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The Toarcian Oceanic Anoxic Event (T-OAE, c. 182 Ma) represents a major perturbation of the carbon cycle marked by widespread black shale deposition. Consequently, the onset of the T-OAE has been linked to the combined effects of global warming, high productivity, basin restriction and salinity stratification. However, the processes that led to termination of the event remain elusive. Here, we present palynological data from Arctic Siberia (Russia), the Viking Corridor (offshore Norway) and the Yorkshire Coast (UK), all spanning the upper Pliensbachian - upper Toarcian stages. Rather than a 'dinoflagellate cyst black-out', as recorded in T-OAE strata of NW Europe, both the Arctic and Viking Corridor records show high abundance and dinoflagellate diversity throughout the T-OAE interval as calibrated by C-isotope records. Significantly, in the Arctic Sea and Viking Corridor, numerous species of the Parvocysta and Phallocysta suites make their first appearance in the lower Toarcian Falciferum Zone much earlier than in Europe, where these key dinoflagellate species appeared suddenly during the Bifrons Zone. Our results indicate migrations of Arctic dinoflagellate species, driven by relative sea-level rise in the Viking Corridor and the establishment of a S-directed circulation from the Arctic Sea into the Tethys Ocean. The results support oceanographic models, but are at odds with some interpretations based on geochemical proxies. The migration of Arctic dinoflagellate species coincides with the end of the T-OAE and marks the arrival of oxygenated, low-salinity Arctic waters, triggering a regime change from persistent euxinia to more dynamic oxygen conditions. © Cambridge University Press 2019.

The Toarcian Oceanic Anoxic Event (T-OAE, c. 182 Ma) represents a major perturbation of the carbon cycle marked by widespread black shale deposition. Consequently, the onset of the T-OAE has been linked to the combined effects of global warming, high productivity, basin restriction and salinity stratification. However, the processes that led to termination of the event remain elusive. Here, we present palynological data from Arctic Siberia (Russia), the Viking Corridor (offshore Norway) and the Yorkshire Coast (UK), all spanning the upper Pliensbachian – upper Toarcian stages. Rather than a ‘dinoflagellate cyst black-out’, as recorded in T-OAE strata of NW Europe, both the Arctic and Viking Corridor records show high abundance and dinoflagellate diversity throughout the T-OAE interval as calibrated by C-isotope records. Significantly, in the Arctic Sea and Viking Corridor, numerous species of the Parvocysta and Phallocysta suites make their first appearance in the lower Toarcian Falciferum Zone much earlier than in Europe, where these key dinoflagellate species appeared suddenly during the Bifrons Zone. Our results indicate migrations of Arctic dinoflagellate species, driven by relative sea-level rise in the Viking Corridor and the establishment of a S-directed circulation from the Arctic Sea into the Tethys Ocean. The results support oceanographic models, but are at odds with some interpretations based on geochemical proxies. The migration of Arctic dinoflagellate species coincides with the end of the T-OAE and marks the arrival of oxygenated, low-salinity Arctic waters, triggering a regime change from persistent euxinia to more dynamic oxygen conditions.

Several studies indicate that North Atlantic Deep Water (NADW) formation might have initiated during the globally warm Eocene (56–34 Ma). However, constraints on Eocene surface ocean conditions in source regions presently conducive to deep water formation are sparse. Here we test whether ocean conditions of the middle Eocene Labrador Sea might have allowed for deep water formation by applying (organic) geochemical and palynological techniques, on sediments from Ocean Drilling Program (ODP) Site 647. We reconstruct a long‐term sea surface temperature (SST) drop from ~30°C to ~27°C between 41.5 to 38.5 Ma, based on TEX86. Superimposed on this trend, we record ~2°C warming in SST associated with the Middle Eocene Climatic Optimum (MECO; ~40 Ma), which is the northernmost MECO record as yet, and another, likely regional, warming phase at ~41.1 Ma, associated with low‐latitude planktic foraminifera and dinoflagellate cyst incursions. Dinoflagellate cyst assemblages together with planktonic foraminiferal stable oxygen isotope ratios overall indicate low surface water salinities and strong stratification. Benthic foraminifer stable carbon and oxygen isotope ratios differ from global deep ocean values by 1–2‰ and 2–4‰, respectively, indicating geographic basin isolation. Our multiproxy reconstructions depict a consistent picture of relatively warm and fresh but also highly variable surface ocean conditions in the middle Eocene Labrador Sea. These conditions were unlikely conducive to deep water formation. This implies either NADW did not yet form during the middle Eocene or it formed in a different source region and subsequently bypassed the southern Labrador Sea.

