rates of ~350 to 2,000 m/m.y. over 0.6 to 1.4 m.y. Locally, these rates reach peak rates up to 7,500 m/m.y. in the Wolverine Lake group, which are interpreted to reflect facies deposition by mass transport complexes or turbidity currents. These new dates indicate that rapid accumulation of volcanic rocks in the back-arc basins was critical for localizing subseafloor replacement-style mineralization and the development of the Zn-enriched GP4F, Kudz Ze Kayah, and Wolverine VMS deposits. Rapid depositional processes observed in these deposits and their host basins are interpreted to have an important role in developing highly porous and permeable, water-saturated lithofacies that provide optimal conditions for enhancing zone refining processes and subsequent preservation of massive sulfide mineralization, which are key in the development of high-grade and large-tonnage VMS deposits. It is herein suggested that quantitative basin-scale accumulation rates, as a result of new U-Pb geochronological methods and increased precision combined with detailed stratigraphic and facies analysis, may provide important perspectives on the formation of continental back-arc basins and the localization of VMS deposits in other continental margin environments globally.
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Dechesne, Marieke, Ellen D. Currano, Regan E. Dunn, Pennilyn Higgins, Joseph H. Hartman, Kevin R. Chamberlain, and Christopher S. Holm-Denoma. "A new stratigraphic framework and constraints for the position of the Paleocene–Eocene boundary in the rapidly subsiding Hanna Basin, Wyoming." Geosphere 16, no. 2 (January 16, 2020): 594–618. http://dx.doi.org/10.1130/ges02118.1.
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Abstract The Paleocene–Eocene strata of the rapidly subsiding Hanna Basin give insights in sedimentation patterns and regional paleogeography during the Laramide orogeny and across the climatic event at the Paleocene–Eocene Thermal Maximum (PETM). Abundant coalbeds and carbonaceous shales of the fluvial, paludal, and lacustrine strata of the Hanna Formation offer a different depositional setting than PETM sections described in the nearby Piceance and Bighorn Basins, and the uniquely high sediment accumulation rates give an expanded and near-complete record across this interval. Stratigraphic sections were measured for an ∼1250 m interval spanning the Paleocene–Eocene boundary across the northeastern syncline of the basin, documenting depositional changes between axial fluvial sandstones, basin margin, paludal, floodplain, and lacustrine deposits. Leaf macrofossils, palynology, mollusks, δ13C isotopes of bulk organic matter, and zircon sample locations were integrated within the stratigraphic framework and refined the position of the PETM. As observed in other basins of the same age, an interval of coarse, amalgamated sandstones occurs as a response to the PETM. Although this pulse of relatively coarser sediment appears related to climate change at the PETM, it must be noted that several very similar sandstone bodies occur with the Hanna Formation. These sandstones occur in regular intervals and have an apparent cyclic pattern; however, age control is not sufficient yet to address the origin of the cyclicity. Signs of increased ponding and lake expansion upward in the section appear to be a response to basin isolation by emerging Laramide uplifts.
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Atakul-Özdemir, Ayşe. "Paleogeographic implications of the Permian shallow marine carbonates in the eastern Lake Van region (eastern Turkey): Foraminiferal biostratigraphic and sequence stratigraphic constraints." Geological Journal 54, no. 4 (February 20, 2019): 2716–30. http://dx.doi.org/10.1002/gj.3476.
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PAZ, J. D. S., and D. F. ROSSETTI. "Linking lacustrine cycles with syn-sedimentary tectonic episodes: an example from the Codó Formation (late Aptian), northeastern Brazil." Geological Magazine 142, no. 3 (May 2005): 269–85. http://dx.doi.org/10.1017/s0016756805000488.
