Journal articles on the topic 'Eocene sediments'
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1
Fakhruddin, Rakhmat, and Dedy Kurniadi. "Age and Paleobathymetry of Salodik Group in PohPagimana section, East Arm of Sulawesi Based on Foraminiferal Assemblages." Journal of Geoscience, Engineering, Environment, and Technology 4, no. 1 (March 1, 2019): 30. http://dx.doi.org/10.25299/jgeet.2019.4.1.2751.
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Planktonic and benthic foraminiferal assemblages were used for age and paleobathymetry analysis of outcropping carbonate succession of the Salodik Group in Poh–Pagimana section, East Arm of Sulawesi. Twenty spot samples of carbonate rocks were collected from cut slope along the road between Poh and Pagimana. Age analysis conducted for each sample by its planktonic foraminifera assemblages and group into their age interval. The age range from Early Eocene to Pliocene. Benthic foraminiferal assemblages indicate paleobathymetry ranging from middle shelf to upper bathyal settings. Age analysis of the studied section show an older sediments (Early–Middle Eocene) overlie younger sediment (Early Miocene). This is interpreted as the evidence of thrust fault in the Poh–Pagimana section as part of thrust sheets of Batui thrust complex which imbricated on deformation zone. The youngest sediment which have suffered deformations shown by disordered age sequence is Pliocene in age (N20-21). The Eocene to Pliocene carbonate succession in the studied section was deposited relatively in the more basinward position compared to the carbonate-dominated sediments in the Tomori area which was deposited in the more landward position.
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Deyu, Zhang. "Clay mineralogy of the Upper Paleocene and Eocene clay sediments in Denmark." Bulletin of the Geological Society of Denmark 36 (December 31, 1987): 249–58. http://dx.doi.org/10.37570/bgsd-1988-36-06.
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The clay mineralogy of the Upper Paleocene and Eocene "plastic clay" sediments has been investigated from a new borehole in the Great Belt of Denmark. Predominant smectite, with small amounts of illite, kaolinite and, in the Holmehus Fm., chlorite, have been identified in the Upper Paleocene sediments. Abundant smectite and increased amounts of kaolinite and illite, with little chlorite, are present in the Eocene sediments. The Tertiary section of the borehole has been divided into two zones; one dominated by smectite with trace amount of kaolinite, including the Upper Paleocene and the Rl-R3 Beds of R!llsnres Clay Fm.; another characterized by the distinct increase of kaolinite and the relative decrease of smectite, including the R4-R6 and the Ll-lA Beds of Eocene sediments. Regionally, smectite content decreases, while kaolinite and illite increase from the north to the south and southeast in the Eocene sediments. No clear trend has been recognized in the Upper Paleocene sediments. The effect of material source, palaeoclimate and depositional environment on clay mineral distribution is discussed. The high content of smectite is considered to be mainly attributed to the alteration and/or weathering of volcanic material, contributions of smectitic clay from carbonate terrains and far transported suspended matter from north-northwest. The change in climatic conditions may also be of importance. The distinct increase in kaolinite content of the Eocene sediments is thought to be related to a elastic source to the south and southeast and to the warmer climatic conditions.
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Hojati, S., H. Khademi, J. M. Arocena, A. Faz Cano, and S. Ayoubi. "Chronostratigraphic distribution and genesis of palygorskite in Tertiary sediments of the Isfahan region, central Iran." Clay Minerals 47, no. 1 (March 2012): 11–29. http://dx.doi.org/10.1180/claymin.2012.047.1.11.
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AbstractNo comprehensive study has yet been conducted to determine the chronostratigraphic distribution of palygorskite in the Tertiary sediments of Iran. Thirty sediment samples of different Tertiary epochs were taken, based on the field observations and geological maps. The clay fraction of samples was then investigated by X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM), and inductively coupled plasma mass spectrometry (ICP-MS). Results showed that sediments of the Miocene and Pliocene had large amounts of palygorskite whereas no trace of this mineral was found in the sediments from the Palaeocene, Eocene and Oligocene. Geochemical analyses revealed that sediments younger than the Oligocene had greater amounts of soluble Mg and H4SiO4and a higher pH than those of the Palaeocene and Eocene. The stability diagram of the smectite-palygorskite system suggests that smectite is unstable and transforms to palygorskite in Neogene sediments. The SEM micrographs showed palygorskite as interwoven fibrous mats, coatings, pore-fillings and pore-bridging material in Neogene sediments. This textural evidence suggests a direct chemical precipitation of palygorskite by dissolution of silicates under the alkaline conditions. The results also suggest that geochemical conditions in the Early Tertiary era, represented by deep-sea conditions in central Iran, were not apparently favourable for palygoskite formation until the Late Oligocene.
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Kalender, Leyla, and Gamze Aytimur. "REE Geochemistry of Euphrates River, Turkey." Journal of Chemistry 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/1012021.
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The study area is located on the Euphrates River at 38°41°32.48′′N–38°14′24.10′′N latitude and 39°56′4.59′′E–39°8°13.41′′E longitude. The Euphrates is the longest river in Western Asia. The lithological units observed from the bottom to the top are Permo-Triassic Keban Metamorphites, Late Cretaceous Kömürhan Ophiolites, Upper Cretaceous Elazığ Magmatic Complex, Middle Eocene Maden Complex and Kırkgeçit Formation, Upper Pliocene and Lower Eocene Seske Formation and Upper Miocene, Pliocene Karabakır and Çaybağı Formations, Palu Formation, and Holocene Euphrates River sediments. The geochemical studies show that87Sr/86Sr and143Nd/144Nd isotopic compositions in the Euphrates River bank sediments are 0.7053, 0.7048, and 0.7057 and 0.512654, 0.512836, and 0.512775, respectively. These values indicate mixing of both carbonate-rich shallow marine sediment and felsic-mafic rocks from Elazığ Magmatic Complex into the stream sediments. The positiveεNd (0)values (0.35, 3.9, and 2.7) are higher downstream in the studied sediments due to weathering of the mafic volcanic rocks. The chondrite, NAS, and UCC normalized patterns show that the REE compositions of the Euphrates River sediments are higher than chondrite composition but close to NAS and UCC. The river sediments in the tectonic zone and the weathered granodioritic rocks of the Elazığ Magmatic complex affect upstream water compositions.
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Havryshkiv, Halyna, and Yuliya Haievska. "Facial features of the Paleocene-Eocene deposits of advanced units of the Skyba zone of Ukrainian Carpathians." Geology and Geochemistry of Combustible Minerals 3-4, no. 185-186 (2021): 44–55. http://dx.doi.org/10.15407/ggcm2021.03-04.044.
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There three main types of facies of Paleocene-Eocene complexes: sandy, siltstone and argillite distinguished within the study area by the nature of the distribution of the strata of the forming components were highlighted. Тhey accumulated avalanche at the foot of the continental slope and formed various facial parts of the foehn (Upper, Middle and Lower foehn). In the upper part of the Foehn was accumulated coarse-grained sediments (clusters of deep boulders and other psephyto-psammitic material containing edaphogenic rocks). Under the action of geostrophic and bottom currents, silt streams of pelitic and psammitic material moved in the direction to the south and south-east of the Carpathian sedimentation basin, forming sandy-clay and clay facies (Middle and Lower foehn). During the turbidite movement of a large amount of sediment from the first (shelf) to the second (foot of the continental slope) level of avalanche sedimentation, sorting and distribution of sediments on the continental slope took place. Based on the analysis of the material composition of Paleocene-Eocene sediments of the study area by such criteria as the size of the fragment, sedimentary textures and the ratio of different rocks, 7 facies were identified, which were deposited as gravitational flows down on the continental slope. Reconstructions of Paleocene-Eocene age flysch deposits showed that terrigene material in the studied sedimentation basin came from two sources – one of which was northwest of the study area and was characterized by a predominance of coarse-grained sandy sediments, while the source wear, which was in the central part of the studied basin was characterized by a predominance of clay silt and fine-grained psammitic material. This nature of the distribution of terrigenous material had a decisive influence on the further formation of Paleocene end Eocene sedimentary strata in the process of sedimentogenesis and post-sedimentary transformations of sediments, and on the formation of reservoir rocks and rocks with potential reservoir properties for hydrocarbon exploration. It has been established that the composition of the Psamitolites of the flysch formation of the Paleocene and Eocene ages of the Carpathians was formed on the passive continental margin or in the inland and boundary seas, and their genesis mostly corresponds only to the platform source of material wear.
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Tripathi, S. K. M. "Palynological changes across subsurface Palaeocene-Eocene sediments at Barmer, Rajasthan, India." Journal of Palaeosciences 46, no. (1-2) (December 31, 1997): 168–71. http://dx.doi.org/10.54991/jop.1997.1335.
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Palynofloras recovered from core samples from two bore-holes MK 327 and MK 332 drilled near Kapurdi, Barmer, Rajasthan are rich and diversified. Restricted occurrence of Matanomadhiasulcites maximus and Triangulorites pachyexinus alongwith other long-ranging taxa demarcates the Palaeocene sediments from those of Eocene. Presence of Eocene sediments in the studied bore-holes is indicated by the restricted occurrence of Meliapollis pachydermis, M. symplex, Lygodiumsporites lakiensis and Foveotricolporites reticuloidus. Two palynological zones, Assemblage Zone A indicating Late Palaeocene age and Assemblage Zone B indicating Early Eocene age, have been identified in the bore-hole sequences and sediments representing these zones have been correlated with Akli and Mataji Ka Dungar formations, respectively of the Barmer Basin.
