Danolestes moelleri gen. et sp. nov., the first lestoid (Zygoptera: Odonata) from the early Ypresian Fur Formation of Denmark shows faunistic affinity to South America

<p>During the early Paleogene, a long-term warming trend of Earth’s climate was punctuated by a major global warming event, known as the Paleocene-Eocene Thermal Maximum (PETM) and marked by a carbon isotope excursion (CIE) and an acidification episode. The associated worldwide environmental perturbations are best studied in open marine settings, and resulted in a major extinction event in deep-sea benthic foraminifera, followed by migration and diversification. Yet, the evolutionary impact on shelf foraminiferal faunas is still poorly constrained due the inherent stratigraphic complexities in these environments. In order to understand the prelude and aftermath of peak warming during the PETM, we study the South Dover Bridge core (SDB), drilled in the US Atlantic Coastal Plain in Maryland. Here, the Paleocene-Eocene transition is stratigraphically well constrained by calcareous nannoplankton and stable isotope records. Additionally, the PETM is regionally characterized by the appearance of fine-grained sediments, known as the Marlboro Clay, contrasting with the late Paleocene glauconitic sands. Our newly generated high-resolution foraminiferal stable isotope, biotic and grain size data enable an assessment of the stratigraphic completeness of this site, and the disentanglement of the successive recovery-phases, by correlation across the paleoshelf.</p><p>The mid-shelf benthic foraminiferal assemblage we recorded in the upper Paleocene indicates well-oxygenated, continuously oligo- to mesotrophic bottom water conditions. These conditions were temporarily interrupted during a pre-PETM CIE, which initiated minor, but prominent, changes in foraminiferal assemblage. The relationship with the PETM is still unclear, but it may indicate that the latest Paleocene climate was not as stable as previously assumed and instead exhibited a more gradual change towards the PETM. At the onset of the PETM diversity decreases, as more stress-resistant benthic taxa become predominant and planktic abundances increase. This probably points to periodically dysoxic bottom waters due to river-induced stratification, resulting from enhanced regional river outflow, as well as to a shift to episodic food fluxes to the sea floor.</p><p>The studied expanded SDB sequence also presents an excellent and nearly complete record of the PETM isotope recovery phase. Throughout this recovery phase a third, more diverse foraminiferal assemblage starts to prevail, indicating a gradual return to sustained high food levels and increasing oxygen levels, related to a decrease of river influence. Species, dominant during the core phase of the PETM, like<em> Anomalinoides acutus</em> or <em>Pseudouvigerina wilcoxensis</em>, show strongly declining numbers in the recovery phase. Other taxa, like <em>Cibicidoides alleni</em>, returned to the shelf ecosystem, after disappearing nearly completely from the sediments during the initial PETM CIE interval. This coincides with reduced planktic foraminiferal abundances and a tendency towards more silty and less clayey sediments, linked to renewed bottom current activities and winnowing.</p><p>The lack of severe benthic extinction among shelf-dwelling benthic foraminifera and the observed lateral variability in environmental conditions, demonstrate how foraminiferal shelf communities can adapt to massive global carbon perturbations. As more regional data will become available, these will enable more constraints on environmental parameters and variations along the Atlantic Coastal Plain prior and during the PETM.</p>

We studied the rapid paleo-environmental changes and the corresponding biotic responses of benthic foraminifera of a shallow shelf site during the late Paleocene and the Paleocene-Eocene Thermal Maximum (PETM). The PETM is globally characterized by a negative δ13C excursion in marine and terrestrial sediments. Isotope data from the Atlantic Coastal Plain from the South Dover Bridge core, Maryland, show an additional small δ13C excursion just below the base of the PETM: the “pre-onset excursion” (POE). The benthic foraminiferal and coupled grain-size record of the late Paleocene indicates a well-oxygenated, current-dominated environment with a stable, high food supply. During the POE, bottom currents become subdued and finer-grained sediment accumulation increased. These changes are partially reversed after the end of the POE. Before the PETM the river influence increases again, food supply becomes more pulsed and the benthic taxa, typically connected to the PETM, start to appear in those gradually warming conditions. During the PETM, the environment shifts to a river-dominated one, with strongly reduced currents. The low-diversity PETM fauna thrives under episodic low-oxygen conditions, caused by river-induced stratification, while the Paleocene assemblage nearly vanishes from the record. Gradually the environment begins to recover, the grain size shows an uptick in bottom currents and pre-PETM foraminifera become more abundant again, indicating increased oxygen levels and a more stable food supply. While the overall environmental shifts at South Dover Bridge fit within the observations across the shelf, the POE related insights are so far unique. Our bathymetric reconstructions show an outer neritic paleodepth (∼100 m) during the Paleocene, with a modest sea level rise in the core phase of the PETM, which is subsequently reversed during the recovery phase.