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The Codó Formation exposed in the eastern Grajaú Basin, northeastern Brazil, consists mostly of black shales, limestones and evaporites arranged into several shallowing-upward cycles formed by progradation of lake deposits. Three ranks of cycles are distinguished. The lower-rank cycles correspond to millimetric interbeddings of: bituminous black shales with evaporites, calcimudstones or peloidal wackestone–packstone; grey/green shale with calcimudstone, peloidal wackestone–packstone or ostracodal wackestone/grainstone; and ostracodal wackestone/grainstone and/or calcimudstones with cryptomicrobial mats and ooidal/pisoidal packstones. The intermediate-rank cycles average 1.7 m in thickness and are formed by complete and incomplete cycles. Complete cycles show a transition from central to intermediate and then to marginal facies associations and include two types: C1 cycle with central lake deposits consisting of evaporites and black shales; and C2 cycle with central lake deposits formed by grey/green shale. Complete cycles were produced by the upward gradation from central to marginal environments of the lake or saline pan–sabkha system. Incomplete cycles are those where at least one facies association is lacking, having been formed by successions either with central and intermediate facies associations (I1) or intermediate and marginal facies associations (I2). The higher-rank cycles are, on average, 5.2 m thick and consist of four depositional units that display shallowing-upward successions formed by complete and incomplete intermediate-rank cycles that vary their distribution upward in the section, and are bounded by sharp surfaces. While the lower-rank cycles display characteristics that reveal their seasonal signature, detailed sedimentological characterization and understanding of stratal stacking patterns related to the intermediate and higher-rank cycles support a genesis linked to syn-sedimentary tectonic activity. This is particularly suggested by the high facies variability, limited lateral extension, and frequent and random thickness changes of the intermediate-rank cycles. Additionally, the four higher-rank cycles recognized in the Codó Formation match with stratigraphic zones having different styles of soft-sediment deformation structures attributed to seismic activities. Therefore, the several episodes of lake shallowing recorded in the Codó Formation are linked to seismic pulses that alternated with sediment deposition. This process would have created significant changes in the lake water level and resulted in sharply bounded successions with upward gradation from deeper to relatively shallower facies associations.
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Stratton, Laurel E., and Gordon E. Grant. "Autopsy of a reservoir: Facies architecture in a multidam system, Elwha River, Washington, USA." GSA Bulletin 131, no. 11-12 (April 2, 2019): 1794–822. http://dx.doi.org/10.1130/b31959.1.
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AbstractThe 2011–2014 removal of two large dams on the Elwha River, Washington State, the largest dam removal yet completed globally, created extensive cutbank exposures of reservoir sediments, allowing the first characterization of the facies architecture of sediments through direct observation in reservoirs worldwide and providing an unparalleled opportunity to assess the relationship between environmental influences, such as changes in sediment supply, and their expression in the stratigraphic record. Using a combination of facies description from observation of 49 measured sections and >100 exposures and analysis of digital elevation models and historic aerial photographs, we delineated the characteristic depositional zones of each reservoir and mapped the evolution of the subaerial delta over the life span of the reservoir. Former Lake Mills, the younger, upstream reservoir, was characterized by a tripartite, subaerial Gilbert-style delta that prograded >1 km into the main reservoir from 1927 to 2011. Sediments were composed of coarse-grained topset beds, steeply dipping foreset beds, and a fine-grained, gently dipping prodelta. While individual event horizons were discernible in fine-grained sediments of former Lake Mills, their number and spacing did not correspond to known drawdown or flood events. Former Lake Aldwell, impounded from 1913 to 2011, was initially defined by the rapid progradation of a Gilbert-style, subaerial delta prior to the upstream completion of Glines Canyon Dam. However, the 1927 closure of Glines Canyon Dam upstream caused the delta to evolve to a fine-grained, mouth-bar–type delta indicative of low, finer-grained sediment. This evolution, combined with a previously unrecognized landslide deposit into the upper delta plain, suggests that understanding the exogenic influences on reservoir sedimentation is critical to interpretation and prediction of the sedimentation within individual systems.
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Csoma, Vivien, Imre Magyar, Andrea Szuromi-Korecz, Krisztina Sebe, Orsolya Sztanó, Krisztina Buczkó, and Emőke Tóth. "Pannonian (late Miocene) ostracod fauna from Pécs-Danitzpuszta in Southern Hungary." Földtani Közlöny 151, no. 3 (December 4, 2021): 305–26. http://dx.doi.org/10.23928/foldt.kozl.2021.151.3.305.
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The large outcrop at Pécs-Danitzpuszta, southern Hungary, exposes a 65-meter-thick succession of calcareous marls, clay marls and calcareous sands that were deposited during the early history of Lake Pannon, a vast, Caspian-type lake in Central Europe in the late Miocene. Within the framework of the complex stratigraphic investigation of this succession, well preserved, relatively diverse benthic ostracod assemblages containing 39 taxa were recovered from 29 samples (16 samples were barren). Palaeoecological interpretation of the ostracod genera suggests that deposition took place in a low-energy environment, in the shallow sublittoral zone of Lake Pannon, in pliohaline (9–16‰ salinity) water. The entire succession was divided into four interval zones based on the first occurrences of assumedly useful marker fossils: Hemicytheria lorentheyi Zone (from sample D29), Hemicytheria tenuistriata Zone (from sample D17), Propontoniella candeo Zone (from sample D115) and Amplocypris abscissa Zone (from sample D209). Based on comparison to the Beočin section 150 km to the SE, where a lithologically and stratigraphically similar section was dated magnetostratigraphically by an international team, we tentatively assume that the Pannonian marl succession of the Pécs-Danitzpuszta outcrop represents the time interval of 11.6 to ca. 10 Ma.