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Strother, Stephanie L., Ulrich Salzmann, Francesca Sangiorgi, Peter K. Bijl, Jörg Pross, Carlota Escutia, Ariadna Salabarnada, Matthew J. Pound, Jochen Voss, and John Woodward. "A new quantitative approach to identify reworking in Eocene to Miocene pollen records from offshore Antarctica using red fluorescence and digital imaging." Biogeosciences 14, no. 8 (April 24, 2017): 2089–100. http://dx.doi.org/10.5194/bg-14-2089-2017.
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Abstract. Antarctic palaeoclimate evolution and vegetation history after the formation of a continent-scale cryosphere at the Eocene–Oligocene boundary, 33.9 million years ago, has remained a matter of controversy. In particular, the reconstruction of terrestrial climate and vegetation has been strongly hampered by uncertainties in unambiguously identifying non-reworked as opposed to reworked sporomorphs that have been transported into Antarctic marine sedimentary records by waxing and waning ice sheets. Whereas reworked sporomorph grains over longer non-successive geological timescales are easily identifiable within younger sporomorph assemblages (e.g. Permian sporomorphs in Pliocene sediments), distinguishing non-reworked from reworked material in palynological assemblages over successive geological time periods (e.g. Eocene sporomorphs in Oligocene sediments) has remained problematic. This study presents a new quantitative approach to identifying non-reworked pollen assemblages in marine sediment cores from circum-Antarctic waters. We measured the fluorescence colour signature, including red, green, and blue fluorescence; brightness; intensity; and saturation values of selected pollen and spore taxa from Eocene, Oligocene, and Miocene sediments from the Wilkes Land margin Site U1356 (East Antarctica) recovered during Integrated Ocean Drilling Program (IODP) Expedition 318. Our study identified statistically significant differences in red-fluorescence values of non-reworked sporomorph taxa against age. We conclude that red fluorescence is a reliable parameter for identifying the presence of non-reworked pollen and spores in Antarctic marine sediment records from the circum-Antarctic realm that are influenced by glaciation and extensive reworking. Our study provides a new tool to accurately reconstruct Cenozoic terrestrial climate change on Antarctica using fossil pollen and spores.
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Bijl, Peter K., G. Raquel Guerstein, Edgar A. Sanmiguel Jaimes, Appy Sluijs, Silvio Casadio, Victor Valencia, Cecilia R. Amenábar, and Alfonso Encinas. "Campanian-Eocene dinoflagellate cyst biostratigraphy in the Southern Andean foreland basin: Implications for Drake Passage throughflow." Andean Geology 48, no. 2 (May 31, 2021): 185. http://dx.doi.org/10.5027/andgeov48n2-3339.
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The tectonic opening of the Tasmanian Gateway and Drake Passage represented crucial geographic requirements for the Cenozoic development of the Antarctic Circumpolar Current (ACC). Particularly the tectonic complexity of Drake Passage has hampered the exact dating of the opening and deepening phases, and the consequential onset of throughflow of the ACC. One of the obstacles is putting key regional tectonic events, recorded in southern Patagonian sediments, in absolute time. For that purpose, we have collected Campanian-Eocene sediment samples from the Chilean sector of Southern Patagonia. Using U-Pb radiometric dating on zircons and dinoflagellate cyst biostratigraphy, we updated age constraints for the sedimentary formations, and the hiatuses in between. Thick sedimentary packages of shallow-marine and continental sediments were deposited in the foreland basin during the early Campanian, mid-Paleocene, the Paleocene-Eocene boundary interval and the middle Eocene, which represent phases of increased foreland subsidence. We interpret regional sedimentary hiatuses spanning the late Campanian, early-to mid-Paleocene, mid-Eocene and latest Eocene-early Oligocene to indicate times of reduced foreland subsidence, relative to sediment supply. We relate these changes to varying subduction rates and Andean orogeny. Dinoflagellate cyst assemblages suggest that the region was under the influence of the Antarctic-derived waters through the western boundary current of the Subpolar Gyre, developed in the southwest Atlantic Ocean and thus argues for limited throughflow through the Drake Passage until at least the latest Eocene. However, the proliferation of dinoflagellate endemism we record in the southwest Atlantic is coeval with that in the southwest Pacific, and on a species level, dinoflagellate cyst assemblages are the same in these two regions. This suggests that both regions were oceanographically connected throughout the early Paleogene, likely through a shallow opening of a restricted Drake Passage. This implies a continuous surface-water connection between the south Pacific and the South Atlantic throughout the late Cretaceous-early Paleogene.
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Boulter, M. C. "Pollen and spore events from the marine Tertiary of North Europe." Journal of Micropalaeontology 5, no. 2 (December 1, 1986): 75–84. http://dx.doi.org/10.1144/jm.5.2.75.
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Abstract. Results are presented of semi-quantitative palynological analyses from two cored boreholes. One is from the central North Sea (16/1-1) and penetrates sediments from the Middle Miocene to the Palaeocene. The other is from the Voring Plateau of the Norwegian Sea (D.S.D.P. Leg 38 site 338) and penetrates sediments from the Early Miocene to the Early Eocene. The results show a number of interesting palynological features and these are discussed in relation to other evidence. The most important of these are: 1, the small range of angiosperm pollen in the Palaeocene; 2, changes in the dinocyst:pollen ratio in Early Eocene sediments in both cores at about the time of an increase in Subtriporopollenites pollen; 3, the presence of triprojectate pollen in the Late Eocene and Middle Oligocene sediments of site 338 some of which may not be reworked; and 4, a clear difference between Neogene and Palaeogene pollen taxa.
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Hill, Robert S., and Leonie J. Scriven. "Falcatifolium (Podocarpaceae) macrofossils from paleogene sediments in south-eastern Australia: a reassessment." Australian Systematic Botany 11, no. 6 (1998): 711. http://dx.doi.org/10.1071/sb97014.
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A re-investigation of macrofossils previously referred to the extantpodocarpaceous genus Falcatifolium Laubenfels shows thatno records can be sustained. Falcatifolium australisD.R.Greenwood from Middle Eocene sediments in Victoria bears littleresemblance to extant species in the genus and is transferred to the newfossil genus Sigmaphyllum R.S.Hill & L.J.Scriven.Specimens from Early Oligocene sediments in Tasmania previously assigned toFalcatifolium are described as a second species ofSigmaphyllum, S. tasmanensisR.S.Hill & L.J.Scriven, and specimens from mid to late Eocene sediments inTasmania previously assigned to Falcatifolium do notbelong to that genus, although their true generic affinities are uncertain.Dispersed cuticle specimens from Late Eocene–Oligocene sediments inSouth Australia referred to Falcatifolium are notreliable records of the genus and require further investigation. However,Dacrycarpus eocenica D.R.Greenwood, from Middle Eocenesediments in Victoria is transferred to Falcatifolium,and is similar to the extant species F. angustumLaubenfels, which has a leaf morphology unusual for the genus.Falcatifolium eocenica (D.R.Greenwood) R.S.Hill & L.J.Scriven is the only reliable record of the genus in the Australian fossilrecord to date.
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Pälike, Heiko, Nicholas J. Shackleton, and Ursula Röhl. "Astronomical forcing in Late Eocene marine sediments." Earth and Planetary Science Letters 193, no. 3-4 (December 2001): 589–602. http://dx.doi.org/10.1016/s0012-821x(01)00501-5.
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Wagner, Courtney L., Ramon Egli, Ioan Lascu, Peter C. Lippert, Kenneth J. T. Livi, and Helen B. Sears. "In situ magnetic identification of giant, needle-shaped magnetofossils in Paleocene–Eocene Thermal Maximum sediments." Proceedings of the National Academy of Sciences 118, no. 6 (February 1, 2021): e2018169118. http://dx.doi.org/10.1073/pnas.2018169118.
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Near-shore marine sediments deposited during the Paleocene–Eocene Thermal Maximum at Wilson Lake, NJ, contain abundant conventional and giant magnetofossils. We find that giant, needle-shaped magnetofossils from Wilson Lake produce distinct magnetic signatures in low-noise, high-resolution first-order reversal curve (FORC) measurements. These magnetic measurements on bulk sediment samples identify the presence of giant, needle-shaped magnetofossils. Our results are supported by micromagnetic simulations of giant needle morphologies measured from transmission electron micrographs of magnetic extracts from Wilson Lake sediments. These simulations underscore the single-domain characteristics and the large magnetic coercivity associated with the extreme crystal elongation of giant needles. Giant magnetofossils have so far only been identified in sediments deposited during global hyperthermal events and therefore may serve as magnetic biomarkers of environmental disturbances. Our results show that FORC measurements are a nondestructive method for identifying giant magnetofossil assemblages in bulk sediments, which will help test their ecology and significance with respect to environmental change.
