scholarly journals Benthic foraminifera at the Paleocene/Eocene thermal maximum in the western Tethys (Forada section): variability in climate and productivity

2015 ◽  
Vol 11 (5) ◽  
pp. 4205-4272 ◽  
Author(s):  
L. Giusberti ◽  
F. Boscolo Galazzo ◽  
E. Thomas
Keyword(s):  
Environmental Changes ◽  
Hydrological Cycle ◽  
Species Turnover ◽  
Average Chain Length ◽  
Primary Role ◽  
Higher Plant ◽  
Foraminiferal Assemblage ◽  
Western Tethys ◽  
Thermal Maximum ◽  
Biomarker Data

Abstract. The Forada section (northeastern Italy) provides a continuous, expanded deep-sea record of the Paleocene/Eocene thermal maximum (PETM) in the central-western Tethys. We combine a new, high resolution, benthic foraminiferal assemblage record with published calcareous plankton, mineralogical and biomarker data to document climatic and environmental changes across the PETM, highlighting the benthic foraminiferal extinction event (BEE). The onset of the PETM, occurring ~ 30 kyr after a precursor event, is marked by a thin, black, barren clay layer, possibly representing a brief pulse of anoxia and carbonate dissolution. The BEE occurred within the 10 cm interval including this layer. During the first 3.5 kyr of the PETM several agglutinated recolonizing taxa show rapid species turnover, indicating a highly unstable, CaCO3-corrosive environment. Calcareous taxa reappeared after this interval, and the next ~ 9 kyr were characterized by rapid alternation of peaks in abundance of various calcareous and agglutinant recolonizers. These observations suggest that synergistic stressors including deep water CaCO3-corrosiveness, low oxygenation, and high environmental instability caused the extinction. Combined faunal and biomarker data (BIT index, higher plant n-alkane average chain length) and the high abundance of the mineral chlorite suggest that erosion and weathering increased strongly at the onset of the PETM, due to an overall wet climate with invigorated hydrological cycle, which led to storm flood-events carrying massive sediment discharge into the Belluno Basin. This interval was followed by the core of the PETM, characterized by four precessionally paced cycles in CaCO3%, hematite%, δ13C, abundant occurrence of opportunistic benthic foraminiferal taxa, as well as calcareous nannofossil and planktonic foraminiferal taxa typical of high productivity environments, radiolarians, and lower δDn-alkanes. We interpret these cycles as reflecting alternation between an overall arid climate, characterized by strong winds and intense upwelling, with an overall humid climate, with abundant rains and high sediment delivery (including refractory organic carbon) from land. Precessionally paced marl-limestone couplets occur throughout the recovery interval of the CIE and up to ten meters above it, suggesting that these wet-dry cycles persisted, though at declining intensity, after the peak PETM. Enhanced climate extremes at mid-latitudes might have been a direct response to the massive CO2 input in the ocean atmosphere system at the Paleocene–Eocene transition, and may have had a primary role in restoring the Earth system to steady state.

scholarly journals Variability in climate and productivity during the Paleocene–Eocene Thermal Maximum in the western Tethys (Forada section)

2016 ◽  
Vol 12 (2) ◽  
pp. 213-240 ◽  
Author(s):  
L. Giusberti ◽  
F. Boscolo Galazzo ◽  
E. Thomas
Keyword(s):  
Environmental Changes ◽  
Hydrological Cycle ◽  
Species Turnover ◽  
Average Chain Length ◽  
Primary Role ◽  
Higher Plant ◽  
Foraminiferal Assemblage ◽  
Western Tethys ◽  
Thermal Maximum ◽  
Biomarker Data