Anoxic sediments, as compared to oxic settings, encompass a much higher proportion of relatively labile and thus more reactive organic matter, naturally giving rise to structural changes of the organic molecules themselves, as well as cross-linking between them (e.g., through reactive sulfur species). Both processes transform the original biomolecules into geomolecules. For the oxic environment, these intermolecular and intramolecular transformations also operate, but cross-linking may be less important since the labile, reactive component is rapidly removed. As such, one may expect a structurally better preservation of the more refractory initial biomolecules in the oxic environment. To test this hypothesis, initially identical biomolecules need to be compared between different preservational environments. Here, we use the species-specific morphology of organic microfossils to assure a single initial biosynthetic product (the cysts of the fossil dinoflagellate species Thalassiphora pelagica) for comparison. We assess the macromolecular structures of cysts from the Eocene ( ∼ 40 Ma) sulfidic Rhine Graben and the oxic Kerguelen Plateau and compare them with each other and the structures of recent cysts. While between the sites the T. pelagica cysts are morphologically identical and show no signs of morphological modification, pyrolysis gas chromatography mass spectroscopy and micro Fourier transform infrared analyses show that their macromolecular characteristics are strongly different. Comparison with recent cysts shows that the cysts deposited in the sulfidic Rhine Graben show a strong additional contribution of long-chain aliphatic moieties and thus less diagenetic intermolecular cross-linking. The presence of organic sulfur identifies natural volcanization as one of the diagenetic processes. Furthermore, we observe a loss of bound oxygen and no trace of the original carbohydrate signature of the cyst wall biomacromolecule. The material deposited in the oxic sediments of the Kerguelen Plateau shows no traces of sulfurization. It shows a minor contribution of short carbon chains only and thus less diagenetic intermolecular crosslinking. Furthermore, a carbohydrate signature was still preserved evidencing a better molecular preservation of the initial biomacromolecule, supporting our initial hypothesis. This shows that excellent morphological preservation does not imply excellent chemical preservation. It also leads to the conclusion that the best preservation of molecular structure is not necessarily where most organic matter gets preserved, which, in turn, is important for understanding the nature and fate of sedimentary organic matter and its isotopic signature. © 2020 Author(s).

The Southern North Sea Basin area, stretching from the UK to the Netherlands, has a rich hydrocarbon exploration and production history. The past, present and expected future hydrocarbon and geothermal exploration trends in this area are discussed for eight key lithostratigraphic intervals, ranging from the Lower Carboniferous to Cenozoic. In the period between 2007 and 2017, a total of 95 new hydrocarbon fields were discovered, particularly in Upper Carboniferous, Rotliegend and Triassic reservoirs. Nineteen geothermal systems were discovered in the Netherlands onshore, mainly targeting aquifers in the Rotliegend and Upper Jurassic/Lower Cretaceous formations. Although the Southern North Sea Basin area is mature in terms of hydrocarbon exploration, it is shown that with existing and new geological insights, additional energy resources are still being proven in new plays such as the basal Upper Rotliegend (Ruby discovery) for natural gas and a new Chalk play for oil. It is predicted that hydrocarbon exploration in the Southern North Sea Basin area will probably experience a slight growth in the coming decade before slowing down, as the energy transition further matures. Geothermal exploration is expected to continue growing in the Netherlands onshore as well as gain more momentum in the UK.

Next to atmospheric CO2 concentrations, iceproximal oceanographic conditions are a critical factor for

This paper presents the results of a cross-border study of the Middle Jurassic–Early Cretaceous rift phase in the Danish–German–Dutch Central Graben area. Based on long-distance correlations of palynologically interpreted wells, a stepwise basin evolution pattern was determined. Four phases are defined and described as tectonostratigraphic mega-sequences (TMS). The TMS are governed by changes in the tectonic regime. TMS-1 reflects the onset of rifting, triggered by regional east–west extension. Rift climax was reached during TMS-1, reflected by thick mudstone accumulations. TMS-2 reflects a change in the tectonic regime from east–west to NE–SWextension. NW–SE-trending normal faults became active during this phase, switching the depocentres from the graben axis into adjacent basins. TMS-3 displays divergent basin development. In the Dutch Central Graben area, it is characterized by a basal unconformity and widespread sandstone deposition, indicating continued salt and fault activity. Organic-rich mudstone deposition prevails in the Danish and German Central Graben area, indicating sediment starvation and water-mass stratification. With TMS-4 the rift phase ended, reflected by regionally uniform mudstone deposition. The basin evolution model presented here coherently places the lithostratigraphic units occurring in a stratigraphic framework and provides a valuable basis for hydrocarbon exploration activities in the region.

