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1
Teusner, Roger E. "A Original Cave Paintings on the River Marne near Eden Valley, South Australia." Mankind 6, no. 1 (May 10, 2010): 15–19. http://dx.doi.org/10.1111/j.1835-9310.1963.tb01430.x.
2
Le Jeune, Yann. "Fluvial sedimentation and hydrologic response to Holocene environmental change in the low Marne valley (Paris basin, France)." Quaternary International 279-280 (November 2012): 268–69. http://dx.doi.org/10.1016/j.quaint.2012.08.676.
3
Jaillet, Stephane, Edwige Pons-Branchu, Jacques Brulhet, and Bruno Hamelin. "Karstification as geomorphological evidence of river incision: the karst of Cousance and the Marne valley (eastern Paris Basin)." Terra Nova 16, no. 4 (August 2004): 167–72. http://dx.doi.org/10.1111/j.1365-3121.2004.00544.x.
4
Fanton, Mélanie, and Alain Marre. "Les cartes hydrogéomorphologiques en régions tempérées : l'exemple de la vallée de la Marne entre Vitry-le-François et Châlons-en-Champagne (Hydrogeomorpholocial maps in tempered regions : the case of the Marne valley between Vitry-le-François and Châlons-en-Champagne)." Bulletin de l'Association de géographes français 84, no. 1 (2007): 22–34. http://dx.doi.org/10.3406/bagf.2007.2538.
5
Rahman, Md Mostafizur, Edlic Sathiamurthy, Guangfa Zhong, Jianghua Geng, and Zhifei Liu. "Variations of fluvial patterns and infilling history of a paleoincised valley system during Late Pleistocene to Holocene, Offshore Pahang River, Peninsular Malaysia." Interpretation 6, no. 1 (February 1, 2018): T39—T50. http://dx.doi.org/10.1190/int-2016-0055.1.
Анотація:
High-resolution 2D acoustic profiles, combined with time slices from a 3D data volume, were used to investigate the paleoincised valleys offshore of the present-day Pahang River, South China Sea. Paleovalleys were formed during the regressive phase of the last glacial cycle. They were submerged and possibly filled during valley formation and postglacial marine transgression. Interpretation of acoustic profiles illustrates that the valleys were incised and infilled during the regression and low stand followed by subsequent deglacial sea-level rise. They were overlain by a transgressive ravinement surface suggesting transitional deposits between fluvial-dominated filling and shallow-marine deposition. This ravinement surface is overlain by Holocene shallow marine deposits. A low-sinuosity low-stand valley system changed to a high-sinuosity meander belt and eventually evolved into a deltaic distributary channel system before the complete submergence of the area. The average Late Pleistocene surface lies between 53 and 64 m below present-day mean sea level in the study area with approximately 16–50 m of valley incision. The Holocene shallow marine cover thickness varies from 5 to 10 m.
6
Proust, Jean-Noël, Mathieu Renault, Pol Guennoc, and Isabelle Thinon. "Sedimentary architecture of the Loire River drowned valleys of the French Atlantic shelf." Bulletin de la Société Géologique de France 181, no. 2 (March 1, 2010): 129–49. http://dx.doi.org/10.2113/gssgfbull.181.2.129.
Анотація:
Abstract The analysis of a dense grid of high resolution seismic profiles collected offshore the present day Loire River estuary indicates the presence of a thick and complex Pleistocene coastal wedge between the coast and 50 meters water depth. Most of this coastal wedge is preserved in a fossil valley network starting 10 km off the coast on the “Precontinent Breton” topographies and wedging out progressively 50 km in the offshore where the shelf flattens. This system is comprised of three main valleys 30 km long, 40–60 m deep and 0.7 to 4 km wide each, in average, with a northern valley incompletely filled by sediment. These valleys are incised into Eocene (Ypresian-Bartonian) sedimentary rocks lying unconformably on the metamorphic and magmatic rocks of the South Armorican Massif basement. The coastal wedge is comprised of six seismic units. From the base of the valleys to the seafloor, these units are successively interpreted as (1) colluvial (U1) and braided river deposits (U2), overlain by restricted marine to estuarine sediments (U3), and (2) straight to meandering fluvial deposits (U4) giving rise vertically to floodout marine sediments (U5). The whole sediment pile is capped by open marine bioturbated mudstones (U6). This succession of seismic units is organised in two depositional sequences bounded by an unconformity of regional extent, which corresponds to a drastic change in the paleovalley fill architecture. The lower sequence fills up the southern and central valleys when the upper sequence fills up the northern valley network. Both sequences are sharply truncated by a ravinement surface at the base of the offshore shales formed during the Holocene marine transgression. The correlation of the observed depth of the incisions and transgression surfaces with the global sea-level curve provides an indirect estimate of the ages of the depositional sequences. The lower sequence is probably Saalian (130–200 Ka, MIS 6) and the upper one Weischelian (110–12 Ka, MIS 2–4 and 5a–d). The ages and the infill of these valleys are very close to the ones observed in the largest paleovalleys of the inner French Atlantic shelf (Gironde, English Channel) and consistent with the sedimentary record of the continental Loire River (stepped terraces). In the later case, the Saalian period corresponds to a sharp increase on the incision of the river that shaped the morphology and determined the location of the present-day Loire valley.
7
Tesson, Michel, Caroline Labaune, Bernard Gensous, and Vincent Delhaye-Prat. "Quaternary compound incised valleys of the Roussillon coast (SE France): correlation of seismic data with core data." Bulletin de la Société Géologique de France 181, no. 2 (March 1, 2010): 183–96. http://dx.doi.org/10.2113/gssgfbull.181.2.183.
Анотація:
Abstract A detailed study of a Pliocene to Quaternary incised-valley system located under the Roussillon coastal area (Gulf of Lion) is carried out by means of a high-resolution seismic data set (coastal lagoons and adjacent shelf area), drill reports and analysis of a cored drill (Leucate SC1) performed in 2007 on the barrier beach in the North of Leucate lagoon. The lowermost surface (S100/S200), correlated with a pebbles level on the Leucate core SC1 (R0), erosionnally overlies pliocene deposits. It is incised by a thalweg 15 m depth and deepens progressively from the coastal plain to the outer shelf and dips under the Quaternary forced regressive wedges. Above this basal surface, the infilling of the incised valley corresponds to the seismic unit U1. The lower part of U1 shows continuous sub-horizontal reflectors and is correlated (Leucate SC1) to marine muds with levels of mud-supported gravels (body B). The upper part of unit U1 comprises seismic erosional reflectors that are almost amalgamated under the barrier beach. It is correlated on the Leucate well to body C comprising coarse levels (gravels and pebbles) alternating with marine muds (lower part) and marine coarse sands (upper part). The upper part of the unit is dated 12900 cal yr B.P. This unit is interpreted as resulting of successive phases of incision and infilling due to base-level changes during Pleistocene glacial and interglacial periods. Coarse levels of sand and gravel corresponding to river stages and sands and muds shelly levels representing marine stages. The overlying units represent post-glacial late transgressive (S650) and highstand (U660, U661, U662) deposits. This system is a rare example of well preserved compound incised valleys correlated offshore with Quaternary lowstand wedges. By comparison, the incised valleys along the Atlantic coast of France are “simple” incised valleys where only the last episode of incision/infilling is observable. The Quaternary “compound” incised valleys cited in the literature represent examples of the fluvial part of incised systems, whereas the Languedoc-Roussillon incised valleys probably correspond to estuary or embayment, successively reoccupied during the various Quaternary eustatic cycles. Tectonics is the main factor controlling the depositional stratigraphic architecture. The studied area is located at the hinge point between continental uplift and marine subsidence and favoured the preservation of successive phases of erosion/infilling. The geometry of the Pliocene deposits has also an impact on the shape and orientation of the buried paleovalleys.
8
Menier, David, Bernadette Tessier, Jean-Noël Proust, Agnès Baltzer, Philippe Sorrel, and Camille Traini. "The Holocene transgression as recorded by incised-valley infilling in a rocky coast context with low sediment supply (southern Brittany, western France)." Bulletin de la Société Géologique de France 181, no. 2 (March 1, 2010): 115–28. http://dx.doi.org/10.2113/gssgfbull.181.2.115.
Анотація:
Abstract A combination of morphobathymetric studies, very high-resolution seismics, core sampling and radiocarbon age data is used to investigate the latest stage of the sedimentary infilling of incised valleys in southern Brittany, related to the Holocene transgression. Owing to the bedrock morphology of this highly irregular rocky coast, two main types of valleys are defined by topographic rocky highs parallel to the coastline: 1) wide and rather shallow incised valleys offshore from a topographic sill, 2) narrow and relatively deep valleys between the sill and the coast (ria-type valley). The sedimentary infilling in both types of valleys becomes highly differentiated as the transgression advances onto the coastal area. In the wide valley seaward of the topographic sill, the infilling consists mainly of offshore heterolithic facies while, in the ria-type valley, most of the infill is composed of brackish mudflat deposits and estuarine tidal muddy sands. As the transgression proceeds, the rocky highs are flooded and the whole area is finally covered by the offshore facies. Radiocarbon dating indicates that: 1) the marine ravinement surface is highly diachronous (a few thousand years cross-shore); 2) the top of the offshore facies, coarser and very shelly, represents an episode of condensed sedimentation from about 3000 to 4000 years ago, amalgamating the maximum flooding surface (MFS) and the highstand systems tract (HST). However, we observe a muddy drape, strongly bioturbated in places, in the most proximal areas, overlying the offshore facies. It is thought to represent the modern and most recent stage of sedimentary infilling. This mud cover is made of fine-grained sediments of fluvial and biological origin, and is interpreted as a prograding HST. It reflects an increased influx, partly due to human activities. Finally, the main features of incised valley sedimentary infilling in a rocky coast context with low sediment supply can be characterized by (i) the very strong control of bedrock morphology, (ii) the diachronous character of the transgression, (iii) the late position of the MFS, and (iv), the highly reduced volume of the HST.