Response of calcareous nannoplankton to the Paleocene–Eocene Thermal Maximum in the Paratethys Seaway (Tarim Basin, West China)

The Palaeocene–Eocene Thermal Maximum was associated with a massive release of carbon. Marine sediments suggest a temporary deepening of the calcite compensation depth, indicating extensive silicate weatheringin the aftermath of the event. The Palaeocene–Eocene Thermal Maximum was associated with a massive release of carbon. Marine sediments suggest a temporary deepening of the calcite compensation depth, indicating extensive silicate weatheringin the aftermath of the event. During the Palaeocene–Eocene Thermal Maximum (PETM) about 56 million years ago, thousands of petagrams of carbon were released into the atmosphere and ocean in just a few thousand years, followed by gradual sequestration over approximately 200,000 years. If silicate weathering is one of the key negative feedbacks that removed this carbon, a period of seawater calcium carbonate saturation greater than pre-event levels would be expected during the event's recovery phase. In marine sediments, this should be recorded as a temporary deepening of the depth below which no calcite is preserved — the calcite compensation depth (CCD). Previous and new sedimentary records from sites that were above the pre-PETM CCD show enhanced carbonate accumulation following the PETM. A new record from an abyssal site in the North Atlantic that lay below the pre-PETM CCD shows a period of carbonate preservation beginning about 70,000 years after the onset of the PETM, providing the first direct evidence for an over-deepening of the CCD. This record confirms an overshoot in ocean carbonate saturation during the PETM recovery. Simulations with two earth system models support scenarios for the PETM that involve a large initial carbon release followed by prolonged low-level emissions, consistent with the timing of CCD deepening in our record. Our findings indicate that sequestration of these carbon emissions was most likely the result of both globally enhanced calcite burial above the CCD and, at least in the North Atlantic, an over-deepening of the CCD.

In two continental sections in the Tremp basin, northern Spain, the initial Eocene thermal maximum (also known as the Paleocene-Eocene thermal maximum) is registered by an ∼6‰ fall in δ 1 3 C values in soil carbonate nodules. High-resolution correlations, using the δ 1 3 C excursion, can be made to nearby shelf and bathyal marine settings, allowing a detailed reconstruction of soil formation on land and transport of detritus to the sea during the initial Eocene thermal maximum. Soils that formed before and after the initial Eocene thermal maximum in the Tremp region reflect arid to semiarid conditions, with abundant evaporative minerals, whereas initial Eocene thermal maximum soils reflect seasonally wetter but generally dry conditions. During the initial Eocene thermal maximum, land erosion was intensified and accumulation rates of terrigenous detritus in the sea increased. This reflects both increased topographic relief associated with a prominent sea-level lowstand and enhanced seasonal precipitation over a dry landscape with sparse vegetation. Deeper erosion led to an increase in the flux of kaolinite from buried Mesozoic soils to the oceans. The association of the initial Eocene thermal maximum with a sea-level lowstand in northern Spain, as well as at other marginal North Atlantic sites, may reflect coeval large-scale magmatic activity in the northernmost Atlantic.