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Lozano, Jorge G., Alejandro Tassone, Emanuele Lodolo, Marco Menichetti, María E. Cerredo, Donaldo M. Bran, Federico Esteban, Juan P. Ormazabal, Luca Baradello, and Juan F. Vilas. "Origin and evolution of lago Yehuin (Tierra del Fuego, Argentina): Results from a geophysical survey." Andean Geology 45, no. 3 (June 6, 2018): 318. http://dx.doi.org/10.5027/andgeov45n3-3085.
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Lago Yehuin, a WNW-ESE elongated basin located in the outer fold-and-thrust belt of the Fuegian Andes, occupies a compartmented structural depression originated along a segment of the left-lateral Lago Deseado fault system. This paper describes the first geophysical survey performed within the lake. New acquired high-resolution single-channel seismic data, integrated with geological information in the surroundings of the Lago Yehuin, allowed to: (i) produce a complete bathymetric map of the lake, (ii) reconstruct the basement surface of the lake, and (iii) analyze the geometry, distribution, and thickness of the sedimentary infill. Two sub-basins were recognized within Lago Yehuin: A western sub-basin, 7.5 km long, with a maximum depth of 118 m; an eastern sub-basin, 7.2 km long with a maximum depth of 80 m. Both sub-basins are limited by a set of normal faults which overprint NE-verging thrusts. Three seismo-stratigraphic units have been identified in the seismic records: (1) a lower unit with wedged geometry interpreted as a mass flow deposits; (2) a thick (up to 120 m) intermediate unit of glacio-lacustrine nature and irregularly distributed in the Yehuin basin; (3) a thin (generally
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Li, Shuang-Qing, Song He, and Fukun Chen. "Provenance changes across the mid-Cretaceous unconformity in basins of northeastern China: Evidence for an integrated paleolake system and tectonic transformation." GSA Bulletin 133, no. 1-2 (June 1, 2020): 185–98. http://dx.doi.org/10.1130/b35660.1.
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Abstract Detrital zircon U-Pb dating and whole-rock Nd isotopic analyses were carried out on selected stratigraphic horizons across a major unconformity between synrift and postrift stages in the Songliao Basin and Dasanjiang basin group of NE China to constrain the crustal evolution of the source area providing detritus into these basins. The strata underlying the mid-Cretaceous unconformity in the Songliao Basin show regionally distinct detrital zircon age populations and Nd isotopic compositions, which generally are characterized by Phanerozoic age peaks and relatively depleted Nd isotopic compositions, indicating derivation from nearby highlands. In contrast, the overlying strata are dominated by Proterozoic zircon ages and enriched Nd isotopic compositions, which imply that the provenance source region shifted to the northern part of the North China craton. A coeval provenance change also affected the sedimentary architecture in the eastern Dasanjiang basin group, marking the migration of erosion centers from west to east. The contribution from Lesser Xing’an–Zhangguangcai ranges was pronounced during deposition of synrift strata but became negligible afterward in the Songliao and Dasanjiang areas, which is consistent with both basin complexes temporarily forming an extensive lake system during the early Late Cretaceous. This paleolake was likely responsible for transgressive events recorded in the Late Cretaceous strata of basins in NE China. Combining observations from seismic reflection profiles and the stratigraphic record of neighboring intracontinental sedimentary basins as well as widespread contemporaneous exhumation and denudation events, we suggest that the provenance variation in basin strata was controlled by large-scale tectonic transitions in East Asia. The switch from extension to contraction during the mid-Cretaceous is attributed to the docking of the Okhotomorsk block along the East Asian continental margin. The resulting lithospheric buckling might have been responsible for reshaping the basin-and-range configuration in NE Asia.
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Paulissen, Wieske, Stefan Luthi, Patrick Grunert, Stjepan Ćorić, and Mathias Harzhauser. "Integrated high-resolution stratigraphy of a Middle to Late Miocene sedimentary sequence in the central part of the Vienna Basin." Geologica Carpathica 62, no. 2 (April 1, 2011): 155–69. http://dx.doi.org/10.2478/v10096-011-0013-z.