Abstract. The Forada section (northeastern Italy) provides a continuous, expanded deep-sea record of the Paleocene–Eocene Thermal Maximum (PETM) in the central-western Tethys. We combine a new, high-resolution, benthic foraminiferal assemblage record with published calcareous plankton, mineralogical and biomarker data to document climatic and environmental changes across the PETM, highlighting the benthic foraminiferal extinction event (BEE). The onset of the PETM, occurring  ∼ 30 kyr after a precursor event, is marked by a thin, black, barren clay layer, possibly representing a brief pulse of anoxia and carbonate dissolution. The BEE occurred within the 10 cm interval including this layer. During the first 3.5 kyr of the PETM, several agglutinated recolonizing taxa show rapid species turnover, indicating a highly unstable, CaCO3-corrosive environment. Calcareous taxa reappeared after this interval, and the next  ∼9 kyr were characterized by rapid alternation of peaks in abundance of various calcareous and agglutinated recolonizers. These observations suggest that synergistic stressors, including deepwater CaCO3 corrosiveness, low oxygenation, and high environmental instability caused the extinction. Combined faunal and biomarker data (BIT index, higher plant n-alkane average chain length) and the high abundance of the mineral chlorite suggest that erosion and weathering increased strongly at the onset of the PETM, due to an overall wet climate with invigorated hydrological cycle, which led to storm flood events carrying massive sediment discharge into the Belluno Basin. This interval was followed by the core of the PETM, characterized by four precessionally paced cycles in CaCO3 %, hematite %, δ13C, abundant occurrence of opportunistic benthic foraminiferal taxa, and calcareous nannofossil and planktonic foraminiferal taxa typical of high-productivity environments, radiolarians, and lower δDn-alkanes. We interpret these cycles as reflecting alternation between an overall arid climate, characterized by strong winds and intense upwelling, and an overall humid climate, with abundant rains and high sediment delivery (including refractory organic carbon) from land. Precessionally paced marl–limestone couplets occur throughout the recovery interval of the carbon isotope excursion (CIE) and up to 10 m above it, suggesting that these wet–dry cycles persisted, though at declining intensity, after the peak PETM. Enhanced climate extremes at mid-latitudes might have been a direct response to the massive CO2 input in the ocean atmosphere system at the Paleocene–Eocene transition, and may have had a primary role in restoring the Earth system to steady state.

scholarly journals Multiple early Eocene carbon isotope excursions associated with environmental changes in the Dieppe-Hampshire Basin (NW Europe)

2020 ◽  
Vol 191 ◽  
pp. 33
Author(s):  
Sylvain Garel ◽  
Christian Dupuis ◽  
Florence Quesnel ◽  
Jérémy Jacob ◽  
Johan Yans ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Environmental Changes ◽  
Climatic Changes ◽  
Coastal Sediments ◽  
Carbonate Dissolution ◽  
Early Eocene ◽  
Higher Plant ◽  
Carbon Isotopic ◽  
Paleoclimatic Changes ◽  
Thermal Maximum

The early Eocene experienced a series of short-lived global warming events, known as hyperthermals, associated with negative carbon isotope excursions (CIE). The Paleocene-Eocene Thermal Maximum (PETM or ETM-1) and Eocene Thermal Maximum 2 (ETM-2) are the two main events of this Epoch, both marked by massive sea-floor carbonate dissolution. Their timing, amplitude and impacts are rather well documented, but CIEs with lower amplitudes also associated with carbonate dissolution are still poorly studied (e.g. events E1 to H1), especially in the terrestrial realm where hiatus/disconformities and various sedimentary rates in a single succession may complicate the assignation to global isotopic events. Here we present a new high-resolution multi-proxy study on the terrestrial, lagoonal and shallow marine late Paleocene-early Eocene succession from two sites of the Cap d’Ailly area in the Dieppe-Hampshire Basin (Normandy, France). Carbon isotope data (δ13C) on bulk organic matter and higher-plant derived n-alkanes, and K-Ar ages on authigenic glauconite were determined to provide a stratigraphic framework. Palynofacies, distribution and hydrogen isotope values (δ2H) of higher-plant derived n-alkanes allowed us to unravel paleoenvironmental and paleoclimatic changes. In coastal sediments of the Cap d’Ailly area, δ13C values revealed two main negative CIEs, from base to top CIE1 and CIE2, and 3 less pronounced negative excursions older than the NP11 nannofossil biozone. While the CIE1 is clearly linked with the PETM initiation, the CIE2 could either correspond to 1) a second excursion within the PETM interval caused by strong local environmental changes or 2) a global carbon isotopic event that occurred between the PETM and ETM-2. Paleoenvironmental data indicated that both main CIEs were associated with dramatic changes such as eutrophication, algal and/or dinoflagellate blooms along with paleohydrological variations and an increase in seasonality. They revealed that the intervals immediately below these CIEs are also marked by environmental and climatic changes. Thus, this study shows either 1) a PETM marked by at least two distinct intervals of strong environmental and climatic changes or 2) at least one “minor” CIE: E1, E2, F or G, was associated with strong environmental and climatic changes similar to those that occurred during the PETM.

