Eocene Interval Research Articles

The Reference Section of Eocene Deposits in the Belaya River Valley, Adygea, Western Ciscaucasia

The Eocene interval of the section in the Belaya River valley is continuously exposed and is represented (from the bottom up) by green clays of the Cherkessk Formation, the marl–clayey member of the Keresta Formation, bituminous marls of the Kuma Formation, and light intensely bioturbated marls of the Belaya Glina Formation. There are gradual transitions between formations without signs of hiatuses. Eocene deposits are characterized by rich assemblages of nannoplankton, planktonic and benthic foraminifers (PF, BF), and organic-walled phytoplankton. The shallower water facies are recorded in the composition of benthos and mollusks at the boundaries of formations. The data on these groups of fossils make it possible to trace an almost complete zonal characterization of nannoplankton, dinocysts and PF and to compare these subdivisions of the middle–upper Eocene and early Oligocene both with other reference sections of the Eastern Peri-Tethys and standard zones and stages of the international stratigraphic scale. The following zones are distinguished: the upper part of the Cherkessk Formation—nannoplankton (NP15) and Acarinina bullbrooki PF zones; the Keresta Formation—nannoplankton (NP15+NP16) and Hantkenina “alabamensis” PF zones; the Kuma Formation—the nannoplankton (NP16+NP17) zones, Hantkenina “alabamensis” (at the lower boundary of the formation) and Subbotina turсmenica PF zones (above basal part), and Areosphaeridium diktyoplokum–Rhombodinium porosum dinocyst zone; the Belaya Glina Formation—nannoplankton (NP18, NP19+NP20, NP21) zones, Turborotalia centralis–Globigerinatheka tropicalis PF zone, and Charlesdowniea clathrata angulosa dinocyst zone; the lower part of the Pshekha Formation—nannoplankton (NP21) zone, Globigerina officinalis PF zone, and Phtanoperidinium amoenum dinocyst zone. These data make it possible to clearly correlate the Belaya River section with the sections studied in detail in Ciscaucasia (Kheu, Kuban, and Gubs rivers) and to reconstruct the conditions of sedimentation.

Benthonic foraminiferal biostratigraphy and faunal turnover events during the Late Paleocene-Early Eocene at Darb Gaga, Western Desert, Egypt: Paleoenvironmental and sequence stratigraphic interpretations

The present study depends on qualitative and quantitative analyses for the Late Paleocene-Early Eocene benthonic foraminifera at Darb Gaga area, Baris Oasis, Western Desert, Egypt. The study Late Paleocene-Early Eocene succession consists of two rock units; Esna Formation at base and Thebes Formation (lowermost part) at top. Esna Formation is subdivided into four members stratigraphically arranged as follow: El Hanadi, Dababiya Quarry, Darb Gaga and Abu Had. Dababiya Quarry Member (marker of the P/E boundary) is characterized by the occurrence of glauconitic grains at the base confirming a minor hiatus at the P/E boundary. This hiatus led to the missing of the beds no. 1 & 2 of the five beds (lowermost part) of Dababiya Quarry Member. Four benthonic foraminiferal events are defined during the Late Paleocene-Early Eocene interval. The first one is global event at the Paleocene/Eocene (P/E) boundary, and the remainder events are local and define during the Ypresian (Early Eocene). The first event is characterized by a rapid extinction and abrupt faunal changes for the benthonic foraminiferal assemblages. This event led to the extinction of about 80% of the Paleocene foraminiferal taxa. About 72% of these taxa are temporarily extinct and reappeared soon. This event is characterized by carbonate dissolution which suggesting oxygen deficiency of oceanic bottom waters and food supply changes. Afterwards, a recovery phase of the benthonic foraminifers is directly recorded above this event and probably due to improved depositional environmental conditions. Quantitative analyses of benthonic foraminiferal assemblages at Darb Gaga section, suggest an outer shelf paleoenvironmental setting during the deposition of El Hanadi, Dababiya Quarry and Darb Gaga sediments that changes to inner-middle shelf during the deposition of Abu Had Member and inner shelf of Thebes Formation. This succession is subdivided into four depositional sequences which are bracketed by unconformities and their correlative conformities depending on integrated field investigations, lithofacies and biofacies data. These sequences are controlled by sea-level changes and/or tectonic activities that prevailed during the deposition.

