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... The confirmed late Paleocene to early Eocene age range for the whole Red Bank means that this stratigraphic unit encompasses the Paleocene-Eocene Thermal Maximum (PETM) global climatic event, as well as the time interval of some significant eustatic high and low sea-level stands (see the global sea-level curve in Miller, 2009; also see Miller et al., 2005). Apparently, evidence for the effects of the PETM in Belize are evaporite-bearing beds within the Red Bank, including layers with decimeter-scale, inter-grown crystals of gypsum and anhydrite. ...
... We suggest that the depositional model presented here, including the hypothesis about the Red Bank's geometry with respect to paleo-valleys, may be helpful in future efforts at more accurate seismic exploration processing in the study area. Figure 5. Eustatic sea-level curve in meters of elevation above present (data points from Miller, 2009) (from Ricketts, 2020. In this rendering of the data, points were plotted for the pertinent portion of the Early Cenozoic global sea-level curve. ...
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The informal upper Paleocene to lower Eocene Red Bank group crops out in several areas of the Cayo and Orange Walk districts of northern Be-lize including the study area of the present report, which is the area around the oil fields of Spanish Lookout and Never Delay. Previous studies, which assigned the wrong age to the Red Bank group, described the Red Bank as mainly a clay (or soft claystone) deposit containing minor carbonate and evaporite beds and nodules. However, our present research, which relies on new petrographic and cartographic techniques, revealed that the Red Bank group is a complex stratigraphic unit of open estuarine origin that has a depositional history closely linked to global climatic and eustatic events. Well-log correlation in the study area around the Spanish Lookout and Never Delay oil fields suggests that the Red Bank unconformably overlies the Upper Cretaceous Barton Creek limestones. In fact, the clay deposits of the Red Bank fill caverns and karstic features within the upper part of the Bar-ton Creek limestones, and thick clay accumulations lie within karstic paleo-valleys such as the long, northeast-trending, fault-bounded karstic valley within the study area.
... Ma), which is consistent with the age of the Numidian Sandstones from Tunisia, allows us to correlate the Numidian sand event with the global sea-level curve. More precisely, the onset of Numidian Sandstone sedimentation occurs in correspondence with the beginning of a sea-level drop at ca. 20.4 Ma (Miller et al., 1998(Miller et al., , 2005(Miller et al., , 2020(Miller et al., , 2005Miller, 2009). Furthermore, the sedimentological features and the depositional environment reconstructed for the Numidian Sandstones are in agreement with a stage of sea-level fall. ...
... Tectonics that were responsible for the early Miocene growth of the Atlas Chain played a primary role in providing a regional extended source area for quartz grain supply. However, the global sea level lowstand occurred at 20.4 Ma (Miller, 2009;Miller et al., 2020), and the warm-humid climate that affected the North African region in the early Miocene (Jacobs, 2004;Prista et al., 2015) were equally relevant in supplying significant quantities of sediments into the Mediterranean sedimentary basins, thereby strongly enhancing the effect of tectonic uplift. ...
Article
The Numidian Sandstones are widespread throughout the western Mediterranean, from Spain and North Africa to southern Italy. They consist of intercalations of thick ultra-mature sandstones within brownish shale deposits. Crucial issues about the Numidian Sandstones are still under debate, such as their pertinence to an undisputed paleogeographic domain and their age. In addition, in the Moroccan Rif, detailed sedimentological studies are still lacking, preventing the understanding of the main features of the sedimentary basin in which the Numidian Sandstones were deposited. This paper aims to reconstruct the Numidian Sandstone depositional environment via a detailed sedimentological study and provides new time constraints through quantitative analyses of calcareous nannofossil assemblages. The Numidian Sandstone sedimentary features suggest a depositional environment located in the transition between a lower muddy slope and a deeper basin plain. Quartz-rich sandy turbidites supplied sediments to this basin during a tectono-sedimentary event lasting ca. 1 Myr in the early Burdigalian. A key section from the Tanger Unit shows the Numidian Sandstones in stratigraphic continuity with the pre-Numidian deposits of the External Tanger Unit (Intrarif sub-domain). This evidence allows us to reject the notion of the Numidian Sandstones as a nappe, detached at their base from the pre-Oligocene deposits of the more internal units of the Flysch Basin. The new biostratigraphic analyses performed on the Numidian Sandstones from northern Morocco mostly correlate with the depositional age of the Numidian Sandstones outcropping in the rest of the Maghrebian Chain. The Numidian sand event, which affected the SW sector of the Mediterranean Basin from the Betics to the southern Apennines, was a unique and extensive event that was possibly triggered by the interplay among the uplift of the Atlas Chain, the sea-level drop at 20.4 Ma, and the establishment of a humid climate in North Africa at the beginning of the Miocene.
... During the early Paleogene, the study area was near the east flank of the Cordilleran orogen, and moisture was mainly derived from the paleo-Gulf of Mexico and recycled vapor from lakes in Wyoming, Utah, and Colorado (USA) (Feng et al., 2013). The large-scale atmospheric circulation pattern likely remained the same from the early to the late Paleogene because of the high Cordilleran hinterland , but the moisture from the paleo-Gulf of Mexico may have reduced during the Paleogene (Chamberlain et al., 2012) because of southward shoreline retreat (Miller, 2009;Galloway et al., 2011). ...
... Our suggestion of gradual late Paleogene drying in northwestern Montana and southeastern British Columbia is consistent with the interpretation of gradual drying based on increasing vadose zone carbonate δ 18 O and δ 13 C values in the Sage Creek Basin in southwestern Montana (Schwartz et al., 2019). The drying trend and changes in molluscan diversity recorded in the Kishenehn Basin likely resulted from weakening of the North American monsoon (Chamberlain et al., 2012;Feng et al., 2013) in association with sea-level drop and southward movement of the paleo-Gulf of Mexico during global climate cooling (Miller, 2009;Galloway et al., 2011). ...
Article
The paleotopographic history of the North American Cordilleran orogen holds the key to understanding mechanisms of orogenesis and subsequent orogenic collapse. It has been suggested that the orogenic front in western Montana (USA) and Alberta (Canada) was more than 4 km high during Late Cretaceous−early Eocene contractional deformation and during the initial phase of extension in the middle Eocene; however, the late Eocene−Oligocene topographic evolution during continued extensional collapse remains poorly constrained. Here we extend the paleotopographic record in the Kishenehn Basin in northwestern Montana and southeastern British Columbia (Canada) to the late Oligocene by studying δ18O values of fossil mollusks and cement and paleosol carbonates. The molluscan taxa changed from three sympatric groups with preferred habitats ranging from tropical wet, semi-arid subtropical, and temperate during the middle and late Eocene, to mainly a single group associated with temperate environment during the Oligocene, reflecting a decline in molluscan biodiversity induced by climate cooling across the Eocene−Oligocene transition. Reconstructed δ18O values of alpine snowmelt and basinal precipitation decreased by 1.4‰ and 3.8‰, respectively, from the middle to late Eocene, reflecting climate cooling and ∼1 km surface uplift of the basin floor. The reconstructed alpine snowmelt δ18O values then increased by 2.9‰ in the Oligocene suggesting a ∼0.5 km drop in elevation of the orogenic front. Collectively, the results of our new and previously published δ18O data chronicle the paleotopographic response to the change from flat-slab subduction to slab rollback over a 45 m.y. period. These data suggest that the orogenic front was characterized by high elevation (>4 km) in the ancestral Lewis-Clark-Livingston ranges during latest Cretaceous−early Eocene (ca. 75−52 Ma) contraction. The initial phase of extension related to the Kishenehn Basin created a lowland basin with a surface elevation of only ∼1.5 km during the early middle Eocene (ca. 46−44 Ma) whereas the ranges remained >4 km high. The high range elevations were sustained for at least 12 m.y. in the middle to late Eocene concurrent with extension, while the basin floor elevation was uplifted to ∼2.5 km by the latest Eocene (ca. 36−34 Ma). Basin aggradation can explain at most half of the 1 km basin floor uplift. The remaining amount (at least 0.5 km) and sustained high range elevation suggest that range denudation and crustal extension was compensated by the isostatic and thermal effects of slab rollback and/or passage of a slab window and infusion of hot asthenosphere beneath the continent. The range elevation in the orogenic front decreased ∼0.5 km by the late Oligocene (ca. 28 Ma), associated with a decrease in rock uplift rate associated with extension. A post-Oligocene elevation drop of ∼1 km resulted in both the ranges and basin floor reaching modern topography in the Kishenehn Basin drainage, likely due to the regional effect of Neogene Basin and Range extension. This study, along with the previous investigation of the Kishenehn Basin by Fan et al. (2017), are the first studies that systematically investigate paleorelief of the orogenic belt by reconstructing paleoelevations of the mountains and the basin at the same time. The results highlight that the Cordilleran orogenic front of northern Montana and southern British Columbia sustained its high elevation edifice for at least 12 m.y. after the start of extension. We suggest that initial crustal extension did not result in orogenic demise because of concurrent thermal and isostatic uplift.
... Comparison between the depositional sequences and isotopic curve of the Asmari succession with eustatic sea-level change during the Oligocene-Miocene period illustrated by Haq et al. (1987) and Abreu and Haddad (1988) and global oxygen isotopes (Miller, 2009) shows a good link between global sea-level change and sea-level fluctuation during deposition of the Asmari Formation during the Oligocene-Miocene time (Fig. 13). Therefore, depositional sequences of the Asmari succession have been affected by the global sea-level change. ...
... Depositional sequence stratigraphy correlation of this study with other studies from Dezful Embayment (Ehrenberg et al., 2007;Van Buchem et al., 2010;Avarjani et al., 2015) and Arabian Plate (Sharland et al., 2001(Sharland et al., , 2004. . 13. Correlation between depositional sequences and isotopic curves of the Oligocene-Miocene Asmari succession with global oxygen isotopes (Miller, 2009) and eustatic sea level curves derived from coastal onlap patterns for the Oligocene-Miocene boundary interval from Haq et al. (1987). ...
Article
Integrated methods have been applied for the high resolution sequence stratigraphic analysis of a mixed petroliferous carbonate-siliciclastic succession of the Asmari Formation (Oligocene-Miocene) in the Zagros Basin. Detailed sedimentological (core description) and petrographical (one thousand one hundred fifty thin sections) analysis led to identification of more than 38 carbonate and siliciclastic facies (basin wide) that have been deposited in four types of depositional environments, including inner ramp, mid ramp, outer ramp and basin, in homoclinal ramp type carbonate platform. An integrated multidisciplinary approach including core descriptions, petrography, biostratigraphy, gamma-ray spectrometry (e.g., uranium (U), thorium (Th) and Potassium (K)), oxygen and carbon isotopes (Chemo-stratigraphy) and trace element analysis have been used for stratigraphic interpretations of this succession. Based on petrography, biostratigraphy, lateral and vertical facies changes, and GR log, 6 third-order cycles distinguished, whose boundaries correspond to distinct δ¹³C and δ¹⁸O negative peaks. Trace elements (Fe and Mn) contents along with oxygen and carbon isotopes variations are compared with distribution of sedimentary facies and depositional sequences to investigate and correlate stratigraphic boundaries, which are determined by sequence stratigraphy (GR log and facies analysis) and stable isotope stratigraphy (Chemo-stratigraphic) in shallow marine carbonate platform of the Asmari. Negative isotope and elemental peaks coinciding with the sequence boundaries while the positive isotope and elemental peaks are correlated with maximum flooding surfaces. Changes in the frequency of uranium (U), thorium (Th), and Potassium (K) has been used to investigate the stratal surface and sequence boundaries as well as oxidation and reduction states. Fourth-order sequences that formed during the formation of the third-order sequence could be distinguished and separated by uranium log.
... During the early Paleogene, the study area was near the east flank of the Cordilleran orogen, and moisture was mainly derived from the paleo-Gulf of Mexico and recycled vapor from lakes in Wyoming, Utah, and Colorado (USA) (Feng et al., 2013). The large-scale atmospheric circulation pattern likely remained the same from the early to the late Paleogene because of the high Cordilleran hinterland , but the moisture from the paleo-Gulf of Mexico may have reduced during the Paleogene (Chamberlain et al., 2012) because of southward shoreline retreat (Miller, 2009;Galloway et al., 2011). ...
... Our suggestion of gradual late Paleogene drying in northwestern Montana and southeastern British Columbia is consistent with the interpretation of gradual drying based on increasing vadose zone carbonate δ 18 O and δ 13 C values in the Sage Creek Basin in southwestern Montana (Schwartz et al., 2019). The drying trend and changes in molluscan diversity recorded in the Kishenehn Basin likely resulted from weakening of the North American monsoon (Chamberlain et al., 2012;Feng et al., 2013) in association with sea-level drop and southward movement of the paleo-Gulf of Mexico during global climate cooling (Miller, 2009;Galloway et al., 2011). ...
... Thus, Plaziat (1981) found evidence of a late Lutetian transgression throughout western Europe and Canudo et al. (1991), Toledo (1992) and Montes-Santiago (2009) related the upper Lutetian unconformity with a third-order eustatic cycle of Haq et al. (1987). More recent data on global sea level changes (Miller, 2009;Miller et al., 2005Miller et al., , 2011Kominz et al., 2008) also support a transgressive phase at the Lutetian-Bartonian transition. However, the~50 m rise in sea level calculated in the External Sierras exceeds the late Lutetian global sea level rise of approximately 10 m estimated by Miller (2009) and Miller et al. (2005. ...