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Caplan, Charlotte A., Helen C. Gildersleeves, Al G. Harding, Benedict J. R. Harris, Benedict W. W. Johnson, James A. Kershaw, and Matthew J. Maltby. "Geology of the Northwestern Krania Basin." Bulletin of the Geological Society of Greece 54, no. 1 (November 19, 2019): 113. http://dx.doi.org/10.12681/bgsg.19375.
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We present a new map of 30 km2 of the northwestern Krania Basin at 1:10,000 scale, including rocks of the Pindos Ophiolite Group and associated units, and the sedimentary fill of the Krania Basin. The Krania Basin is a flexural basin developed in the Middle – Late Eocene and filled first with alluvial fan conglomerates and later with turbidite sandstones and siltstones, following a deepening of the basin. Analysis of the clasts within the sediment, combined with paleoflow analyses, suggest sediment input from the eroding Pindos Ophiolite to the west. The Pindos Ophiolite Group is represented in the area by pillow lavas, sheeted dykes and serpentinized harzburgites of the Aspropotamos Complex. The ophiolite forms imbricated, thrust bounded blocks which show two phases of thrusting, corresponding to Late Jurassic and Eocene stages of ophiolite emplacement. We identify five stages of deformation within the basin itself, starting with Early - Middle Eocene syndepositional extensional faulting associated with the formation of the basin. This was followed by four stages of post-depositional deformation, starting with Late Eocene compression associated with basin closure, which caused thrust faulting and folding of the sediments. Oligocene dextral faulting with a thrust component affected the basin margins. Finally, two normal faulting events with different orientations have affected the basin since the Miocene.
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OKAY, ARAL I., ERCAN ÖZCAN, AYNUR HAKYEMEZ, MUZAFFER SIYAKO, GÜRSEL SUNAL, and ANDREW R. C. KYLANDER-CLARK. "The Thrace Basin and the Black Sea: the Eocene–Oligocene marine connection." Geological Magazine 156, no. 1 (September 18, 2017): 39–61. http://dx.doi.org/10.1017/s0016756817000772.
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AbstractThe Late Cretaceous – Recent West Black Sea Basin and the Eocene–Oligocene Thrace Basin are separated by the Strandja arch comprising metamorphic and magmatic rocks. Since Late Cretaceous time the Strandja arch formed a palaeo-high separating the two basins which accumulated clastic sediment of >9 km thickness. During late Eocene – early Oligocene time the marine connection between these basins existed through the Çatalca gap west of Istanbul. The Çatalca gap lies on the damage zone of a major Cretaceous strike-slip fault; it formed a 15 km wide marine gateway, where carbonate-rich sediments of thicknessc.350 m were deposited. The sequence consists of upper Eocene shallow marine limestones (SBZ18-20) overlain by upper Eocene – lower Oligocene (P16-P19 zones) pelagic marl with a rich fauna of planktonic foraminifera; the marls are intercalated with 31–32 Ma acidic tuff and calc-arenite beds. The Çatalca gap is bounded in the west by a major normal fault, which marks the eastern boundary of the Thrace Basin. Seismic reflection profiles, well data and zircon U–Pb ages indicate that the Thrace Basin sequence west of the fault is late Eocene – middle Oligocene (37–27 Ma) in age and that the fault has accommodated 2 km of subsidence. Although there was a marine connection between the West Black Sea and Thrace basins during late Eocene – early Oligocene time, no significant exchange of clastic sediment took place. Sedimentation in the Çatalca gap ended abruptly during early Oligocene time by uplift, and this eventually led to the paralic conditions in the Thrace Basin.
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Hnylko, Oleh, Svitlana Hnylko, and Ksenia Navarivska. "Stratigraphy and sedimentary environments of the black-shale formation of the Ukrainian Carpathians." Paleontological Collection 53 (2021): 35–54. http://dx.doi.org/10.30970/pal.53.03.
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Materials on stratigraphy of sediments containing black shale potentially oil-generating strata were generalized and supplemented, their comparison with the modern Geological Time Scale was performed and reconstructions of sedimentary environments were clarified on tha basis of small foraminifera analysis and sedimentological data. In the Lower Cretaceous, the black shale formations are represented by the Spas and Shypot formations (Boryslav-Pokuttya, Skyba, Silesian, Dukla, Chornohora, Svydovets and Krasnoshora nappes), as well as the lower part of the Tyssalo Formation (Pieniny Klippen Belt), in the Upper Cretaceous – by the Bereznyi Formation (Dukla Nappe), in the Eocene – by the Soimy Formation (Silesian Nappe) and in the Oligocene-Miocene – by the Menilite Formation and its analogues existing in the most tectonic units of the Carpathians. Most of the sediments containing black shales were accumulated by turbidite and other gravitational flows. (Hemi)pelagic sedimentation was a background. In the absence of oxygen, the clay (hemi)pelagic sediments were enriched with organic matter giving the sediments a black color, and when the aeration improved, lighter sediments were accumulated. According to the microfauna and sedimentological study, the depth of the Carpathian Basin, where black shale formations were deposited, ranged from the bathyal above CCD in Barremian (lower parts of the Spas and Shypot formations) to the bathyalabyssal depths mostly below CCD in the Aptian (upper parts of the Spas and Shypot formations). Deepwater turbidite sedimentation continued in the Late Cretaceous (the Bereznyi Formation) and Eocene (Soimy Formation). At the end of the Eocene, the depth of the basin changed from bathyal-abyssal depth to the upper bathyal depth (the horizon of “globigerin marls” of the Eocene-Oligocene boundary). Black shales are confined either to certain stratigraphic levels (Lower Cretaceous, Oligocene) or to individual tectonic unitss (Upper Cretaceous of the Dukla Nappe, Black Eocene of the Silesian Nappe). Accordingly, their accumulation is due either to the dominant influence of global (early Cretaceous anoxic events), regional (isolation of the Carpathian Basin due to the collissional processes in the future Alps and the formation of the Paratethys in the Oligocene), or local (the presence of intra-basin uplifts restricted the circulation of bottom oxygen-enriched currents in the Late Cretaceous and Eocene) factors.
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Vakalas, I., G. Ananiadis, N. Kontopoulos, K. K. Stoykova, and A. Zelilidis. "AGE DETERMINATION AND PALAEOGEOGRAPHIC RECONSTRUCTION OF PINDOS FORELAND BASIN BASED ON CALCAREOUS NANNOFOSSILS." Bulletin of the Geological Society of Greece 36, no. 2 (July 23, 2018): 864. http://dx.doi.org/10.12681/bgsg.16834.
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The study area is part of the Pindos foreland (Underhill, 1985). Pindos foreland is a tertiary turbiditic foreland basin fill trending parallel to the external Hellenides and occupies Gavrovo and Ionian isopic zones (Aubouin, 1959). The age of Pindos foreland sediments is still a matter of discussion. B.P. (1971) proposed an early Miocene to middle Miocene age, explaining the presence of Oligocene fauna as a product of large scale erosion and reworking of older sediments during Miocene. IGSR&IFP(1966) suggested a late Eocene to early Miocene age for the basin fill while Fleury (1980), Leigh (1991), Wilpshaar (1995), Bellas (1997) assigned an Oligocene age. Avramidis et al (1999) proposes a middle Eocene to early Miocene age assessment, using nannofosil zones from three studied cross sections in the Klematia-Paramythia basin (middle Ionian zone). The determination of the sediment ages was based on the study of calcareous nannofossils, which came from almost 120 samples covering 11 geological cross sections. The nannofosil marker species that were found in the samples were classified using the biozones proposed by Martini in 1971. According to the age assessments arose from the studied samples, clastic sedimentation in the study area began in the Middle Eocene, with small differences among the basin. The end of clastic sedimentation seems to be at different times in different parts of the basin.
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Wang, Huapei, Jun Wang, Yu-chen Karen Chen-Wiegart, and Dennis V. Kent. "Quantified abundance of magnetofossils at the Paleocene–Eocene boundary from synchrotron-based transmission X-ray microscopy." Proceedings of the National Academy of Sciences 112, no. 41 (September 29, 2015): 12598–603. http://dx.doi.org/10.1073/pnas.1517475112.
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The Paleocene–Eocene boundary (∼55.8 million years ago) is marked by an abrupt negative carbon isotope excursion (CIE) that coincides with an oxygen isotope decrease interpreted as the Paleocene–Eocene thermal maximum. Biogenic magnetite (Fe3O4) in the form of giant (micron-sized) spearhead-like and spindle-like magnetofossils, as well as nano-sized magnetotactic bacteria magnetosome chains, have been reported in clay-rich sediments in the New Jersey Atlantic Coastal Plain and were thought to account for the distinctive single-domain magnetic properties of these sediments. Uncalibrated strong field magnet extraction techniques have been typically used to provide material for scanning and transmission electron microscopic imaging of these magnetic particles, whose concentration in the natural sediment is thus difficult to quantify. In this study, we use a recently developed ultrahigh-resolution, synchrotron-based, full-field transmission X-ray microscope to study the iron-rich minerals within the clay sediment in their bulk state. We are able to estimate the total magnetization concentration of the giant biogenic magnetofossils to be only ∼10% of whole sediment. Along with previous rock magnetic studies on the CIE clay, we suggest that most of the magnetite in the clay occurs as isolated, near-equidimensional nanoparticles, a suggestion that points to a nonbiogenic origin, such as comet impact plume condensates in what may be very rapidly deposited CIE clays.