9
Amos, Kathryn, Carley Goodwin, and Angel Soria. "Incised valleys in marginal-lacustrine depositional environments: a new reservoir analogue from Lake Eyre, central Australia." APPEA Journal 52, no. 1 (2012): 513. http://dx.doi.org/10.1071/aj11040.
Анотація:
Incised-valley fill deposits can form important hydrocarbon reservoirs and provide pathways for hydrocarbon migration. Incised-valleys formed in marginal-marine environments are well described, however, marginal-lacustrine incised-valleys have been the focus of extremely few investigations and are poorly understood. This paper provides a new description of incised-fluvial systems that are presently constructing terminal deposits in embayments around the shoreline of Lake Eyre, central Australia. It is anticipated that better awareness of such deposits will assist in the recognition of these depositional environments in the rock record, which should be useful for exploration purposes and for the generation of improved models for continental dryland fluvial-lacustrine reservoir deposits. A classification of all significant river mouth deposits around Lake Eyre (width >300 m; n = 104), from topographic map and satellite image data, found that 54% are incised-valleys presently accreting a terminal deposit in a shoreline embayment (playa lake estuary). The depositional elements of three incised-valley systems have been mapped using satellite imagery in a GIS platform, from which element geometries are described. Controls on incised-valley formation are investigated by comparing these observations with evidence for past lake highstands and neotectonics and observations from satellite images, geological map data, and digital elevation model data. The terminal splay deposits of rivers around Lake Eyre are well-used analogues for dryland reservoirs; however, the focus has been on deposits accreting directly onto the playa. It is likely the incised-valleys and terminal deposits in the embayments described here will be of interest to companies exploring in, and producing from, ancient drylands and other lacustrine depositional environments.
10
Williamson, B. R., K. J. Kreutz, P. A. Mayewski, N. A. N. Bertler, S. Sneed, M. Handley, and D. Introne. "A coastal transect of McMurdo Dry Valleys (Antarctica) snow and firn: marine and terrestrial influences on glaciochemistry." Journal of Glaciology 53, no. 183 (2007): 681–93. http://dx.doi.org/10.3189/002214307784409225.
Анотація:
Samples of snow and firn from accumulation zones on Clark, Commonwealth, Blue and Victoria Upper Glaciers in the McMurdo Dry Valleys (∼77–78º S, 161–164º E), Antarctica, are evaluated chemically and isotopically to determine the relative importance of local (site-specific) factors vs regional-scale influences in defining glaciochemistry. Spatial variation in snow and firn chemistry confirms documented trends within individual valleys regarding major-ion deposition relative to elevation and to distance from the coast. Sodium and methylsulfonate (MS–), for example, follow a decreasing gradient with distance from the coast along the axis of Victoria Valley (350–119 µg L−1 for Na+; 33–14 µg L−1 for MS–); a similar pattern exists between Commonwealth and Newall Glaciers in the Asgaard Range. When comparing major-ion concentrations (e.g. Na+, MS−, Ca2+) or trace metals (e.g. Al, Fe) among different valleys, however, site-specific exposures to marine and local terrestrial chemical sources play a dominant role. Because chemical signals at all sites respond to particulates with varying mixtures of marine and terrestrial sources, each of these influences on site glaciochemistry must be considered when drawing temporal climate inferences on regional scales.
11
Conti, Luis Américo, and Valdenir Veronese Furtado. "Topographic registers of paleo-valleys on the southeastern Brazilian continental shelf." Brazilian Journal of Oceanography 57, no. 2 (June 2009): 113–21. http://dx.doi.org/10.1590/s1679-87592009000200004.
Анотація:
The evolution of paleo-incised-valleys in the São Paulo State region of the southeastern Brazilian continental shelf is presented in this study in relation to the post Last Glacial Maximum (LGM) sea-level rises based on the submarine topography modeled by a detailed Digital Elevation Model and evidences noted in high resolution seismic profiles. The hypothesis that has guided this study is that the set of paleo-valley characteristics (i.e. the fluvial parameters of modern coastal drainage systems, the topographical shape and dimensions of the valleys and of the subsurface channels) may indicate aspects of the relation between the influence of the fluvial and the eustatic variation regime in geomorphological-stratigraphic registers. Models described in the literature sustain the view that faster marine transgressions tend to increase erosion in estuaries, which may explain the lack of registers of paleo-drainage both in topography and the sub-surface in areas with wider shelves. On the other hand, on narrower shelves, with a higher slope angle, the transgression process can preserve, or even enhance, the incised valley registers during shoreface retreat. In the area studied, we observed that the dimensions and form of the continental shelf varies from the northern to the southern part of the area, affecting aspects of the geomorphological registers of the submerged incised valleys.
12
Schweinsberg, Avriel D., Jason P. Briner, Joseph M. Licciardi, Ralph R. Shroba, and Eric M. Leonard. "Cosmogenic 10Be exposure dating of Bull Lake and Pinedale moraine sequences in the upper Arkansas River valley, Colorado Rocky Mountains, USA." Quaternary Research 97 (April 27, 2020): 125–39. http://dx.doi.org/10.1017/qua.2020.21.
Анотація:
AbstractMany formerly glaciated valleys in the western United States preserve detailed glacial features that span the penultimate glaciation through the last deglaciation; however, numerical age control is limited in many of these systems. We report 35 new cosmogenic 10Be surface exposure ages of moraine boulders in the Sawatch Range, Colorado. Eight ages suggest Bull Lake moraines in Lake Creek (range: 132–120 ka, n = 4) and Clear Creek (range: 187–133 ka, n = 4) valleys may correlate with Marine Isotope Stage 6. In Lake Creek valley, 22 10Be ages from Pinedale end moraines average 20.6 ± 0.6 ka, and 5 10Be ages from a recessional moraine average 15.6 ± 0.7 ka, indicating that glaciers occupied two extended positions at ~21–20 and ~16 ka. The glacial extent dated to ~16 ka was nearly as great as that of the earlier glacial phase, suggesting that climate conditions in the Colorado Rocky Mountains at this time were similar to those of the last glacial maximum. Combining these moraine ages with seven previously published 10Be ages from cirque and valley-bottom bedrock reveals that the Lake Creek paleoglacier lost 82% of its full glacial length in ~1.5 ka and was completely deglaciated by ~14 ka.
13
Perkins, Edward J., Andrew R. Gorman, Emily J. Tidey, Gary S. Wilson, Christian Ohneiser, Christopher M. Moy, Christina R. Riesselman, Greer Gilmer, and Ben S. Ross. "High-resolution seismic imaging reveals infill history of a submerged Quaternary fjord system in the subantarctic Auckland Islands, New Zealand." Quaternary Research 93 (October 28, 2019): 255–66. http://dx.doi.org/10.1017/qua.2019.58.
Анотація:
AbstractQuaternary processes and environmental changes are often difficult to assess in remote subantarctic islands due to high surface erosion rates and overprinting of sedimentary products in locations that can be a challenge to access. We present a set of high-resolution, multichannel seismic lines and complementary multibeam bathymetry collected off the eastern (leeward) side of the subantarctic Auckland Islands, about 465 km south of New Zealand's South Island. These data constrain the erosive and depositional history of the island group, and they reveal an extensive system of sediment-filled valleys that extend offshore to depths that exceed glacial low-stand sea level. Although shallow, marine, U-shaped valleys and moraines are imaged, the rugged offshore geomorphology of the paleovalley floors and the stratigraphy of infill sediments suggests that the valley floors were shaped by submarine fluvial erosion, and subsequently filled by lacustrine, fjord, and fluvial sedimentary processes.
14
DeMaria, Alfred T. "Campaign Targets Silicon Valley Companies as Joint Employers." Management Report for Nonunion Organizations 38, no. 12 (November 18, 2015): 3–4. http://dx.doi.org/10.1002/mare.30120.
15
Bednarski, Jan. "Glacial advances and stratigraphy in Otto Fiord and adjacent areas, Ellesmere Island, Northwest Territories." Canadian Journal of Earth Sciences 32, no. 1 (January 1, 1995): 52–64. http://dx.doi.org/10.1139/e95-006.
Анотація:
Hvitland and Svartfjeld peninsulas have been glaciated at least two or three times since the Late Pliocene. The earliest recognized glaciation is constrained by amino acid ratios on in situ pelecypods from marine sediments stratigraphically overlying till in Otto Fiord. High amino acid ratios suggest that the shells may be Pliocene and related to recently discovered Late Pliocene Hvitland beds at White Point. The same samples yielded finite radiocarbon ages in the 30.2–34.8 ka BP range, which cautions against their acceptance. A second, mid Quaternary glaciation is suggested by intermediate amino acid ratios from in situ pelecypods and shell-bearing till covering coastal uplands along Nansen Sound. During the last glaciation the peninsula was covered by coalesced ice caps, with glacial tongues descending tributary valleys and extending into the fiords. Deglaciation of a tributary valley in outer Otto Fiord proceeded before 11.6 ka BP and before 9.1 ka BP in mid Otto Fiord, but major ice margins remained at the coast until 8–8.5 ka BP. Lateral meltwater channels record systematic ice retreat up tributary valleys into the interior of the peninsulas. The highest recognized marine limits are marked by prominent deltas at least 164 m asl on western Hvitland Peninsula. The marine limit declines eastward inside Otto, Jugeborg, and Hare fiords. The highest strandlines could not be dated; however, by ~8.3 ka BP relative sea level stood at 103 m asl.