The taxonomic revision of the dinoflagellate cyst subfamily Wetzelielloideae by Williams et al. (2015) places primary emphasis on the type of archaeopyle, and secondarily on wall ornamentation. Williams et al. (2015) argues that this provides more clarity for taxonomic differentiation within the subfamily of Wetzelielloideae, and adds to the stratigraphical significance of species within. We find, however, that their proposed revision (1) introduces taxonomic criteria that divert drastically from these in other dinoflagellate cyst subfamilies, (2) unnecessarily erects and emends many new genera and species, and (3) poses serious practical limitations, which together (4) lead to profound reduction of the stratigraphical applicability of many marker species. In this contribution, we substantiate our concerns regarding the approach and criteria used by Williams et al. (2015). We propose to retain the generic definitions of Wetzelielloideae that existed prior to the revisions by Williams et al. (2015), until a revision supported by the community is available

The past few decades the focus of hydrocarbon exploration and production in the Middle East progressively has moved to deeper/older plays. In fact, the Jurassic succession of the Arabian Platform is now among the major hydrocarbon-producing intervals of the Middle East. On this platform, widespread carbonate deposition resulted in a vertical and lateral mosaic of shallow-water facies adjacent to deeper water coarser-grained deposits. An improved high-resolution sequence stratigraphic framework is crucial for building highly resolved geological models for reservoir distribution and characterization. Currently, there is a good understanding of the structural features of the Jurassic in the region, primarily based on sedimentology and seismic mapping (Yousif and Nouman, 1995, 1997; Haq and Al-Qahtani, 2005, Figure 1). However, in order to start understanding the genesis and sequence stratigraphic position of Jurassic plays, a firm chronostratigraphic framework is essential. Unfortunately, the application of a single, routinely used biostratigraphic tool appears problematic in the generally carbonate-rich and oil-saturated depositional systems of the Jurassic of the Arabian Platform. Here we present the results of a multidisciplinary study performed with the aim of constructing a chronostratigraphic framework for the Jurassic of West Kuwait, an area that hosts an important Jurassic hydrocarbon play.

Paleoclimate studies suggest that increased global warmth during the Eocene epoch was greatly amplified at high latitudes, a state that climate models cannot fully reproduce. However, proxy estimates of Eocene near-Antarctic sea surface temperatures (SSTs) have produced widely divergent results at similar latitudes, with SSTs above 20 degrees C in the southwest Pacific contrasting with SSTs between 5 and 15 degrees C in the South Atlantic. Validation of this zonal temperature difference has been impeded by uncertainties inherent to the individual paleotemperature proxies applied at these sites. Here, we present multiproxy data from Seymour Island, near the Antarctic Peninsula, that provides well-constrained evidence for annual SSTs of 10-17 degrees C (1 sigma SD) during the middle and late Eocene. Comparison of the same paleotemperature proxy at Seymour Island and at the East Tasman Plateau indicate the presence of a large and consistent middle-to-late Eocene SST gradient of similar to 7 degrees C between these two sites located at similar paleolatitudes. Intermediate-complexity climate model simulations suggest that enhanced oceanic heat transport in the South Pacific, driven by deep-water formation in the Ross Sea, was largely responsible for the observed SST gradient. These results indicate that very warm SSTs, in excess of 18 degrees C, did not extend uniformly across the Eocene southern high latitudes, and suggest that thermohaline circulation may partially control the distribution of high-latitude ocean temperatures in greenhouse climates. The pronounced zonal SST heterogeneity evident in the Eocene cautions against inferring past meridional temperature gradients using spatially limited data within given latitudinal bands.