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Reinhardt, Lutz, Werner von Gosen, Andreas Lückge, Martin Blumenberg, Jennifer M. Galloway, Christopher K. West, Markus Sudermann, and Martina Dolezych. "Geochemical indications for the Paleocene-Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM-2) hyperthermals in terrestrial sediments of the Canadian Arctic." Geosphere 18, no. 1 (January 7, 2022): 327–49. http://dx.doi.org/10.1130/ges02398.1.
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Abstract During the late Paleocene to early Eocene, clastic fluvial sediments and coals were deposited in northern high latitudes as part of the Margaret Formation at Stenkul Fiord (Ellesmere Island, Nunavut, Canada). Syn-sedimentary tectonic movements of the Eurekan deformation continuously affected these terrestrial sediments. Different volcanic ash layers occur, and unconformities subdivide the deposits into four sedimentary units. Rare vertebrate fossils indicate an early Eocene (Graybullian) age for the upper part of the Stenkul Fiord outcrop. Here, we present carbon isotope data of bulk coal, related organic-rich mud and siltstones, a plant leaf wax-derived alkane, and additional plant remains. These data provide a complete carbon isotope record of one stratigraphic section with defined unconformity positions and in relation to other Eurekan deformation features. A previously dated ash layer MA-1 provided a U-Pb zircon age of 53.7 Ma and is used as a stratigraphic tie point, together with a discrete negative carbon isotope excursion found above MA-1 in a closely sampled coal seam. The excursion is identified as the likely expression of the I-1 hyperthermal event. Based on our isotope data that reflect the early Eocene dynamics of the carbon cycle, this tie point, and previous paleontological constraints from vertebrate fossils, the locations of the Paleocene-Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM-2) hyperthermals and their extent along the complete section are herein identified. Within the intervals of the PETM and ETM-2 hyperthermal events, increasing amounts of clastic sediments reached the site toward the respective end of the event. This is interpreted as a response of the fluvial depositional system to an intensified hydrological system during the hyperthermal events. Our study establishes an enhanced stratigraphic framework allowing for the calculation of average sedimentation rates of different intervals and considerations on the completeness of the stratigraphic record. As one of the few high-latitude outcrops of early Eocene terrestrial sediments, the Stenkul Fiord location offers further possibilities to study the effects of extreme warming events in the Paleogene.
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Kar, R. K., and Poonam Sharma. "Palynostratigraphy of Late Palaeocene and Early Eocene sediments of Rajasthan, India." Palaeontographica Abteilung B 256, no. 4-6 (February 7, 2000): 123–57. http://dx.doi.org/10.1127/palb/256/2000/123.
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Shcherbinina, E., A. Iakovleva, Y. Gavrilov, O. Golovanova, and N. Muzylev. "Lower Eocene sedimentary succession and microfossil biostratigraphy in the central northern Caucasus basin." Geologica Acta 18 (January 29, 2020): 1–15. http://dx.doi.org/10.1344/geologicaacta2020.18.1.
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The lower Eocene sediments from the classical Paleogene section exposed along the Kheu River, northern Caucasus, southern Russia are here studied. This ca. 50m thick succession is lithologically contrasting: the lower and upper parts are composed by soft marls separated by a thick Radiolaria-rich unit of non-calcareous and low-calcareous mudstones with intercalations of compact cherty layers. According to nannofossil and dinocyst biostratigraphy, the unique intercalation of Total Organic Carbon (TOC)-rich sediment (sapropelitic bed) in the lower part of the lower Eocene correspond to the Paleocene-Eocene Thermal Maximum (PETM) and a series of sapropelitic interlayers in the upper marly part of the lower Eocene succession correlates with the Early Eocene Climatic Optimum (EECO). The study of nannofossil and dinocyst assemblages enabled detailed zonal subdivision and first-order calibration of nannofossil and dinocyst bio-events during this time-span. The studied interval of the section embraces the complete succession of nannofossil zones NP9-NP13 of Martini, 1971, CP8-CP11 of Okada and Bukry, 1980 and CNP11-CNE5 of Agnini et al., 2014. By means of dinocyst stratigraphy, the succession of Apectodinium hyperacanthum, Axiodinium augustum, Deflandrea oebisfeldensis, Dracodinium astra, Stenodinium meckelfeldense, Dracodinium varielongitudum, Ochetodinium romanum/Samlandia chlamydophora and Areosphaeridium diktyoplokum zones are identified in the Ypresian part of the Kheu section.
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Wade, Bridget S., James F. O'Neill, Chawisa Phujareanchaiwon, Imran Ali, Mitchell Lyle, and Jakub Witkowski. "Evolution of deep-sea sediments across the Paleocene-Eocene and Eocene-Oligocene boundaries." Earth-Science Reviews 211 (December 2020): 103403. http://dx.doi.org/10.1016/j.earscirev.2020.103403.
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Heller, James A., and Jonathan R. Bryan. "First Oligocene occurrence of the irregular echinoid Macropneustes mortoni (Conrad)." Journal of Paleontology 66, no. 2 (March 1992): 345–46. http://dx.doi.org/10.1017/s0022336000033874.
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A nearly complete test and several test fragments of the irregular echinoid species Macropneustes mortoni (Conrad) were recently discovered in Lower Oligocene (Vicksburgian) strata of southern Alabama. To date, M. mortoni has only been reported from Upper Eocene (Jacksonian) sediments of Alabama, Georgia, and Florida (Cooke, 1959; Toulmin, 1977; Carter, 1987). This is one of the very few species of the diverse Eocene echinoid fauna of this region to survive the terminal Eocene extinctions.
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Bijl, Peter K., Joost Frieling, Margot J. Cramwinckel, Christine Boschman, Appy Sluijs, and Francien Peterse. "Maastrichtian–Rupelian paleoclimates in the southwest Pacific – a critical re-evaluation of biomarker paleothermometry and dinoflagellate cyst paleoecology at Ocean Drilling Program Site 1172." Climate of the Past 17, no. 6 (November 25, 2021): 2393–425. http://dx.doi.org/10.5194/cp-17-2393-2021.
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Abstract. Sea surface temperature (SST) reconstructions based on isoprenoid glycerol dialkyl glycerol tetraether (isoGDGT) distributions from the Eocene southwest (SW) Pacific Ocean are unequivocally warmer than can be reconciled with state-of-the-art fully coupled climate models. However, the SST signal preserved in sedimentary archives can be affected by contributions of additional isoGDGT sources. Methods now exist to identify and possibly correct for overprinting effects on the isoGDGT distribution in marine sediments. Here, we use the current proxy insights to (re-)assess the reliability of the isoGDGT-based SST signal in 69 newly analyzed and 242 reanalyzed sediments at Ocean Drilling Program (ODP) Site 1172 (East Tasman Plateau, Australia) following state-of-the-art chromatographic techniques. We compare our results with paleoenvironmental and paleoclimatologic reconstructions based on dinoflagellate cysts. The resulting ∼ 130 kyr resolution Maastrichtian–Oligocene SST record based on the TetraEther indeX of tetraethers with 86 carbon atoms (TEX86) confirms previous conclusions of anomalous warmth in the early Eocene SW Pacific and remarkably cool conditions during the mid-Paleocene. Dinocyst diversity and assemblages show a strong response to the local SST evolution, supporting the robustness of the TEX86 record. Soil-derived branched GDGTs stored in the same sediments are used to reconstruct mean annual air temperature (MAAT) of the nearby land using the Methylation index of Branched Tetraethers with 5-methyl bonds (MBT'5me) proxy. MAAT is consistently lower than SST during the early Eocene, independent of the calibration chosen. General trends in SST and MAAT are similar, except for (1) an enigmatic absence of MAAT rise during the Paleocene–Eocene Thermal Maximum and Middle Eocene Climatic Optimum, and (2) a subdued middle–late Eocene MAAT cooling relative to SST. Both dinocysts and GDGT signals suggest a mid-shelf depositional environment with strong river runoff during the Paleocene–early Eocene progressively becoming more marine thereafter. This trend reflects gradual subsidence and more pronounced wet/dry seasons in the northward-drifting Australian hinterland, which may also explain the subdued middle Eocene MAAT cooling relative to that of SST. The overall correlation between dinocyst assemblages, marine biodiversity and SST changes suggests that temperature exerted a strong influence on the surface-water ecosystem. Finally, we find support for a potential temperature control on compositional changes of branched glycerol monoalkyl glycerol tetraethers (brGMGTs) in marine sediments. It is encouraging that a critical evaluation of the GDGT signals confirms that most of the generated data are reliable. However, this also implies that the high TEX86-based SSTs for the Eocene SW Pacific and the systematic offset between absolute TEX86-based SST and MBT'5me-based MAAT estimates remain without definitive explanation.