16
Arce-Chamorro, Carlos, Juan Ramón Vidal-Romaní, and Jorge Sanjurjo-Sánchez. "New Model of Coastal Evolution in the Ria de Vigo (NW Spain) from MIS2 to Present Day Based on the Aeolian Sedimentary Record." Journal of Marine Science and Engineering 10, no. 10 (September 22, 2022): 1350. http://dx.doi.org/10.3390/jmse10101350.
Анотація:
Galician Rias are fluvial valleys that were flooded during the last marine transgression in the Atlantic margin. The study of fossil dunes in the Cies Islands, a small archipelago in the mouth of the one of the rias (Ria de Vigo), allowed us to reconstruct the coastal evolution from the end of the Late Pleistocene to the present day. During this period, sea-level was 100 metres below the present one and the shoreline located about 5–10 kilometres away. About 15,000 years ago, sea-level rise began, radically modifying the coastline. This started with a gradual advance of large dune fields on both sides of the valley. The aeolian accretion continued until the Late Holocene, finishing when the sea reached its present level.
17
Salomonsen, Inger. "Origin of a deep buried valley system in Pleistocene deposits of the eastern central North Sea." Danmarks Geologiske Undersøgelse Serie C 12 (December 31, 1995): 7–19. http://dx.doi.org/10.34194/seriec.v12.7106.
Анотація:
In the North Sea, the sedimentary development of the late Tertiary and early Quaternary was dominated by deltaic sedimentation in a fast subsiding basin. During the Pleistocene, pronounced climatic changes affected the sedimentation of the area and progradation of the delta systems ceased. The Middle and Upper Pleistocene sedimentary successions consist of alternations of marine and fluvial deposits, partly reworked during glacial periods. Seismic records from the Danish sector of the North Sea reveal numerous deep incisions cut down from various levels of the Middle and Upper Pleistocene successions. These incisions are concluded to form a pattern of buried valleys. Detailed seismic stratigraphic analysis shows the occurrence of various internal unconformities within these buried valleys. It is concluded that the valleys originate from a river system developed in periods of repeated sea-level changes. Pluvial erosion during glacial sea-level lowstand and glacial meltwater action is proposed to have been responsible for the origin of the valley system. Thus, in Middle and Upper Pleistocene glacial periods drainage and associated sediment transport occurred from Northwest and Central European land areas via a presently buried river system in the southeastern North Sea towards a depositional basin north and northwest of the Danish North Sea sector.
18
Plint, A. Guy. "Clastic Sediment Partitioning in a Cretaceous Delta System, Western Canada: Responses to Tectonic and Sea-Level Controls." Geologia Croatica 56, no. 1 (2003): 39–68. http://dx.doi.org/10.4154/gc.2003.03.
Анотація:
The early–mid Cenomanian Dunvegan Formation represents a largedelta complex that prograded at least 400 km from NW to SE. Aregional stratigraphy based on marine transgressive surfaces andequivalent subaerial interfluves allows the formation to be subdividedinto ten transgressive–regressive allomembers, labelled J to A inascending order, each with an average duration of < 200 ky. Analysisof stacking patterns and facies distributions of parasequenceswithin allomembers allows transgressive, highstand, falling stageand lowstand systems tracts to be identified. Extensive valley systemsthat average 1–2 km wide and 21 m deep can be traced for up to320 km across the top surfaces of allomembers H to E. In their lower20–40 km, valleys are filled with muddy heterolithic tidal facies butthis changes to fluvial-dominated multi-storey channel-fills furtherup-valley. Interfluve surfaces are marked by palaeosols, the characterof which indicate a protracted hiatus with extensive physical, chemicaland biological modification of the parent material.Changes in flexural subsidence rate are indicated by isopach patterns.Allomembers J–F have a sigmoidal prismatic geometry, successivelyofflapping to the SE. There is no evidence of thickening towardthe orogen. In contrast, overlying allomembers E–A show progressivedevelopment of a depocentre along the western margin of the basin.The increasing accommodation rate on the updip coastal plain causedmarine deltas to be starved of sediment, leading to progressive backstepof shorelines. Simultaneously, alluvial deposits within the depocentreshow an upward increase in the proportion of subaqueous tosubaerial facies, culminating in the incursion of brackish and finallymarine waters. Thus tectonic subsidence rate had a first-order affecton both the volume of sediment available to build marine deltas andalso on the local character of facies that accumulated on the coastalplain. The onset of flexural subsidence in allomember E appears tohave resulted in subtle uplift of a forebulge, resulting in dramaticdeflection of river systems.Despite the clear tectonic signature, successive transgressions andregressions involved similar horizontal displacements of the shoreline,regardless of subsidence rate. This suggests that modest eustaticchanges also influenced the accommodation available. Based on themeasured horizontal excursions of the shoreline, the vertical thicknessof alluvial strata, and realistic alluvial gradients, an average eustaticexcursion of about 24 m is calculated. The incision of valley systemsis attributed in part to periods of eustatic fall. However, valleys seemtoo long to be explained by eustasy alone, and hence secular changesin discharge are postulated as an additional forcing factor. Climaticcycles in the Milankovitch band may have been responsible for botheustatic and discharge variations.
19
Banerjee, Indranil, Santosh K. Ghosh, Hugh J. Abercrombie, and Edward H. Davies. "An integrated subsurface study of the Mannville–Colorado group boundary in the Cessford Field, Alberta." Canadian Journal of Earth Sciences 31, no. 3 (March 1, 1994): 489–504. http://dx.doi.org/10.1139/e94-044.
Анотація:
The stratigraphic boundary separating the Mannville and the Colorado groups in Alberta, occupying incised valleys cut within the Upper Mannville strata, has previously been interpreted as an unconformity recording post-Mannville erosion followed by a late Albian marine transgression initiated by the deposition of the Joli Fou Shale and locally by the Basal Colorado Sandstone (both of the Colorado Group). Sedimentology, paleontology, organic and inorganic geochemistry, mineralogy, and petrography of strata above and below the unconformity or the sequence boundary have been studied in 106 samples from 37 wells within the Cessford Field covering an area of 3600 km2. Cores through the boundary show a distinct physical break represented by a scoured surface overlain by basal conglomerates. Paleontological data, based on dinoflagellates and foraminifers, show establishment of restricted marine conditions in the Basal Colorado times (initial transgression) and onset of open marine condition (maximum flooding) during the Joli Fou times. Although paleosol horizons have not been found near the boundary, influence of meteoric water in the Upper Mannville sandstones is inferred from development of spherulitic siderite and extensive early kaolinization of the feldspar, mica, and lithic grains. The absence of paleosol or fluvial strata within the incised valley fills suggests that the subaerial unconformity was modified by tidal erosion during the Joli Fou transgression.
20
Devi, Salam Ranjeeta. "Weathering and Source Rock Characteristics of the Upper Disang Sedimentary Rock of the Indo-Myanmar Ranges, NE India." Journal of The Indian Association of Sedimentologists 39, no. 1 (June 30, 2022): 86–95. http://dx.doi.org/10.51710/jias.v39i1.232.
Анотація:
The Eocene Disang Group occupies a vast area of Manipur and extends in parts of Tista and Tirap valley in Arunachal Pradesh, Nagaland Hills, and small portions of North Cachar Hills (Assam) and continues up to Chin Ranges of Myanmar Ranges. The Disang Group is characterized by a group of monotonous sequences of dark grey to black splintery shales and has intercalation of siltstones and light to brownish grey, fine- to medium-grained sandstones of especially in the upper horizons, occasionally giving rise to rhythmic character. ICV vs. CIA, K2O/Na2O vs. Fe2O3+MgO and TiO2 vs. Al2O3 diagrams reveal that sediments from the Tista and Tirap river valleys in Arunachal Pradesh and towards the central portion of the Naga Hills in Nagaland are more weathered and recycled than sediments from the study area (most of Imphal valley or Manipur valley in Manipur). The sediments for the study area were dominantly derived from the unweathered rising Indo-Myanmar Ranges. The pre-Himalayan rocks might have been supplied sediments for the Disang Group. Sediments were also possibly derived from the uplifted fold thrust belt of Myanmar’s landmass comprising of igneous and metamorphic basement complex with older sedimentary sequences with minor contributions of detritus from Mishmi Hills region lying to the NE of the Arunachal Pradesh. The Disang sediments were deposited in different sedimentary environments from tidal flat to nearshore lagoon and neritic shallow marine environment and different in composition might have been related to variation in source rock for these sediments which was deposited in the Indo-Myanmar basin formed by rifting and crustal stretching on the continental margin of the Myanmar landmass.
21
Dedova, Irina. "Landscape and Geomorphological Features of Ravine Systems Developed in Sand Deposits of the Southern Part of the Volga Upland." Natural Systems and Resources, no. 1 (July 2020): 49–56. http://dx.doi.org/10.15688/nsr.jvolsu.2020.1.6.