During the middle and late Eocene (∼ 48-34 Myr ago), the Earth's climate cooled and an ice sheet built up on Antarctica. The stepwise expansion of ice on Antarctica induced crustal deformation and gravitational perturbations around the continent. Close to the ice sheet, sea level rose despite an overall reduction in the mass of the ocean caused by the transfer of water to the ice sheet. Here we identify the crustal response to ice-sheet growth by forcing a glacial-hydro isostatic adjustment model with an Antarctic ice-sheet model. We find that the shelf areas around East Antarctica first shoaled as upper mantle material upwelled and a peripheral forebulge developed. The inner shelf subsequently subsided as lithosphere flexure extended outwards from the ice-sheet margins. Consequently the coasts experienced a progressive relative sea-level rise. Our analysis of sediment cores from the vicinity of the Antarctic ice sheet are in agreement with the spatial patterns of relative sea-level change indicated by our simulations. Our results are consistent with the suggestion that near-field processes such as local sea-level change influence the equilibrium state obtained by an ice-sheet grounding line.

The results described in this thesis provide a rather complex picture of climatic, environmental and biotic changes preceding and arising from the onset of Antarctic glaciation. This period is commonly known as the greenhouse to icehouse transition across the Eocene-Oligocene Transition (EOT, 34-33 million years ago). The studies, based on fossil remains of algae and micro-organisms, do now for the first time constrain the timing and magnitude of cooling and ice-growth across the EOT. Environmental change occurred in two steps with the first, the EOT-1 shift (33.9 million years ago), representing cooling, bottom water production and ephemeral ice sheet-development, to be followed ~300.000 year later by abrupt ice sheet expansion towards a continent-scale size at the Oi-1 shift. Seen in the light of the reconstructed late Eocene evolution of the Southern Ocean, it is proposed that a series of intimately coupled positive feedbacks became active before glacial expansion across the Oi-1 shift. Enhanced west-ward circum-Antarctic circulation acted to support cooling of Antarctica, through 'thermal isolation', leading to increased latitudinal temperature gradients. The enhanced gradients enhanced polar wind-fields that spurred the westward circulation. Associated with this circulation-regime, bottom water was produced and enhanced vertical mixing supported biological productivity, which eventually may have acted to sequester CO2 from the atmosphere. This all may have resulted in the accelerated cooling during the initial phases of the EOT. With orbital preconditioning, the Antarctic ice-sheets could expand rapidly to eventually reach a continent-scale across the Oi-1 shift. Consequences of the Oi-1 glaciation were profound. Low-latitude shelf biota are notably affected by cooling and sea-level change during the initial phases of the EOT. The most profound reorganization is recorded in the Southern Ocean, where the onset of modern plankton ecosystems responds to the inception of seasonal sea-ice conditions along Antarctica's margins during the Oi-1. In contrary to what was intuitively assumed, sea-level variations act strongly non-linear. Close to Antarctica, the sea-level increased by ~100 m. This provides a containing feedback for the newly established ice-sheets. The origin of the present-day Antarctic ice-sheets provides an example of a strongly non-linear process, with a series of positive feedbacks leading to relatively rapid and abrupt glacial expansion. Once established, stabilizing feedbacks (e.g., albedo, circum-Antarctic sea-level change) prevent a return to the initial ice-free state. The evaluation of these processes using numerical climate models will yield crucial insight in the role of the climate-ocean-atmosphere systems with regard to ice-sheet stability. This is important because ice-sheets are already affected at observable rate by anthropogenic carbon dioxide emissions and elevated earth surface temperatures

The Integrated Ocean Drilling Program Expedition 318 to the Wilkes Land margin of Antarctica recovered a sedimentary succession ranging in age from lower Eocene to the Holocene. Excellent stratigraphic control is key to understanding the timing of paleoceanographic events through critical climate intervals. Drill sites recovered the lower and middle Eocene, nearly the entire Oligocene, the Miocene from about 17 Ma, the entire Pliocene and much of the Pleistocene. The paleomagnetic properties are generally suitable for magnetostratigraphic interpretation, with well-behaved demagnetization diagrams, uniform distribution of declinations, and a clear separation into two inclination modes. Although the sequences were discontinuously recovered with many gaps due to coring, and there are hiatuses from sedimentary and tectonic processes, the magnetostratigraphic patterns are in general readily interpretable. Our interpretations are integrated with the diatom, radiolarian, calcareous nannofossils and dinoflagellate cyst (dinocyst) biostratigraphy. The magnetostratigraphy significantly improves the resolution of the chronostratigraphy, particularly in intervals with poor biostratigraphic control. However, Southern Ocean records with reliable magnetostratigraphies are notably scarce, and the data reported here provide an opportunity for improved calibration of the biostratigraphic records. In particular, we provide a rare magnetostratigraphic calibration for dinocyst biostratigraphy in the Paleogene and a substantially improved diatom calibration for the Pliocene. This paper presents the stratigraphic framework for future paleoceanographic proxy records which are being developed for the Wilkes Land margin cores. It further provides tight constraints on the duration of regional hiatuses inferred from seismic surveys of the region.