... More recent data on global sea level changes (Miller, 2009;Miller et al., 2005Miller et al., , 2011Kominz et al., 2008) also support a transgressive phase at the Lutetian-Bartonian transition. However, the~50 m rise in sea level calculated in the External Sierras exceeds the late Lutetian global sea level rise of approximately 10 m estimated by Miller (2009) and Miller et al. (2005. The previous estimate of a late Lutetian global sea level rise of 20 m (Haq et al., 1987) is also far below the magnitude of the sea level rise deduced in this work. ...
Article
A detailed sedimentological and magnetostratigraphic analysis of three selected sections of the Eocene carbonate platforms of the South Pyrenean Jaca-Pamplona foreland basin has been carried out in the Aragonese External Sierras (Huesca, Spain). The stratigraphic record spans from the middle-late Lutetian (Chron 20r, SBZ15) to the Bartonian (Chron 18r, SBZ17). The Lutetian-Bartonian transition was characterized by a major paleogeographic change, from a turbiditic foredeep with associated peripheral carbonate ramps to deltaic sedimentation. In most of the outcrops of the External Sierras, the peripheral carbonate platforms (Guara Formation) are overlained by prodelta and outer ramp marls (Arguis Formation). The drowning unconformity between these two formations in the outcrops located in the westernmost tip of the External Sierras is documented herein for the first time. In this area, the Guara Formation is overlain by glauconitic limestones deposited in a carbonate ramp setting. Between these units a characteristic unconformity is observed, with hard-ground formation and local evidence of subaerial exposure in the shallowest domains of the study area. The abundant glauconite found on top of this unconformity records a starvation period in the basin, followed by the development of a new carbonate ramp system during Bartonian times (Santo Domingo Member of the Arguis Formation). Magnetostratigraphic and sedimentological data show that tectonic tilting occurred in latest Lutetian times, prior to the drowning process. This suggests the influence of the flexural subsidence in the cratonic margin of the foreland as a result of the advance of a basement thrust in the hinterland. Nevertheless, the correlation of the uppermost Lutetian drowning unconformity with a basinwide regional sea level rise, which may have further been global, suggests an interplay between tectonic and eustatic processes in the drowning of the late Lutetian South Pyrenean carbonate ramps. In this work we point out a narrowing of the carbonate ramp, together with a relative sea level rise, as the processes responsible for the drowning of the Upper Guara Mb carbonate ramp. These processes could be responsible for the development of drowning unconformities in cratonic margins of other foreland basins. As carbonate ramps have a high sediment production potential, the narrowing of the carbonate factory could provide the conditions for the drowning of the carbonate ramp system in a subsequent sea level rise.
... In this paper, the present author's attempt to emphasize that brackish water have been entered to the Sabaragamu Basin (Ratnapura Basin) through Kalu Ganga (river) valley during the high relative sea levels occurred during the Quaternary period. Such relative sea levels have been described by Miller (2009), Martin (2002 Martı´nez-Bot (2015) and many others. Deraniyagala (1986) proved that Late Pleistocene altithermal episodes have occurred in Sri Lanka. ...
... The entire Quaternary Period is referred to as an ice age due to the presence of at least one permanent ice sheet covered an Antarctica; however, the Pleistocene Epoch was generally much drier and colder than the present time. This situation has clearly identified from different locations of the world by many scientists (Chappell et al. 1996;Chappell, 2004;Emiliani, 1955;Evens, 1972;Hansen et al., 2013;Holmes 1966;Lambeck, 2001;Lambeck et al., 2002;Loutre, 2003;Miller, 2009;Wunsch, 2004). ...
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The Quaternary Research Working Group (QRWG) of Sri Lanka was set up at the 11th AGM of Geological Society of Sri Lanka (GSSL) in 1995 to encourage the researchers who are keen on Quaternary Studies of Sri Lanka. For this purpose, the QRWS successfully completed two field visits in the southern and northwestern coastal zones to observe the Quaternary and Holocene formations of Sri Lanka, although, we failed to organize an International Conference or proposed a one-day awareness Workshop/Seminar due to lack of funding. Hence, the Quaternary Research in Sri Lanka comes into view as a neglected field. However , the Group compiled a bibliography including twenty-six (26) subject categories relating to the Sri Lankan Quaternary. However, it is very difficult to fulfill the research gaps in relation to Quaternary Geography, Quaternary Climatology and Quaternary Ecology in detail. The Quaternary studies of Sri Lanka emerged since 1908, and pioneer scientists were British, Canadians, Germans, Indians and Sri Lankans. They described the Palaeolithic stone tools, cannibalistic Balangoda Man, the fossils of extinct animals and past climatic phases of Sri Lanka. Stratigraphic sequences, constituent material, locations and some age determina-tions on Quaternary formations have been completed by a few scientists. These scientists are undertaking Quaternary studies emphasizing different disciplines with limited facilities and funding. Also, the lack of age determination facilities in Sri Lanka is the main obstacle for the Quaternary studies of Sri Lanka.
... Bu dönemde başlıca alüvyon yelpazeleri, grabenin güney kenarındaki aktif normal fay boyunca birleşik yelpazeler oluşturarak gelişmiş, kuzey kenarda ise yelpaze gelişimi göreli sınırlı kalmıştır. (Shackleton, 1987;Fairbanks, 1989;Colonna vd.,1996;Fleming vd., 1998;Waelbroeck, 2001;Chappell, 2005;Miller, 2005;Caputo, 2007) ve Ege Denizi Menemen batısında bir körfez oluşturmaktaydı. Buradaki körfezin doğu kenarında batı yönünde akan bir akarsuyun önünde oluşan bir yelpaze deltası denize doğru büyümeye başlamış ve bu akarsu yatağını Dumanlı Dağ ile Yamanlar Dağı arasında geriye, doğuya doğru aşındırmaya başlamıştı. ...
... It is strongly possible that the ancestors of present Gördes Stream and some recent parts out of the graben of Gediz River were jointed the ancient Gediz River from northeast as tributaries along the incised valleys in the basement rocks. One of them located in north of Salihli was incised in a basalt flow erupted from the Divlittepe cone, 14.5 km NE of Adala town in the northern margin of the Gediz Graben, about 25.000 years ago (Divlittepe volcanics: Ercan, 1982Ercan, , 1993 Shackleton, 1987;Fairbanks, 1989;Colonna et al.,1996;Fleming et al., 1998;Waelbroeck, 2001;Chappell, 2005;Miller, 2005;Caputo, 2007). There was a bay of the Aegean Sea to the west of Menemen and a fan delta in front of a small stream running to the west began to prograde towards the sea at the eastern end of this bay. ...
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Z Batı Anadolu'nun en genç ve önemli yapısal elemanlarından biri olan Gediz Grabeni havzası, Kuvaterner döneminde dikkat çekici jeolojik ve jeomorfolojik aşamaları olan bir evrim geçirmiştir. Kuvaterner başından bu yana akmış olan eski ve yeni Gediz nehirleri ile değişik boyutlardaki göller, K-G genişleme rejimi içinde gelişen tektonik denetimli bir havza evrimi sürecinde çökellerini dolgulamıştır. Bu çalışmada Gediz havzasının erken ve geç Kuvaterner sırasında sinsedimanter tektonizmayla değişen karakteristikleri çökel fasiyesleri ve ortamsal özellikleri tanıtılmakta, nehrin denizle buluşma serüveninin Kuvaterner sonlarında, olasılıkla Holosen ortalarında gerçekleştiği vurgulanmakta ve havzanın Kuvaterner boyunca geçirdiği jeolojik-jeomorfolojik evrim yorumlanmaktadır. ABSTRACT The Gediz Graben basin, one of the youngest and important structural elements of the Western Anatolia, has an evolutionary history with markedly geologic and geomorphologic phases during the Quaternary. The old and actual Gediz River, running since the beginning of the Quaternary, and various sized lake have deposited their sediments during a tectonic-controlled basin evolution processes developed in N-S extension regime. In this study, sedimentary facies, environmental properties and characteristics of the Gediz basin changed by synsedimentary tectonics during the early and late Quaternary are explained. Also it is emphasized that the joining adventure of the river with the sea was probably lived in the middle of the Holocene, and the geologic and geomorphologic evolution of the river in the Quaternary is interpreted.
... Öte yandan Holosen başlarında, Menemen'in doğusunda başlıca Neojen volkanitlerinden meydana gelen KD-GB uzanımlı bir sırt, Manisa gölü ile Ege Denizi arasında bir bariyer konumundaydı. En geç Pleyistosen-erken Holosen'de tüm dünya denizlerindeki gibi Akdeniz ve Ege Denizi'nde de deniz düzeyi bugünküne göre yaklaşık 90-130 m daha alçaktı (Shackleton, 1987;Fairbanks, 1989;Colonna ve diğ.,1996;Fleming ve diğ., 1998;Waelbroeck, 2001;Chappell, 2005;Miller, 2005;Caputo, 2007) Erinç (1954Erinç ( , 1955 Menemen boğazının açılması ile ilgili olarak çeşitli alternatifler ileri sürmüştür. Erkal ve Hakyemez (1993) ile Hakyemez ve diğ. ...
... It is strongly possible that the ancestors of present Gördes Stream and some recent parts out of the graben of Gediz River were jointed the ancient Gediz River from northeast as tributaries along the incised valleys in the basement rocks. One of them located in north of Salihli was incised in a basalt flow erupted from the Divlittepe cone, 14.5 km NE of Adala town in the northern margin of the Gediz Graben, about 25.000 years ago (Divlittepe volcanics: Ercan, 1982Ercan, , 1993 Shackleton, 1987;Fairbanks, 1989;Colonna et al.,1996;Fleming et al., 1998;Waelbroeck, 2001;Chappell, 2005;Miller, 2005;Caputo, 2007). There was a bay of the Aegean Sea to the west of Menemen and a fan delta in front of a small stream running to the west began to prograde towards the sea at the eastern end of this bay. ...
Article
Full-text available
The Gediz Graben basin, one of the youngest and important structural elements of the Western Anatolia, has an evolutionary history with markedly geologic and geomorphologic phases during the Quaternary. The old and actual Gediz River, running since the beginning of the Quaternary, and various sized lake have deposited their sediments during a tectonic-controlled basin evolution processes developed in N-S extension regime. In this study, sedimentary facies, environmental properties and characteristics of the Gediz basin changed by synsedimentary tectonics during the early and late Quaternary are explained. Also it is emphasized that the joining adventure of the river with the sea was probably lived in the middle of the Holocene, and the geologic and geomorphologic evolution of the river in the Quaternary is interpreted.
... The decreasing upward trend in log (Zr/Rb) in the studied succession indicates decreasing sediment grain sizes (e.g., Spofforth et al., 2008;Beil et al., 2018), thus supporting the interpretation of a deepening upward trend.The provenance of sediments assigned to the Man Aike Formation does not suggest the occurrence of any major tectonic environmental events that could lead to a change in sedimentary sources (Dickinson, 1985;Weltje and Evhatten, 2004). Conversely, global sea level reconstructions during the Eocene point to transgressive episodes, coupled with warming episodes, marked by a significant marine incursion over parts of southern South American and the Antarctica Peninsula (Haq et al., 1987;Ivany et al., 2008;Malumián, 2002;Miller and Gornitz, 2008;Huyghe et al., 2012;Payros et al., 2012;Westerhold et al., 2017;Fosdick et al., 2020). Furthermore, there is a correspondence between high abundances of glauconite and the occurrence of warm climates during the Paleogene (Zachos et al., 2001;Royer, 2006;Zachos et al., 2008;Benerjee et al., 2020). ...
... By the time of OWM and NWM separation, Old World and New World were alreadỹ 2000 km apart, which raises the question of how and where exactly NWM have entered South America as there was no land bridge present and sea levels remained approximately 200 m higher than nowadays [36]. Accepted explanatory approaches for the transatlantic migration of primates consider "island hopping" and, particularly, the presence of "floating islands" [37][38][39][40][41]. ...
Article
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Alu-elements comprise a large part of the human genome and some insertions have been shown to cause diseases. Here, we illuminate the protective role of an Alu-element in the 3’UTR of the human Factor 9 gene and its ability to ameliorate a poly(A) site mutation in a hemophilia B patient, preventing him from developing a severe disease. Using a minigene, we examined the disease-causing mutation and the modifying effect of the transposon in cellulo. Further, we simulated evolutionary scenarios regarding alternative polyadenylation before and after Alu insertion. A sequence analysis revealed that Old World monkeys displayed a highly conserved polyadenylation sites in this Alu-element, whereas New World monkeys lacked this motif, indicating a selective pressure. We conclude that this transposon has inserted shortly before the separation of Old and New World monkeys and thus also serves as a molecular landmark in primate evolution.
... The Cenozoic is distinguished by remarkable climate and paleoceanographic global changes that have been recorded during the Oligocene and Miocene epochs, including the Late Oligocene Warming the Miocene Climate Optimum, and the Middle Miocene Climate Transition (Lear et al., 2015;Frigola et al., 2018;Steinthorsdottir et al., 2021 and references therein). These changes have resulted from alternating cold and warm periods, coupled with fluctuations in sea levels (Kominz et al., 2008;Müller et al., 2008;Miller, 2009), which have had notable impacts on marine ecosystems. ...