Анотація:
The article deals with the morphological features of the profile and slopes of ravine systems developed in sand deposits of the southern part of the Volga Upland. The author notes that the southern part of the Volga Upland is a vast inter-river space bounded by the river valleys of the Don and the lower reaches of the Ilovlya river in the west and the Volga river and Volgograd reservoir in the east. This area has a potential for water and wind erosion. This is determined by the features of the geological structure (the development of Cenozoic Eocene-Oligocene marine deposits represented by alternating layers of clays, siltstones, sandstones and sands and Neogene-Quaternary sand-loam covers), as well as hilly type of terrain. The density of the erosion net here is 0.8–1.0 km/km2. The ravine and river valleys of the territory under consideration are typified by the age and morphological criteria into 4 types: middle and late Pliocene valleys of the Don drainage basin; Pleistocene valleys of widespread distribution; late Pleistocene valleys of the Don drainage basin; modern Holocene erosional forms. Broad floodplains with sandy loam alluvium, flattened valley slopes, and trough-shaped cross-sections are noted as common features of the structure of ravine and river valleys. The role of deflation and water erosion in the evolution of the slope microrelief of erosion forms is analyzed. The role of ravine systems in the formation of natural-territorial complexes of psammophytic steppes with a significant share of rare plant species, as well as the spread of bayrachny forest in the dry-steppe zone is noted. The predominant role of such natural-territorial complexes as psammophytic sagebrush-cereal sparse steppes on the sodsandy soils of the Don above-floodplain terraces; sparse dry sheep fescue and white artemisia steppe on the light mechanical composition of the soils of the Ergeninsk sands on the ravine slopes is noted. Among the intrazonal natural-territorial complexes, ravine and floodplain poplar-oak and old-growth aspen-poplar forests are distinguished.
22
Clague, John J. "Delaciation of the Prince Rupert – Kitimat area, British Columbia." Canadian Journal of Earth Sciences 22, no. 2 (February 1, 1985): 256–65. http://dx.doi.org/10.1139/e85-022.
Анотація:
Late Wisconsinan sediments in the Prince Rupert – Kitimat area of west-central British Columbia were deposited in an isostatically depressed marine environment affected by grounded tidewater glaciers. The most common sediments are (1) massive, bedded, and laminated muds, and (2) stratified sand and gravel. The former are accumulations of clay- and silt-size detritus transported in suspension from the mouths of meltwater streams and possibly in turbidity flows generated by submarine slope failures. The muds locally contain scattered ice-rafted stones, fossil marine molluscs, and foraminifera. The main sand and gravel deposits are elevated deltas, including both small incised fan-shaped forms at the margins of the main valleys and enormous ice-contact delta–sandur complexes on the floor of Kitsumkalum–Kitimat trough, the largest valley in the study area.Delaciation occurred by downwasting and complex frontal retreat between about 13 000 and 10 000 BP. The open outer coast became ice free first, in response to wholesale destabilization of the western periphery of the Cordilleran ice sheet by eustatically rising seas. Glaciers retreated rapidly by calving and soon were confined to fjords and mountain valleys; thereafter, they receded more slowly. The distribution of glaciomarine mud and raised deltaic deposits in Kitsumkalum–Kitimat trough indicates that retreat there was nonuniform, with intervals of catastrophic retreat separated by periods during which glacier snouts were relatively stable.Delaciation was accompanied and followed by rapid isostatic uplift. In Kitsumkalum–Kitimat trough, shorelines fell from about 200 m elevation at 10 500 BP to present sea level at about 8000 BP; about half of this fall occurred in perhaps as little as 500 years.
23
Rotem, Dotan, Vladimir Lyakhovsky, Hanne Hvidtfeldt Christiansen, Yehudit Harlavan, and Yishai Weinstein. "Permafrost saline water and Early to mid-Holocene permafrost aggradation in Svalbard." Cryosphere 17, no. 8 (August 21, 2023): 3363–81. http://dx.doi.org/10.5194/tc-17-3363-2023.
Анотація:
Abstract. Deglaciation in Svalbard was followed by seawater ingression and deposition of marine (deltaic) sediments in fjord valleys, while elastic rebound resulted in fast land uplift and the exposure of these sediments to the atmosphere, whereby the formation of epigenetic permafrost was initiated. This was then followed by the accumulation of aeolian sediments, with syngenetic permafrost formation. Permafrost was studied in the eastern Adventdalen valley, Svalbard, 3–4 km from the maximum up-valley reach of post-deglaciation seawater ingression, and its ground ice was analysed for its chemistry. While ground ice in the syngenetic part is basically fresh, the epigenetic part has a frozen freshwater–saline water interface (FSI), with chloride concentrations increasing from the top of the epigenetic part (at 5.5 m depth) to about 15 % that of seawater at 11 m depth. We applied a one-dimensional freezing model to examine the rate of top-down permafrost formation, which could be accommodated by the observed frozen FSI. The model examined permafrost development under different scenarios of mean average air temperature, water freezing temperature and degree of pore-water freezing. We found that even at the relatively high air temperatures of the Early to mid-Holocene, permafrost could aggrade quite fast down to 20 to 37 m (the whole sediment fill of 25 m at this location) within 200 years. This, in turn, allowed freezing and preservation of the freshwater–saline water interface despite the relatively fast rebound rate, which apparently resulted in an increase in topographic gradients toward the sea. The permafrost aggradation rate could also be enhanced due to non-complete pore-water freezing. We conclude that freezing must have started immediately after the exposure of the marine sediment to atmospheric conditions.
24
Riedel, Jon L., John J. Clague, and Brent C. Ward. "Timing and extent of early marine oxygen isotope stage 2 alpine glaciation in Skagit Valley, Washington." Quaternary Research 73, no. 2 (March 2010): 313–23. http://dx.doi.org/10.1016/j.yqres.2009.10.004.
Анотація:
Twenty-two new radiocarbon ages from Skagit valley provide a detailed chronology of alpine glaciation during the Evans Creek stade of the Fraser Glaciation (early marine oxygen isotope stage (MIS) 2) in the Cascade Range, Washington State. Sediments at sites near Concrete, Washington, record two advances of the Baker valley glacier between ca. 30.3 and 19.5 cal ka BP, with an intervening period of glacier recession about 24.9 cal ka BP. The Baker valley glacier dammed lower Skagit valley, creating glacial Lake Concrete, which discharged around the ice dam along Finney Creek, or south into the Sauk valley. Sediments along the shores of Ross Lake in upper Skagit valley accumulated in glacial Lake Skymo after ca. 28.7 cal ka BP behind a glacier flowing out of Big Beaver valley. Horizontally laminated silt and bedded sand and gravel up to 20 m thick record as much as 8000 yr of deposition in these glacially dammed lakes. The data indicate that alpine glaciers in Skagit valley were far less extensive than previously thought. Alpine glaciers remained in advanced positions for much of the Evans Creek stade, which may have ended as early as 20.8 cal ka BP.
25
Hooke, Roger LeBaron, and Paul R. Hanson. "Late- and Post-glacial history of the East Branch of the Penobscot River, Maine, USA." Atlantic Geology 53 (October 2, 2017): 285–300. http://dx.doi.org/10.4138/atlgeol.2017.012.
Анотація:
Between ~20 and 15 ka the Laurentide Ice Sheet retreated from the edge of the continental shelf, ἀrst to the Maine coast and then across Maine to the northern reaches of the Penobscot Lowland. The Lowland, being isostatically depressed, was inundated by the sea. As ice then retreated into Maine’s western mountains, valleys through the mountains became estuaries. In the estuary now occupied by the Penobscot River’s East Branch, ten ice-marginal deltas were built during pauses in this part of the retreat. By 14 ka the ice had retreated far enough to expose land in the valley bottom between the ice front and the sea, and the Penobscot River was (re)born. This occurred near the present conᴀuence of the Seboeis River and the East Branch. The river gradually extended itself northward as the ice retreated and southward as relative sea level fell. Braidplains were formed and incised, leaving terraces. High initial discharges eroded the eastern ᴀanks of the esker and deltas, redepositing silt, sand, and gravel all the way to the present head of Penobscot Bay. By ~10 ka the discharge had decreased, the river was adjusting to on-going differential isostatic rebound, and finer sediment was accumulating, forming the present floodplain.
26
Verbeek, J. W., C. S. de Leeuw, N. Parker, and Th E. Wong. "Characterisation and correlation of Tertiary seismostratigraphic units in the Roer Valley Graben." Netherlands Journal of Geosciences - Geologie en Mijnbouw 81, no. 2 (August 2002): 159–66. http://dx.doi.org/10.1017/s0016774600022393.
Анотація:
AbstractWithin the Cenozoic sedimentary section of the Roer Valley Graben ten seismostratigraphic units have been identified. They are closely related to the lithological framework which makes it possible to recognize diem also on well logs in this region. The Lower Tertiary seismic units, representing mainly marine sediments, have a uniform development mat can be correlated over large distances into the German part of the Roer Valley Graben. The marine to continental Upper Tertiary and Quaternary seismic units display a more complex development due to lateral facies changes (including prograding delta systems) and rift tectonics.