Low-latitude vegetation and climate dynamics at the Paleocene-Eocene transition – A study based on multiple proxies from the Jathang section in northeastern India

We present a multi-proxy study of an upper Paleocene-lower Eocene succession from the paleo-equatorial region. The study is carried out on a coal-bearing, shallow-marine succession exposed at Jathang, east Khasi hills, Meghalaya, northeastern India. The succession was deposited in a low-energy, coastal marsh-bay complex. Dinoflagellate cyst biostratigraphy yields a late Paleocene to early Eocene age for the section. The deposits of the lower part of the succession represent a transgressive systems tract (TST) defined by seven parasequences, each starting with bay sediments deposited during transgression, followed by a shallowing-upward bay fill-marsh deposit. In the vertical succession, each parasequence acquires an increasingly marine character, culminating in a maximum flooding surface at the Paleocene-Eocene boundary. It is followed by four shallowing upward parasequences deposited in a highstand systems tract (HST). Enhanced chemical weathering and high terrestrial supply are testified by raised SiO2 and Al2O3 contents and high percentages of terrestrial palynomorphs. The pollen flora recovered from the Jathang section was used for quantitative paleoclimate and vegetation reconstructions. The Coexistence Approach was applied based on Nearest Living Relatives (NLRs) of sixty fossil species recorded at different stratigraphic levels. Seven climate variables were determined for the fossil assemblages, and, as a measure of the seasonality of climate, the number of dry months was estimated. Our study shows that during the Paleocene there existed warm, seasonally dry tropical climate conditions with mean annual temperature at ca. 24–26 °C and mean annual precipitation at ca. 700–1800 mm, and with a dry season of 5–6 months. Particularly warm and wet, perhumid climate conditions with 26–27 °C and 2200–3200 mm mean annual precipitation with a dry period of 2–3 months were reconstructed for the latest Paleocene-earliest Eocene interval. The study shows a distinct vegetational turnover from palm-dominated, seasonally dry tropical forest during the Paleocene to highly diversified dicotyledonous megathermal rainforest during the latest Paleocene-early Eocene. The present study demonstrates that the reduced duration of the dry period during the latest Paleocene-earliest Eocene, due to a more active hydrological cycle, played a major role in determining the climate and shaping the vegetation cover in the paleo-equatorial region. There is evidence from our data that seasonality of rainfall is the determining factor for the tropical forest vegetation pattern of the equatorial region rather than mean annual rainfall condition. As the main trigger for the observed step-wise changes of the hydrology along the studied succession, the fast northward movement of the Indian Plate is inferred.

A preliminary assessment of plant–biotic interactions in the Eocene of South China: Evidence from Liquidambar L. (Saxifragales: Altingiaceae)

The study of fossil plant–biotic (mainly arthropod) interactions offers an opportunity to understand the evolutionary process in palaeoecosystems and their response to climate fluctuation. Despite the importance of such investigations, not much is known about plant–arthropod associations from the Cenozoic floras of Asia. Exceptionally diverse Eocene floras from adjacent Maoming and Changchang sedimentary basins of southern China provide valuable insights into low-latitude palaeoecosystems. These floras indicate different intensities of plant–arthropod interactions and probably viral, bacterial or fungal infection. Two upper Eocene floras from the Maoming Basin are markedly distinct from two approximately contemporaneous middle Eocene floras of the Changchang and Maoming basins in exhibiting much more abundant and diverse plant damage types (DTs). For equivalent comparisons we focus on well-sampled fossil leaves of Liquidambar L. (Altingiaceae) present and relatively abundant in both basins. L. maomingensis and Liquidambar sp. 1 from both upper Eocene Maoming floras exhibit mainly external foliage feeding. In contrast, almost only galling occurs on Liquidambar sp. 2 leaves from the middle Eocene Changchang flora. The differences in the diversity and frequency of DTs in the studied palaeofloras could have been affected by a progressive warming and increase in climate seasonality over the middle–late Eocene interval as well as by habitat conditions and plant successional status. We hypothesize that L. maomingensis and Liquidambar sp. 1 from the Maoming Basin inhabited the early successional riparian forests on an alluvial plain, whereas Liquidambar sp. 2 from the Changchang Basin was a component of more mature plant communities.