Article
Sedimentary carbonate outcrops of the Pirabas Formation at the Bragantina platform in North Brazil represent the exposed portion of the entire carbonate succession in the marine equatorial platform from the subsurface Ilha de Santana Formation (Cretaceous/Maastrichtian-Miocene/Messinian) in the Pará-Maranhão Basin. The transgressive deposits, flooding, and advance of the carbonate platform were investigated through the study of outcrops of the Pirabas Formation (type locality in the Ilha de Fortaleza, Pará state) and the analogous carbonate from the uppermost section of the Ilha de Santana Formation from the well 1-MAS-16-MA (510–660 m below sea floor). The stratigraphic analyses were based on petrography, microCT, microfossil assemblages (foraminifera, ostracods, and bryozoans) and index species (Amphistegina, Archaias, Pyrgo, Quinqueloculina, Pirabasoporella, Nellia, Skylonia, and Alpheus), and biofacies approach. The Ilha de Santana Formation (Burdigalian/Langhian at 510–660 mbsf section of 1-MAS-16-MA) and the Pirabas Formation (Burdigalian at the Ilha de Fortaleza outcrops) suggest that shallow-water sedimentary facies are similar to those deposited in the marginal basins and mark the start of siliciclastic supplies to the inner platform and the decline of coralline algae carbonate factories. Full text free download for the next 50 days https://authors.elsevier.com/c/1iRm73BkFSdna-
... Our high-resolution data improves over Abul-Nasr and Thunell's (1987) sea level curve (Fig. 8). In general, for the studied section (including the Thebes, Darat and Khaboba formations), sea level gradually decreases, consistent with the global eustatic sea level curve (Miller, 2009). A gradual sea level rise from the base to the middle of the Thebes Formation culminates in a maximum flooding surface that also marks the maximum sea level rise noted for the entire studied section (Fig. 8). ...
... Sealevel fluctuation is one of the basic factors affected the evolution of the Earth's surface system. In particular, sea-level change has a significant effect on the surface process of sedimentary evolution (Christie-Blick and Driscoll, 2005;Hallam, 1992;Haq and Al-Qahtani, 2005;Haq et al., 1987;Miller, 2009). Here, we use the ideal sea-level change curve in all models. ...
Article
Strike-slip faults in pull‐apart basins commonly display complex 3D geometric structures, which makes it challengeable to interpret spatial and temporal evolution of the basins. Coupled thermo-mechanical and surface process models represent a powerful tool to investigate structural development of pull-apart basins and the associated sedimentary architectures. We set up three cases with representative end-member strike-slip fault patterns: 45° underlapping releasing stepover, 90° non-overlapping releasing stepover, and 135° overlapping releasing stepover. Our numerical models have successfully simulated the evolution of the developed dextral strike-slip fault systems. According to the simulation results, we found that the sediment distribution varied in each model at different stages of the basin evolution. In the beginning, the sedimentary range is the largest in the 45° underlapping releasing stepover model, but it is the smallest at the end. However, the 135° overlapping releasing stepover model showes the opposite result. Furthermore, the geometry of the basin usually depends on the underlying fault system. We observed that the activity of internal/inside faults is gradually becoming higher than that of external/outside faults as the basin evolves. Therefore, we conclude that internal normal faults are more important for basin development than external normal faults, especially in the 135° overlapping releasing stepover model. Specifically, the shape of basin basement changes from U to V at this stage because the newly developed faults are mainly concentrated in the depocenter causing rapid subsidence in the final stage of the overlapping model.
... It is clear that, for the examined rock units, the sea level decreases from the base (Gehannam and Birket Qarun formations) to top (Temple Member), and is regular with the global decline in sea level curve (Miller, 2009 ...
Article
The present study focuses principally on the late Middle Eocene–early Late Eocene ostracods from two successions (Garet Umm Rigl section and Qasr El Sagha sections), in the northwestern portion of Fayoum area, Egypt. Stratigraphically, the studied successions are classified into three formations (from base to top), the Gehannam, Birket Qarun, and Qasr El Sagha (Temple Member). The recorded ostracod assemblage contains 33 species belonging to 20 genera and 9 families. According to their stratigraphic ranges, three local biozones are recognized, Asymmetricythere yousefi–Loxoconcha pseudopunctatella, Reticulina heluanensis–Leguminocythereis sadeki, and Trachyleberis nodosus nodosulcatus–Ruggeria (Keijella) glabella. The comparison of the proposed biozones with their equivalents inside Egypt denotes a Middle–Late Eocene age for the studied sections. Based on the character of investigated ostracods, three ecozones are distinguished. An inner–outer neritic environment is suggested for the first ecozone, inner-middle neritic conditions for the second, while shallow water conditions are proposed for the third ecozone. In addition, this paper represents an attempt to detect the palaeobiogeographic provinces of Eocene ostracods by means of multivariate analyses (principle component analysis, Q-mode cluster analysis and similarity index). These analyses are applied on a matrix composed of some selected Eocene species from 10 regions located at the southern Tethys and western Africa. The results identify three distinctive provinces, North Africa (Algeria, Tunisia, Libya, and Egypt), the Middle East (Jordan and Israel) and West Africa (Senegal, Togo, Ivory Coast and Nigeria). The distinctive affinities between these provinces suggests ostracod migration along the southern Tethys during the Eocene age.
... The Tethys and Paratethys anoxia in the global context. A comparison with atmospheric CO2 measurements and estimates, stable isotopes (δ13C and δ18O) from benthic foraminifera(Westerhold et al. 2020), global sea-level curve(Miller 2009) and key volcanic and oceanographic events (references in the text). ...
Article
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A complex interplay of palaeoclimatic, eustatic and tectonic processes led to fragmentation and dissipation of the vast Tethys Ocean in Eocene-Oligocene times. The resulting Paratethys Sea occupied the northern Tethys region on Eurasia, grouping water masses of various subbasins, separated from each other and from the open ocean through narrow and shallow gateways and land bridges. Changes in marine gateway configuration and intra-basinal connectivity affected the regional hydrology, shifting most Paratethyan basins to extreme carbon-sink anoxic environments, anomalohaline evaporitic or brackish conditions or even endorheic lakes. Paratethys gateway restriction triggered the onset of a long-lasting (∼20 Myr) giant anoxic sea, characterised by stratified water masses and anoxic bottom water conditions, resulting in thick hydrocarbon source rocks. Here, we review the geological evolution of the “dire straits” of Paratethys that played a crucial role in the Eocene-Oligocene connectivity history of the Central Eurasian seas and we show that the main anoxic phases (Kuma and Maikop) correspond to restricted connectivity with the global ocean and a period of CO2 depletion in the atmosphere. Paratethys represents one of the largest carbon sinks of Earth's history and may thus have played a prominent role in global climate change.
... X. subglobosa was recorded by Bosquet (1852) in France and Belgium and by Şafak and Güldürek (2016) (Bassiouni & Luger, 1996) with common occurrences in Egypt (Elewa, 2005), confirming the connection of Somalia with the southern Tethyan by epicontinental seas by which exchange and migration of taxa could occur during the Middle-Late Eocene (Shahin et al., 2008). According to the relative sea level, it gradually decreases in the three studied sections and is compatible with the global eustatic sea-level curve (Miller, 2009) and surrounding areas in Egypt such as Wadi Nukhul in Siani (Farouk, Jain, Belal, Omran, & Al-Kahtany, 2020). Moreover, the rapid decline of the microfossil assemblages (foraminifera, calcareous nannoplanktons, and ostracods) in the study area shows a distinct drop in their abundance towards the Middle/Upper Eocene unconformity (Hassan & Korin, 2019). ...
Article
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In an attempt to define the palaeoecology and palaeobiogeography of the Middle-Late Eocene rock units in the North Eastern Desert of Egypt, 121 rock samples of three representative localities, namely, Wadi Degla, Gebel Abu-Shama, and Gebel Qattamiya sections were collected and investigated. Qualitative and quantitative analysis of ostracods associations and sedimentological data were used to identify three ostracod biozones; two acme zones (Cytherella tarabulusensis and Loxoconcha vetustopunctatella) of the Middle Eocene age and one assemblage zone (Xestoleberis subglobosa–Uromuellerina saidi) of Middle-Late Eocene age, reflecting palaeoenvironments in the study area. The Cytherella tarabulusensis Zone, located at the bottom of all sections, is characterized by restricted shallow water, low dissolved oxygen, high salinity, and water depth below 100 m. The Loxoconcha vetustopunctatella Zone, located in Wadi Degla and Gebel Qattamiya sections, is characterized by shallow normal warm waters in the range of 20–50 m, whereas Xestoleberis subglobosa–Uromuellerina saidi Assemblage Zone, located in all studied sections, reflects restricted shallow water with a reduced dissolved oxygen condition palaeoenvironment. Palaeobiogeographically, the recorded ostracod assemblage exhibits similarities with those recorded in the Middle East and North and East Africa bioprovinces.
... Below 21.0m the limestone is partially weathered, but the clay content is definitely calcareous. The borehole stratigraphy enables one to study the climatic and sea-level fluctuations during the Quaternary (Miller 2009). It further emphasized that the Miocene limestone deposits extend further south than the represented lines in Geology maps (Katupotha and Dias 2001). ...
Article
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The Muthupanthiya Lagoon, situated south of the Mundal Lake, on the west coast of Sri Lanka is located incorporating both lagoonal and estuarine deposits. An investigation of five numbers boreholes was drilled on the lagoon bed, out of which, one boring was drilled deep to reveal Miocene limestone as the basement rock at a depth of 20.50m. The Quaternary in these borings is represented by a sequence of unconsolidated deposits, which include peat, organic clays, sandy clays, sand, and plastic clays in the overburden horizons. The sandstone in the boreholes was fairly dense, consolidated, and friable. The friability of the sandstone indicates de-cementation by fresh acidic water from inland. The sandstone along its profile shows variability, with patches of mudstone, indicating a fluctuation in the sedimentation process. It was also interesting to note that "fluvial worked gravels" and marine sands, below the sandstone from 18.80 to 20.50m. These deposits can be correlated with the Early Pleistocene to Late Holocene period. The fifth borehole was terminated within limestone at 22.70m, which reveals that Miocene limestone is the basement rock at a depth of 20.50m. In northwest Sri Lanka, the Miocene limestone is represented by a hypothetical boundary south of Puttalam due to the lack of outcrops. By this investigation, the Miocene belt has been proven further south, up to the Deduru Oya estuary, on the west coast.
... In light of the clear affinity of Cannosphaeropsis taxa with less restrictive marine settings, a more offshore preference for Cannosphaeropsis franciscana is supported by the marine palynological assemblage data from the Oyster Bay Formation. The most elevated C. franciscana cyst concentrations occur within Zone D3 (~1-361 cysts g -1 , avg.~123 cysts g -1 ) and subzone D4a (~20-370 cysts g -1 , avg.~133 cysts g -1 ) in association with the highest relative abundances of taxa belonging to the coastal Cordosphaeridium group and distally transported saccate pollen within intervals presumed to coincide with periods of sea level rise including that of the prominent global transgressive regime in the early Danian (e.g., Miller, 2009;Esmeray-Senlet et al., 2015;see McLachlan and Pospelova, 2021). Pyrite crystal infill is also a frequent occurrence among specimens recovered from Zone D3 and their octahedral shapes (Plate XII, 1) indicate diagenetic formation under sulfur-rich suboxic or anoxic conditions likely related to processes of bacterial sulphate reduction in organic-rich sediments due to high primary productivity in the upper water column (e.g., Schoonen, 2004;Barnard and Russo, 2009). ...
Article
Wall structure and process type have long been essential taxonomic characters used in generic and specific determinations among spiniferate gonyaulacacean dinoflagellate cysts. We observe solid to fully vesiculate wall structure as well as a range of surface texture and process development all within a suite of over 400 specimens of the species Cannosphaeropsis franciscana recovered from the sedimentary rocks of the upper Maastrichtian–lower Selandian Oyster Bay Formation, Vancouver Island (British Columbia, Canada). The genus Cannosphaeropsis is herein provided with an emended diagnosis and description to accommodate this variability as is the species Cannosphaeropsis franciscana which represents a plexus of conspecific morphology unparalleled within the fossil Gonyaulacaceae. In addition, we propose three subspecies of Cannosphaeropsis franciscana: Cannosphaeropsis franciscana subsp. franciscana (autonym), Cannosphaeropsis franciscana subsp. vacuoseptata subsp. nov., and Cannosphaeropsis franciscana subsp. vesiculata subsp. nov. Most vesiculate forms of the species are stratigraphically constrained to within localized Dinoflagellate Cyst Zone D3 situated immediately above the K/Pg boundary. Vesicles are suggested as an adaptation prolonging cyst buoyancy in the water column. Within C. franciscana, prominent vesiculation occurs during an interval characterized by unstable, stratified marine conditions associated with the post-Cretaceous transgressive phase. Assemblage data throughout the formation also indicate that abundances of the vesiculate genus Hafniasphaera increase in nutrient-rich and likely stratified coastal waters when Spiniferites species are also abundant. The paleoecology of Cannosphaeropsis and the value of these dinoflagellate cysts as paleoenvironmental indicators is considered as well as all currently accepted members of the genus and their chronostratigraphic and geographic distributions.