scholarly journals Environmental changes during the Paleocene–Eocene Thermal Maximum in Spitsbergen as reflected by benthic foraminifera

2013 ◽  
Vol 32 (1) ◽  
pp. 19737 ◽  
Author(s):  
Jenö Nagy ◽  
David Jargvoll ◽  
Henning Dypvik ◽  
Malte Jochmann ◽  
Lars Riber
Keyword(s):  
Benthic Foraminifera ◽  
Environmental Changes ◽  
Thermal Maximum

scholarly journals Blooms of aberrant planktic foraminifera across the K/Pg boundary in the Western Tethys: causes and evolutionary implications

Paleobiology ◽  
2018 ◽  
Vol 44 (3) ◽  
pp. 460-489 ◽  
Author(s):  
Ignacio Arenillas ◽  
José A. Arz ◽  
Vicente Gilabert
Keyword(s):  
Environmental Changes ◽  
Low Frequency ◽  
Meteorite Impact ◽  
Planktic Foraminifera ◽  
Western Tethys ◽  
Quantitative Studies ◽  
El Kef ◽  
Abnormality Index ◽  
The One ◽  
Aberrant Tests

AbstractWe report a detailed study of the different categories and types of abnormal morphologies in planktic foraminifera recognizable in the lowermost Danian, mainly from the El Kef and Aïn Settara sections, Tunisia. Various types of abnormalities in the test morphology were identified, including protuberances near the proloculus, abnormal chambers, double or twinned ultimate chambers, multiple ultimate chambers, abnormal apertures, distortion in test coiling, morphologically abnormal tests, attached twins or double tests, and general monstrosities. Detailed biostratigraphic and quantitative studies of the Tunisian sections documented a major proliferation of aberrant planktic foraminifera (between approximately 5% and 18% in relative abundance) during the first 200 Kyr of the Danian, starting immediately after the Cretaceous/Paleogene (K/Pg) boundary mass extinction (spanning from theGuembelitria cretaceaZone to the lower part of theP. pseudobulloidesZone). This contrasts with the proportionately low frequency of aberrant tests (generally <2%) identified within the uppermost Maastrichtian, suggesting more stable environmental conditions during the last ~50–100 Kyr of the Cretaceous. Two main pulses with abundant aberrant tests were recognized in the earliest Danian, the one recorded in the well-known K/Pg boundary clay being the more intense of those (maxima of >18%). These main pulses of aberrants coincide approximately with relevant quantitative and evolutionary turnovers in the planktic foraminiferal assemblages. In this paper, we explore the relation of these high values of the foraminiferal abnormality index with the environmental changes induced by the meteorite impact of Chicxulub in Yucatan, Mexico, and the massive eruptions of the Deccan Traps, India.

Stratigraphic and sedimentological aspects of the worldwide distribution of Apectodinium in Paleocene/Eocene Thermal Maximum deposits

2021 ◽  
pp. SP511-2020-46
Author(s):  
Christopher N. Denison
Keyword(s):  
Global Warming ◽  
Sea Level ◽  
Environmental Changes ◽  
Calcareous Nannofossil ◽  
Shallow Marine ◽  
Worldwide Distribution ◽  
Carbon Isotope Excursion ◽  
Thermal Maximum ◽  
Taxonomic Changes ◽  
Data Gap