Paleocene-Eocene Thermal Maximum lacustrine sediments in deep drill core SKD1 in the Jianghan Basin: A record of enhanced precipitation in central China

Research Article| November 01, 2008 Paleogene paleosols and changes in pedogenesis during the initial Eocene thermal maximum: Big Bend National Park, Texas, USA Paul D. White; Paul D. White † 1Physics Department, Community College of Rhode Island, 400 East Avenue, Warwick, Rhode Island, 02886, USA †E-mail: pdwhite1@ccri.edu Search for other works by this author on: GSW Google Scholar Judith Schiebout Judith Schiebout 2Museum of Natural Science and the Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2008) 120 (11-12): 1347–1361. https://doi.org/10.1130/B25987.1 Article history received: 10 Feb 2006 rev-recd: 14 Dec 2006 accepted: 25 Jul 2007 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Paul D. White, Judith Schiebout; Paleogene paleosols and changes in pedogenesis during the initial Eocene thermal maximum: Big Bend National Park, Texas, USA. GSA Bulletin 2008;; 120 (11-12): 1347–1361. doi: https://doi.org/10.1130/B25987.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract This paper tests the hypothesis that continental chemical weathering increased during the initial Eocene thermal maximum (IETM) by comparing paleosols that formed before and during the event in western Texas. The chemical index of alteration (CIA) was used to investigate the weathering of silicate minerals. Paleosols generated before the IETM have CIA values ranging from 62 to 72, and CIA values during the IETM range from 67 to 82. The CIA values for pre–initial Eocene thermal maximum paleosols indicate moderate weathering conditions, and CIA values during the event indicate moderate to extreme weathering conditions. The clay mineralogy of the paleosols is dominated by smectite, and it is only within paleosols that formed during the IETM that there is a change. There is a notable increase in the amount of kaolinite in one paleosol horizon that is associated with the carbon excursion. In addition, there is an increase in the translocation of clays and iron, and an increase in the leaching of calcite and plagioclase in initial Eocene thermal maximum paleosols. The differences between soils that formed before and during the initial Eocene thermal maximum indicate that chemical weathering did increase during this ancient global warming event. The mechanism responsible for increased weathering is interpreted to be an increase in hydrolysis reactions caused by an increase in humidity and an increase of carbonic acid in the soil due to elevated CO2 levels during the initial Eocene thermal maximum. Documentation of an increase in chemical weathering during the initial Eocene thermal maximum is significant because it may have served as a negative feedback to reduce atmospheric CO2. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Paleocene Eocene thermal Maximum (PETM) was a rapid global warming event, which occurred ~ 56 million years ago and lasted for ~200 ka. It is characterized by a massive rapid input of 13C-depleted carbon into the atmosphere and ocean, causing a 2-7‰ negative carbon isotope excursion (CIE). As a result of high atmospheric CO2 levels, high temperatures, and an enhanced hydrological cycle during the PETM, increases in physical and chemical weathering intensity have previously been reconstructed across the globe. Chemical weathering of silicate rocks predominates in humid climates and significantly influences the major and trace element composition of resulting sediments. Numerous studies  suggest that the intensified chemical weathering of silicate rocks occurred during the PETM, driven by the warm conditions and enhanced hydrological cycle.Here we present the first results of elemental geochemical analysis of sediment samples collected from the mid-Norwegian margin during IODP Expedition 396. Our initial results focus on variations in chemical weathering across the PETM as inferred from geochemical proxies.In the samples examined here, chemical index of alteration (CIA), a proxy for chemical weathering intensity, values show a sharp drop from pre-PETM to mid-PETM. In contrast to other locations, these observations suggest a shift in the intensity of weathering from intermediate to weak and indicates chemical weathering was not intensified during the PETM in our study region. As this is opposite to previous studies, we consider whether changes in sediment provenance may explain these data. However, the provenance discrimination plots (La-Th-Sc ternary diagram Th/Co vs. La/Sc bivariate plot) shows mixed source with no clustering regardless of the time period. This indicates that the sediment source of the Vøring basin did not change at the PETM onset and we suggest that our CIA data truly represent a decrease in the intensity of chemical weathering during the PETM in the Vøring Basin. 