... Haq et al. (1988) record global transgressive deposits and a sea level increase of~50 m over~0.5 myr in the lead up to the K/Pg boundary. Miller (2009) questioned the validity of these estimates while providing evidence of an abrupt transgression in the early Danian alongside a composite eustatic trend line indicating a~10 m sea level rise throughout the Danian on average. Early Danian sea level elevation has been corroborated by a range of foraminiferal studies (e.g., Brinkhuis and Zachariasse, 1988;Keller et al., 1993) and greater paleodepth resolution has been attained from work on transgressive system tracts in Europe and eastern North America (Esmeray-Senlet et al., 2015) as well as Africa (Farouk and Jain, 2016) signalling a highstand in the earliest Danian following a sea level rise of !25 m beginning below the K/Pg boundary. ...
Article
A conformable K/Pg boundary succession is reported for this first time in North America west of the Rocky Mountains and in the north-eastern Pacific based on biostratigraphic controls, occurring within the upper Maastrichtian–lower Selandian marine sedimentary rocks of the Oyster Bay Formation, Vancouver Island, British Columbia. Approximate placement of the boundary is made possible by a suite of temporally constrained palynological K/Pg interval indicator taxa. The low-diversity, homogenous coastal dinoflagellate cyst assemblages of the Cordosphaeridium, Glaphyrocysta, Hystrichosphaeridium and Spiniferites-dominated uppermost Maastrichtian of the Lynnwood section transition to that of a more intermixed estuarine setting dominated by Areoligera, Exochosphaeridium and Ginginodinium along with peaks of low-salinity tolerant Senegalinium into the Danian–Selandian strata of the Appian Way and Oyster River sections. A marine assemblage turnover in the middle Oyster Bay Formation under conditions of elevated primary productivity and community heterogeneity owing to nutrient-rich waters is observed. Evidence for this interpretation is reinforced by the presence of overall higher cyst concentrations, peridinioid abundance and greater species diversity in association with botanical and shallow marine invertebrate fossil assemblages. The palynological data record probable eustatic regressive and transgressive sequences which illustrate a history of fluctuation between a predominantly coastal and largely estuarine paleoenvironment punctuated by the end-Cretaceous event. The presence of heavily negative δ¹³Corg values in addition to facies changes throughout the succession support a neritic profile for the Oyster Bay Formation. The palynological assemblages reflect localized paleoenvironmental conditions and climatic changes across the K/Pg boundary consistent with observations from numerous localities across both hemispheres.
... There would also have been more local tectonic and geographical controls of relative sea level (eurybatic shifts of Haq, 2014) including subsidence, uplift and sediment supply (Miller, 2009), and their influence on the construction and destruction of coastal barrier complexes (Allen, 1998;Radley, 2002). For example, fault-induced subsidence was proposed by Underhill (2002) to account for the rapid submergence of basal Purbeck trees and at least some subsequent episodes of marine recharge and the vertical movement of massifs no doubt modified gulf entrances regionally (Allen, 1998). ...
Article
Durlston Bay in Dorset, southern UK, type section of the Tithonian-Berriasian Purbeck Limestone Group, has been intensely studied with regard to its marginal marine palaeoenvironments, rich fossil biota and evidence for earliest Cretaceous climate change. Here we appraise aspects of these topics, incorporating new field observations. We offer changes in charcoal density as a further line of support for a mid-Berriasian moistening of the climate, but suggest that the primary driver of palaeoenvironmental and biotic changes observed through the Purbeck succession was varying input of marine water, with climate change having an overlying and often more subtle influence.
... The cores stratigraphy enable to study the climatic and sea level fluctuations during the Quaternary (Miller 2009). ...
... Sea-level change has always been considered as one of the basic factors that affected the evolution of the Earth's surface system. Especially, sea-level rise or fall will have a significant effect on the whole process of sedimentary evolution in the continental shelf basins (Christie-Blick and Driscoll, 2005;Hallam, 1992;Haq and Al-Qahtani, 2005;Haq et al., 1987;Miller, 2009). Thus, the global eustatic sea-level change data of Haq et al. (1987) was applied in our model setup. ...
Article
The interaction between the Earth's surface and deep geodynamic processes has a great influence on sedimentary patterns and characteristics of sedimentary systems, especially in the continental margin, such as the southern part of the East China Sea Continental Shelf Basin (ECSCSB). However, the exact processes and dynamics are poorly understood. The numerical tool (Badlands) was adopted to simulate the geological evolution of the southern ECSCSB during the Mesozoic transitional regime of the West Pacific continental margin, between 200 and 100 Ma. The numerical model involving four-dimensional (4D) sequence stratigraphy was validated by comparing with the tectono-morphology, sedimentary environments and sediment distribution. According to our findings, the transition was mainly controlled by three structural stages. The first transitional stage of the southern ECSCSB was mainly controlled by lithospheric-scale tectonic evolution. In the second stage, the dynamic topography contributed to slow regional uplift, while the last stage showed mantle-induced dynamic subsidence. The model results on 4D geomorphic characteristics, sediment distribution of basin evolution and deep dynamic topography, provided a quantitative image for geological evolution of the West Pacific continental margin in the Mesozoic.
... This finding suggests that, rather than being an inactive foreland basin during this time [140,141], a more continuous foldand-thrust belt and basin depocenter may have connected the Patagonian and Fuegian Andes during development of the Fuegian orocline [44]. Figure 6: Implications for revised timing of sedimentation of the middle Cenozoic Magallanes-Austral Basin strata compared to changes in regional tectonics [47,50,156], plate convergence rate [151], global climate [157], and eustatic sea level [158]. Published chronostratigraphy of proximal foothills was compiled from Malumián et al. [98], Malumián and Náñez [52], Perkins et al. [117], and references therein. ...
Article
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New detrital zircon U-Pb geochronology data from the Cenozoic Magallanes-Austral Basin in Argentina and Chile ~51° S establish a revised chronostratigraphy of Paleocene-Miocene foreland synorogenic strata and document the rise and subsequent isolation of hinterland sources in the Patagonian Andes from the continental margin. The upsection loss of zircons derived from the hinterland Paleozoic and Late Jurassic sources between ca. 60 and 44 Ma documents a major shift in sediment routing due to Paleogene orogenesis in the greater Patagonian-Fuegian Andes. Changes in the proportion of grains from hinterland thrust sheets, comprised of Jurassic volcanics and Paleozoic metasedimentary rocks, provide a trackable signal of long-term shifts in orogenic drainage divide and topographic isolation due to widening of the retroarc fold-thrust belt. The youngest detrital zircon U-Pb ages confirm timing of Maastrichtian-Eocene strata but require substantial age revisions for part of the overlying Cenozoic basinfill during the late Eocene and Oligocene. The upper Río Turbio Formation, previously mapped as middle to late Eocene in the published literature, records a newly recognized latest Eocene-Oligocene (37-27 Ma) marine incursion along the basin margin. We suggest that these deposits could be genetically linked to the distally placed units along the Atlantic coast, including the El Huemul Formation and the younger San Julián Formation, via an eastward deepening within the foreland basin system that culminated in a basin-wide Oligocene marine incursion in the Southern Andes. The overlying Río Guillermo Formation records onset of tectonically generated coarse-grained detritus ca. 24.3 Ma and a transition to the first fully nonmarine conditions on the proximal Patagonian platform since Late Cretaceous time, perhaps signaling a Cordilleran-scale upper plate response to increased plate convergence and tectonic plate reorganization.
... Our high-resolution data improves over Abul-Nasr and Thunell's (1987) sea level curve (Fig. 8). In general, for the studied section (including the Thebes, Darat and Khaboba formations), sea level gradually decreases, consistent with the global eustatic sea level curve (Miller, 2009). A gradual sea level rise from the base to the middle of the Thebes Formation culminates in a maximum flooding surface that also marks the maximum sea level rise noted for the entire studied section (Fig. 8). ...
... This finding suggests that, rather than being an inactive foreland basin during this time [140,141], a more continuous foldand-thrust belt and basin depocenter may have connected the Patagonian and Fuegian Andes during development of the Fuegian orocline [44]. Figure 6: Implications for revised timing of sedimentation of the middle Cenozoic Magallanes-Austral Basin strata compared to changes in regional tectonics [47,50,156], plate convergence rate [151], global climate [157], and eustatic sea level [158]. Published chronostratigraphy of proximal foothills was compiled from Malumián et al. [98], Malumián and Náñez [52], Perkins et al. [117], and references therein. ...
Preprint
New detrital zircon U-Pb geochronology data from the Cenozoic Magallanes Basin in Argentina and Chile ~51°S establish a revised chronostratigraphy of Paleocene – Miocene foreland synorogenic strata and document the rise and subsequent isolation of hinterland sources in the Patagonian Andes from the continental margin. The upsection loss of zircons derived from the hinterland Paleozoic and Late Jurassic sources between ca. 60-44 Ma documents a major shift in sediment routing due to Paleogene orogenesis in the greater Patagonian-Fuegian Andes. Changes in the proportion of grains from hinterland thrust sheets, comprised of Jurassic volcanics and Paleozoic metasedimentary rocks, provide a trackable signal of long-term shifts in orogenic drainage divide and topographic isolation due to widening of the retroarc fold-thrust belt. Youngest detrital zircon U-Pb ages confirm timing of Maastrichtian – Eocene strata, but require substantial age revisions for overlying Cenozoic basinfill. The upper Río Turbio Formation, previously mapped as Eocene in the published record, records a newly recognized Oligocene (34-26 Ma) marine incursion along the basin margin. We suggest that these deposits are genetically linked to the distal Oligocene-Miocene San Julián Formation along the Atlantic coast via an eastward deepening within the foreland basin system that culminated in the Juliense phase of the Patagonian Sea incursion in the Southern Andes. The overlying Río Guillermo Formation records onset of tectonically generated coarse-grained detritus ca. 24.3 Ma and a transition to the first Cenozoic fully nonmarine conditions on the proximal Patagonian platform since Late Jurassic time, perhaps signaling a Cordilleran-scale upper plate response to increased plate convergence and tectonic plate reorganization.
... Regardless, it seems far too early to allow for an interpretation in terms of high-frequency glacial eustatic fluctuations. Occurrence of continental ice caps in the Antarctic region during parts of the Cretaceous period has also been advocated by Miller (Miller et al., 2003;Miller, 2009). Therefore, it seems reasonable to question the old idea of nonglacial conditions during the Cretaceous period. ...
... This method progressively disposed of influences of compaction, sediment loading, and thermal reduction; and left behind an estimation of eustatic sea-level. Backstripping method also requires information on age estimation, sediment type (for decompaction), and paleo -bathymetry (Kenneth, 2005) which usually are obtained from benthic foraminifera and lithology data. These two data are great sources of uncertainty. ...
Article
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In the history of Quaternary geology, global climate changes influenced worldwide sea-level variations. On this study, these phenomena are tried to be assessed through sea-bottom morphology changes using bathymetric and seismic strata box data obtained during field survey in Singkawang Waters, West Kalimantan. Sea-level changes in this area are referred to global variations that had been studied by many researchers. Maximal depth attained during bathymetry mapping was -52 meters which take place as a depression between Lemukutan and Penata Besar Islands. General depths are - 30 m; thus, morphology reconstruction was done for sea-level positions - 10 m, - 20 m, and - 30 m from mean sea level. At the study area, sea-level dropped more than -30 m was only occurred in sea bottom morphology of isolated depressions. These isolated depressions are assumed as paleo-lakes which occurred throughout Sunda Land by some authors. The study also shows that sea-level history in Singkawang’s area span from approximately 10,000 years ago or Holocene time to Recent. During low sea-levels, the sea-bottom morphology was characterized by more extension of Singkawang land, formations of narrow straits between islands and developments of paleo-lakes assumed as fresh water lakes in the past. These events, based on Voris’s Diagram, occurred about 10,200 up to 8,300 years ago. On the other hand, marine clays appeared on coastal area of Singkawang. These might be evidence of sea-level rise in this area. About + 5m sea-level rise flooded this area approximately 4,200 years ago. Influences of sea-level changes to subbottom geological conditions were also assessed. The assessment was carried out by analyzing shallow seismic reflection records by using strata box. The records demonstrated that subsurface geology were characterized by truncation reflector configurations interpreted as fluvial environments. Keywords : sea-level changes, sea-bottom morphology, bathymetry, strata box, Singkawang Waters, West Kalimantan. Dalam sejarah geologi Kuarter, perubahan iklim global mempengaruhi variasi permukaan laut di seluruh dunia. Pada kajian ini fenomena tersebut dicoba dipelajari melalui perubahan morfologi dasar laut menggunakan data batimetri dan seismik pantul dangkal yang diperoleh selama survei lapangan di Perairan Singkawang, Kalimantan Barat. Perubahan muka laut di daerah ini mengacu pada variasi global yang telah dikaji oleh beberapa peneliti. Kedalaman tertinggi yang diperoleh selama pemetaan batimetri adalah 52 meter, yaitu berupa suatu daerah depresi antara Pulau Lemukutan dan Penata Besar. Umumnya kedalaman adalah -30 m; sehingga, rekonstruksi morfologi dilakukan pada posisi muka laut - 10 m, - 20 m, dan -30 m dari muka laut rata-rata. Di daerah kajian, muka laut turun lebih dari - 30 m hanya terjadi dalam morfologi dasar laut yang berupa daerah-daerah depresi yang terisolasi. Morfologi depresi terisolasi ini diduga sebagai danau purba oleh beberapa penulis yang terdapat pada Daratan Sunda. Kajian ini juga menunjukkan bahwa sejarah muka laut di daerah Singkawang mulai dari sekitar 10.000 tahun lalu (Holosen) hingga saat ini (Resen). Selama turunnya muka laut, morfologi dasar laut dicirikan oleh semakin meluasnya daratan Singkawang, terbentuknya beberapa selat sempit dan berkembangnya danau-danau purba yang diduga sebagai danau air tawar di masa lalu. Peristiwa tersebut, berdasarkan diagram umur terhadap muka laut Voris, terjadi sekitar 10.200 hingga 8.300 tahun lalu. Sementara itu, keterdapatan lempung endapan laut dari data pemboran pantai di Singkawang merupakan bukti naiknya muka laut di daerah ini. Kenaikan muka laut sekitar + 5 m telah menggenangi daerah ini kira-kira 4.200 tahun lalu. Tulisan ini juga membahas tentang pengaruh perubahan muka laut terhadap kondisi geologi bawah dasar laut. Kajian dilaksanakan dengan menganalisa rekaman seismik pantul dangkal. Rekaman menunjukkan bahwa geologi bawah dasar laut dicirikan oleh konfigurasi reflektor ’toreh dan isi’ atau truncation yang ditafsirkan sebagai lingkungan fluvial. Kata kunci : perubahan muka laut, morfologi dasar laut, batimetri, strata box, Perairan Singkawang, Kalimantan Barat.