IODP Expedition 318 drilled several sites on the Wilkes Land margin of East Antarctica in Jan.–Feb. 2010. The principle objective of the cruise was to obtain a better understanding of the Cenozoic cryospheric evolution of Antarctica, in conjunction with the dating of major regional seismic unconformities WL-U3 thru U8. Unconformity WL-U3 was suggested to be related to the inception of Antarctic glaciation during the Eocene-Oligocene Transition (~34 Ma). Changes in biotic assemblages distinctly denote an ecological transition from warm, Eocene ice-free ‘greenhouse’ conditions to colder, highly productive, Oligocene ‘icehouse’ conditions, more akin to the modern shelf environment of Antarctica. Preliminary dinoflagellate, and TEX86 results will be discussed. In addition, our paleoecological interpretations provide constraints for on-going geophysical studies aimed at modelling changes in relative sea level in response to East Antarctic glaciation and ice-sheet arrival at the Wilkes Land margin

Increasingly high resolution isotope- and novel organic geochemical proxy records have revealed that the long-term cooling trend of the middle Eocene was interrupted by a warming phase designated the Middle Eocene Climatic Optimum (MECO). It is suggested to represent an increase in sea surface temperatures of about 4°C, lasting approximately 400 kyr. The temperature evolution of the MECO is notably well-documented in the Southern Ocean. However, records of temperature- and biotic change during the MECO are largely missing from the higher northern latitudes. Here we document on the sea surface temperature evolution during the MECO reconstructed using TEX86 from Ocean Drilling Program (ODP) site 647 situated in the Labrador Sea. In addition, organic walled remains of dinoflagellates (i.e. dinocysts) were investigated in order to identify environmental change in response to the MECO

Paleogene sediments of the Tarim basin in western China hold the easternmost extent of the Paratethys Sea, an epicontinental sea that covered a large part of Eurasia and probably extended to the Mediterranean Tethys in the west. The late Cretaceous and Paleogene sedimentary record of the Tarim basin is characterized by several trans- and regressions before the sea finally retreated. The final regression has been suggested to be associated with the Indo-Asia collision and with eustatic sea level fall during the initiation of Antarctic glaciation at the Eocene-Oligocene transition (EOT, ~34 million years ago). However, the timing, cause and consequences of Paratethys Sea retreat are largely unknown. In 2010, a field campaign to the Tarim Basin was organized during which five sections were sampled, from west to east respectively: Mine, Kansu, Kezi, Aertashi & Keliyang. We investigated the organic walled remains of surface dwelling dinoflagellates (dinocysts), that allow for biostratigraphic correlation between the sections and distant locations elsewhere. In addition, ensuing paleomagnetic studies, aid towards constraining the timing of these sea-level cycles. Furthermore, dinocyst assemblages sensitively record environmental change, this provides the opportunity to reconstruct the paleo-environment in the Tarim Basin and to elucidate on the magnitude of sea-level variation

The Eocene-Oligocene transition (EOT, ~34 Myr ago) represents the final transition from the early Paleogene “Greenhouse” into the present “Icehouse” by the initiation of Antarctic glaciation. The EOT is recorded in deep-sea benthic foraminiferal oxygen isotope (δ18O) records as two increasing steps, ~200 kyr apart. However, the relative contribution of cooling and increasing ice-volume cannot be separated from such δ18O records. Independent temperature- and sea-level reconstructions are crucial for understanding the order of events enveloping the onset of Antarctic glaciation. The classic reference section for the EOT, St Stephens Quarry (SSQ) in Alabama, USA, contains a relatively expanded and complete shelf succession. Previous studies at SSQ have already provided benthic foraminiferal stable isotope- and Mg/Ca based temperature information. Sea surface temperatures were reconstructed using TEX86 and planktonic Mg/Ca analyses. Altogether, these data show that the first step of the EOT (precursor or EOT-1) primarily reflects cooling, whereas the second step (or Oi-1) primarily reflects increasing ice-volume. Here, we report on biotic change revealed by evaluating assemblages of fossil remains of organic walled dinoflagellates (dinocysts). Dinoflagellates are a group of unicellular surface dwelling algae and are often used to sensitively record environmental changes. We have inferred sea level change by evaluating dinocyst assemblages in the relatively shallow section of SSQ. This led us to revise the sequence stratigraphy and age model for SSQ. We document a minor sea-level fall associated with the EOT-1 and a more substantial sea-level fall at the Oi-1. At the EOT-1 we furthermore recorded the occurrence of a taxon typically associated with cold water. This is in accordance with the geochemically reconstructed temperature drop of 4–6°C. Early Oligocene assemblages above the Oi-1 are indicative of more productive and shallower lagoonal settings. Our records show that the EOT was a period of profound environmental change, also in the (sub)tropics