Tectonic forcing to global cooling and aridification at the Eocene-Oligocene transition in the Iranian plateau

Abstract The transition from the extreme global warmth of the early Eocene ‘greenhouse’ climate to the present glaciated state is one of the most fundamental reorganizations of global climate known in the geologic record. The Middle to Late Eocene interval between 49 and 33 Ma was a globally important transition period from greenhouse to initial icehouse conditions. The Middle Eocene Climatic Optimum (MECO, ~ 40 Ma) was a transient period of global warming that interrupted the secular Cenozoic cooling trend. The Eocene-Oligocene transition (ca. 33.5 Ma) marks the first major decline in Cenozoic global temperatures and the initiation of Antarctic glaciation. However, a major challenge comes from recent investigations of plateau uplift processes and resulting environmental changes. The tectonic evolution of the Iranian plateau offers an explanation for global cooling during the Cenozoic, as a result of the gradual closure of the Neotethyan Sea, which led to the disappearance of the Indian Ocean-Mediterranean Sea connection, mountain building, extensional collapse, rifting, and flare-up type volcanism, erosion, and exhumation. Increasing topography by shortening as a result of subduction of the distal Arabian margin beneath the Iranian Plateau and contemporaneous exhumation of a metamorphic core complex between 49 and 33 Myr ago led to aridification of Iranian plateau and to the some elevation of the plateau. This rise in elevation is roughly contemporaneous with the emplacement of flare-up-type volcanics in the Urumiyeh-Dokhtar zone and over large portions of Central Iran. Peak volcanism occurred during the transient warming event MECO. New findings suggest that this global transition is linked to significant aridification and cooling in southwest Asia, and thus support the idea that global cooling is associated with the Eocene-Oligocene transition. The good match of tectonic deformation and uplift of the Iranian Plateau with climatic changes is significant.

Early Eocene Radiolarian Fauna from the Sangdanlin, Southern Tibet: Constraints on the Timing of Initial India‐Asia Collision

AbstractThis is a new report on the early Eocene radiolarian fauna from the Sangdanlin section in the Gyirong region, along the southern margin of the Yarlung Zangbo Suture Zone. The Sangdanlin section measured in this study is divided into three lithostratigraphic units from bottom to top: the Zongzhuo, Sangdanlin, and Zheya formations. Abundant radiolarian fossils were obtained from the Sangdanlin section and 54 species of 30 genera were identified and assigned as follows: Cryptamphorella conara‐C. macropora the late Cretaceous Zone and Amphisphaera coronate, Buryella tetradica‐Bekoma campechensis, and B. bidartensis‐B. divaricata the Paleocene‐early Eocene Interval Zones. The Paleocene‐early Eocene radiolarian zones are comparable to the radiolarian zones RP4‐RP8 in New Zealand. Based on the data of radiolaria and lithofacies, it is suggested that the Zongzhuo Formation should be deposited along the base of the north‐facing, continental slope of the Greater Indian continental margin, and the Sangdanlin Formation should be a deep marine, sedimentary sequence located in a foreland basin. The early Eocene radiolarian fauna in the Sangdanlin Formation constrains the initial age of the India‐Asia collision to no later than 53.6 Ma.

Structural, stratigraphic, and petrological clues for a Cretaceous–Paleogene abortive rift in the southern Adria domain (southern Apennines, Italy)

This study provides new structural, stratigraphic, and geochemical data and a literature review of the Cretaceous–Paleogene stratigraphy, biostratigraphy, tectonics, and magmatism in the southern Apennines belt, Italy, with the aim to demonstrate the occurrence of an Albian to Eocene abortive rifting stage in the southern Adria domain. During this time, the tectono‐stratigraphic evolution of the Adria domain is characterized by episodes of coeval uplift and drowning. Different sectors of the Apennine and Apulian platforms were so characterized by changes in the paleoenvironments, leading to different stratigraphic records (from shallow‐water to slope and basin), as well as the development of thick bauxitic levels. Contemporaneously, a large amount of calciclastic sediments supply from the emerging sectors was deposited in the basins surrounding the carbonate platforms (i.e., Ligurian and Lagonegro–Molise basins). The Albian–Eocene interval was also characterized by the occurrence of anorogenic magmatism and synsedimentary extensional faulting that, along with the changed sedimentary facies distribution, points out for a crustal‐scale extensional tectonics. We suggest that such tectonics is the result of a rifting episode, characterized by limited anorogenic magmatism, starting in the Albian and reaching its climax in the uppermost Cretaceous–Eocene times. In this scenario, the extensional tectonics recorded in the Adria domain was the product during an event of a single abortive rift system, which extended toward the south, from the southern margin of the Ligurian Ocean to the Hyblean (Sicily), Pelagian (Tunisia), and Sirte Basin Province Rift (Libya).