... Pulses of anoxia imprinted in four recognized anoxic horizons are coupled with the attenuation of siliciclastic components (Fig. 4). If these pulses were indeed hothouse developments, sensu Kidder & Worsley (2010), sourceland retreats may be tied to thermal eustatic transgressions, in compliance with predicted thermal sea-level rise by 10-13 m per 10-12°C of ocean warming (Miller 2009). Thermal expansion of the oceanic water mass, however, does not offer a mechanism for amplitudes of sea-level change exceeding 15-20 m, whereas other causes of eustasy in the ice-free Middle-Late Devonian Ocean (e.g. ...
Article
Abstract:At least four horizons of enhanced anoxia (anoxic horizons; AHs) are recognized in the uppermost Eifelian–MiddleFrasnian mudrock-dominated strata of the Mackenzie Valley and Peel area of NW Canada. Aluminium-normalized Mo and Ulogs in two cored sections reveal AH-I at the Eifelian–Givetian boundary, AH-II in basal Frasnian, and AH-III and AH-IVbundled in the Middle Frasnian interval. These four horizons are characterized by attenuated siliciclastic components. Spectralgamma-ray K + Th and U are the best tools to trace these horizons in wells and outcrops. AHs are biostratigraphically correlatedwith‘black-shale events’in several basins of the world. Depositional environment is depicted as a stratified basin where thewater-column chemocline defined co-sedimentation of anoxic mudrocks in topographic lows and oxic grey shales andcarbonate banks on seafloor elevations. Based on inductively coupled plasma elemental data from 1687 samples, siliciclastic-lean basinal mudrock units that host AHs are strongly enriched in Mo (median EFMo∼97–172 EFMo/EFU≈(3–3.5) × SW,where EFMo and EFU are respectively Al-normalized Mo and U in enrichment factor notation and SW is average present-dayseawater value) compared with siliciclastic-rich units (median EFMo∼17–37) and show strong EFU/EFMo covariation (r≈0.8 in Canol Formation and Bluefish Member). Supported by a lack of geological evidence for an oceanographic barrier, thisenrichment indicates unrestricted water exchange with Panthalassa. At the same time, development of oligotrophy is indicatedby a lack of P enrichment and weak to non-existent enrichment in Zn and Cu. These features are reconciled through a model byearlier workers that involves a global shift to a warm greenhouse mode with slowed oceanic convection, expanded oxygenminimum zones and a failure of nutrient resupply from the upwelling. The onset of mass degassing in continental large igneousprovinces represents a potential trigger for this mid-Devonian shift. Devonian black-shale events in this scenario representgenuine oceanic anoxic events marking hothouse episodes in their nascent form. Supplementary material:Details of methods, analytical protocols and data scatterplots, stratigraphic cross-sections showingtraceability of anoxic horizons, and inductively coupled plasma elemental and Rock-Eval 6 data used in this study are availableat: https://doi.org/10.6084/m9.figshare.c.4212428Received7 April 2018;revised20 August 2018;accepted22 August 2018
... The far greater volume fractions of shale during the Miocene and the presence of only three wells with Miocene production in the study area suggest that most sediment reaching the study area was fine-to-very fine grained. Sea-level fall, beginning in the mid-Oligocene, continued into the Miocene, and along with cooler temperatures affected sedimentation coming into the deep basin (Miller, 2009 Figure 11d. Comparison of the percentages of shale and sandstone deposited during the Miocene epoch. ...
Article
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Borehole mudlog data from 80 wells in conjunction with 35 paleontological reports are used to define Cenozoic geological epochs within each borehole, both above and below the allochthonous salt canopy where salt is present. Isochore contour maps show how sediment depositional volumes vary within the study area on a per epoch (Paleocene, Eocene, Oligocene, Miocene, Pliocene, and Pleistocene) basis. The volume fractions of sandstone, shale, siltstone, limestone, and marl were also calculated by epoch, and contoured on a regional basis to understand the changes in the regional distribution of lithologies through time. These maps show how local deposition compares on a regional basis; and how depositional patterns change over the Cenozoic era. From the Paleocene to the Pleistocene, the volume fraction of sandstone in the study area has continuously decreased while during the same time period, the volume fraction of shale has increased. Sand volume fractions appear to have an inverse relationship with both shale and siltstone, meaning where there is a large volume fraction of sandstone present, the volume fraction of both shale and siltstone will be small. Volcanic tuff is present in fourteen wells; but there is insufficient data to map the regional distribution of volcanic tuff that is either Miocene, Oligocene, or Eocene in age according to the paleontological age of encasing sediments. In Part 1 the distribution and depositional histories of sandstone, shale and siltstone are discussed and the distribution and depositional history of Cenozoic limestone and marl is discussed in Part 2.
... Actualmente se admite un ascenso de 1,5-2,0 mm/año para el siglo XX, como con- secuencia del derretimiento de los hielos y del calentamiento de los océanos (Miller, 2009) con períodos extremos, como el que se da desde 1993 influenciado fuerte- mente por un evento mayor ENSO, con un ritmo de ascenso de ~2,8 mm/año. Pero no sólo estamos frente a un ascenso constante. ...
... Actualmente se admite un ascenso de 1,5-2,0 mm/año para el siglo XX, como con- secuencia del derretimiento de los hielos y del calentamiento de los océanos (Miller, 2009) con períodos extremos, como el que se da desde 1993 influenciado fuerte- mente por un evento mayor ENSO, con un ritmo de ascenso de ~2,8 mm/año. Pero no sólo estamos frente a un ascenso constante. ...
... It is likely these deposits formed by off-shelf sediment forcing of high-density turbidite currents (Lowe, 1982;Heller and Dickinson, 1985;Catuneanu et al., 2011) or sandy debris flows (Shanmugam, 2016). We therefore propose that Reservoirs A-E comprise basin floor fan systems deposited during late forced regression and early normal regression, related to global and local sea-level fall during the late Cenomanian and early Turonian (Dingle et al., 1983;Haq et al., 1987Haq et al., , 1988Miller et al., 2005;Miller, 2009). ...
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Within offshore frontier sedimentary basins, legacy data are important tools in basin-scale exploration for potential CO2 storage. We utilise single-channel 2D seismic reflection and well data obtained from the offshore Durban Basin, east coast South Africa, to provide new evidence of reservoir/seal pairs in saline aquifers that may represent potential storage sites for CO2 injection. Multiple, previously undefined and regionally pervasive stratigraphic traps have been mapped through a detailed seismo-sedimentary analysis. These include shelf-bound shallow-marine-sheet and deltaic sandstone packages of Turonian and Maastrichtian age respectively. Coeval with these laterally extensive shelf packages, multiple basin floor fan systems have been identified on the palaeo-slope. We further correlate these systems with analogous hydrocarbon-bearing sequences throughout a large region of the south-east African continental shelf. Using conservative assumptions, we propose that ∼327 Mt CO2 could potentially be stored in two laterally extensive shelf sand sequences, with a further potential for ∼464 Mt CO2 storage in basin floor fan systems in the distal basin.
... In accordance with Siesser and Dingle (1981) and Kuhlmann et al. (2010), we thus suggest that Cenozoic epeirogenesis (Partridge and Maud, 1987) combined with global changes in eustatic sea level (Haq et al., 1987(Haq et al., , 1988Miller et al., 2005;Miller, 2009 andJohn et al., 2011) and changes in global oceanic conditions (Shevenell et al., 2004;Holbourn et al., 2007) have had a profound effect on local sea level around southern Africa. These processes have shaped the stratigraphic architecture of the continental shelves through episodes of erosion and sediment bypass or marine deposition. ...
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Erosional unconformity surfaces are key indicators for the variations in eustatic sea level, ocean dynamics and climatic conditions which significantly affect depositional environments of sedimentary successions. Using a dense grid of 2D seismic data, we present new evidence from a frontier basin, the offshore Durban Basin, of a mid-Miocene age erosional unconformity that can be correlated with analogous horizons around the entire southern African continental margin. In the Durban Basin, this unconformity is typified by the incision of a mixed carbonate-siliciclastic wedge and ramp margin by a series of submarine canyons. Epeirogenic uplift of southern Africa characterised this period, with erosion and sediment bypass offshore concomitant with increases in offshore sedimentation rates. Although epeirogenic uplift appears to be the dominant mechanism affecting formation of the identified sequence boundary, it is postulated that an interplay between global eustatic sea-level fall, expansion of the east Antarctic ice sheets, and changes in deep oceanic current circulation patterns may have substantially contributed to erosion during this period.
... Eustatic records of Haq et al. (1987), Miller et al. (2005), and Kominz et al. (2008) were provided in Miller (2013). Alignment of Pueyo δ 13 C carb 5-point moving average maxima (interpreted as linked with eustatic maxima; Jenkyns, 1996;Li et al., 2000) with highstands of these curves was performed using Analyseries (Paillard et al., 1996) and allowed measuring correlation between our δ 13 C carb record and each global sea-level record. ...
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We explore the potential of high-resolution carbon isotope stratigraphy to provide an independent record of global sea-level changes in a 1600-m-thick succession representing ∼5 m.y. of slope sedimentation in the Eocene Ainsa Basin of Spain. The restricted physiographic setting of the basin results in a bulk δ¹³Ccarb signal that accurately correlates with the coeval eustatic curve from the New Jersey (USA) passive margin. We show that much of the deep-water sediment gravity flow (SGF) deposits are emplaced during eustatic lowstands and fine-grained marly intervals between SGFs correlate with rising and highstand sea levels. However, we also detect a substantial interval of SGF deposition during a sea-level highstand, confirming the nonuniqueness of the controls on clastic deposition. This approach provides a new way to assess the origin of depositional sequences and improve stratigraphic predictions in basins with limited chronostratigraphic control.
... Unit C is truncated by a regional unconformity surface S4 (Angus e Goodlad, 1986), which correlates with a basin-wide early Oligocene hiatus identified in the Jc-A1 well (Du Toit and Leith, 1974). The Oligocene hiatus correlates with hinterland uplift (Partridge and Maud, 1987), as well as a global sea level lowstand during the middle Oligocene (Fig. 8) (Haq et al., 1987;Millar et al., 2005;Millar, 2009). Siesser and Dingle (1981) suggest sea level fall around southern Africa of À500 m during the early to middle Oligocene (Fig. 8), whilst Dingle et al. (1983) propose À100 to À200 m sea level fall along the east coast. ...
... They could therefore provide a different perspective on understanding the forces shaping population structure of different marine organisms in the region. extensive studies on macroalgae using multilocus molecular markers (Coyer et al. 2003;Provan et al. 2005;Olsen et al. 2010;andreakis et al. 2007, 2009 have provided comprehensive information on the evolutionary history of marine organisms in north atlantic. recent phylogeographical studies using macroalgae (e.g., Cheang et al. 2010a) also revealed the importance of land bridges and oceanic current in contributing to the genetic diversification as well as mixing of genetic populations in northwestern Pacific. ...
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Phylogeographical study of the brown macroalga, Sargassum aquifolium using nuclear internal transcribed spacer 2, plastidal RuBisCo spacer, and mitochondrial cytochrome oxidase subunit-III revealed the populations in Southeast Asia to be homogeneous. On the other hand, genetic differences were detected between populations from Southeast Asia and western Pacific Islands/Guam, suggesting the presence of genetic break between these regions. This further suggests that populations of S. aquifolium may have survived east of Sunda Shelf during the Last Glacial Maximum and recent recolonization led to homogeneity of the populations in the Sunda Shelf region. Recolonization could be facilitated by year-round reproduction of the populations and dispersal of germlings on floating thalli by coastal currents. Restricted current flow across Maluku Sea and directional equatorial current flows could have isolated the Pacific Island and Guam populations from those of Southeast Asia. Our results support the presence of multiple refugia as the source of different lineages of S. aquifolium populations with a lack of secondary contact in the post-glacial dispersal between Southeast Asia and western Pacific as the mechanisms behind the phylogeographical patterns observed.