27
Wardlaw, Bruce R., Dora M. Gallegos, Valery V. Chernykh, and Walter S. Snyder. "Early Permian conodont fauna and stratigraphy of the Garden Valley Formation, Eureka County, Nevada." Micropaleontology 61, no. 4-5 (2015): 369–87. http://dx.doi.org/10.47894/mpal.61.4.07.
Анотація:
The lower part of the Garden Valley Formation yields two distinct conodont faunas. One of late Asselian age dominated by Mesogondolella and Streptognathodus and one of Artinskian age dominated by Sweetognathus with Mesogondolella. The Asselian fauna contains the same species as those found in the type area of the Asselian in the southern Urals including Mesogondolella dentiseparata, described for the first time outside of the Urals. Apparatuses for Sweetognathus whitei, Diplognathodus stevensi, and Idioprioniodus sp. are described. The Garden Valley Formation represents a marine pro-delta basin and platform, and marine and shore fan delta complex deposition. The fan-delta complex was most likely deposited from late Artinskian to late Wordian. The Garden Valley Formation records tremendous swings in depositional setting from shallow-water to basin to shore.
28
Spötl, Christoph, and Augusto Mangini. "U/Th age constraints on the absence of ice in the central Inn Valley (eastern Alps, Austria) during Marine Isotope Stages 5c to 5a." Quaternary Research 66, no. 1 (July 2006): 167–75. http://dx.doi.org/10.1016/j.yqres.2006.03.002.
Анотація:
AbstractCalcitic flowstones are present in fractures of a Pleistocene breccia near Innsbruck, Austria, and record periods of carbonate precipitation in the unsaturated zone between 101,500 ± 1500 and 70,300 ± 1800 yr, constrained by U-series disequilibrium dates. The occurrence of these speleothems, their low carbon isotopic composition, and the lack of infiltrated siliciclastic material demonstrate that the central Inn valley – which harbored one of the most extensive valley glaciers during the last glacial maximum – was ice-free during Marine Isotope Stages 5c to 5a. Climatically warm periods are separated by distinct drops in the oxygen isotopic composition of the speleothem calcite, attributed to strong and possibly seasonally biased atmospheric cooling. During these intervening stadials, which mirror those identified in the Greenland ice cores and marine sea-surface temperature records, calcite deposition apparently came to a halt, but the Inn Valley remained ice-free. The youngest calcite layer formed between ∼74,000 and ∼70,000 yr and places a maximum age limit on the likely expansion of alpine glaciers during the Marine Isotope Stage 5/4 transition, consistent with other speleothem records.
29
A.O., Ola-Buraimo, Oladimeji R.G., and Faruk A.K. "Palynology, Paleoenvironment and Stratigraphy Relationship of Tungan Buzu Hill with Adjacent Valley Gwandu Formation, Sokoto Basin, Northwestern Nigeria." African Journal of Environment and Natural Science Research 5, no. 2 (October 3, 2022): 15–26. http://dx.doi.org/10.52589/ajensr-snp4ujwp.
Анотація:
Palynological study of Tungu Buzum Hill was investigated with a view towards determining the age of the outcrop, compare its miospore content with the adjacent Tungu Buzu Valley of carbonaceous shale, their stratigraphic relationship and paleoenvironment of deposition of the litho-sequence. Field study involved litho-description and logging achieved by noting the rock type, mineralogical composition, bed thickness, texture, sorting, roundness, structure, fossil content and diagenetic effect. Palynological slide preparation involved decarbonisation, digestion, sieving, maceral separation using zinc bromide, mounting on slide and petrographic analysis. The litho-sequence is composed sequentially upward of claystone, siltstone, indurated silty claystone, mudstone and ferruginized ironstone characterized by loadcast, fracture, lithification and bioturbation. Palynologically, the litho-section exhibits few marker forms such as Belskipollis elegans, Peregrinipollis nigericus and Retibrevitricolporites obodoensis depictive of early Miocene age. The paleoenvironment was deduced based on the occurrence of peridinacean forms such as Andalusiella sp., Senegalinium sp., Lejeuncysta diversiforma and Paleocystodinium golzowense indicative of marginal marine, while deeper marginal marine forms of gonyaulacacean phytoplanktons present are Micrhystridium sp., Canningia capillata and Dinogymnium sp. There are similarities in palynomorph assemblages of this study and Tunga Buzu Valley section in terms of age and similarity to Gwandu Formation though varied in paleoenvironment in the valley litho-section, marked by continental to marginal marine settings. Field relationship suggests that the Tunga Buzu Hill is stratigraphically overlying the Tunga Buzu Valley, separated by a fault. The Tunga Buzu Hill section represents the footwall while the Tunga Buzu Valley is situated within the hanging wall of a normal fault structure.
30
Lebbe, Luc, Devlin Depret, Jasper Claus, and Gert Jan Devriese. "Salt water intrusion in the breakthrough valley of the river Aa between the Flemish coastal plain and the Saint Omer basin (France)." E3S Web of Conferences 54 (2018): 00017. http://dx.doi.org/10.1051/e3sconf/20185400017.
Анотація:
The salinity distribution in a breakthrough valley has been studied based on field observations and using a numerical model. The studied valley is located in Northern France between the Saint Omer basin and the Flemish coastal plain. The field campaign starts with the installation of observation wells. In these observations wells the electrical conductivity is logged versus depth with an electro-magnetic device. These wells also allow the necessary measurements to deduce the fresh water heads. Some of the wells are used for the performance of a pumping test. The lateral variation of the electrical conductivity of the water in the drainage canals is measured. With a numerical model the evolution of the flow and distribution of the fresh and salt water are simulated. Two simulations are made with the same schematization of the groundwater reservoir consisting of quaternary marine sediments, silt and clay and with the same hydraulic and solute parameters and boundary conditions but with two different initial salinity distributions. The results of both simulations show that the salinity distribution in the quaternary marine sediments depends not only on the lateral variation of the watertable but also on the shape of the incision of the palaeo-valley into the clay of Ypresian age. The salinity distribution in the lower part of the quaternary marine sediments depends first and foremost on the shape of the incision of the palaeo-valley into the clay of Ypresian age whereas the salinity distribution in the upper part of the quaternary marine sediments depends first and foremost on the lateral variation of the watertable.
31
Papenmeier, Svenja, and H. Christian Hass. "Revisiting the Paleo Elbe Valley: Reconstruction of the Holocene, Sedimentary Development on Basis of High-Resolution Grain Size Data and Shallow Seismics." Geosciences 10, no. 12 (December 18, 2020): 505. http://dx.doi.org/10.3390/geosciences10120505.
Анотація:
The Paleo Elbe Valley is the most prominent subsurface structure in the southern North Sea. During the Weichselian (marine isotope stage (MIS) 2), the valley traversed the exposed sea floor and drained the southern margin of the Scandinavian ice sheet. Today the valley is filled with up to 16 m thick sediments, but the responsible processes and drivers remain unknown. To unravel these processes and describe the valley’s evolution with Holocene transgression, we use shallow seismic data and vertical high-resolution grain-size core data. At the base of the western shore, supralittoral fine sands are overlain by a thin layer of clay dated to 9.8 cal. ka BP. The major sediment package consists of marine silt with internal seismic reflectors inclined in a northeastern direction, indicating a sediment transport from the southwest. The valley infill started when the western shore was flooded around 9.6 cal. ka BP and can be divided into two phases. During the first one (9.6–8.1 cal. ka BP) the sedimentation rate was highly driven by wind and waves. The second phase (8.1–5.0 cal. ka BP) was mainly tidal dominated but shows also storm event deposits in the north. Around 5.0 cal. ka BP the valley was almost filled.
32
McMenamin, Mark A. S. "Early Carboniferous Ostracods (Crustacea) from Death Valley, California, USA." Geosciences 12, no. 8 (August 3, 2022): 300. http://dx.doi.org/10.3390/geosciences12080300.
Анотація:
Silicified ostracods from the Tin Mountain Limestone provide new information regarding the Carboniferous paleontology of the Death Valley Region, California, USA. Acid maceration of marine limestones yielded the following ostracods: Acratia spp., Bairdia quasilecta, Bairdia sp. cf. B. orientalis, Ceratobairdia sp., Kirkbya panamintensis sp. nov., Rectobairdia sp. cf. R. legumen, and Silenites sp. This is the first report of Ceratobairdia and Silenites from the Tin Mountain Limestone. These ostracods occupied a carbonate ramp environment that formed during a major Paleozoic transgression. The ostracods played an important paleoecological role, likely as benthic marine scavengers in a shallow marine biotope along the northern shores of Pangea.
33
Solberg, Inger-Lise, Jan Steinar Rønning, Einar Dalsegg, Louise Hansen, Kåre Rokoengen, and Rolf Sandven. "Resistivity measurements as a tool for outlining quick-clay extent and valley-fill stratigraphy: a feasibility study from Buvika, central Norway." Canadian Geotechnical Journal 45, no. 2 (February 2008): 210–25. http://dx.doi.org/10.1139/t07-089.
Анотація:
Thick, marine clay deposits in valleys along the Norwegian coast are occasionally subjected to large landslides involving quick clay. Detailed mapping of the extent of quick clay is of great interest for planning and protection purposes, as the position of quick clay within slopes has a major impact on the landslide risk. Ground conditions in the small valley of Buvika, mid-Norway, are characterized by thick occurrences of quick clay, which are documented in numerous geotechnical investigations. The resistivity method is potentially well suited for outlining pockets of quick clay since quick clay has a slightly higher electric resistivity (10–80 Ωm) than intact unleached clay (1–10 Ωm). This is due to a higher salt content in the latter. These relations are supported in this study by pore-water salt content measurements. The acquired resistivity profiles are compared with other geophysical data and geotechnical drilling information. Results are promising, and acquired resistivity profiles are interpreted in terms of quick-clay extents, stratigraphy, bedrock influence, and groundwater drainage patterns. Mismatch between intersecting resistivity profiles may be an indication of local geological variations.