The Paleocene‐Eocene Thermal Maximum (PETM) is recognized globally by a negative excursion in stable carbon isotope ratios (δ13C) in sedimentary records, termed the carbon isotope excursion (CIE). Based on the CIE, the cause, duration, and mechanisms of recovery of the event have been assessed. Here, we focus on the role of increased organic carbon burial on continental margins as a key driver of CO2 drawdown and global exogenic δ13C during the recovery phase. Using new and previously published sediment proxy data, we show evidence for widespread enhanced primary production, low oxygen waters, and high organic carbon (Corg) burial in marginal and restricted environments throughout the δ13C excursion. With a new biogeochemical box model for deep and marginal environments, we show that increased phosphorus availability and water column stratification on continental margins can explain the increased Corg burial during the PETM. Deoxygenation and recycling of phosphorus relative to Corg were relatively mild, compared to modern day anoxic marine systems. Our model reproduces the conditions reconstructed by field data, resulting in a burial of 6,000 Pg across the PETM, in excess of late Paleocene burial, and ∼3,300 Pg C for the critical first 40 kyr of the recovery, primarily located on continental margins. This value is consistent with prior data and model estimates (∼2,000–3,000 Pg C). To reproduce global exogenic δ13C patterns, this Corg burial implies an injection of 5,000–10,000 Pg C during the first ∼100–150 kyr of the PETM, depending on the source's δ13C (−11‰ to −55‰).

Shallow marine ecosystem collapse and recovery during the Paleocene-Eocene Thermal Maximum

The Palaeocene–Eocene Thermal Maximum (PETM), a geologically brief episode of global warming associated with the Palaeocene–Eocene boundary, has been studied extensively since its discovery in 1991. The PETM is characterized by a globally quasi-uniform 5–8 8C warming and large changes in ocean chemistry and biotic response. The warming is associated with a negative carbon isotope excursion (CIE), reflecting geologically rapid input of large amounts of isotopically light CO2 and/or CH4 into the exogenic (ocean–atmosphere) carbon pool. The biotic response on land and in the oceans was heterogeneous in nature and severity, including radiations, extinctions and migrations. Recently, several events that appear similar to the PETM in nature, but of smaller magnitude, were identified to have occurred in the late Palaeocene through early Eocene, with their timing possibly modulated by orbital forcing. Although debate continues on the carbon source, the mechanisms that caused the input, the mechanisms of carbon sequestration, and the duration and pacing of the event, the research carried out over the last 15 years has provided new constraints and spawned new research directions that will lead to improved understanding of PETM carbon cycle and climate change. A distinct period of extreme global warmth was initiated close to the boundary between the Palaeocene and Eocene epochs, approximately 55.5 Ma ago (Gradstein et al. 2004). This event, termed the Palaeocene–Eocene Thermal Maximum (PETM), occurred during a time of generally warm, ‘greenhouse’ climate conditions, but stands out against the background warmth as an abrupt and short-lived spike in global temperatures. Evidence for global warming is preserved by the TEX86 0 temperature proxy (Sluijs et al. 2006; Zachos et al. 2006), oxygen isotope (dO) excursions in marine foraminiferal calcite (Fig. 1) (Kennett & Stott 1991; Thomas et al. 2002) and terrestrial carbonates (Koch et al. 1995), increased Mg/Ca values in planktonic and benthic foraminifera (Zachos et al. 2003; Tripati & Elderfield 2005), poleward migrations of (sub)tropical marine plankton (Kelly et al. 1996; Crouch et al. 2001) and terrestrial plant species (Wing et al. 2005), and mammal migrations across high northern latitudes (Bowen et al. 2002, 2006; Smith et al. 2006). Associated with the warming is a negative 2.5–6‰ carbon isotope (dC) excursion (CIE) (Kennett & Stott 1991; Koch et al. 1992; Thomas et al. 2002; Pagani et al. 2006), generally accepted to reflect the geologically rapid injection of C-depleted carbon, in the form of CO2 and/or CH4, into the global exogenic carbon pool (Fig. 1). The apparent conjunction between carbon input and warming has fuelled the hypothesis that increased greenhouse gas concentrations resulted in greenhouse warming during the PETM. The total amount of carbon input during the PETM, which is known to within an order of magnitude (Dickens et al. 1997; Zachos et al. 2005; Pagani et al. 2006), was about 4–8 times the anthropogenic carbon release from the start of the industrial era up From: WILLIAMS, M., HAYWOOD, A. M., GREGORY, F. J. & SCHMIDT, D. N. (eds)Deep-Time Perspectives on Climate Change: Marrying the Signal from Computer Models and Biological Proxies. The Micropalaeontological Society, Special Publications. The Geological Society, London, 323–349. 1747-602X/07/$15.00 # The Micropalaeontological Society 2007. to today (Marland et al. 2005), and comparable to that expected from gross anthropogenic emissions through the end of the 21st century (Intergovernmental Panel on Climate Change 2001). In association with carbon cycle and climatic change, the PETM also stands out as a time of major biotic restructuring. Given the probable ties between releases of near-modern levels of carbon-based greenhouse gases and PETM climatic and biotic change, the PETM has developed as a provocative geological case study in global change, and many of the event’s characteristics and mechanisms are under intensive study. A large volume of research on the PETM has appeared over the past decade (Fig. 2), and in this paper we aim to review and synthesize this material, including the duration and magnitude of carbon cycle perturbation, magnitude of warming, changes in ocean chemistry and marine and terrestrial biotic response. 167