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Fine-grained sedimentary rocks of the Madingo Formation in the Lower Congo Basin (LCB), are significant targets for Upper Cretaceous–Paleogene depositional system analysis in West Africa. Six types of fine-grained sedimentary rocks of the Madingo Formation were identified based on integrated analyses of petrographic characteristics, geochemical element analysis and electron back-scattered diffraction of thin sections, including (1) siliceous mudstone, (2) claystone, (3) marlstone, (4) radiolarian-rich mudstone, (5) foraminifera-rich mudstone, and (6) phosphatic mudstone. Geochemical indexes (U/Th, V/(V + Ni), V/Cr, and Ni/Co) indicate that the Madingo Formation on the deep-water slope was characterized by typical oxygen-poor and even anaerobic environment, preserving organic matter and thus preserving sediments with relatively high TOC, abundant marine fossils and framboidal pyrite. The LCB experienced two different marginal marine environments during the deposition of the Madingo Formation. The lower Madingo Formation was characterized by a radiolarian-rich mudstone (the first stage of upwelling) deposited in a marginal semi-restricted sea bay environment (correlated with the Coniacian–Santonian Oceanic Anoxic Event 3; OAE-3), with up to 4.0% TOC, and types II2 and II1 organic matter. The upper Madingo Formation was characterized by foraminifera-rich and phosphatic mudstone (the second stage of upwelling) deposited in a marginal open marine environment (correlated with the Paleocene-Eocene Thermal Maximum; PETM), with up to 4.83% TOC and 5.0 mg/g phosphate that is rich in types I and II1 organic matter. The whole Madingo deposition is estimated to have spanned a 52-Myr period, and the low sediment accumulation rate of approximately 9 μm/yr can lead to a high TOC content. The three identified condensed sections include radiolarian-rich, foraminifera-rich or phosphatic mudstones that deposited in the deep-water slope, were probably marine source rocks for post-salt exploration in West Africa.
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Albian–Cenomanian successions (Kazhdumi and Sarvak formations) represent remarkable variations in thickness, facies, fauna, and environments throughout the Zagros area. In the Coastal Fars (Charmu section), sedimentological and paleontological data evidence an intrashelf, with depths of 10s–100s m, surrounded by a shallow carbonate platform. Due to its depth, deposition of sequences in this setting has been controlled by eustatic sea-level changes rather than eurybathic changes, and several condensation episodes occurred related to marine transgressions. These observations are different from those in the adjacent sections in the Coastal Fars which recorded subaerial exposures instead. Combined with previous studies, this study denotes several intrashelf basins enclosed by a shallow carbonate platform on the southeastern margin of the Neo-Tethys during the Albian–Cenomanian. Development of intrashelf basins corresponds to basement faults in the Fars Salient. Likely, an extensional tectonic regime associated with a rifting event created horst–graben architecture by exerting extension along the basement faults and reactivating salt structures. Deposition on these troughs and highs led to the facies and thickness variations of the concomitant sequences. Development of several intrashelf basins on the southeastern margin of the Neo-Tethys indicates that syn-depositional continental rifting event could occur during the Albian–Cenomanian, prior to the tectonic inversion around the earliest Turonian.
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The Turonian-Coniacian Smoky Hollow Member of the Straight Cliffs Formation in the Kaiparowits basin of southern Utah records a stratigraphic transition from isolated fluvial channel bodies to increasingly amalgamated channel belts capped by the Calico bed, a sheet-like sand-gravel unit. Characteristics of the Smoky Hollow Member are consistent with a prograding distributive fluvial system including: up-section increases in average grain size, bed thickness, and channel-body amalgamation, a fan-shaped planform morphology, and a downstream increase in channel sinuosity. The system prograded to the northeast based on thickness and facies patterns, and paleocurrent indicators. This basin-axial sediment-dispersal trend, which was approximately parallel to the fold-thrust belt at this latitude, is supported by provenance data including detrital zircons and modal sandstone compositions indicating sediment derivation mainly from the Mogollon Highlands and Cordilleran magmatic arc to the southwest, with episodic input from the more proximal Sevier fold-thrust belt to the west. Progradation occurred during a eustatic still-stand, relatively stable climatic conditions, and continuous tectonic subsidence, thus suggesting increased extrabasinal sediment supply as a primary control on basin-fill. Progradation of the Smoky Hollow Member fluvial system culminated in a ~2–3 My hiatus at the top of the lower Calico bed. Correlation with the Notom delta of the Ferron Sandstone, 80 km northeast in the Henry basin, is proposed on the basis of facies relationships and geochronology. The Calico bed unconformity is linked to regional tectonically-driven tilting and erosion observed in both basins. This article is protected by copyright. All rights reserved.
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Barremian-Aptian sedimentary successions along the northern Arabian margin have been described as a transition from a siliciclastic to a carbonate-dominated marine environment, deposited upon a low-relief shelf or platform formed as a consequence of continuous regional subsidence. A long (360 m) core from northern Israel offers a unique look at this transition, providing valuable insights for the paleoceanography, geometry and ventilation conditions that lead to Oceanic Anoxic Event 1 (OAE1) in this region. Results from high-resolution elemental, mineralogical, sedimentological and petrophysical analyses carried out revealed the emplacement of abundant mass-transport deposits (MTDs) during the Late Barremian and the Aptian. The transplanted units are characterized by fine grained calcareous shales with elevated organic matter, sulfur and iron contents. The scarcity or absence of bioturbation in the disturbed sequences provides a hint to the sediment/water interface conditions. However, a decrease in sulfur and iron occurring at the contact between the shales and the MTDs is explained as increased oxic conditions at the sediment-water interface as a result of turbulence and mixing associated with the descending sediment masses. Such recurrent events ventilation of the low-energy basinal environment during the Late Barremian and Aptian, predate the wide-scale establishment of OAE1 in the northern Arabian margin. Moreover, the identification of coarse-grained MTDs within deep-water calcareous sediments indicates a much steeper gradient of the northern Arabian margin, challenging previous studies. This article is protected by copyright. All rights reserved.
Thesis
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The mixed carbonate-siliciclastic sedimentary successions of Early Miocene age outcropping in the northern and southern Falcón Basin (northwestern Venezuela) were analyzed by multidisciplinary and multiscale approaches involving geological mapping, stratigraphic section logging, sampling, facies analysis, sequence stratigraphy, biostratigraphy of larger foraminifera, structural geology, total subsidence curves and geochemistry. The basin analysis presented in this thesis compiles and revises previous published and unpublished geological data from the Falcón Basin, and provides novel results and interpretations such as a cartography and an Early Miocene alaeogeographic map of the basin, sequence- and chrono-stratigraphic frameworks for the successions studied, depositional and architectural models of the mixed carbonate-siliciclastic systems investigated, an evaluation of the evolution of accommodation (mainly controlled by subsidence, eustasy and tectonic uplift) in the basin during the Oligocene-Miocene, and stable C- and O-isotopic data. Lastly, the results are compared with the knowledge available from the Oligo-Miocene subsurface carbonate gas reservoir of Perla (Gulf of Venezuela) to establish analogies and differences between the onshore and offshore carbonate platforms. The results presented in this thesis indicate that in the Falcón Basin, the Oligocene Epoch was characterized by continental to deep-marine siliciclastic sedimentation into a west-east trending rift basin. Carbonate banks were developed during the Early Miocene on top of tilted fault blocks in the northern and southern margins of the basin (San Luis and Churuguara formations, respectively), while hemipelagic and pelagic sedimentation occurred in half-grabens and troughs. The limestones of the San Luis and Churuguara formations occur interdigitated and alternated with siliciclastic systems. Middle to lower ramp carbonates are mainly preserved in the southern Churuguara Formation. The San Luis Formation exhibits both distal facies and more proximal parts of the depositional system including deltaic to upper carbonate ramp transitions. Faciesdiagnostic skeletal components constituting the platform carbonates investigated correspond to red algae, frequently forming rhodoliths, larger foraminifera, corals and echinoids. Carbonate production mainly occurred in the meso-oligophotic zone of distally-steepened ramps (middle ramp domain). Synrift subsidence was the most important mechanism in providing accommodation but it did not entirely overprint the eustatic signature. Six Aquitanian to Burdigalian third-order transgressive-regressive sequences were recognized in the northern and southern margins of the basin. These sequences are mainly comprehended within a higher-rank (second order) Early Miocene transgressive event. Shorter-term trends of relative sea level gave rise to ten distinct types of parasequences. Coarse siliciclastics were mainly deposited during regressive pulses linked to such lower-rank higher-frequency cycles. The San Luis and Churuguara formations are dated as Early Miocene on account of the co-occurrence of Lepidocyclina favosa/undosa, Lepidocyclina canellei, Heterostegina antillea, Operculinoides panamensis, Miosorites americanus and Annulosorites spiralis. In the Falcón Basin, the boundary between the Aquitanian and the Burdigalian is marked by a change to more complex (larger number of lateral chambers) and larger-sized faunas of miogypsinids. The platform carbonates of San Luis were buried by coarse siliciclastic deposits in the late Burdigalian, whereas in the southern margin, the Churuguara limestones experienced two drowning events followed by hemipelagic to pelagic sedimentation around the boundary between the Aquitanian and Burdigalian and in the late Burdigalian. Similarly to the San Luis and Churuguara mixed carbonate-siliciclastic systems, the carbonate reservoir of Perla, in the offshore of Venezuela, exhibits a distally-steepened ramp depositional profile, was formed during an overall major transgressive context and is mainly consituted by red algal- and larger foraminifera-rich middle ramp carbonates. However, the spatial extension, thickness and architecture of the Perla reservoir are not comparable to those from the onshore case studies due to differences in the geotectonic settings and the antecedent topographies. Furthermore, the lower ramp-to-basin passage in San Luis is by escarpment with olistoliths occuring in basinal settings, whereas in Churuguara and Perla this transition seems to be more gradual with lower ramp carbonates fading out into shale deposits. Carbonate sedimentation in Perla and San Luis occurred uninterruptedly throughout most of the Early Miocene, whereas the Churuguara succession exhibits a lower carbonate bank of Aquitanian age and an upper bank of Burdigalian age separated by a shale interval. The Perla reservoir shows an overall retrograding stacking pattern. In contrast, the carbonates of Churuguara and San Luis are stacked in an aggrading pattern. Therefore, the San Luis and Churuguara carbonates are not regarded as suitable analogues for the Perla reservoir highlighting the fact that each depositional system and thus, each hydrobarbon reservoir, has its own singularities and is physically unique.
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This study investigates the depositional environment and sequence stratigraphy of the Asmari Formation that is exposed at the Rig anticline in the Izeh zone of the Zagros foreland basin with a thickness of 374 m as a sequence of thin, medium, thick, and massive carbonate rocks. The Asmari Formation is Oligocene-Early Miocene (Burdigalian) in age at the study area. In this area 12 microfacies are distinguished on the basis of their depositional texture, petrographic analysis, and fauna. These facies deposited in four major depositional environment including tidal flat, lagoon, shoal, and basin. The Asmari Formation represents sedimentation on a homoclinal carbonate ramp system. Based on the microfacies analysis, sequence stratigraphic studies, and distribution of planktonic and benthic foraminifera, six third-order sequences, three in Oligocene (Rupelian, Early Chattian, and Late Chattian in age) and three in Miocene (Early Aquitanian, Late Aquitanian, and Early Burdigalian in age), in Rig mountain section were identified.
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The Neogene history of the Namib Desert is reasonably well understood, thanks to the presence of abundant sediments and fossils in Namaqualand, the Sperrgebiet and the Namib-Naukluft Park. Hyper-arid desert has existed along the west coast of Southern Africa since the Early Miocene. It has been demonstrated on the basis of stable isotope studies of struthious eggshells and mammalian dental enamel, that throughout the Neogene winter rainfall regime occurred in the south and summer rainfall regime in the north, although the boundary zone between the two regimes fluctuated latitudinally by several hundred kilometres through the Miocene. The pre-Miocene geological history of the region is much less well understood.The aim of this contribution is to discuss the palaeoclimate and palaeoenvironment of the richly fossiliferous pre-Miocene deposits related to the recently recognised Lutetian-Bartonian Ystervark Carbonatite Formation in the Sperrgebiet, with a view to throwing light on the development of arid climatic conditions in the subcontinent during the Palaeogene, and the consequences that aridification had on the Southern African biota. In pre-Bartonian time the climate in the Sperrgebiet was relatively humid and tropical with summer rainfall, but by Bartonian time there were signs of increasing aridity and a switch to predominantly winter rainfall was achieved by the Aquitanian. Fluctuations in groundwater levels were driven by the rise and fall of sea levels, resulting in alternating cycles of erosion and deposition in the zone along the coast.