NATICID CONFAMILIAL DRILLING PREDATION THROUGH TIME

Gastropod drilling predation in the fossil record is prevalent and has been documented by many workers; however, vivid documentation of confamilial naticid predation is poor. Here, data compiled from previously published sources, supplemented by unpublished museum collections, document different aspects of naticid confamilial predation (NCP) in a temporal-latitudinal context. Confamilial drilling frequency (DF) showed a Cretaceous low, a small rise to a stable plateau in the Eocene, followed by a peak in the Oligocene, and finally a drop to a stable level from the Miocene to the Holocene. The stepwise rise in DF is comparable with the overall history of drilling predation. However, the temporal increase in DF was visible only in the mid-latitudes, while in other latitudes, no temporal trend was observed. The frequency of failed attack has always been very low. In comparison, a decrease in prey effectiveness (PE) was observed in the Neogene relative to the Cretaceous and Paleocene–Eocene intervals. In case of site selectivity, either apertural or abapertural sites were targeted until the Oligocene, and subsequently became more random. Some of these trends may be biased based on insufficient site selectivity data as well as uneven sampling from different latitudes representing different time intervals. More data on quantification of predation intensities along with the behavioral aspects of NCP are required to properly document other aspects of this interaction.

Stratigraphic evolution of Eocene clinoforms from northern Santos Basin, offshore Brazil: Evaluating controlling factors on shelf-margin growth and deep-water sedimentation

In order to assess the controlling factors on the evolution of a shelf margin and the timing of sediment transfer to deep waters, a seismic stratigraphic investigation was carried out in the Eocene interval of northern Santos Basin, offshore Brazil. The studied succession configures a complex of prograding slope clinoforms formed in a passive margin and encompasses five seismic facies and their respective depositional settings: shelf-margin deltas/shorefaces, oblique slope clinoforms, sigmoidal slope clinoforms, continental to shelfal deposits and mass-transport deposits. These are stratigraphically arranged as seven depositional sequences recording a total shelf-edge progradation of about 35 km and a progradation rate of 1,75 km/My. Two main types of sequences can be recognized, the first one (type A) being dominated by oblique slope clinoforms and shelf-margin deltas/shorefaces in which shelf-edge trajectories were essentially flat to descending and extensive sandy turbidites were deposited on the foreset to bottomset zones. Sequences of this type are dominated by forced-regressive units deposited during extensive periods of relative sea-level fall. Type B comprises an upper part represented by aggradational shelfal deposits and a lower part composed of mass-transport deposits and high-relief sigmoidal clinoforms with descending shelf-edge trajectory. Steep slump scars deeply cut the shelfal strata and constitutes the boundary between the two intervals observed in type B sequences. Sandy turbidites occur at the same frequency in both forced- and normal-regressive units but are more voluminous within forced-regressive clinoforms associated with shelf-margin deltas/shorefaces. Major slope failures and mass-transport deposits, by the other hand, occurred exclusively in type B sequences during the onset of sea-level fall and their volume are directly related to the thickness of the shelfal sediments formed during the pre-failure normal regressions.

Mesozoic and Cenozoic accretionary orogenic processes in Borneo and their mechanisms

AbstractThe Borneo Accretionary Orogen (BAO) is located in a central position of SE Asia, surrounded by the long‐lived westward subduction of the Pacific Plate, northward subduction of the Indian Plate beneath the Eurasian Plate and a passive continental margin of the South China Sea. Based on the previous studies in stratigraphy, structural geology and geophysics, a number of tectonic models on the BAO have been proposed, but these models do not perfectly match all of the geological facts. A field‐based structural analysis of the rocks of Sabah in Malaysia has recognized that the deformation in Sabah can be divided into four episodes (D1‐D4). The D1 deformation developed complete displacement foliation (S1) and NNE‐trending thrusts. Then D1 structures were reworked by the subsequent D2 deformation. D2 deformation resulted in WNW‐ or NW‐striking thrusts, followed by NNW–SSE‐trending thrusts and folds (D3). Some NNE‐trending sinistral strike‐slip faults and WNW‐trending dextral tension‐shear faults (D4) offset the D3 structures. D1 is related to the collisional event in the Sabah Orogeny during 23‐16 Ma, and D2 corresponds to the formation of the Deep Regional Uncomformity (DRU) at 16 Ma. D3 is related to the Shallow Regional Uncomformity (SRU) at 10 Ma. D4 is associated to the NW–SE‐trending extension after the multi‐stage collisional events. Analysis of the sedimentary and magmatic data reveals that the BAO is a Mesozoic and Cenozoic accretionary orogeny, represented by the intensely deformed Rajang‐Crocker Group Accretionary prism, ophiolites and calc‐alkaline igneous rocks. The accretionary orogen is related to the evolution of the Proto‐South China Sea Ocean (PSCS). The PSCS continuously subducted under the Borneo Block and closed in the Late Eocene–Early Miocene time. The subduction zone of the PSCS retreated to the north in the Mesozoic and Cenozoic and migrated to the present‐day Nansha Trough. The BAO is still active, as represented by a series of thrusting and subduction of the Dangerous Grounds under the Borneo Block. The NNE‐trending subduction‐related faults are considered as transform faults, rotating to the present‐day NW‐trending faults due to the anti‐clockwise rotation of the entire Borneo Block. In particular, the previous NNE‐trending Tinjar Fault is regarded as a major boundary in sedimentation and magmatism. To the NE of the fault, the strata and igneous rocks are Oligocene–Early Miocene, but to the SW of the fault, the strata and igneous rocks developed during the Cretaceous–Late Eocene interval. Copyright © 2016 John Wiley & Sons, Ltd.