Contrasting response of the calcareous nannoplankton communities after the Eocene hyperthermal events in the tropical Atlantic Ocean

Continental sedimentary records of early Paleogene hyperthermals are typically limited to weathered, often discontinuous, outcrop exposures. In 2011, the Bighorn Basin Coring Project (BBCP) collected the first continuous terrestrial records of the Paleocene‐Eocene Thermal Maximum (PETM) in the Bighorn Basin, Wyoming. Organic matter preservation was poor during the PETM, even in core material. Concentrations of leaf waxes during the PETM are too low for compound‐specific carbon isotope analysis by conventional means. However, the recent development of picomolar‐scale compound‐specific isotope analyses (pico‐CSIA) has reduced sample requirements and enabled measurements of carbon isotope ratios of n‐alkanes across the PETM in the Basin Substation core. While the prominent, negative carbon isotope excursion in total organic carbon that typically identifies the PETM in the sedimentary record is absent from the core, lithostratigraphic, biostratigraphic, and chemostratigraphic data suggest that the most likely position of the PETM is from ~87.82‐ to ~50‐m composite depth. This ~40‐m interval coincides with the lowest weight percent organic carbon, n‐alkane abundances, and n‐alkane δ13C values and the highest n‐alkane average chain lengths. Comparison of the n‐alkane isotope record from the core with that from organic‐rich rocks exposed in the SE Bighorn Basin suggests that n‐alkanes in the core fail to express the full magnitude of the carbon isotope excursion. We hypothesize that floodplain sediments at Basin Substation contain a mixture of PETM and reworked fossil n‐alkanes. Low total organic carbon suggests that PETM climate accelerated organic matter decay rates and floodplains may have acted as a carbon source during the PETM.

Paleohydrologic response to continental warming during the Paleocene–Eocene Thermal Maximum, Bighorn Basin, Wyoming

In the New Jersey Coastal Plain, a silty to clayey sedimentary unit (the Marlboro Formation) represents deposition during the Paleocene‐Eocene thermal maximum (PETM). This interval is remarkably different from the glauconitic sands and silts of the underlying Paleocene Vincentown and overlying Eocene Manasquan Formation. We integrate new and published stable isotope, biostratigraphic, lithostratigraphic and ecostratigraphic records, constructing a detailed time frame for the PETM along a depth gradient at core sites Clayton, Wilson Lake, Ancora and Bass River (updip to downdip). The onset of the PETM, marked by the base of the carbon isotope excursion (CIE), is within the gradual transition from glauconitic silty sands to silty clay, and represented fully at the updip sites (Wilson Lake and Clayton). The CIE “core” interval is expanded at the updip sites, but truncated. The CIE “core” is complete at the Bass River and Ancora sites, where the early part of the recovery is present (most complete at Ancora). The extent to which the PETM is expressed in the sediments is highly variable between sites, with a significant unconformity at the base of the overlying lower Eocene sediments. Our regional correlation framework provides an improved age model, allowing better understanding of the progression of environmental changes during the PETM. High‐resolution benthic foraminiferal data document the change from a sediment‐starved shelf setting to a tropical, river‐dominated mud‐belt system during the PETM, probably due to intensification of the hydrologic cycle. The excellent preservation of foraminifera during the PETM and the lack of severe benthic extinction suggest there was no extreme ocean acidification in shelf settings.