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The Neogene history of the Namib Desert is reasonably well understood, thanks to the presence of abundant sediments and fossils in Namaqualand, the Sperrgebiet and the Namib-Naukluft Park. Hyper-arid desert has existed along the west coast of Southern Africa since the Early Miocene. It has been demonstrated on the basis of stable isotope studies of struthious eggshells and mammalian dental enamel, that throughout the Neogene winter rainfall regime occurred in the south and summer rainfall regime in the north, although the boundary zone between the two regimes fluctuated latitudinally by several hundred kilometres through the Miocene. The pre-Miocene geological history of the region is much less well understood. The aim of this contribution is to discuss the palaeoclimate and palaeoenvironment of the richly fossiliferous pre-Miocene deposits related to the recently recognised Lutetian-Bartonian Ystervark Carbonatite Formation in the Sperrgebiet, with a view to throwing light on the development of arid climatic conditions in the subcontinent during the Palaeogene, and the consequences that aridification had on the Southern African biota. In pre-Bartonian time the climate in the Sperrgebiet was relatively humid and tropical with summer rainfall, but by Bartonian time there were signs of increasing aridity and a switch to predominantly winter rainfall was achieved by the Aquitanian. Fluctuations in groundwater levels were driven by the rise and fall of sea levels, resulting in alternating cycles of erosion and deposition in the zone along the coast.
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Backstripping analysis of three continuously cored, well-dated boreholes from the New Jersey Coastal Plain (Ocean Drilling Program [ODP] Leg 150X) indicates a long-term (108-107 yr) eustatic fall of ≈100 m since 55 Ma (early Eocene) and suggests short-term (0.5-3 m.y.) eustatic falls of less than ≈70 m. Eustatic estimates are calculated from residuals between the decompacted unloaded, and paleodepth-corrected records and tectonic subsidence (assuming a cooling lithospheric plate). Because the residuals are similar among the three sites, we interpret them as an approximation of the eustatic signal.
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We provide a record of global sea-level (eustatic) variations of the Late Cretaceous (99- 65 Ma) greenhouse world. Ocean Drilling Program Leg 174AX provided a record of 11- 14 Upper Cretaceous sequences in the New Jersey Coastal Plain that were dated by in- tegrating Sr isotopic stratigraphy and biostratigraphy. Backstripping yielded a Late Cre- taceous eustatic estimate for these sequences, taking into account sediment loading, com- paction, paleowater depth, and basin subsidence. We show that Late Cretaceous sea-level changes were large (.25 m) and rapid (K1 m.y.), suggesting a glacioeustatic control. Three large d18O increases are linked to sequence boundaries (others lack sufficient d18O data), consistent with a glacioeustatic cause and with the development of small (,106 km3) ephemeral ice sheets in Antarctica. Our sequence boundaries correlate with sea-level falls recorded by Exxon Production Research and sections from northwest Europe and Russia, indicating a global cause, although the Exxon record differs from backstripped estimates in amplitude and shape.
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We have investigated the sequence stratigraphy of two widely separated marine Cenomanian successions in southeast India and northwest Europe, and used high-resolution ammonite biostratigraphy to demonstrate that sea-level changes are globally synchronous and therefore must be eustatically controlled. Sequence-scale sea-level changes in the Cenomanian were driven by the long eccentricity cycle (400 k.y.) in the Milankovitch band. We hypothesize that, during pre-Quaternary time, the third-order sequences of Vail and Haq are essentially a sediment response to sea-level changes driven by the 400 k.y. cycle. Construction of a relative sea-level curve for the marginal marine succession in India demonstrates that the short-term sea-level changes are rapid (10 100 m/m.y.) and have a magnitude of 2 20 m. Glacioeustasy is a possible but unproven driving mechanism.
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We document nine lower-middle Eocene sequences on the New Jersey coastal plain and compare them with global δ18O and Haq et al. records. Early Eocene hiatuses do not match δ18O changes, and it is unlikely that they are the result of glacioeustasy, consistent with an ice-free early Eocene. Early-middle Eocene (49 43 Ma) evidence for a link between sequences and δ18O is equivocal, and the presence of large ice sheets is uncertain. Beginning in the late-middle Eocene (43 42 Ma), concomitant increases in planktonic and benthic δ18O records coincide with the timing of hiatuses on the New Jersey coastal plain and a change from carbonate-dominated to siliciclastic-dominated sedimentation. These represent the development of the Antarctic ice cap and the beginning of the “icehouse” world. Of the 14 sequences predicted by Haq et al. for this interval, 9 are resolvable on the New Jersey margin, and the other 5 appear to be combined with others. We conclude that although ice-volume changes controlled sequences since at least 42 Ma, mechanisms for sea-level change prior to then are still not fully understood.
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We demonstrate quantitatively that the world-wide Mid to Upper Cretaceous transgression and subsequent regression may have been caused by a contemporaneous pulse of rapid spreading at most of the mid-oceanic ridges between −110 to −85 m.y. The rapid spreading caused the ridges to expand and hence reduced the volumetric capacity of the basins. The subsequent regression was caused by a reduction in spreading rates beginning at −85 m.y.
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Oligocene to middle Miocene sequence boundaries on the New Jersey coastal plain (Ocean Drilling Project Leg 150X) and continental slope (Ocean Drilling Project Leg 150) were dated by integrating strontium isotopic stratigraphy, magnetostratigraphy, and biostratigraphy (planktonic foraminifera, nannofossils, dinocysts, and diatoms). the ages of coastal plain unconformities and slope seismic reflectors (unconformities or stratal breaks with no discernible hiatuses) match the ages of global delta(18)O increases (inferred glacioeustatic lowerings) measured in deep-sea sites. These correlations confirm a causal link between coastal plain and slope sequence boundaries: both formed during global sea-level lowerings, The ages of New Jersey sequence boundaries and global delta(18)O increases also correlate well with the Exxon Production Research sea-level records of Haq et al, and Vail et al., validating and refining their compilations.
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The New Jersey Sea Level Transect was designed to evaluate the relationships among global sea level (eustatic) change, unconformity-bounded sequences, and variations in subsidence, sediment supply, and climate on a passive continental margin. By sampling and dating Cenozoic strata from coastal plain and continental slope locations, we show that sequence boundaries correlate (within +/-0.5 myr) regionally (onshore-offshore) and interregionally (New Jersey-Alabama-Bahamas), implicating a global cause. Sequence boundaries correlate with delta18O increases for at least the past 42 myr, consistent with an ice volume (glacioeustatic) control, although a causal relationship is not required because of uncertainties in ages and correlations. Evidence for a causal connection is provided by preliminary Miocene data from slope Site 904 that directly link delta18O increases with sequence boundaries. We conclude that variation in the size of ice sheets has been a primary control on the formation of sequence boundaries since ~42 Ma. We speculate that prior to this, the growth and decay of small ice sheets caused small-amplitude sea level changes (
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Oligocene foraminiferal delta18O records suggest the development of ice caps (= inferred glacio eustatic falls) at ca. 36, 31, and 25 Ma. Biostratigraphic analyses of wells from the United States east coast and Irish continental margins consistently show that upper Oligocene sediments overlie a diachronous erosional surface, underlain by lower Oligocene to Eocene strata. At the minimum, the hiatus extends between ca. 34 and 30 Ma. We speculate that erosion during a glacio eustatic fall near the early/late Oligocene boundary (ca. 32 31 Ma) developed (1) an unconformity on the margins, (2) numerous canyons noted in seismic profiles from the margins of the North Atlantic, and (3) a coastal offlap event. Using delta18O data, we apply a model for eustatic changes and margin response that explains the relationships of sea level, unconformities, and coastal onlap/offlap events.
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The timing of the last deglaciation is important to our understanding of the dynamics of large ice sheets and their effects on the Earth's surface. Moreover, the disappearance of the glacial ice sheets was responsible for dramatic increases in freshwater fluxes to the oceans, which probably disturbed the ocean's thermohaline circulation and, hence, global climate. Sea-level increase bear witness to the melting of continental ice sheets, but only two such records - from Barbados and New Guinea corals - have been accurately dated. But these corals overlie active subduction zones, where tectonic movements are large and often discontinuous (especially in New Guinea), so the apparent sea-level records may be contamined by a complex tectonic component. Here we date fossil corals from Tahiti, which is far from plate boundaries (and thus is likely to be tectonically relatively stable) and remote from the locations of large former ice sheets. The resulting record indicates a large sea-level jump shortly before 13,800 calendar years BP, which correponds to meltwater pulse 1 A in the Barbados coral records. The timing of this event is more accurately constrained in the Tahiti record, revealing that the meltwater pulse coincides with a short and intense climate cooling event that followed the initiation of the Bolling-Allerod warm period, but preceded the Younger Dryas cold event by about 1 000 years. (Résumé d'auteur)
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Lower Cretaceous bulk carbonate from deep sea sediments records sudden inputs of strontium resulting from the exposure of continental shelves. Strontium data from an interval spanning 7 million years in the Berriasian-Valanginian imply that global sea level fluctuated about 50 meters over time scales of 200,000 to 500,000 years, which is in agreement with the Exxon sea level curve. Oxygen isotope measurements indicate that the growth of continental ice sheets caused these rapid sea level changes. If glaciation caused all the rapid sea level changes in the Cretaceous that are indicated by the Exxon curve, then an Antarctic ice sheet may have existed despite overall climatic warmth.
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We review Phanerozoic sea-level changes [543 million years ago (Ma) to the present] on various time scales and present a new sea-level record for the past 100 million years (My). Long-term sea level peaked at 100 ± 50 meters during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. Sea level mirrors oxygen isotope variations, reflecting ice-volume change on the 104- to 106-year scale, but a link between oxygen isotope and sea level on the 107-year scale must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations. Sea-level change has influenced phytoplankton evolution, ocean chemistry, and the loci of carbonate, organic carbon, and siliciclastic sediment burial. Over the past 100 My, sea-level changes reflect global climate evolution from a time of ephemeral Antarctic ice sheets (100 to 33 Ma), through a time of large ice sheets primarily in Antarctica (33 to 2.5 Ma), to a world with large Antarctic and large, variable Northern Hemisphere ice sheets (2.5 Ma to the present).
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Advances in sequence stratigraphy and the development of depositional models have helped explain the origin of genetically related sedimentary packages during sea level cycles. These concepts have provided the basis for the recognition of sea level events in subsurface data and in outcrops of marine sediments around the world. Knowledge of these events has led to a new generation of Mesozoic and Cenozoic global cycle charts that chronicle the history of sea level fluctuations during the past 250 million years in greater detail than was possible from seismic-stratigraphic data alone. An effort has been made to develop a realistic and accurate time scale and widely applicable chronostratigraphy and to integrate depositional sequences documented in public domain outcrop sections from various basins with this chronostratigraphic framework. A description of this approach and an account of the results, illustrated by sea level cycle charts of the Cenozoic, Cretaceous, Jurassic, and Triassic intervals, are presented.
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Biostratigraphic data from the COST B-2 well off New York and four deep commercial wells off Nova Scotia have been used to remove the effect of sediment loading at the Atlantic-type continental margin off the East Coast of North America. The resulting subsidence contains terms due to both 'tectonic' and 'eustatic' effects. By assuming the tectonic subsidence is thermal in origin these effects can be separated. The 'eustatic' effects have been isolated by least squares fitting an exponential curve to the subsidence data. The resulting sea-level curve shows a maximum rise in sea level during the Late Cretaceous era which probably does not exceed 150 m. The tectonic subsidence has been interpreted in terms of a simple thermal model for the cooling lithosphere. Based on this model the thermal thickness of the lithosphere and the total amount of crustal thinning are estimated. These estimates which are consistent with surface ship gravity and GEOS-3 altimeter measurements are used to define the structural elements which control the tectonic evolution of the margin.
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In the eastern Gulf Coastal Plain, four, third-order unconformity-bounded depositional sequences are recognized for upper Paleocene and lower Eocene marginal marine to marine shelf strata of the Wilcox Group. In this area, the Wilcox Group includes the Nanafalia Formation (TAGC-2.1 depositional sequence), the Tuscahoma Sand (in part, the TAGC-2.1 and the TAGC-2.2 and TAGC-2.3 sequences), and the Hatchetigbee Formation (TAGC-2.4 depositional sequence). These cycles are interpreted to result from changes in sea level and coastal onlap during the late Paleocene and early Eocene epochs. The Paleocene-Eocene Epoch boundary (ca. 54-55 Ma) occurs in the Wilcox Group and coincides with the lithostratigraphic contact of the upper Paleocene Tuscahoma Sand with the lower Eocene Hatchetigbee Formation. Planktonic foraminiferal zone boundaries generally occur at depositional sequence boundaries dividing the upper Paleocene and lower Eocene marginal marine to marine shelf strata in the eastern Gulf Coastal Plain. The development of a major fluvial-dominated delta complex in this area during Paleocene and early Eocene time had a significant influence on depositional conditions. -from Authors
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We have used the stratigraphy of the central part of the Russian platform and surrounding regions to construct a calibrated eustatic curve for the Bajocian through the Santonian. The study area is centrally located in the large Eurasian continental craton, and was covered by shallow seas during much of the Jurassic and Cretaceous. The geographic setting was a very low-gradient ramp that was repeatedly flooded and exposed. Analysis of stratal geometry of the region suggests tectonic stability throughout most of Mesozoic marine deposition. The paleogeography of the region led to extremely low rates of sediment influx. As a result, accommodation potential was limited and is interpreted to have been determined primarily by eustatic variations. The central part of the Russian platform thus provides a useful frame of reference for the quantification of eustatic variations throughout the Jurassic and Cretaceous. The biostratigraphy of the Russian platform provides the basis for reliably determining age and eustatic events. The Mesozoic section of the central part of the Russian platform is characterized by numerous hiatuses. In this study, we filled the sediment gaps left by unconformities in the central part of the Russian platform with data from stratigraphic information from the more continuous stratigraphy of the neighboring subsiding regions, such as northern Siberia. Although these sections reflect subsidence, the time scale of variations in subsidence rate is probably long relative to the duration of the stratigraphic gaps to be filled, so the subsidence rate can be calculated and filtered from the stratigraphic data. We thus have compiled a more complete eustatic curve than would be possible on the basis of Russian platform stratigraphy alone.