Palaeocommunities, diversity and sea-level change from middle Eocene shell beds of the Paris Basin

The middle Eocene interval at some Paris Basin localities was studied through high-resolution stratigraphy. Abundance data (499 species, 37 719 individuals) on the distribution of molluscs, collected at 12 shell beds of the middle Lutetian and lower Bartonian, formed the basis for a palaeoecological study. The middle Lutetian succession is subdivided into several elementary depositional sequences (EDS) interpreted as the product of relative sea-level change. Species-abundance distributions are better correlated with EDS than with geographical locality, suggesting that sea level played an important role in the distribution of palaeocommunities. Diversities were compared with analogous data from modern subtropical and warm-temperate intertidal and subtidal communities. We found that sea-level variation is responsible for a major change in the upper part of the middle Lutetian succession, leading from high- to low-diversity palaeocommunities. From base to top sampled palaeocommunities indicate a transition from high-energy and mesotrophic (EDS 2) to oligotrophic low-energy conditions of a sandy lower shoreface (EDS 4) to an upper shoreface (EDS 5 and lower Bartonian), the last with mangroves and a seagrass cover. Notwithstanding the Lutetian cooling, we found that subtropical conditions reached as far north as the Paris Basin. Our study suggests that climatic fluctuations might be obscured by facies control.

New marine ostracod species from the Middle Eocene of west-central Sinai, Egypt

The study of two Eocene sections exposed at Wadi Nukhul and Wadi Tayiba in west-central Sinai, Egypt for ostracods yielded diverse fauna. Investigation of the recorded taxa revealed findings of eight new marine ostracod species, one belonging to the family Krithidae, Parakrithe tayibaensis n. sp., three to the family Cytheruridae, Cytheropteron bicostsatum n. sp., Cytheropteron nukhulensis n. sp. and Cytheropteron speijeri n. sp., three to the family Trachyleberididae: Digmocythere centroreticulata n. sp. in subfamily Brachycytherinae and Buntonia bassiounii n. sp. and Buntonia posteroacuta n. sp. in subfamily Buntoniinae, and one, Xestoleberis posterotruncata n. sp., to the family Xestoleberididae. The newly erected species have been described and compared with nearest known and probably related taxa. Their records in the studied sections are stratigraphically confined to the Middle Eocene (Lutetian-Bartonian) interval.

Myrtaceae fossil leaves from the Río Turbio Formation (Middle Eocene), Santa Cruz Province, Argentina

Myrtaceae, the gum tree family, is a large angiosperm clade of 5671 species mostly distributed in tropical and subtropical regions of the world. In the southernmost tip of South America (Santa Cruz province) where the fossils analysed in this study come from (Río Turbio Formation), this family is virtually absent and the extant vegetation is largely dominated by deciduous Nothofagus pumilio and Nothofagus antarctica. During the early Paleogene, however, the Myrtaceae were an important element in southern Patagonian floras. Here, we report and describe ten taxa related to the extant genera Eugenia, Myrcia, Psidium, Myrcianthes and possible Eucalyptus and Campomanesia. The presence of a high diversity of Myrtaceae during the Eocene in one of the southernmost regions of the world could be thought as unusual. However, during this period of time (45 Ma), a number of other tropical lineages also reached these high latitudes probably as a consequence a warming climatic trend. In fact, through the Paleocene–Early Eocene interval, climatic conditions were the warmest of the Cenozoic. After this period of time, a progressive decline in temperature forced the migration of megathermal elements towards lower latitudes and, at the same time, led to the expansion of forest dominated by Nothofagus which predominate the region today.