AbstractThe Paleocene/Eocene Thermal Maximum (PETM) is characterized by pronounced global warming and associated environmental changes. In the more-or-less two decades since prior regional syntheses of Apectodinium distribution at the PETM, extensive biological and geochemical datasets have elucidated the effect of rising world temperatures on climate and the biome. A Carbon Isotope Excursion (CIE) that marks the Paleocene/Eocene Boundary (PEB) is associated with an acme of marine dinocysts of the genus Apectodinium in many locations. Distinctive foraminiferal and calcareous nannofossil populations may also be present.For this up-dated, dinocyst-oriented view of the PETM, data from worldwide locations have been evaluated with an emphasis on stratigraphic and sedimentological context. What has emerged is that a change in lithology is common, often to a distinctive siltstone or claystone unit, which contrasts with underlying and overlying lithotypes. This change, present in shallow marine/coastal settings and in deepwater turbidite deposits, is attributed to radical modifications of precipitation and erosional processes. An abrupt boundary carries the implication that some time (of unknowable duration) is potentially missing, which then requires caution in the interpretation of the pacing of events in relation to that boundary. In most instances an ‘abrupt’ or ‘rapid’ CIE onset can be attributed to a data gap at a hiatus, particularly in shallow shelf settings where transgression resulted from sea-level rise associated with the PETM. Truly gradational lower boundaries of the PETM interval are quite unusual, and if present, are poorly known so far. Gradational upper boundaries are more common, but erosional upper boundaries have been reported.Taxonomic changes have been made to clarify identification issues that have adversely impacted some biostratigraphic interpretations. Apectodinium hyperacanthum has been retained in Wetzeliella, its original genus. The majority of specimens previously assigned to Apectodinium hyperacanthum or Wetzeliella (Apectodinium) hyperacanthum have been re-assigned to an informal species, Apectodinium sp. 1. Dracodinium astra has been retained in its original genus as Wetzeliella astra, and is emended.

scholarly journals Rapid carbon injection and transient global warming during the Paleocene-Eocene thermal maximum

2008 ◽  
Vol 87 (3) ◽  
pp. 201-206 ◽  
Author(s):  
A. Stuijs ◽  
H. Brinkhuis
Keyword(s):  
Global Warming ◽  
High Latitude ◽  
Elevated Temperatures ◽  
Hydrological Cycle ◽  
Warming Trend ◽  
Early Eocene ◽  
Biotic Response ◽  
Thermal Maximum ◽  
Carbon Injection

The Paleocene-Eocene Thermal Maximum (PETM), ~55.5 Myr ago, was a geologically brief (~170 kyr) episode of globally elevated temperatures, which occurred superimposed on the long-term late Paleocene and early Eocene warming trend (Fig. 1). It was marked by a 5 – 8° C warming in both low and high-latitude regions, a perturbation of the hydrological cycle and major biotic response on land and in the oceans, including radiations, extinctions and migrations (see overviews in Bowen et al., 2006; Sluijs et al., 2007a).

Changes in hydrological behaviour: case studies of the Unica and Rižana karst springs, Slovenia

2020 ◽  
Author(s):  
Natasa Ravbar ◽  
Gregor Kovačič ◽  
Metka Petrič
Keyword(s):  
Land Use ◽  
Large Scale ◽  
Environmental Changes ◽  
Hydrological Cycle ◽  
Land Use Changes ◽  
Precipitation Amount ◽  
Flood Pulse ◽  
Karst Springs ◽  
The Impact ◽  
Gauging Station

&lt;p&gt;Environmental changes, such as alterations in precipitation and evapotranspiration regimes, changes in vegetation type, etc. are triggering direct impact on hydrological cycle through modified amounts and patterns of recharge conditions, as well as occurrence of more frequent and severe hydrometeorological events. Karst aquifers are particularly vulnerable to these effects due to highly dynamic hydrological processes. In this study, we were interested in studying the possibilities to observe changed hydrological behaviour of karst springs on a human timescale. Therefore, we focused on two examples in Slovenia, both regionally important for freshwater supply, agriculture and hydropower. The Unica spring mostly drains areas under moderate continental climate. Its catchment has been repeatedly and severely hit by natural disasters (e.g., ice break, bark beetle attack, windthrow) after 2014 causing large-scale forest disturbances. The catchment of Ri&amp;#382;ana spring, on the other hand, belongs to the moderate Submediterranean climate. There these types of disturbance did not occur in recent years (excluding some wildfires), but the catchment has been liable to substantial land use changes in the past six decades. For assessment of vegetation cover changes and large-scale disturbances in forests, historical digital orthophotos of the Surveying and Mapping Authority of the Republic of Slovenia since 1957 have been compared with the recent land use data provided by Ministry of Agriculture, Economy and Food and forest state database of Slovenian Forest Service. At the same time, hydrological data of the Unica (Hasberg gauging station) in the period 1962-2018 and Ri&amp;#382;ana springs (Kubed gauging station) in the period 1966-2018 and precipitation data from Postojna (period 1962-2018) and Podgrad (period 1966-2018) meteorological stations have been processed. Individual flood pulse events over the 57 years for Unica and 53 years for Ri&amp;#382;ana have been separated. For each flood pulse various information about precipitation amount and intensity, duration of discharge increase, its intensity and amplitude have been specified. We compared these findings with the calculated trends of meteorological and hydrological variables and also changes in land use. The impact of particular environmental change on discharge values of both springs has been evaluated, showing that both, climate and land-use changes, have considerable impact on hydrological regime of studied karst springs. In particular, altered duration of flood pulses increase, their amplitude and intensity have been observed, meaning that the most important issues of water availability that are crucial for water-dependant economic sectors are under threat.&lt;/p&gt;