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Carbonate buildups, including reefs and banks, are ideally suited for stratigraphic interpretation from reflection seismic data because of pronounced differences in depositional or bedding characteristics between the buildups and enveloping strata. Geophysical criteria that allow recognition of buildups can be either direct--those seismic parameters that directly outline buildups such as reflections from the boundaries of the buildups, onlap of overlying cycles, or seismic facies changes between the buildups and enveloping beds; or indirect--those seismic parameters that indirectly outline or indicate the presence of buildups such as drape, velocity anomalies, and spurious events. Use of basin architecture is an additional indirect, but generally geologic, line of evidence to infer locations of buildups. All available geologic and geophysical data should be used; the techniques of seismic stratigraphic and seismic facies analysis provide the framework for this interpretation.
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We developed a Late Cretaceous sealevel estimate from Upper Cretaceous sequences at Bass River and Ancora, New Jersey (ODP [Ocean Drilling Program] Leg 174AX). We dated 11-14 sequences by integrating Sr isotope and biostratigraphy (age resolution +/-0.5 m.y.) and then estimated paleoenvironmental changes within the sequences from lithofacies and biofacies analyses. Sequences generally shallow upsection from middle-neritic to inner-neritic paleodepths, as shown by the transition from thin basal glauconite shelf sands (transgressive systems tracts [TST]), to medial-prodelta silty clays (highstand systems tracts [HST]), and finally to upper-delta-front quartz sands (HST). Sea-level estimates obtained by backstripping (accounting for paleodepth variations, sediment loading, compaction, and basin subsidence) indicate that large (>25 m) and rapid (much less than1 m.y.) sea-level variations occurred during the Late Cretaceous greenhouse world. The fact that the timing of Upper Cretaceous sequence boundaries in New Jersey is similar to the sea-level lowering records of Exxon Production Research Company (EPR), northwest European sections, and Russian platform outcrops points to a global cause. Because backstripping, seismicity, seismic stratigraphic data, and sediment-distribution patterns all indicate minimal tectonic effects on the New Jersey Coastal Plain, we interpret that we have isolated a eustatic signature. The only known mechanism that can explain such global changes-glacio-eustasy-is consistent with foraminiferal delta(18)O data. Either continental ice sheets paced sea-level changes during the Late Cretaceous, or our understanding of causal mechanisms for global sea-level change is fundamentally flawed. Comparison of our eustatic history with published ice-sheet models and Milankovitch predictions suggests that small (5-10 x 10(6) km(3)), ephemeral, and areally restricted Antarctic ice sheets paced the Late Cretaceous global sea-level change. New Jersey and Russian eustatic estimates are typically one-half of the EPR amplitudes, though this difference varies through time, yielding markedly different eustatic curves. We conclude that New Jersey provides the best available estimate for Late Cretaceous sea-level variations.
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A large (30 40 m), rapid (≪1 m.y.), earliest Maastrichtian sea-level drop inferred from New Jersey sequence stratigraphic records correlates with synchronous δ18O increases in deep-water benthic and low-latitude surface-dwelling planktonic foraminifera. The coincidence of these events argues for the development of a moderate-sized ice sheet during the early Maastrichtian.
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Global calcareous nannofossil biostratigraphy is used to correlate the Paleogene chronostratigraphic units of northwestern Europe and standard nannofossil biozones. Such biostratigraphic correlations show that the lithostratigraphic sequence is discontinuous and allows interpretation of the paleogeography of northwestern Europe during the Paleogene and evaluation of the influence of global sea-level (eustatic) changes on northwestern European stratigraphy. A well-documented unconformity occurs near the lower/middle Eocene boundary in the Paris Basin. This unconformity, which also can be traced in the London-Hampshire Basin and in Belgium, correlates with a coastal offlap event (presumed sea level) of Vail et al. On the basis of magnetostratigraphic-biostratigraphic correlations, the duration of the hiatus associated with this unconformity can be estimated to be 0.6 to 1.5 m.y. in the Hampshire Basin and 2 to 4 m.y. in the Paris Basin.
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Estimates of the magnitudes of changes in third-order (0.522 m.y.) eustasy were obtained for Oligocene sequences defined by a suite of largely onshore boreholes of the New Jersey coastal plain. Benthic fo- raminiferal biofacies and multiple age con- straints in a sequence stratigraphic frame- work formed the database for this study. The geometry of the margin through time was determined using two-dimensional backstripping. The depth ranges of benthic foraminiferal biofacies were determined from a combination of standard factor analysis techniques and the backstripped geometries. Benthic foraminiferal biofacies were then used to determine the depths of the Oligocene margin profiles obtained from backstripping. The water depths of 16 of these horizons were confirmed by inde- pendent benthic biofacies determinations from at least two wells. This internal con- sistency indicates that the data and the two- dimensional backstripping approach were robust. Where benthic biofacies require a vertical shift of the horizons generated by two-dimensional backstripping, eustatic changes were required and were readily calculated. Results indicate a major eustatic fall from the end of the Eocene to the first re- cord of Oligocene deposition. Subsequent long-term shoaling of sea level through the Oligocene was ;30 m in 10 m.y. Superim- posed on this long-term trend were higher frequency (third-order) variations in eus- tasy with amplitudes of ;40 m or less.
Article
The concept of major rock-stratigraphic units of interregional scope was introduced in 1948 (Longwell, 1949). It is now possible to restate the concept and to define more explicitly the sequences delimited by interregional unconformities in the continental interior of North America. The sedimentary record of the North American craton from late Precambrian to present is characterized by six major unconformities. These interregional unconformities subdivide the cratonic stratigraphic column into six sequences - major rock-stratigraphic units (of higher than group, megagroup, or supergroup rank) which can be identified, where preserved, in all cratonic interior areas. At the cratonic margins the bounding unconformities tend to disappear in continuous successions, and the cratonic sequences are replaced by others controlled by events in the marginal basins and eugeosynclinal borders. Although the time values of the unconformities vary widely because of differences in degree of nondeposition and amount of erosion, the approximate dates of the regressional maxima represented are: (1) very late Precambrian, (2) early Middle Ordovician, (3) early Middle Devonian, (4) "post-Elvira" Mississippian, (5) early Middle Jurassic, and (6) late Paleocene. A seventh major regression is now in progress.
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Possible factors responsible for world-wide sea level changes are reviewed. The major causes are variationsin the volume of land ice and changes in oceanic ridge syjtems, with sediment accumulation in the oceans and desiccation of isolated basins producing second-order effects. Alterations in effective water volume (by ice sheet growth or desiccation) are much faster than changes in ocean basin capacity, but the latter are considered likely to be the cause of long-term trends, which are ultimately related to the history of mantle convection.
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Backstripping analysis of the Bass River and Ancora boreholes from the New Jersey coastal plain (Ocean Drilling Project Leg 174AX) provides new Late Cretaceous sea-level estimates and corroborates previously published Cenozoic sea-level estimates. Compaction histories of all coastal plain boreholes were updated using porosity–depth relationships estimated from New Jersey coastal plain electric logs. The new porosity estimates are considerably lower than those previously calculated at the offshore Cost B-2 well. Amplitudes and durations of sea-level variations are comparable in sequences that are represented at multiple boreholes, suggesting that the resultant curves are an approximation of regional sea level. Both the amplitudes and durations of third-order (0.5–5 Myr) cycles tend to decrease from the Late Cretaceous to the late Miocene. Third-order sea-level amplitudes in excess of 60 m are not observed. Long-term (108–107 years) sea level was approximately constant at 30–80 m in the Late Cretaceous, rose to a maximum early Eocene value of approximately 100–140 m, and then fell through the Eocene and Oligocene.
Article
The New Jersey margin contains an extensive record of Cretaceous to Eocene sea-level fluctuations. These events have been documented on the basis of sedimentology, benthic foraminiferal paleobathymetry (paleoslope), biostratigraphic recognition of unconformities and their associated hiatuses, and on seismic reflection records. The record of sea-level change for the New Jersey margin shows a long-term (second-order) rise beginning in the upper Albian that is punctuated by numerous third-order cycles of change in the Upper Cretaceous, Paleocene, and Eocene. The sequences deposited during these cycles that are most readily recognizable, are separated by type 1 unconformities. Sequences bracketed by one or two type 2 unconformities are more difficult to resolve, although many have been identified. Sequences shown on the cycle chart of Haq et al. (1987) of less than 1 Ma duration are the most difficult to recognize and many have not been identified in the New Jersey section.Benthic foraminiferal paleoslope studies indicate that relative sea-level rise on the New Jersey margin varied on the order of 10–120 m above present sea level. Much of the preserved record in the coastal plain consists of sediments deposited during rising sea level. This has led to a stacked record of sea-level rise events separated by unconformities.
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A major discrepancy between the Late Quaternary sea level changes derived from raised coral reef terraces at the Huon Peninsula in Papua New Guinea and from oxygen isotopes in deep sea cores is resolved. The two methods agree closely from 120 ka to 80 ka and from 20 ka to 0 ka (ka = 1000 yr before present), but between 70 and 30 ka the isotopic sea levels are 20–40 m lower than the Huon Peninsula sea levels derived in earlier studies. New, high precision U-series age measurements and revised stratigraphic data for Huon Peninsula terraces aged between 30 and 70 ka now give similar sea levels to those based on deep sea oxygen isotope data planktonic and benthic δ18O data. Using the sea level and deep sea isotopic data, oxygen isotope ratios are calculated for the northern continental ice sheets through the last glacial cycle and are consistent with results from Greenland ice cores. The record of ice volume changes through the last glacial cycle now appears to be reasonably complete.
Article
The reef-crest coral Acropora palmata from late Pleistocene reefs on Barbados has recorded the same global variations in oxygen isotopes as planktonic and benthonic foraminifera. Although the record of oxygen isotopes in Acropora palmata is discontinuous, it offers several advantages over the isotope records from deep-sea sediments: (1) the coral grows at water depths of less than 5 m; (2) the samples are unmixed; (3) specimens may be sampled from various elevations of paleo-sea level; and (4) aragonitic corals are suitable for and dating techniques. The latter advantage means that direct dating of the marine oxygen isotope record is possible. Oxygen isotope stage 5e corresponds to Barbados III, dated at 125,000 ± 6000 yr BP. Petrographic and geochemical evidence from five boreholes drilled into the south coast of Barbados indicates a major eustatic lowering (greater than 100 m below present sea level) occurred between 180,000 and 125,000 yr BP. The age and isotopic data suggest correlation of this change in sea level to Emiliani's oxygen isotope stage 6. Acropora palmata deposited at various elevations of sea level during oxygen isotope stage 6 vary by 0.11 ‰ δ18O for each 10 m of change in sea level. We further hypothesize a minimum drop of 2°C in the average temperature occurred during the regressive phase of oxygen isotope stage 6. These data indicate that temperature lowering of surface water near Barbados lagged behind a major glacial buildup during this time period. Using the δ18O vs sea level calibration herein derived, we estimate the relative height of sea stands responsible for Barbados coral reef terraces in the time range 80,000 to 220,000 yr BP.
Article
Coral reefs drilled offshore of Barbados provide the first continuous and detailed record of sea level change during the last deglaciation. The sea level was 121 ± 5 metres below present level during the last glacial maximum. The deglacial sea level rise was not monotonic; rather, it was marked by two intervals of rapid rise. Varying rates of melt-water discharge to the North Atlantic surface ocean dramatically affected North Atlantic deep-water production and oceanic oxygen isotope chemistry. A global oxygen isotope record for ocean water has been calculated from the Barbados sea level curve, allowing separation of the ice volume component common to all oxygen isotope records measured in deep-sea cores.
Article
In 1830-33, Charles Lyell laid the foundations of evolutionary biology with Principles of Geology, a pioneering three-volume book that Charles Darwin took with him on the Beagle. Lyell championed the ideas of geologist James Hutton, who formulated one of the fundamental principles of modern geology - uniformitarianism. This proposed that natural processes always operate according to the same laws, allowing us to understand how features of the Earth's surface were produced by physical, chemical, and biological processes over long periods of time. Volume 1 consists of 26 chapters, a comprehensive index and woodcut illustrations of various mechanisms of geological change. Lyell begins with a definition of geology and then reviews ancient theories of the successive destruction and renovation of the world. He mentions James Hutton's ideas in chapter four, and goes on to discuss the effects of climate change, running water, volcanic eruptions and earthquakes on the Earth's crust.
Oscillation of pulsation Report of the XVI session, International Geological Congress
  • A W Grabau
College Station, TX. Available at
  • A R Isern
  • F S Anselmetti
  • P Blum
Pozzuoli’s pillars revisited
  • S J Gould
Oceanic ridge volumes and sea-level change – An error analysis
  • M A Kominz
The effect of sea-level change on the shelf edge and slope of passive margins. Society of Economic Paleontology and Mineralogy (SEPM) Special publication 33
  • W C Pitman
  • Iii
  • X Golovchenko
Grundfragen der Vergleichenden Tektonik
  • H Stille