ORTHOPHRAGMINIDS (FORAMINIFERA) ACROSS THE PALEOCENE-EOCENE TRANSITION FROM NORTH AFRICA: TAXONOMY, BIOSTRATIGRAPHY, AND PALEOBIOGEOGRAPHIC IMPLICATIONS

The platform margin and slope deposits in Galala, Egypt, record a larger benthic foraminiferal turnover (LFT), previously proposed to coincide with the Paleocene-Eocene (P/E) boundary based on the negative carbon isotope excursion (CIE) consistent with the Paleocene-Eocene Thermal Maximum (PETM). The LFT in these deposits was established on the basis of supposed synchronous first appearances of such taxa as Alveolina , Nummulites , and Orbitolites at or around the P/E boundary, although the response of orthophragminids, assigned only to the genus Discocyclina , was not studied. The orthophragminids in the late Paleocene–early Eocene interval in some of these deposits (sections B3, D5, D6, and D8) are represented by species of Discocyclina Gumbel, Orbitoclypeus Silvestri, and Nemkovella Less, reported for the first time from the southern margin of the Tethys. The Thanetian orthophragminids consist of Orbitoclypeus multiplicatus , O. schopeni , Discocyclina seunesi , and D. tenuis , while assemblages in the early Eocene are characterized by Discocyclina archiaci , D. dispansa , Orbitoclypeus schopeni , and Nemkovella stockari , suggesting a significant change in composition through the sections. The assemblages below and above the P/E boundary, only recorded in sections B3 and D8, mark the orthophragminid zones OZ 1B and 3, respectively. The OZ 2, correlated to shallow benthic zones SBZ 5 and 6 in the basal part of the Eocene and recognized by the first appearance of asterocyclinids, nemkovellids, and some ribbed orbitoclypeid species in northern Tethyan platforms, was not found. This may suggest either a hiatus, recorded previously in section D8 based on calcareous plankton, across the P/E transition in section B3 or an artifact of sampling. Consequently, our data raise some doubts about the aforementioned compositional changes related to the LFT and P/E boundary. We discovered an advanced developmental stage of N. stockari ( N. stockari bejaensis n. subsp.) from a new section in Tunisia. This subspecies seems to be a key taxon for the early Eocene of the southern Tethyan platforms and extends the geographic and stratigraphic range of the species. We conclude that orthophragminids at Galala bear a close resemblance to those in the northern Tethyan platforms, especially assemblages from Turkey.

A high-resolution benthic stable-isotope record for the South Atlantic: Implications for orbital-scale changes in Late Paleocene–Early Eocene climate and carbon cycling

The Late Paleocene and Early Eocene were characterized by warm greenhouse climates, punctuated by a series of rapid warming and ocean acidification events known as “hyperthermals”, thought to have been paced or triggered by orbital cycles. While these hyperthermals, such as the Paleocene Eocene Thermal Maximum (PETM), have been studied in great detail, the background low-amplitude cycles seen in carbon and oxygen-isotope records throughout the Paleocene–Eocene have hitherto not been resolved. Here we present a 7.7 million year (myr) long, high-resolution, orbitally-tuned, benthic foraminiferal stable-isotope record spanning the late Paleocene and early Eocene interval (∼52.5–60.5 Ma) from Ocean Drilling Program (ODP) Site 1262, South Atlantic. This high resolution (∼2–4 kyr) record allows the changing character and phasing of orbitally-modulated cycles to be studied in unprecedented detail as it reflects the long-term trend in carbon cycle and climate over this interval. The main pacemaker in the benthic oxygen-isotope (δ18O) and carbon-isotope (δ13C) records from ODP Site 1262, are the long (405 kyr) and short (100 kyr) eccentricity cycles, and precession (21 kyr). Obliquity (41 kyr) is almost absent throughout the section except for a few brief intervals where it has a relatively weak influence. During the course of the Early Paleogene record, and particularly in the latest Paleocene, eccentricity-paced negative carbon-isotope excursions (δ13C, CIEs) and coeval negative oxygen-isotope (δ18O) excursions correspond to low carbonate (CaCO3) and coarse fraction (%CF) values due to increased carbonate dissolution, suggesting shoaling of the lysocline and accompanied changes in the global exogenic carbon cycle. These negative CIEs and δ18O events coincide with maxima in eccentricity, with changes in δ18O leading changes in δ13C by ∼6 (±5) kyr in the 405-kyr band and by ∼3 (±1) kyr in the higher frequency 100-kyr band on average. However, these phase lags are not constant, with the lag in the 405-kyr band extending from ∼4 (±5) kyr to ∼21 (±2) kyr from the late Paleocene to the early Eocene, suggesting a progressively weaker coupling of climate and the carbon-cycle with time. The higher amplitude 405-kyr cycles in the latest Paleocene are associated with changes in bottom water temperature of 2–4 °C, while the most prominent 100 kyr-paced cycles can be accompanied by changes of up to 1.5 °C. Comparison of the 1262 record with a lower resolution, but orbitally-tuned benthic record for Site 1209 in the Pacific allows for verification of key features of the benthic isotope records which are global in scale including a key warming step at 57.7 Ma.