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Robinson, P. H., and P. R. King. "Hydrocarbon Reservoir Potential of the Taranaki Basin, Western New Zealand." Energy Exploration & Exploitation 6, no. 3 (June 1988): 248–62. http://dx.doi.org/10.1177/014459878800600306.
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Taranaki Basin is a proven petroleum producing region, with commercial quantities of hydrocarbons from late Eocene paralic and terrestrial sands, and Miocene-latest Pliocene shelf sands. Other sediments with sub-commercial hydrocarbon accumulations, shows or potential reservoir features have also been encountered. The paralic and terrestrial sediments were deposited during periodic shoreline fluctuations in the Paleogene and were capped by transgressive terrigenous and carbonate muds. Other sand bodies, generally of bathyal and shelf setting and representing increasing regional tectonism, are found throughout the late Eocene to Pliocene sequence. Paleogeographic reconstructions depicting the maximum sand development during the Paelocene to Pliocene provide potential sandstone reservoir maps. These highlight onshore Taranaki and the Eocene paleoshoreline trend as areas of greatest prospectivity. Future activity should also consider the potential of the relatively unexplored late Cretaceous-Paleocene and Pliocene sandstone sequences.
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Renaudie, Johan, Effi-Laura Drews, and Simon Böhne. "The Paleocene record of marine diatoms in deep-sea sediments." Fossil Record 21, no. 2 (August 20, 2018): 183–205. http://dx.doi.org/10.5194/fr-21-183-2018.
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Abstract. Marine planktonic diatoms, as today's ocean main carbon and silicon exporters, are central to developing an understanding of the interplay between the evolution of marine life and climate change. The diatom fossil record extends as far as the Early Cretaceous, and the late Paleogene to Recent interval is relatively complete and well documented. Their early Paleogene record, when diatoms first expanded substantially in the marine plankton, is hampered by decreased preservation (notably an episode of intense chertification in the early Eocene) as well as by observation bias. In this article, we attempt to correct for the latter by collecting diatom data in various Paleocene samples from legacy Deep Sea Drilling Project and Ocean Drilling Program deep-sea sediment sections. The results show a different picture from what previous analyses concluded, in that the Paleocene deep-sea diatoms seem in fact to have been as diverse and abundant as in the later Eocene, while exhibiting very substantial survivorship of Cretaceous species up until the Eocene.
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PAL, TAPAN, PARTHA PRATIM CHAKRABORTY, TANAY DUTTA GUPTA, and CHANAM DEBOJIT SINGH. "Geodynamic evolution of the outer-arc–forearc belt in the Andaman Islands, the central part of the Burma–Java subduction complex." Geological Magazine 140, no. 3 (May 2003): 289–307. http://dx.doi.org/10.1017/s0016756803007805.
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The Andaman Islands, the central part of Burma–Java subduction complex, expose tectonostratigraphic units of an accretionary prism in an outer-arc setting and turbidites of a forearc setting. A number of N–S-trending dismembered ophiolite slices of Cretaceous age, occurring at different structural levels with Eocene trench-slope sediments, were uplifted and emplaced by a series of E–dipping thrusts. Subsequently, N–S normal and E–W strike-slip faults resulted in the development of a forearc basin with deposition of Oligocene and Mio-Pliocene sediments. Metapelites and metabasics of greenschist to amphibolite grade occur in a melange zone of ophiolites. The Eocene Mithakhari Group represents pelagic trench sediments and coarser clastics derived from ophiolites. Evidence of frequent facies changes, predominance of mass flow deposits, syn-sedimentary basinal disturbance and wide palaeogeographic variation indicate deposition of Eocene sediments in isolated basins of an immature trench-slope setting. Deposition of the Oligocene Andaman Flysch Group in a forearc setting is indicated by the large-scale persistence of beds, lack of small-scale lithological variation, bimodal provenance, less deformation, a well-defined submarine fan sequence and development predominantly on the eastern part of the outer arc. The Mio-Pliocene Archipelago Group includes alternations of siliciclastic turbidites and subaqueous pyroclastic flow deposits in the lower part and carbonate turbidites in the upper part, suggesting its deposition in the shallower forearc compared to the siliciclastic Oligocene sediments.
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Wang, C. W., H. L. Hong, B. W. Song, K. Yin, Z. H. Li, K. X. Zhang, and J. L. Ji. "The early-Eocene climate optimum (EECO) event in the Qaidam basin, northwest China: clay evidence." Clay Minerals 46, no. 4 (December 2011): 649–61. http://dx.doi.org/10.1180/claymin.2011.046.4.649.
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AbstractClay mineralogy and its palaeoclimatic interpretation of the early-Eocene (∼53.3–49.70 Ma) sediments at Lulehe, Qaidam basin, northwest China, were investigated using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The interval of ∼53.3–49.70 Ma, including the early-Eocene climate optimum (EECO) with isotopic events, was the transition period of “greenhouse” to “icehouse”. Climate changes during the episode were documented in the sediments and were expressed by the proportion of clay species and clay indices, as well as by the proportion of non-clay minerals, gypsum, halite and calcite. Our results suggest that a warm and humid climate prevailed over the period ∼53.3–52.90 Ma, followed by a warm and seasonally dry and humid climate in the period ∼52.90–51.0 Ma and a subsequently warm and humid climate in the period ∼51.0–49.70 Ma. Three warmer and more humid intervals were observed at 52.7, 51.0 and 50.5 Ma based on clay indices. The climate evolution in the Qaidam Basin during the period derived from the clay mineralogical study is in good agreement with the early Eocene global climate change, and the warm and seasonally dry and humid episode in the early Eocene in Qaidam basin is a regional response to the global early-Eocene climate optimum.
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Hill, RS, and MS Pole. "Leaf and shoot morphology of extant Afrocarpus, Nageia and Retrophyllum (Podocarpaceae) species, and species with similar leaf arrangement, from tertiary sediments in Australia." Australian Systematic Botany 5, no. 3 (1992): 337. http://dx.doi.org/10.1071/sb9920337.
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A cuticular micromorphological study confirms the separate generic status of Afrocarpus, Nageia and Retrophyllum and increases the number of available diagnostic characters. A re-investigation of fossil species previously assigned to this complex demonstrates that in all cases the generic designation was incorrect. Decussocarpus maslinensis from Eocene sediments at Mash Bay is transferred to the new genus Willungia; specimens from Eocene sediments at Anglesea referred to Decussocarpus brownei are transferred to Smithtonia victoriensis; Prumnopitys lanceolata and specimens assigned to P. aff. tasmanica from Anglesea are combined and transferred to Smithtonia. Previously undescribed fossil specimens from Oligocene sediments in Tasmania are assigned to Smithtonia jonesii and Willungia oppositifolia. Specimens of Retrophyllum are reported from Oligocene sediments in Western Australia and Miocene sediments in the South Island of New Zealand. These new fossil genera and species demonstrate that foliage characters which are now unique to Retrophyllum among the Podocarpaceae were once more widespread, providing further evidence for the hypothesis that many podocarpaceous taxa converged towards the production of flattened short shoots to increase photosynthetic efficiency.
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Singh, H. P., and S. K. M. Tripathi. "Palynology of the Jaintia Group (Palaeocene-Eocene) exposed along Jowai-Sonapur Road, Meghalaya, India (Part II). Data analysis and interpretations." Journal of Palaeosciences 35, no. (1-3) (December 31, 1986): 301–13. http://dx.doi.org/10.54991/jop.1986.1544.
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The palynoflora recovered from the Jaintia Group (Palaeocene-Eocene) exposed along the road between Jowai and Sonapur, Jaintia Hills have been dated and compared with various Lower Tertiary palynological assemblages. The present studies support tropical to subtropical vegetation during the Palaeocene-Eocene times. It has also been inferred that the Jaintia Group sediments were deposited under shallow marine conditions.
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Kessler, Franz L., John Jong, and Mazlan Madon. "Eocene Sediments in the South China Sea, precursor deposits of the Oligocene expansion?" Berita Sedimentologi 47, no. 2 (October 2, 2021): 1–24. http://dx.doi.org/10.51835/bsed.2021.47.2.319.
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The stratigraphic record of Eocene in the Malaysian waters of the South China Sea is scarce; the few deep petroleum exploration wells and outcrops are located on the fringes of the SCS. Yet, despite the paucity of data we observe a variety of sediments that cover the range from fluviatile to (at least) neritic marine deposits. Whilst fluvial deposits dominate the Western Rim (Penyu, Malay basins), the Southern Rim (Sarawak) is characterized by deposits of a narrow and rapidly deepening shelf, with fluviatile, shallow marine clastics and carbonates passing seawards to outer shelf and neritic deposits. The proven record of the Eocene to-date is located in relatively small and deep sub-basins. Possibly, the Eocene underlies additional areas of the SCS, but there is to-date no sufficient well data to offer further confirmation. The presence of Eocene strata on the margins of Sundaland is associated with an early phase of extensional and/or transpressional tectonism, probably acting as precursor movements related to the onset of rifting of the crust underlying the SCS.
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Zhang, Zehua, and Hongliang Wang. "Comprehensive Provenance Analysis and Its Applications to Eocene Clastic Rocks in the Huimin Depression, Bohai Bay Basin, China." Minerals 9, no. 9 (August 28, 2019): 517. http://dx.doi.org/10.3390/min9090517.