34
Sarkar, Sharmistha, George Mathew, Kanchan Pande, Naveen Chauhan, and Ashok Singhvi. "Rapid denudation of Higher Himalaya during late Pliestocence, evidence from OSL thermochronology." Geochronometria 40, no. 4 (December 1, 2013): 304–10. http://dx.doi.org/10.2478/s13386-013-0124-7.
Анотація:
AbstractOptically Stimulated Luminescence (OSL) of quartz, with closure temperatures of 30–35°C in conjunction with Apatite Fission Track (AFT; closure temp. ∼120°C) and 40Ar-39Ar (biotite closure temperature ∼350°C), were used to obtain cooling ages from Higher Himalayan crystalline rocks of Western Arunachal Himalaya (WAH). Cooling age data based on OSL, AFT and Ar-Ar thermochronology provide inference on the exhumation — erosion history for three different time intervals over million to thousand year scale.Steady-state exhumation of ∼0.5 mm/yr was observed during Miocene (>7.2 Ma) till Early Pleistocene (1.8 Ma). Onset of Pleistocene glacial/interglacial conditions from ∼1.8 Ma formed glaciated valleys and rapid erosion with rivers incising deep valleys along their course. Erosion enables midcrustal partial melts to move beneath the weak zone in the valley and causes an erosion-induced tectonic uplift. This resulted in a rapid increase in exhumation rate. The OSL thermochronology results suggest increased erosion over ∼21 ka period from Late Pleistocene (2.5 mm/yr) to Early Holocene (5.5 mm/yr) and these are to be contrasted with pre 1.8 Ma erosion rate of 0.5 mm/yr. Enhanced erosion in the later stage coincides with the periods of deglaciation during Marine Isotope Stages (MIS) 1 and 2. The results of the present study suggest that in the present setting OSL thermochronology informed on the short-term climatic effect on landscape evolution and techniques like the AFT and 40Ar-39Ar provided longer-term exhumation histories.
35
DE LA PARRA, FELIPE, DIEGO PINZON, GUILLERMO RODRIGUEZ, OMAR BEDOYA, and ROGER BENSON. "LACUSTRINE SYSTEMS IN THE EARLY MIOCENE OF NORTHERN SOUTH AMERICA—EVIDENCE FROM THE UPPER MAGDALENA VALLEY, COLOMBIA." PALAIOS 34, no. 10 (October 24, 2019): 490–505. http://dx.doi.org/10.2110/palo.2019.025.
Анотація:
ABSTRACT Extensive areas covered by semi-permanent water bodies were common during the Miocene in the Neotropics. These floods are noteworthy because of their possible role in promoting the high biological diversity observed today in the Amazonia. In particular, a relatively good understanding of the floods has been achieved for the Llanos basin of Colombia and western Amazonia. In these two basins the evidence suggests episodes of marine incursions and development of lacustrine systems at different times during the Miocene. Other intra-montane basins in Colombia, like the Middle and Upper Magdalena basins, also show clear evidence that water bodies covered them during that time. However, the chronostratigraphy and paleoecology of these deposits are still unclear. In this study, we use the palynological record of the Middle and Upper Magdalena valleys to establish the age of the deposits of the Barzalosa Formation, a unit that preserves a detailed record of a lacustrine system deposited during the late early Miocene in the Upper Magdalena Valley. The results indicate that the Barzalosa Formation is correlative with the lacustrine deposits of the La Cira fossiliferous horizon in the Middle Magdalena Valley. This indicates that extensive lacustrine systems covered the intramontane basins of the northern Andes during the early Miocene. Paleoecologically, the Barzalosa Formation is the result of the evolution of a lacustrine system in three phases, which show marked differences in the proportion of algae, palynological composition and sedimentary depositional sequence. Climate and tectonic processes were the most probable mechanisms controlling the evolution of the Barzalosa system.
36
Ghinassi, Massimiliano, Mauro Aldinucci, Valeria Bianchi, Andrea Brogi, Enrico Capezzuoli, Tsai-Luen Yu, and Chuan-Chou Shen. "Lifecycle of an Intermontane Plio-Pleistocene Fluvial Valley of the Northern Apennines: From Marine-Driven Incision to Tectonic Segmentation and Infill." Geosciences 11, no. 3 (March 18, 2021): 141. http://dx.doi.org/10.3390/geosciences11030141.
Анотація:
Downcutting and infill of incised valley systems is mostly controlled by relative sea-level changes, and studies on valley-fill successions accumulated independently from relative sea-level or lake-level oscillations are limited. This study focuses on the Plio-Pleistocene evolution of a fluvial drainage system developed in Southern Tuscany (Italy) following a regional marine forced regression at the end of Piacentian. Subsequent in-valley aggradation was not influenced by any relative sea-level rise, and valley morphological and depositional history mainly resulted from interaction between sediment supply and tectonic activity, which caused segmentation of the major valley trunk into localized subsiding depocenters separated by upwarping blocks. Fluvial sedimentation occurred until late Calabrian time, when the major river abandoned that valley, where minor fluvio-lacustrine depocenters allowed accumulation of siliciclastic and carbonate deposits. The present study demonstrates that the infill of the valley was not controlled by the forcing that caused its incision. Accumulation of the fluvial succession is discussed here in relation with localized, tectonic-controlled base levels, which commonly prevent from establishing of a clear downdip stratigraphic correlations. Chronological reconstruction of the study depositional dynamics provides solid constrains to frame them in the tectono-sedimentary evolution of the Northern Apennines.
37
Matoshko, A. V., P. F. Gozhik, and A. S. Ivchenko. "The fluvial archive of the Middle and Lower Dnieper (a review)." Netherlands Journal of Geosciences - Geologie en Mijnbouw 81, no. 3-4 (December 2002): 339–55. http://dx.doi.org/10.1017/s0016774600022642.
Анотація:
AbstractInformation about the morphology and alluvial sediments of the Dnieper Valley is reviewed. The Dnieper Valley originated in the Late Miocene. The Middle Dnieper Valley is an intercontinental alluvial basin and the Lower Dnieper Valley is a shallow canyon that ends with a delta. Identification of the alluvial dynamic facies (channel, overbank, abandoned channel) is crucial for stratigraphical analysis. The dynamic facies form regular sequences - alluvial suites that combine into series. Individual suites and series are characterized by their mode of occurrence, facies composition, lithological features and expression in the modern landscape. Their stratigraphie position is established with reference to index beds and palaeontological, geochrono-logical and archaeological research, allowing them to be correlated along the valley. Correlation between different parts of the Dnieper system uses a combination of facies and geomorphological analyses, whereas correlation with other river systems makes use of mammalian and molluscan biostratigraphy. Global events (marine regressions and glaciations) that brought about similar reactions in different fluvial systems can be also used for correlation.
38
Batterson, Martin J., and Norm R. Catto. "Topographically-controlled Deglacial History of the Humber River Basin, Western Newfoundland." Géographie physique et Quaternaire 55, no. 3 (October 15, 2003): 213–28. http://dx.doi.org/10.7202/006851ar.
Анотація:
AbstractThe Humber River in western Newfoundland flows through a large interior basin, that influenced Late Wisconsinan ice flow from major dispersal centres to the north, in the Long Range Mountains, and to the east in The Topsails. An early southward ice flow from a source to the north covered coastal areas in the western part of the basin. Subsequent regional ice flow was southwestward to northwestward from The Topsails, while south to southwestward flowing ice from the Long Range Mountains occupied the upper Humber River valley. This flow was confluent with ice from The Topsails and moved northwestward toward Bonne Bay. Regional deglaciation began about 13 ka from the inner coast. Ice occupying the Deer Lake valley dammed glacial Lake Howley in the adjacent Grand Lake and Sandy Lake basins to an elevation up to 85 m above present lake levels, which were controlled by drainage through a western outlet feeding into St. George’s Bay. The lake was lowered by exposure of the South Brook valley outlet, and finally drained catastrophically through a spillway at Junction Brook. Marine limit at the coast was 60 m asl. Inland deltas at the head of Deer Lake and fine-grained sediment exposed in the Deer Lake valley show inundation below 45 m present elevation. This produced a narrow embayment extending at least 50 km inland from the modern coast and is named here as ‘Jukes Arm’. Dated marine macrofossils in the Humber Arm and lower Humber River valley, indicate the deltas at the head of Deer Lake formed about 12.5 ka.
39
Miccadei, Enrico, Tommaso Piacentini, and Marcello Buccolini. "Long-term geomorphological evolution in the Abruzzo area, Central Italy: twenty years of research." Geologica Carpathica 68, no. 1 (February 1, 2017): 19–28. http://dx.doi.org/10.1515/geoca-2017-0002.