Upper Maastrichtian to Lutetian nannofossil biostratigraphy, United Arab Emirates, west of the Northern Oman Mountains

The latest Cretaceous (Maastrichtian) to Middle Eocene (Lutetian) interval of shallow water carbonate rocks in the NE part of the Arabian Pensinsula (Oman Mountains) includes important regional oil reservoir units. These carbonates are richly fossiliferous in foraminifera, which have been useful in correlating sequences and formations. Previous foraminiferal studies have indicated the existence of several hiatuses or lacunae related to sea level changes or due to erosion. Subsequent studies of the abundant calcareous nannofossils have permitted definition of these hiatuses via high resolution biostratigraphy. However, these previous studies were of limited extent. In this study a total of 103 nannofossil species were identified from the upper Maastrichtian–Lutetian successions at Jabal Qarn El Barr, El Faiyah Range Mountains (Jabal Thanays and western side of Jabal Buhays), United Arab Emirates, as well as Jabal El Rawdah, west of the Northern Oman Mountains, Oman.

Sea-level changes across the Paleocene–Eocene interval in the Spanish Pyrenees, and their possible relationship with North Atlantic magmatism

The issue of whether major and rapid global sea-level changes existed on a preglacial Earth can be resolved by the detailed study of the Paleocene–Eocene (P–E) interval, where a large and rapid carbon isotope excursion linked to an important global warming event, the Paleocene Eocene Thermal Maximum, allows for high-resolution correlation between terrestrial, coastal and marine settings. Based primarily on outcrop and borehole information from the Tremp-Graus Basin in the southern Spanish Pyrenees, it is shown that a sea-level fall of at least 20m occurred less than 75kyr prior to the PETM. This forced a seaward displacement of the shoreline of ca. 20km, a widespread incision of valleys in the alluvial plains and the subaerial exposure and excavation of the adjacent marine carbonate platform. The subsequent sea-level rise caused the infilling of the incised valleys, a process completed before the onset of the PETM, and continued rising during and after the event, leading to the aggradation of the alluvial plain and eventually to the transgression of the whole Tremp-Graus Basin. However, the sea level did not regain its pre-fall position until near the end of the PETM. Therefore, although rising, the sea level was comparatively low in the southern Pyrenean area during most of the PETM. The pre-PETM sea-level fall has been reported in other basins of the southern Pyrenees, in the North Sea area, the Austrian Alps and in Egypt, and the subsequent sea-level rise has been documented in widely separated sites around the Earth, an evidence of their global (eustatic) scope. The causal mechanism(s) of the pre-PETM sea-level fall is (are) unresolved, although glacioeustasy may have played a role. The subsequent sea-level rise was most likely caused by tectonomagmatic activity in the North Atlantic.

Do the large carbon isotopic excursions in terrestrial organic matter across Paleocene–Eocene boundary in India indicate intensification of tropical precipitation?

Five distinct transient warming (hyperthermal) events (Paleocene–Eocene Thermal Maximum [PETM], H1/ETM2/ELMO, H2, I1, and I2), marked by negative carbon isotope excursions (CIEs) occurred between Late Paleocene and Early Eocene (~56 to 52Ma) interval. However, not many records of either the PETM or definitive Early Eocene Hyperthermals (EEHs) are yet available from terrestrial realm in the tropics except two neo-tropical sections of Colombia and Venezuela (Jaramillo et al., 2010). Therefore, response of the tropical biosphere to these warming events is not very well known. Here we report high resolution carbon isotope (δ13C) chemostratigraphy, biomarker, calcareous nannofossils, and pollen data from the Cambay shale Formation of Western India (paleolatitude~5°S), which show complete preservation of all the above CIE events including the PETM, hitherto unknown from tropical terrestrial record. Comparatively larger magnitudes of CIEs for all the hyperthermal events (the PETM and EEHs) point towards a possible intensification of precipitation during the PETM and all the early Eocene hyperthermal/CIE events. This inference is supported by data of lignin phenols and presence of tropical rain forest elements spanning the entire time period ~56–52Ma and suggest that higher organic burial and soil erosion favored deposition of thick lignitic seams as a consequence of high tropical precipitation.