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Clarification of the source of the Eocene sediments filling the Huimin depression provides significant support for current and future oil and gas exploration in the Bohai Bay Basin, China. A comprehensive assessment of sediment provenance based on sandstone petrography, heavy mineral assemblages, seismic reflection data, and distribution of sandstone bodies of the Shahejie Formation (Es2) to the Dongying Formation (Ed) productive interval based on both its macroscopic and microscopic provenance aspects. This method of analysis has the advantages of easy data acquisition, high accuracy, strong flexibility, wide application range, and making the analysis of sedimentary provenances more systematic. Comprehensive analysis of the Huimin depression, Bohai Bay Basin has revealed further that the origin of the Eocene second member of the Shahejie Formation (Es2) to the Dongying Formation (Ed) provenance system was derived from the Linfanjia high, the Chengning uplift, and the Luxi uplift.
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Pälike, Heiko, Nicholas J. Shackleton, and Ursula Röhl. "Erratum to “Astronomical forcing in Late Eocene marine sediments”." Earth and Planetary Science Letters 197, no. 3-4 (April 2002): 301–2. http://dx.doi.org/10.1016/s0012-821x(02)00488-0.
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Glass, B. P. "Upper Eocene Impact Ejecta/Spherule Layers in Marine Sediments." Geochemistry 62, no. 3 (2002): 173–96. http://dx.doi.org/10.1078/0009-2819-00017.
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El-Beialy, Salah Y. "The dinocyst biostratigraphy of the Upper Eocene subsurface sediments, west Nile Delta, Egypt." Newsletters on Stratigraphy 19, no. 3 (October 26, 1988): 131–41. http://dx.doi.org/10.1127/nos/19/1988/131.
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Pisera, Andrzej, Peter A. Siver, and Alexander P. Wolfe. "A First Account of Freshwater Potamolepid Sponges (Demospongiae, Spongillina, Potamolepidae) from the Middle Eocene: Biogeographic and Paleoclimatic Implications." Journal of Paleontology 87, no. 3 (May 2013): 373–78. http://dx.doi.org/10.1666/12-079.1.
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We report the oldest fossil occurrence of freshwater potamolepid sponges (Demospongiae, Spongillina, Potamolepidae) to date, originating from middle Eocene lake sediments accumulated in the Giraffe kimberlite maar, northern Canada. Sponges are represented by strongyle spicules that are gemmuloscleres. These are described herein as belonging to a new species,Potamophloios canadensis. Because the most similar extant potamolepid sponges inhabit subtropical to tropical water bodies, these observations provide further evidence of biogeographic reorganizations in response to warm high-latitude Eocene paleoclimates.
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Slotnick, B. S., V. Lauretano, J. Backman, G. R. Dickens, A. Sluijs, and L. Lourens. "Early Paleogene variations in the calcite compensation depth: new constraints using old borehole sediments from across Ninetyeast Ridge, central Indian Ocean." Climate of the Past 11, no. 3 (March 17, 2015): 473–93. http://dx.doi.org/10.5194/cp-11-473-2015.
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Abstract. Major variations in global carbon cycling occurred between 62 and 48 Ma, and these very likely related to changes in the total carbon inventory of the ocean-atmosphere system. Based on carbon cycle theory, variations in the mass of the ocean carbon should be reflected in contemporaneous global ocean carbonate accumulation on the seafloor and, thereby, the depth of the calcite compensation depth (CCD). To better constrain the cause and magnitude of these changes, the community needs early Paleogene carbon isotope and carbonate accumulation records from widely separated deep-sea sediment sections, especially including the Indian Ocean. Several CCD reconstructions for this time interval have been generated using scientific drill sites in the Atlantic and Pacific oceans; however, corresponding information from the Indian Ocean has been extremely limited. To assess the depth of the CCD and the potential for renewed scientific drilling of Paleogene sequences in the Indian Ocean, we examine lithologic, nannofossil, carbon isotope, and carbonate content records for late Paleocene – early Eocene sediments recovered at three sites spanning Ninetyeast Ridge: Deep Sea Drilling Project (DSDP) Sites 213 (deep, east), 214 (shallow, central), and 215 (deep, west). The disturbed, discontinuous sediment sections are not ideal, because they were recovered in single holes using rotary coring methods, but remain the best Paleogene sediments available from the central Indian Ocean. The δ13C records at Sites 213 and 215 are similar to those generated at several locations in the Atlantic and Pacific, including the prominent high in δ13C across the Paleocene carbon isotope maximum (PCIM) at Site 215, and the prominent low in δ13C across the early Eocene Climatic Optimum (EECO) at both Site 213 and Site 215. The Paleocene-Eocene thermal maximum (PETM) and the K/X event are found at Site 213 but not at Site 215, presumably because of coring gaps. Carbonate content at both Sites 213 and 215 drops to <5% shortly after the first occurrence of Discoaster lodoensis and the early Eocene rise in δ13C (~52 Ma). This reflects a rapid shoaling of the CCD, and likely a major decrease in the net flux of 13C-depleted carbon to the ocean. Our results support ideas that major changes in net fluxes of organic carbon to and from the exogenic carbon cycle occurred during the early Paleogene. Moreover, we conclude that excellent early Paleogene carbonate accumulation records might be recovered from the central Indian Ocean with future scientific drilling.
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Michelsen, Olaf. "Late Cenozoic basin development of the eastern North Sea Basin." Bulletin of the Geological Society of Denmark 43 (July 14, 1996): 9–21. http://dx.doi.org/10.37570/bgsd-1996-43-02.
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The Cenozoic succession in the Danish part of the North Sea Basin includes two significant breaks in sedimentation; 1) at the Eocene-Oligocene boundary and 2) at mid Miocene time. The sediment transport direction was from the west during the Middle-Late Eocene and mainly from northeast and east in post Eocene times, and a change from a concordant seismic reflection pattern to a progradational pattern is seen. A clear change in Iithology occurs at the Eocene-Oligocene boundary, from a finegrained clay-dominated deposit below the boundary to a clay with silt and mica above. Near shore marine and fluvial sediments of Early Oligocene to mid Miocene age are known from the offshore and onshore areas, witnessing that the coastline migrated into the basin for the first time since the earliest Cretaceous. This change in sedimentation pattern was probably caused by the initial uplift of Scandinavia. At mid Miocene time a significant environmental change occurred in the North Sea. A change from dark coloured to light coloured deposits indicates introduction of a well-oxygenated environment. A marked increase in rate of sedimentation (and subsidence) is evidenced by the approx. 1500 m thick sedimentary package in the central part of the basin. Late Middle Miocene starved sedimentation seen in the central North Sea may indicate a significant increase in subsidence rates. The base of the Quaternary is a major erosional unconformity, mainly created by erosion caused by uplift of Scandinavia. 1000-1200 m of uplift is calculated for the eastern part of the North Sea Basin. With a post-Eocene subsidence of 2500 m in the central North Sea, the amplitude of the post-Eocene tectonic movements is approx. 3700 m.
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Hill, RS. "Leaves of Eucryphia (Eucryphiaceae) from tertiary sediments in south-eastern Australia." Australian Systematic Botany 4, no. 3 (1991): 481. http://dx.doi.org/10.1071/sb9910481.
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Eucryphia leaves recovered from Tertiary sediments in south-eastern Australia are assigned to three new species, E. falcata (Late Palaeocene, Lake Bungarby), E. microstoma (Early Eocene, Regatta Point) and E. aberensis (Middle to Late Eocene, Loch Aber). Leaves from Early Pleistocene sediments at Regatta Point are re-examined and are considered to be closely related to the extant species, E. lucida and E. milliganii. An examination of the leaf morphology of the fossil and extant species suggests that evolution has taken place, resulting in smaller leaves at higher latitudes and/or altitudes probably in response to climatic change. There is also evidence for an increase in the size and complexity of peltiform cuticular extensions on the abaxial leaf surface from the Early Tertiary to the present, which may be a response to lower water availability or increasing occurrence of frost.
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Tribe, Selina. "Eocene paleo-physiography and drainage directions, southern Interior Plateau, British Columbia." Canadian Journal of Earth Sciences 42, no. 2 (February 1, 2005): 215–30. http://dx.doi.org/10.1139/e04-062.
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A map of reconstructed Eocene physiography and drainage directions is presented for the southern Interior Plateau region, British Columbia south of 53°N. Eocene landforms are inferred from the distribution and depositional paleoenvironment of Eocene rocks and from crosscutting relationships between regional-scale geomorphology and bedrock geology of known age. Eocene drainage directions are inferred from physiography, relief, and base level elevations of the sub-Eocene unconformity and the documented distribution, provenance, and paleocurrents of early Cenozoic fluvial sediments. The Eocene landscape of the southern Interior Plateau resembled its modern counterpart, with highlands, plains, and deeply incised drainages, except regional drainage was to the north. An anabranching valley system trending west and northwest from Quesnel and Shuswap Highlands, across the Cariboo Plateau to the Fraser River valley, contained north-flowing streams from Eocene to early Quaternary time. Other valleys dating back at least to Middle Eocene time include the North Thompson valley south of Clearwater, Thompson valley from Kamloops to Spences Bridge, the valley containing Nicola Lake, Bridge River valley, and Okanagan Lake valley. During the early Cenozoic, highlands existed where the Coast Mountains are today. Southward drainage along the modern Fraser, Chilcotin, and Thompson River valleys was established after the Late Miocene.