Despite warm polar climates and low meridional temperature gradients, a number of different high-latitude plankton assemblages were, to varying extents, dominated by endemic species during most of the Paleogene. To better understand the evolution of Paleogene plankton endemism in the high southern latitudes, we investigate the spatiotemporal distribution of the fossil remains of dinoflagellates, i.e., organic-walled cysts (dinocysts), and their response to changes in regional sea surface temperature (SST). We show that Paleocene and early Eocene (∼65-50 Ma) Southern Ocean dinocyst assemblages were largely cosmopolitan in nature but that a distinct switch from cosmopolitan-dominated to endemic-dominated assemblages (the so-called "transantarctic flora") occurred around the early-middle Eocene boundary (∼50 Ma). The spatial distribution and relative abundance patterns of this transantarctic flora correspond well with surface water circulation patterns as reconstructed through general circulation model experiments throughout the Eocene. We quantitatively compare dinocyst assemblages with previously published TEX86-based SST reconstructions through the early and middle Eocene from a key locality in the southwest Pacific Ocean, ODP Leg 189 Site 1172 on the East Tasman Plateau. We conclude that the middle Eocene onset of the proliferation of the transantarctic flora is not linearly correlated with regional SST records and that only after the transantarctic flora became fully established later in the middle Eocene, possibly triggered by large-scale changes in surface-ocean nutrient availability, were abundances of endemic dinocysts modulated by regional SST variations. Fil: Bijl, Peter K.. Utrecht University; Países Bajos Fil: Pross, Jörg. Goethe Universitat Frankfurt; Alemania Fil: Warnaar, Jeroen. Utrecht University; Países Bajos Fil: Stickley, Catherine E.. University Of Norway; Noruega Fil: Huber, Matthew. Purdue University; Estados Unidos Fil: Guerstein, Gladys Raquel. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina Fil: Houben, Alexander J. P.. University of Utrecht; Países Bajos Fil: Sluijs, Appy. Utrecht University; Países Bajos Fil: Visscher, Henk. Utrecht University; Países Bajos Fil: Brinkhuis, Henk. Utrecht University; Países Bajos

The Eocene-Oligocene Transition (EOT, ~. 34. Ma) represents the culmination of Eocene cooling by the initiation of large-scale Antarctic glaciation. Recognition and correlation of the EOT in Southern Ocean sedimentary successions have been difficult as a result of the general lack of well-calibrated biostratigraphic markers. Here we describe an unusual hypnozygotic organic walled dinoflagellate cyst (dinocyst) that originated in the Southern Ocean in conjunction with the onset of major Antarctic glaciation as reflected by 'oxygen isotope event 1' (Oi-1).We restudied samples from Deep Sea Drilling Program (DSDP) Site 511 using Light Microscopy and Scanning Electron Microscopy and found that a taxon previously known as Forma T constitutes a new protoperidinioid dinocyst genus and species that we name Malvinia escutiana. Published and re-evaluated data from other Southern Ocean sites show that M. escutiana did not occur before the Oi-1 (33.7. Ma), emphasizing its potential as a useful biostratigraphic marker for this key interval in the Southern Ocean's Cenozoic climate history. Fil: Houben, Alexander J. P.. Utrecht University; Países Bajos Fil: Bijl, Peter K.. Utrecht University; Países Bajos Fil: Guerstein, Gladys Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina Fil: Sluijs, Appy. Utrecht University; Países Bajos Fil: Brinkhuis, Henk. Utrecht University; Países Bajos

The Dependable Warmer During the middle of the Eocene, about 40 million years ago, a transient warming event interrupted the long-term cooling trend that had been in progress for the previous 10 million years. Bijl et al. (p. 819 ; see the Perspective by Pearson ) constructed records of sea surface temperature and atmospheric CO 2 concentrations across the warming period. It appears that vast amounts of CO 2 were injected into the atmosphere, and a sea surface temperature increase of as much a 6°C accompanied the atmospheric CO 2 rise.