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Integrated high-resolution stratigraphy of a Middle to Late Miocene sedimentary sequence in the central part of the Vienna BasinIn order to determine the relative contributions of tectonics and eustasy to the sedimentary infill of the Vienna Basin a high-resolution stratigraphic record of a Middle to Late Miocene sedimentary sequence was established for a well (Spannberg-21) in the central part of the Vienna Basin. The well is located on an intrabasinal high, the Spannberg Ridge, a location that is relatively protected from local depocentre shifts. Downhole magnetostratigraphic measurements and biostratigraphical analysis form the basis for the chronostratigraphic framework. Temporal gaps in the sedimentary sequence were quantified from seismic data, well correlations and high-resolution electrical borehole images. Stratigraphic control with this integrated approach was good in the Sarmatian and Pannonian, but difficult in the Badenian. The resulting sedimentation rates show an increase towards the Upper Sarmatian from 0.43 m/kyr to > 1.2 m/kyr, followed by a decrease to relatively constant values around 0.3 m/kyr in the Pannonian. The sequence reflects the creation of accommodation space during the pull-apart phase of the basin and the subsequent slowing of the tectonic activity. The retreat of the Paratethys from the North Alpine Foreland Basin during the Early Sarmatian temporarily increased the influx of coarsergrained sediment, but eventually the basin acted mostly as a by-pass zone of sediment towards the Pannonian Basin. At a finer scale, the sequence exhibits correlations with global eustasy indicators, notably during the Sarmatian, the time of greatest basin subsidence and full connectivity with the Paratethyan system. In the Pannonian the eustatic signals become weaker due to an increased isolation of the Vienna Basin from Lake Pannon.
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Schweger, Charles E., and John V. Matthews. "Early and Middle Wisconsinan Environments of Eastern Beringia: Stratigraphic and Paleoecological Implications of the Old Crow Tephra." Géographie physique et Quaternaire 39, no. 3 (December 4, 2007): 275–90. http://dx.doi.org/10.7202/032608ar.
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ABSTRACTThe widespread Beringian Old Crow tephra occurs in Imuruk Lake (Alaska) core V, above the Blake paleomagnetic event and below Radiocarbon dates, which provide an extrapolated tephra age between 87 000 - 105 000 BP. Exposure KY-11 (Alaska), where the tephra occurs in a dated lacustrine sequence, provides corroboration. Fossil pollen records show that O.C.T. was deposited across northern Beringia on birch-shrub tundra vegetation during an interval of colder climate. A series of climatic oscillations followed tephra deposition. A prolonged period of cold-arid climate ( = marine isotope Stage 4) preceded an interval of warmer than present climate starting ca. 60 000 BP (beginning Stage 3). During this interval, designated the Koy-Yukon thermal event, an exposed Bering land bridge promoted an interglacial type climate that led to significant biotic changes and permafrost degradation. O.C.T. occurs on drift of the Mirror Creek Glaciation which is equivalent to other presumed Early Wisconsinan glaciations in Alaska and Yukon. These glaciations could not have occurred later than marine Stage 5. Stage 4 was fully as cold as Stage 2 (Late Wisconsinan), yet seems not to have been a time of extensive glaciation. The Middle Wisconsinan, 30 000 to more than 80 000 BP, was a nonglacial interval with several climate fluctuations, one of which, the Koy-Yukon thermal event, was warmer than at present.
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Sweeney, Mark R., Eric V. McDonald, Lucas P. Chabela, and Paul R. Hanson. "The role of eolian-fluvial interactions and dune dams in landscape change, late Pleistocene–Holocene, Mojave Desert, USA." GSA Bulletin 132, no. 11-12 (April 2, 2020): 2318–32. http://dx.doi.org/10.1130/b35434.1.
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Abstract The formation of the Kelso Dunes in the eastern Mojave Desert, California, was a landscape-changing event triggered by an increase in sediment supply that followed the incision of Afton Canyon by the Mojave River ca. 25 ka. Eastward migration of sand dunes occurred along a well-defined eolian transport corridor. Dunes temporarily blocked washes resulting in substantial aggradation of eolian and fluvial sediments. Stratigraphic exposures reveal numerous fining-up sequences with interbedded eolian sands that provide evidence of dune dams and subsequent aggradation. Luminescence ages reveal that dune blocking and aggradation correspond to a regional pulse of alluvial fan sedimentation that occurred ca. 14–9 ka. Meanwhile, relative landscape stability occurred downstream of dune dams, resulting in the formation of a moderately developed soil on abandoned fluvial deposits. The next pulse of alluvial fan activity ca. 6–3 ka likely resulted in the breaching of the dune dams, followed by incision. Eolian system sediment state theory suggests that eolian activity in the Mojave Desert is closely tied to enhanced sediment supply, primarily related to the Mojave River–Lake Mojave system. Our data suggests that Intermittent Lake Mojave I, ca. 26–22 ka, triggered a large dune-building event that impounded massive amounts of sediment derived from alluvial fans deposited during the Pleistocene-Holocene transition. Breaching of dune dams and sediment recycling may have also increased sediment supply that contributed to late Holocene eolian activity. This profound impact on the regional geomorphology highlights the critical importance of eolian-fluvial interactions in desert environments.