Changes in the hydrological cycle in tropical East Africa during the Paleocene–Eocene Thermal Maximum

2012 ◽  
Vol 329-330 ◽  
pp. 10-21 ◽  
Author(s):  
Luke Handley ◽  
Aoife O'Halloran ◽  
Paul N. Pearson ◽  
Elizabeth Hawkins ◽  
Christopher J. Nicholas ◽  
...  
Keyword(s):  
East Africa ◽  
Hydrological Cycle ◽  
Thermal Maximum

scholarly journals Organic-matter quality of deep permafrost carbon – a study from Arctic Siberia

2015 ◽  
Vol 12 (7) ◽  
pp. 2227-2245 ◽  
Author(s):  
J. Strauss ◽  
L. Schirrmeister ◽  
K. Mangelsdorf ◽  
L. Eichhorn ◽  
S. Wetterich ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Stable Carbon Isotopes ◽  
Average Chain Length ◽  
Frozen Ground ◽  
Higher Plant ◽  
Organic Matter Quality ◽  
Microbial Decomposition ◽  
Geochemical Parameters

Abstract. The organic-carbon (OC) pool accumulated in Arctic permafrost (perennially frozen ground) equals the carbon stored in the modern atmosphere. To give an idea of how Yedoma region permafrost could respond under future climatic warming, we conducted a study to quantify the organic-matter quality (here defined as the intrinsic potential to be further transformed, decomposed, and mineralized) of late Pleistocene (Yedoma) and Holocene (thermokarst) deposits on the Buor-Khaya Peninsula, northeast Siberia. The objective of this study was to develop a stratigraphic classified organic-matter quality characterization. For this purpose the degree of organic-matter decomposition was estimated by using a multiproxy approach. We applied sedimentological (grain-size analyses, bulk density, ice content) and geochemical parameters (total OC, stable carbon isotopes (δ13C), total organic carbon : nitrogen (C / N) ratios) as well as lipid biomarkers (n-alkanes, n-fatty acids, hopanes, triterpenoids, and biomarker indices, i.e., average chain length, carbon preference index (CPI), and higher-plant fatty-acid index (HPFA)). Our results show that the Yedoma and thermokarst organic-matter qualities for further decomposition exhibit no obvious degradation–depth trend. Relatively, the C / N and δ13C values and the HPFA index show a significantly better preservation of the organic matter stored in thermokarst deposits compared to Yedoma deposits. The CPI data suggest less degradation of the organic matter from both deposits, with a higher value for Yedoma organic matter. As the interquartile ranges of the proxies mostly overlap, we interpret this as indicating comparable quality for further decomposition for both kinds of deposits with likely better thermokarst organic-matter quality. Supported by principal component analyses, the sediment parameters and quality proxies of Yedoma and thermokarst deposits could not be unambiguously separated from each other. This revealed that the organic-matter vulnerability is heterogeneous and depends on different decomposition trajectories and the previous decomposition and preservation history. Elucidating this was one of the major new contributions of our multiproxy study. With the addition of biomarker data, it was possible to show that permafrost organic-matter degradation likely occurs via a combination of (uncompleted) degradation cycles or a cascade of degradation steps rather than as a linear function of age or sediment facies. We conclude that the amount of organic matter in the studied sediments is high for mineral soils and of good quality and therefore susceptible to future decomposition. The lack of depth trends shows that permafrost acts like a giant freezer, preserving the constant quality of ancient organic matter. When undecomposed Yedoma organic matter is mobilized via thermokarst processes, the fate of this carbon depends largely on the environmental conditions; the carbon could be preserved in an undecomposed state till refreezing occurs. If modern input has occurred, thermokarst organic matter could be of a better quality for future microbial decomposition than that found in Yedoma deposits.

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