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Osorio-Granada, E., A. Pardo-Trujillo, S. A. Restrepo-Moreno, F. Gallego, J. Muñoz, A. Plata, R. Trejos-Tamayo, et al. "Provenance of Eocene–Oligocene sediments in the San Jacinto Fold Belt: Paleogeographic and geodynamic implications for the northern Andes and the southern Caribbean." Geosphere 16, no. 1 (November 21, 2019): 210–28. http://dx.doi.org/10.1130/ges02059.1.
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Abstract Mesozoic and Cenozoic strata of the San Jacinto Fold Belt (Colombian Caribbean) provide insights about sedimentary environments and paleogeographic evolution in the transition between the northern Andes and the South Caribbean deformed belt. We report new provenance (conventional sandstone petrography, heavy mineral analysis, and detrital zircon U-Pb geochronology and typology) and micropaleontologic data (palynology, calcareous nannofossils, and foraminifera) in samples collected from the lower Eocene (San Cayetano Formation) and upper Eocene–Oligocene (Toluviejo and Ciénaga de Oro Formations) rocks in boreholes drilled by the Colombian Agencia Nacional de Hidrocarburos as well as from recently exposed Oligocene outcrops from the Ciénaga de Oro Formation. Sandstone petrography shows modal variations, with high feldspar content in the lower Eocene rocks and high quartz content in the Oligocene deposits. This shift in compositional maturity may be due to climatic variations, tectonic activity, and/or changes in source areas. Heavy mineral analyses indicate variations that suggest sources primarily related to felsic igneous and/or low-grade metamorphic and mafic and ultramafic rocks. Zircon U-Pb geochronology displays age populations mainly in the Late Cretaceous, Late Jurassic, Permian–Triassic, and Precambrian (ca. 900–1500 Ma). In addition, zircon typology analyses indicate that the igneous zircons came primarily from monzogranites and granodiorites. Finally, the micropaleontologic and sedimentary data sets indicate that the sediments were deposited in tropical coastal and shallow marine environments. The sediments were transported by short rivers from the crystalline massifs of the Lower Magdalena Valley and the northern Central Cordillera basements, while distal transport of sediments may have occurred along longer rivers, which brought sediments from southern regions located between the Central and Western Cordilleras.
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Tripathi, S. K. M. "Palynology of subsurface Palaeocene-Eocene sediments pear Kapurdi, Barmer District, Rajasthan, India." Journal of Palaeosciences 43, no. 1-3 (December 31, 1994): 45–53. http://dx.doi.org/10.54991/jop.1994.1164.
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Palynological study on subsurface samples from four Well Sections drilled near Kapurdi, Barmer District, Rajasthan has been carried out. Recorded palynoflora is rich and diversified being represented by dinoflagellate cysts, fungal remains, pteridophytic spores and angiospermic pollen grains and closely resemble those recorded from Palaeocene-Eocene sediments of Kutch and Rajasthan. Most of the palynotaxa present in the assemblage are presently confined to tropical to subtropical areas. Abundance of pteridophytic spores and epiphyllous microthyriaceous fungi in the assemblage indicates that vicinity of the area where investigated sediments were deposited experienced plenty of rainfall. It is also inferred that sediments under study were deposited in a coastal environment.
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Górska, Martyna E. "Verification of gravity-flow models: case study from the Lower Eocene sediments (Tylmanowa site, SE Poland)." Baltica 32, no. 1 (August 1, 2019): 33–50. http://dx.doi.org/10.5200/baltica.2019.1.4.
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The thick-bedded, deep-water sandstone succession was described at the Tylmanowa site from the Polish Outer Carpathians. This part of the Carpathians is built mainly of the Upper Jurassic to Paleogene deep-water rocks. Succession at the Tylmanowa site is composed of massive, ripple-cross laminated, planar and trough cross-stratified, horizontally laminated and deformed sandstones as well as massive and horizontally laminated mudstones. All these sediments derived from gravity flows that prograde downslope from a basin margin towards the widespread abyssal plain. Exposed succession records the gradual transition from a decelerating debris flow to a turbidity current what is extraordinary in the recent investigations of deep-water sediments. The study succession has been compared with the widely known sediment models, such as: the classic Bouma Sequence (Bouma 1962), the high-density turbidite model (Lowe 1982), the fluxoturbidite model (Ślączka, Thompson 1981) and the hybrid event bed model (Haughton et al. 2009).
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Kar, R. K. "Palynostratigraphy of the tertiary sediments in north-east India with comments on the terminal eocene events." Journal of Palaeosciences 49, no. (1-3) (December 31, 2000): 281–92. http://dx.doi.org/10.54991/jop.2000.148.
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The Tertiary rocks in North-East India rest unconformably on the granitic basement. They represent more or less a continuous sequence except a post Barail unconformity. The palynological assemblage is more or less known from all the formations. The assemblage by and large is dominated by the pteridophytic spores in all the formations followed by the angiospermic pollen. The gymnospermic pollen are rare in Palaeocene-Middle Eocene and are found in Late Eocene onwards and occur in good numbers in Miocene-Pliocene rocks. The index fossils for each formation have been marked. The Terminal Eocene events have been analysed. It has been observed that during that time India was enjoying a tropical climate and there was no cooling effect as has been advocated from the other parts of the world.
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Mehrotra, R. C., Yi-Feng Yao, and Cheng-Sen Li. "Fossil wood of Bischofia palaeojavanica Awasthi from the Eocene of the Changchang Formation of Hainan Island, China." Journal of Palaeosciences 59, no. (1-3) (December 31, 2010): 121–27. http://dx.doi.org/10.54991/jop.2010.194.
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A fossil wood of Bischofia palaeojavanica Awasthi resembling the extant Bischofia javanica Blume of the family Euphorbiaceae, is described from the Eocene sediments of the Changchang Basin of Hainan Island, China. The fossil not only forms the first record of Bischofia from the basin, but is also the earliest from China. Its presence indicates the occurrence of humid valley forests in the region during the deposition of the sediments.
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Nicholson, Uisdean, Andrew Carter, Paula Robinson, and David I. M. Macdonald. "Eocene–Recent drainage evolution of the Colorado River and its precursor: an integrated provenance perspective from SW California." Geological Society, London, Special Publications 488, no. 1 (December 20, 2018): 47–72. http://dx.doi.org/10.1144/sp488-2019-272.
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AbstractThe Colorado River in the SW of the USA is one of Earth's few continental-scale rivers with an active margin delta. Deformation along this transform margin, as well as associated intra-plate strain, has resulted in significant changes in sediment routing from the continental interior and post-depositional translation of older deltaic units. The oldest candidate deposits, fluvial sandstones of the Eocene Sespe Group, are now exposed in the Santa Monica Mountains, 300 km to the north of the Colorado River. Heavy mineral data from this basin indicate that sediment was sourced by a large river system, with some affinity to the early Pliocene Colorado River, but was unlikely to have been integrated across the Colorado Plateau. Sedimentological and mineralogical evidence from the earliest (c. 5.3 Ma) unequivocal Colorado River-derived sediments in the Salton Trough provide evidence for a rapid transition from locally derived sedimentation. Lack of evidence for a precursor phase of suspended-load sediment suggests that drainage capture took place in a proximal position, favouring a ‘top-down’ process of lake spillover. Following drainage integration, significant changes in heavy mineral assemblages of fluvio-deltaic sediments, particularly evident from apatite–tourmaline and garnet–zircon indices, as well as U–Pb ages of detrital zircons, document the integration of the fluvial system to its present form and progressive incision of the Colorado Plateau from the Miocene to the present.
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Ćosović, Vlasta, Katica Drobne, Bojan Ogorelec, Alan Moro, Mladen Koić, Ivan Šoštarko, Alceo Tarlao, and Giorgio Tunis. "Decastronema barattoloi (DE CASTRO), characteristic fossil of the Palaeocene and the Eocene peritidal sediments from the Adriatic carbonate platform." Geologia Croatica 61, no. 2-3 (December 25, 2008): 321–32. http://dx.doi.org/10.4154/gc.2008.24.
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The renewed deposition in the Palaeogene and the oldest part of the non-interrupted Palaeocene succession is characterized by the presence of Decastronema barattoloi (DE CASTRO), cyanobacterial tubes originally described in the Apennines. The reinterpretation of limestones from several sections located in the Kras region (NW part of the AdCP: Basovizza, Dolenja vas, Sopada, ?ebulovica) confi rmed the presence of these microfossils in peritidal sediments of Danian age (SBZ 1). The Cuisian (Late Lower Eocene) sediments, from eastern Istria (Brnjci section), Cres Island (Koroma?na Cove section) and Ravni kotari (Benkovac–Korlat section) contain individuals of this species in great numbers. The cyanobacterial tubes are scattered in laminated, fi ne grained mudstones and wackestones, immediately above the Cretaceous sediments (occasionally above bauxites or breccias). The Decastronema-bearing sediments pass upward into the Foraminiferal limestones of Cuisian age (SBZ 11, based on conical agglutinated foraminifera and alveolinids), allowing the age determination of the cyanobacterial remnants. The Palaeocene specimens are minute (up to about 180 ?m long), thick walled tubes that occur with the index fossil Bangiana hanseni DROBNE. The Eocene forms accompanied by ostracods, pelecypods, and miliolid and rotaliid foraminifera are segmented tubes, up to 400 mm long and usually thin walled.