Анотація:
AbstractThe most recent research studies into the long-term landscape evolution of the Abruzzo area, carried out over the last twenty years at the “G. d’Annunzio” University of Chieti-Pescara, are based on an integrated approach incorporating structural geology and geomorphology and, in particular, the geomorphometry of topographic and hydrographic aspects, geological and structural-geomorphological surveys and mapping supported by morpho-stratigraphic and chronological constraints. The geomorphological analyses have allowed us to outline the main stages of geomorphological evolution and to identify the factors that have contributed to the landscape shaping of the Apennine Chain, the Adriatic Piedmont and the fluvial plains and coastal sectors, up to the Tremiti islands. In the Apennine Chain, landscape evolution — in a ridge, valley and basin system — is connected to the regional uplift, local tectonic subsidence and local base level variations, which have led to changes in the drainage systems, from exoreic to endorheic (in the intermontane basins) and then to exoreic again. In the Adriatic Piedmont, landscape shaping is connected to uplifting and eustatic sea-level fluctuations, which have induced the formation of a structure-controlled drainage system and the shaping of systems of entrenched alluvial fans and large consequent river valleys, with flights of river terraces. In the coastal Adriatic area — composed of a coastal plain-coastal slope system (northern and southern coast) and of a cliffed rocky coast (central coast, Tremiti) interrupted by river valleys — landscape shaping is the result of selective erosion due to the interaction between marine geomorphic processes and slope processes connected to Late Quaternary eustatic fluctuations.
40
DECKERS, JEF, and STEPHEN LOUWYE. "A reinterpretation of the ages and depositional environments of the lower and middle Miocene stratigraphic records in a key area along the southern margin of the North Sea Basin." Geological Magazine 156, no. 3 (December 6, 2017): 525–32. http://dx.doi.org/10.1017/s0016756817000991.
Анотація:
AbstractThe stratigraphic reinterpretation of the palynologically analysed Miocene succession of the Wijshagen borehole along the southern margin of the North Sea Basin allowed an age assessment – late Burdigalian to early Serravalian – for the Genk Sand Member of the Bolderberg Formation. The depositional environment varied during Burdigalian to Serravalian times from continental (peat formation) to open marine (glauconitic sands), respectively from south to north in the Roer Valley Rift System. The study area of the Wijshagen borehole is located in the central part of the Roer Valley Rift System between these extreme environments. During the Burdigalian, the glauconitic fine clayey sands of the Houthalen Sand Member were deposited in the study area. From the late Burdigalian onwards, the glauconite content decreased and lignite content increased as a result of high influx of clastic material in the Roer Valley Rift System, and marked the start of the deposition of the Genk Sand Member. The Genk Sand Member shows an overall coarsening-upwards trend, which is consistent with the gradual infill of the available accommodation space in the Roer Valley Rift System by northwest-prograding clastic delta sequences. Dinoflagellate cyst analyses indicate that the Genk Sand Member was largely deposited in a marginal marine environment with only short pulses of continental input. These pulses of continental input increase in a southerly or landward direction where they led to the development of thick lignite seams.
41
Anderson, Jeffrey E. "Mississippi River Valley Voodoo." Nova Religio: The Journal of Alternative and Emergent Religions 26, no. 4 (May 1, 2023): 33–57. http://dx.doi.org/10.1525/nr.2023.26.4.33.
Анотація:
When visiting New Orleans, it is easy to assume that Voodoo, as practiced by the likes of the nineteenth-century “Voodoo Queen of New Orleans” Marie Laveau, is alive and well, as evidenced by the Voodoo-inspired tourist shops, merchandise, and art that are ubiquitous in the French Quarter. Such is not quite the case. Following more than a century of suppression, the religion that throve into the late nineteenth century was struggling to survive by the 1940s and may have ceased to exist as a living faith shortly thereafter. While some scholars have suggested that the African American Spiritual churches of New Orleans are modern manifestations of Voodoo, these congregations lack key features of the historical Voodoo religion and have but a tenuous connection with it. The city’s current practitioners of Voodoo, meanwhile, tend to be initiates of Haitian Vodou or West African Vodun. Ultimately, Lower Mississippi River Valley Voodoo, both in New Orleans and elsewhere, is best understood as a historical religion rather than a living tradition. Contemporary practitioners of “New Orleans Voodoo” are constructing an emerging religion from elements of African diasporic belief in a city deeply imbued with a legacy of Voodoo.
42
Hancock, Gregory S., and Robert S. Anderson. "Numerical modeling of fluvial strath-terrace formation in response to oscillating climate." GSA Bulletin 114, no. 9 (September 1, 2002): 1131–42. http://dx.doi.org/10.1130/0016-7606(2002)114<1131:nmofst>2.0.co;2.
Анотація:
Abstract Many river systems in western North America retain a fluvial strath-terrace rec ord of discontinuous downcutting into bedrock through the Quaternary. Their importance lies in their use to interpret climatic events in the headwaters and to determine long-term incision rates. Terrace formation has been ascribed to changes in sediment supply and/or water discharge produced by late Quaternary climatic fluctuations. We use a one-dimensional channel- evolution model to explore whether temporal variations in sediment and water discharge can generate terrace sequences. The model includes sediment transport, vertical bedrock erosion limited by alluvial cover, and lateral valley-wall erosion. We set limits on our modeling by using data collected from the terraced Wind River basin. Two types of experiments were performed: constant- period sinusoidal input histories and variable-period inputs scaled by the marine δ18O rec ord. Our simulations indicate that strath-terrace formation requires input variability that produces a changing ratio of vertical to lateral erosion rates. Straths are cut when the channel floor is protected from erosion by sediment and are abandoned—and terraces formed—when incision can resume following sediment-cover thinning. High sediment supply promotes wide valley floors that are abandoned as sediment supply decreases. In contrast, wide valleys are promoted by low effective water discharge and are abandoned as discharge increases. Widening of the valley floors that become terraces occurs over many thousands of years. The transition from valley widening to downcutting and terrace creation occurs in response to subtle input changes affecting local divergence of sediment-transport capacity. Formation of terraces lags by several thousand years the input changes that cause their formation. Our results suggest that use of terrace ages to set limits on the timing of a specific event must be done with the knowledge that the system can take thousands of years to respond to a perturbation. The incision rate calculated in the field from the lowest terrace in these systems will likely be higher than the rate calculated by using older terraces, because the most recent fluvial response in the field is commonly downcutting associated with declining sediment input since the Last Glacial Maximum. This apparent increase in incision rates is observed in many river systems and should not necessarily be interpreted as a response to an increase in rock-uplift rate.
43
Judd, Richard W., and Mark Walker. "Maine Roots: Growing up Poor in the Kennebec Valley." New England Quarterly 69, no. 1 (March 1996): 159. http://dx.doi.org/10.2307/366315.
44
Acharya, Ravi, Saurav Khanal, Surya Prasad Kandel, Rabin Dhakal, Rafel Almeida, Judith Hubbard, Som Nath Sapkota, and Lalu Prasad Paudel. "Balanced cross-section across the Siwaliks of the Trijuga Valley, eastern Nepal." Journal of Nepal Geological Society 60 (September 16, 2020): 51–58. http://dx.doi.org/10.3126/jngs.v60i0.31263.
Анотація:
The strata of the Siwalik Group in the Trijuga valley is dissected by two thrusts, repeating the succession three times and forming a longitudinal Dun Valley. The total thickness of the Siwalik strata exceeds 5000 m in the area. A balanced cross-section has been constructed across the Siwalik Range in the Trijuga valley showing that the Main Himalayan Thrust (MHT) lies at the depth of about 5.2 km from the surface. The Main Frontal Thrust (MFT), Kamala Tawa Thrust (KTT), Marine Khola Thrust (MKT) and Main Boundary Thrust (MBT) ramp-up from the MHT. Along with these faults, fault-bend anticlines associated with these thrusts have shortened the Siwalik of the area. The shortening across the area has been calculated to be approximately 33.7 km.
45
Ortloff, Charles R. "Caral, South America’s Oldest City (2600–1600 BC): ENSO Environmental Changes Influencing the Late Archaic Period Site on the North Central Coast of Peru." Water 14, no. 9 (April 27, 2022): 1403. http://dx.doi.org/10.3390/w14091403.
Анотація:
The Late Archaic Period (2600–1600 BC) site of Caral, located ~20 km inland from the Pacific Ocean coastline in the Supe Valley of the north central coast of Peru, is subject to CFD analysis to determine the effects of ENSO (El Niño Southern Oscillation) events (mainly, El Niño flooding and drought events) on its agricultural and marine resource base that threatened societal continuity. The first step is to examine relics of major flood events that produced coastal beach ridges composed of deposited flood slurries—the C14 dating of material within beach ridges determines the approximate dates of major flood events. Of interest is the interaction of flood slurry with oceanic currents that produce a linear beach ridge as these events are controlled by fluid mechanics principles. CFD analysis provides the basis for beach ridge geometric linear shape. Concurrent with beach ridge formation from major flood events are landscape changes that affect the agricultural field system and marine resource food supply base of Caral and its satellite sites- here a large beach ridge can block river drainage, raise the groundwater level and, together with aeolian sand transfer from exposed beach flats, convert previously productive agricultural lands into swamps and marshes. One major flood event in ~1600 BC rendered coastal agricultural zones ineffective due to landscape erosion/deposition events together with altering the marine resource base from flood deposition over shellfish gathering and sardine and anchovy netting areas, the net result being that prior agricultural areas shifted to limited-size, inner valley bottomland areas. Agriculture, then supplied by highland sierra amuna reservoir water, led to a high water table supplemented by Supe River water to support agriculture. Later ENSO floods conveyed thin saturated bottomland soils and slurries to coastal areas to further reduce the agricultural base of Supe Valley sites. With the reduction in the inner valley agricultural area from continued flood events, agriculture, on a limited basis, shifted to the plateau area upon which urban Caral and the satellite sites were located. The narrative that follows then provides the basis for the abandonment of Caral and its satellite Supe Valley sites due to the vulnerability of the limited food-supply base subject to major ENSO events.