Lutetian calcareous nannofossil events in the Agost section (Spain): implications toward a revision of the Middle Eocene biomagnetostratigraphy

This paper presents a detailed calcareous nannofossil biostratigraphy of the entire Lutetian of the Agost section (Betic Cordillera, SE Spain). This investigation integrates and improves on previous study performed through the Ypresian/Lutetian boundary by the authors on this succession. The new revision of the integrated bio-magnetobiochronology of the Early/Middle Eocene interval revealed highly diversified calcareous nannofossil assemblages, characterizing more than 8 Myr of climatic variability. The studied interval spans from Zone CP11 to Subzone CP14a and from the upper part of Zone NP13 to the base of Zone NP16 of calcareous nannofossil standard zonations. The revision of the calcareous nannofossil content enabled the identification of numerous secondary events which greatly improved the stratigraphic resolution of this time interval. An important re-organization of the nannoflora was observed during the Y/L transition, when Reticulofenestra and Dictyococcites (Noelaerhabdaceae) became the most important genera in terms of abundance and dispersal, dominating the Middle Eocene nannofossil assemblages and replacing Toweius and Discoaster taxa characteristic of the lower Eocene. Pentaliths and Blackites experience a great expansion and diversification, whereas Discoaster and Chiasmolithus which are well diversified but never abundant during the Lutetian show a slow turnover. A reassessment of the major bio-events observed in the Noelaerhabdaceae family as well as revision and correlation of these events with the classical Italian sections (Contessa and Bottaccione) are presented. The new results show that biostratigraphic problems related to the Middle Eocene chronology are not limited to the correlation between calcareous nannofossils and planktonic foraminiferans at the Y/L transition but extend to calcareous nannofossil events commonly used for correlating the Bartonian.

Stratigraphy, sedimentology and tectonic evolution of the Upper Cretaceous/Paleogene succession in north Eastern Desert, Egypt

The stratigraphy, sedimentology and syn-depositional tectonic events (SdTEs) of the Upper Cretaceous/Paleogene (K–P) succession at four localities in north Eastern Desert (NED) of Egypt have been studied. These localities are distributed from south-southwest to north-northeast at Gebel Millaha, at North Wadi Qena, at Wadi El Dakhal, and at Saint Paul Monastery. Lithostratigraphically, four rock units have been recorded: Sudr Formation (Campanian–Maastrichtian); Dakhla Formation (Danian–Selandian); Tarawan Formation (Selandian–Thanetian) and Esna Formation (Thanetian–Ypresian). These rock units are not completely represented all over the study area because some of them are absent at certain sites and others have variable thicknesses. Biostratigrapgically, 18 planktonic foraminiferal zones have been recorded. These are in stratigraphic order: Globotruncana ventricosa Zone (Campanian); Gansserina gansseri, Contusotruncana contusa, Recimguembelina fructicosa, Pseudohastigerina hariaensis, Pseudohastigerina palpebra and Plummerita hantkenenoides zones (Maastrichtian); Praemurica incostans, Praemurica uncinata, Morozovella angulata and Praemurica carinata/Igorina albeari zones (Danian); Igorina albeari, Globanomanlina pseudomenradii/Parasubbotina variospira, Acarinina subsphaerica, Acarinina soldadoensis/Globanomanlina pseudomenardii and Morozovella velascoensis zones (Selandian/Thantian); and Acarinina sibaiyaensis, Pseudohastigerina wilcoxensis/Morozovella velascoensis zones (earliest Ypresian). Sedimentologically, four sedimentary facies belts forming southwest gently-dipping slope to basin transect have been detected. They include tidal flats, outer shelf, slumped continental slope and open marine hemipelagic facies. This transect can be subdivided into a stable basin plain plus outer shelf in the extreme southwestern parts; and an unstable slope shelf platform in the northeastern parts. The unstable slope shelf platform is characterized by open marine hemipelagic, fine-grained limestones and fine siliciclastic shales (Sudr, Dakhla, Tarawan and Esna formations). The northeastern parts are marked by little contents of planktonic foraminifera and dolomitized, slumped carbonates, intercalated with basinal facies. Tectonically, four remarkable syn-depositional tectonic events (SdTEs) controlled the evolution of the studied succession. These events took place strongly within the Campanian–Ypresian time interval and were still active till Late Eocene. These events took place at: the Santonian/Campanian (S/C) boundary; the Campanian/Maastrichtian (C/M) boundary; the Cretaceous/Paleogene (K/P) boundary; and the Middle Paleocene–Early Eocene interval. These tectonic events are four pronounced phases in the tectonic history of the Syrian Arc System (SAS), the collision of the Afro-Arabian and Eurasian plates as well as the closure of the Tethys Sea.