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Frieling, Joost, Emiel P. Huurdeman, Charlotte C. M. Rem, Timme H. Donders, Jörg Pross, Steven M. Bohaty, Guy R. Holdgate, Stephen J. Gallagher, Brian McGowran, and Peter K. Bijl. "Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia." Journal of Micropalaeontology 37, no. 1 (February 13, 2018): 317–39. http://dx.doi.org/10.5194/jm-37-317-2018.
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Abstract. Detailed, stratigraphically well-constrained environmental reconstructions are available for Paleocene and Eocene strata at a range of sites in the southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large discrepancy between temperature proxy data and climate models in this region, suggesting a crucial error in model, proxy data or both. To resolve the origin of this discrepancy, detailed reconstructions are needed from both sides of the Tasmanian Gateway. Paleocene–Eocene sedimentary archives from the west of the Tasmanian Gateway have unfortunately remained scarce (only IODP Site U1356), and no well-dated successions are available for the northern sector of the AAG. Here we present new stratigraphic data for upper Paleocene and lower Eocene strata from the Otway Basin, southeast Australia, on the (north)west side of the Tasmanian Gateway. We analyzed sediments recovered from exploration drilling (Latrobe-1 drill core) and outcrop sampling (Point Margaret) and performed high-resolution carbon isotope geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and pollen biostratigraphy on sediments from the regional lithostratigraphic units, including the Pebble Point Formation, Pember Mudstone and Dilwyn Formation. Pollen and dinocyst assemblages are assigned to previously established Australian pollen and dinocyst zonations and tied to available zonations for the SW Pacific. Based on our dinocyst stratigraphy and previously published planktic foraminifer biostratigraphy, the Pebble Point Formation at Point Margaret is dated to the latest Paleocene. The globally synchronous negative carbon isotope excursion that marks the Paleocene–Eocene boundary is identified within the top part of the Pember Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the dinocyst Apectodinium prior to this negative carbon isotope excursion prohibit a direct correlation of this regional bio-event with the quasi-global Apectodinium acme at the Paleocene–Eocene Thermal Maximum (PETM; 56 Ma). Therefore, the first occurrence of the pollen species Spinizonocolpites prominatus and the dinocyst species Florentinia reichartii are here designated as regional markers for the PETM. In the Latrobe-1 drill core, dinocyst biostratigraphy further indicates that the early Eocene (∼ 56–51 Ma) sediments are truncated by a ∼ 10 Myr long hiatus overlain by middle Eocene (∼ 40 Ma) strata. These sedimentary archives from southeast Australia may prove key in resolving the model–data discrepancy in this region, and the new stratigraphic data presented here allow for detailed comparisons between paleoclimate records on both sides of the Tasmanian Gateway.
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Johnson, Ronald, Justin Birdwell, and Tracey Mercier. "Controls on organic matter distributions in Eocene Lake Uinta, Utah and Colorado." Mountain Geologist 55, no. 4 (December 2018): 177–216. http://dx.doi.org/10.31582/rmag.mg.55.4.177.
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The Green River Formation deposited in Eocene Lake Uinta in the Uinta and Piceance Basins, Utah and Colorado, contains the largest oil shale resource in the world with an estimated 1.53 trillion barrels of oil in place in the Piceance Basin and 1.32 trillion barrels in the Uinta Basin. The Douglas Creek arch, a slowly subsiding hinge-line between the two basins, created separate deep depocenters, one in each basin with shallow water conditions near the crest of the arch. Lake Uinta was a saline lake throughout its history with a lower saline to hypersaline layer (monimolimnion) and an upper less saline layer (mixolimnion). Most of the organic matter in the Green River Formation was derived primarily from algae that lived in the photic zone of the lake and is very hydrogen-rich and oil-prone. In many modern large and deep lakes, rates of organic matter production are highly variable due to differences in nutrient supply. However, cyclonic circulation often leads to winnowing out of organic and mineral matter in the mixolimnion leading to organic matter and fine-grained mineral matter being deposited in increasing amounts toward hydro-dynamically dead zones in the center of the circulation producing concentric bands of increasing organic matter content. Organic matter transport through the dense, hypersaline monimolimnion may have been facilitated by low density organic matter attaching to more dense clay mineral particles. Most of the oil shale intervals deposited in Lake Uinta display similar patterns in their organic matter distributions, increasing in very regular fashion toward the central areas of the lake’s two depocenters. This concentric feature is particularly prominent in the most laminated oil shale zones. Here, we propose that cyclonic circulation was present in Lake Uinta. Each basin appears to have had its own circulation currents, separated by shallow water conditions near the Douglas Creek arch, and one hydrodynamically dead zone in each basin. Sediment gravity flow processes were also very active in some strata of Lake Uinta, leading to the reworking and re-depositing of sediments. Two general types of sediment gravity flows are recognized: (1) organic-rich sediment gravity flows that reworked and may have concentrated organic-rich material closer to the two deep depocenters, and (2) sandstone- and siltstone-rich organic-poor mass movement deposits that originated on marginal shelves. Mass movements could have been triggered by various natural processes and/or possibly by the movement of dense brines that evolved on marginal shelves and moved along the bottom of the water column toward the deep part of the lake. The uppermost, poorly consolidated sediment layer was incorporated in sediment gravity flows as they moved, and in many cases sediment gravity flows scoured down significantly into the more consolidated underlying sediment producing large rip-up clasts of laminated sediments. Truncation of more than 100 ft occurs at the base of a sequence of sediment gravity flows in one well, indicating a significant incised channel. Coarser-grained sediment gravity flows terminated before reaching the lake’s deepest areas, forming thick concentric buildups of organically lean sediment near the base of the marginal slopes. Intervals dominated by organic-rich fine-grained sediment gravity flows have tightly concentric bands of increasing organic matter toward the deepest parts of the lake and can be organically richer than the richest laminated intervals. There is some evidence that the hydrodynamically quiet zones did not always correspond closely to the deepest areas of the lake, extending in some cases into some shallower areas.
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Rolle, Flemming. "Late Cretaceous – Tertiary sediments offshore central West Greenland: lithostratigraphy, sedimentary evolution, and petroleum potential." Canadian Journal of Earth Sciences 22, no. 7 (July 1, 1985): 1001–19. http://dx.doi.org/10.1139/e85-105.
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Five dry exploratory wells were drilled through Upper Cretaceous and Tertiary sediments on the West Greenland shelf in 1976 and 1977. Two of these entered Precambrian basement, two bottomed in Paleocene or Upper Cretaceous basalt, and one in Campanian mudstone. On the basis of samples and logs supplied to the Geological Survey of Greenland the sedimentary sequence has been divided into seven new formations: the Campanian Narssarmiut Formation, consisting of coarse basement wash and black mudstone; the Campanian to Eocene Ikermiut Formation, consisting of marine organic-rich mudstone; the Upper Paleocene to Eocene Hellefisk Formation, comprising shallow-marine to paralic sandstone and mudstone; the Eocene Nukik Formation, consisting of turbiditic sandstone and mudstone; the Eocene to Oligocene Kangâmiut Formation of shelf to shallow-marine clean and argillaceous sandstone; the Oligocene to Neogene Manîtsoq Formation, consisting of coarse paralic to fan delta sandstone; and the Neogene Ataneq Formation, consisting of protected shallow-marine mudstone.The sedimentary evolution of the area fits well with earlier proposed models for the tectonic evolution of the Baffin Bay–Labrador Sea region.Potential petroleum source rocks are present in the Upper Cretaceous to Paleocene mudstone, and, even though they are largely immature in the drilled sections, they are expected to have entered the petroleum generation zone in the deeper parts of the basin. Their potential is mainly for gas, but some oil potential is also present. No reservoir rocks were encountered in the deeper parts of the sedimentary sequences, and the porous sandstones that occur higher in the sequence lack seals.
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Bozukov, Vladimir, Milorad Vatsev, Dimiter Ivanov, and Nikolay Simov. "New fossil flora from Palaeogene sediments near Bersin village (SW Bulgaria)." Review of the Bulgarian Geological Society 82, no. 3 (December 2021): 102–4. http://dx.doi.org/10.52215/rev.bgs.2021.82.3.102.
Full textAbstract:
Data for new local palaeoflora near the village of Bersin (SW Bulgaria) are presented. Eight species of fossil plants have been identified. Eotrigonobalanus furcinervis is dominant over other species. The flora-bearing layers originate from the lower part of the Nevestino Formation, which is formed by alternating sandstone and mudstone sediments. Based on the established fossil macroflora, it can be assumed that the age of the flora-bearing sediments is late Eocene.