46
Tyuleneva, N. V. "LATE-PLEISTOCENE – HOLOCENE SEDIMENT ACCUMULATION IN THE NORTHWESTERN BLACK SEA SHELF." Odesa National University Herald. Geography and Geology 19, no. 4(23) (March 20, 2015): 272–83. http://dx.doi.org/10.18524/2303-9914.2014.4(23).39382.
Анотація:
Main purpose of this study is characterization of the facies and paleogeographical features of sedimentforming processes. The subject of the study is the Late-Pleistocene – Holocene bottom sediments of the Northwestern Black Sea shelf. Methodology includes standard statistical calculations of the thicknesses of bottom marine sediments and their description. Finding:the Late-Pleistocene-Holocene bottom sediments facies’ formation was determined by the repeated coastline position changes. The study area recent underwater landscapes were formed during the Holocene transgression, when subaerial flats were flooded. The land facies within the study area are represented by fluvial, eolian and eolian-deluvil genetic types of sediments. The basin underwent significant environmental transformations after reconnectionwith the Mediterranean Sea and within the study are such stages as lacustrine, brackish water and marine can be traced. Sediment forming processes were determined by the presence of limans during the early Holocene period, which were situated lower than the modern coastline and corresponded to the paleoriver valleys’ position. Considerable sediment thicknesses (from5 to 10 m) were accumulating during this time. The Odessa bay, Dnieper-Bug liman, Dniester coastal waters, paleo-Dniester, Dnieper depression and paleo-Sarata valley are characterized by the high rates of deposits accumulation. Thereby, sediment forming environments in the study area experienced gradual transformation due to considerable riverin waters inflow that is why brackish-water mollusks of Caspian type are wide spread even after the salt Mediterranean water entered the basin. Paleogeographical features such as coastline position and the basin bottom relief influenced strongly the bottom facies disposition and its thicknesses.
47
Deev, E. V., I. D. Zolnikov, R. N. Kurbanov, A. V. Panin, A. Murray, A. M. Korzhenkov, I. V. Turova, N. I. Pozdnyakova, and A. V. Vasiliev. "OSL Dating of the Sukor Earthquake-induced Rockslide in Gorny Altai: Paleoseismological and Paleogeographic Implications." Russian Geology and Geophysics 63, no. 6 (June 1, 2022): 743–54. http://dx.doi.org/10.2113/rgg20204300.
Анотація:
Abstract —Lacustrine sediments, related subaerial aeolian sands, as well as fluvioglacial sands enclosed in ablation moraines in the Chuya River valley between the Chuya and Kurai basins in Gorny Altai, have been dated by optically stimulated (OSL) and infrared stimulated (IRSL) luminescence. The OSL and IRSL ages indicate that the formation of the lake, which spread into the Chuya Basin, was caused by the Sukor rockslide that dammed the Chuya Valley. The rockslide was triggered by a large earthquake (shaking intensity at least IX-X) generated by an active fault in the Kurai Fault Zone about 16 ka, which is the oldest known date for its activity. Thus, large landslides or rockslides can remain geomorphically expressed for at least 16 ka in the climate and landscape conditions as in the Chuya and Kurai basins. The lake existed till ~10 ka BP and then was gradually drained. The Kuyuktanar glacier reached its greatest extent in the early marine isotope stage (MIS) 2, and its ablation moraines formed about 25 ka. Judging by the age and good preservation of moraines left by the glacier, the hilly terrain in the area of the Sukor rockslide, and the presence of lacustrine sands in the vicinity of the lake dam, no catastrophic flooding events in the Chuya and Katun valleys have occurred since the Last Glacial Maximum (LGM; ~20 kyr BP). The water table of the glacier-dammed lake that occupied the Kurai Basin around the LGM could not have exceeded 1750 m above sea level (a.s.l.). Higher lake terraces traceable till elevations of 2100–2200 m a.s.l. should be attributed to more ancient lake stages. Archaeological sites in the area of the junction between the Chuya and Kurai basins were formed in the post-lake period, the oldest dating back to the latest Late Paleolithic time.
48
Occhietti, Serge, Sanda Balescu, Michel Lamothe, Martine Clet, Thomas Cronin, Pierre Ferland, and Pierre Pichet. "Late Stage 5 Glacio-isostatic Sea in the St. Lawrence Valley, Canada and United States." Quaternary Research 45, no. 2 (March 1996): 128–37. http://dx.doi.org/10.1006/qres.1996.0015.
Анотація:
AbstractAlthough post-glacial marine sediments of late Wisconsinan and early Holocene age are common in eastern Canada and the northeastern United States, remnants of older Pleistocene marine sediments are scarce. A fossiliferous marine clay that predates the classical Wisconsinan was recently discovered in the St. Lawrence Valley. A dominantly estuarine environment is inferred from the geochemistry of the shells (δ18O = −7.1) and from benthic foraminifer and ostracode assemblages. The clay indicates a marine invasion (Cartier Sea) shallower and probably shorter than that during the upper late Wisconsinan Champlain Sea episode (12,000–9,500 yr B.P.). The pollen content shows that regional vegetation during the marine episode began as open tundra, then became a Betula and Alnus crispa forest, reached a climatic optimum with Quercus, Corylus, and Abies, and concluded as a Pinus/Picea boreal forest. A corrected infrared stimulated luminescence age of 98,000 ± 9000 yr is compatible with the epimerization ratio of shells. The Cartier Sea resulted from a post-glacial glacio-isostatic marine invasion in the St. Lawrence lowlands. It probably occurred during late stage 5 and is tentatively assigned to the transition of oxygen isotope substages 5b/5a. This marine episode dates to stage 5 of the preceding continental glacier which extended to middle latitudes in NE America.
49
Tofel, Jane Evans, and Peter W. Bretsky. "Middle OrdovicianLophospira(Archaeogastropoda) from the Upper Mississippi Valley." Journal of Paleontology 61, no. 4 (July 1987): 700–723. http://dx.doi.org/10.1017/s0022336000029061.
Анотація:
A detailed morphological study of over 2,500 Middle Ordovician (Black Riveran) lophospirid archaeogastropods from the lower half of the Platteville Formation (Pecatonica Member and Mifflin Submember of the McGregor Member), principally as it is exposed in southern Wisconsin, has permitted the definition of five species ofLophospira. Lophospira perangulata(Hall),L. milleri(Hall),L. serrulata(Salter),L. helicteres(Salter), andL. delicata(n. sp.) are preserved throughout a three-meter interval of fine-grained, heavily bioturbated carbonates, now dolomitized. Deposition took place on a broad, shallow tropical shelf, which was characterized by low rates of deposition and low physical energy. The sampled interval represents about 500,000 years. The benthic marine invertebrate fauna is well preserved, diverse, and characteristic of an environment of normal marine salinity.Of the fiveLophospiraspecies, only one,L. perangulata, has been positively identified in older strata (late Whiterockian, eastern North America). The other four species were endemic to the interior seas, and apparently at least two of these,L. serrulataandL. helicteres, did not survive into post-Platteville (post-Black Riveran) environments. Changes in the proportions of lophospirid species from the Pecatonica into the Mifflin strata probably reflect subtle changes in the distribution of carbonate shelf habitats but no major alteration in the kinds of habitats available for colonization.
50
St-Onge, Denis A., and Jean Lajoie. "The late Wisconsinan olistostrome of the lower Coppermine River valley, Northwest Territories." Canadian Journal of Earth Sciences 23, no. 11 (November 1, 1986): 1700–1708. http://dx.doi.org/10.1139/e86-157.
Анотація:
The late Quaternary olistostrome exposed in the lower Coppermine River valley fills a paleovalley that ranges in apparent width from 150 to 400 m and was cut into Precambrian bedrock before the last glaciation. The olistostrome is here named the Sleigh Creek Formation. The coarse fraction of the formation is matrix supported; beds are massive or reversely graded and have sharp, nonerosive contacts. These characteristics suggest deposition of the coarse fraction by debris flows. The olistostrome sequence is bracketed by, and wedged into, a marine rhythmite sequence, which indicates that deposition occurred in a marine environment.About 10 500 years BP glacier ice in the Coronation Gulf lowland dammed the valley to the south, which was occupied by glacial Lake Coppermine. Sediments accumulated in this lake in a 30 m thick, coarsening upward sequence ranging from glaciolacustrine rhythmites of silt and fine sand at the base to coarse sand alluvium, and deltaic gravels at the top. As the Coronation Gulf lowlands became ice free, the Coppermine River reoccupied its former drainage course to the north. The steep south to north gradient and rapid downcutting by the river through the glacial lake sediments produced unstable slope conditions. The resulting debris flows filled a bedrock valley network below the postglacial sea level, forming the diamicton sequence.The interpretation of the Sleigh Creek Formation raises questions concerning silimar diamicton deposits usually defined as "flowtills." More generally, the results of this study indicate that care must be used when attempting paleogeographic reconstructions of "glaciogenic" deposits in marine sequences in any part of the geologic record.