Larger benthic foraminiferal turnover and carbon isotope excursion during the Paleocene−Eocene Thermal Maximum in the Southern Himalayan carbonate platform (Eastern Neo-Tethys Ocean, Pakistan)

<p>In the Potwar Basin (Pakistan, Eastern Neotethys), the Paleocene-Eocene transition has been investigated and the changes in larger benthic foraminiferal (LBF) assemblages have been compared with the carbon isotope excursion (CIE). The ~5‰ negative CIE is here used to place the exact position of the Paleocene-Eocene boundary that falls in the base of the Shallow Benthic Zone (SBZ) 5. The boundary between the SBZ 5 and 6 corresponds to the early stages of the CIE recovery phase, which is characterized by the disappearance of the some typical Paleocene lamellar-perforate LBF genera such as <em>Miscellanea</em>, <em>Kathina</em>, and possibly <em>Ranikothalia</em>. In the Potwar Basin, some species of <em>Daviesina </em>and <em>Glomalveolina </em>also disappeared at the base of SBZ 6. At the same time, the genus <em>Orbitolites </em>and some species of <em>Alveolina</em>, <em>Nummulites</em>, miliolids, and <em>Assilina </em>appeared and led to the larger foraminiferal extinction and origination (LFEO) event.</p><p>The LFEO event represents the late response of the LBF to the abrupt environmental perturbation induced by the Paleocene-Eocene Thermal Maximum (PETM). At the Duleram section (Potwar Basin), the pre-PETM phase is characterized by highly stable and oligotrophic conditions, as revealed by the dominance of large, K-strategists LBF genera (e.g., <em>Miscellanea</em>, <em>Ranikothalia</em>, and <em>Daviesina</em>). At the onset of the PETM, an increased nutrient supply led to establishment of more eutrophic conditions and a collapse of the oligotrophic LBF with the rise of more nutrient-tolerant, small-sized LBF (e.g., glomalveolinids). At the post-PETM phase, stable oligotrophic conditions were re-established, as revealed by the dominance of new K-strategists LBF genera (<em>Alveolina</em>, <em>Nummulites, </em>and A<em>ssilina</em>).</p><p>As the changes in the LBF assemblages match well with the CIE changes, we can use them as proxies to infer the variations from stable oligotrophic to eutrophic marine conditions during the PETM event in the Eastern Neotethys.</p>

The end of the Cretaceous period (66.04 Ma) was punctuated by a mass extinction event with the disappearance of nearly 75% of all species. Despite its relevance, the extinction in shallow marine environments is still not fully understood. The present study examines the changes in the Larger Benthic Foraminiferal (LBF) assemblages across the Cretaceous/Paleogene (K/Pg) boundary in the Dunghan Formation, N-E Baluchistan Basin, Pakistan (Eastern Neo-Tethys). The Mehrab Tangi section is known for having one of the most extensive and well-preserved K/Pg transitions deposited in a shallow marine environment in this part of the Eastern Neo-Tethys. Thus, the biotic change in the LBF assemblages can be attributed to two distinct phases, namely the pre-K-Pg phase and the post-K-Pg phase. The pre-K/Pg phase is identified by the presence of the Maastrichtian Omphalocyclus-Orbitoides-Lepidorbitoides assemblages, while the post-K/Pg phase is marked by the Danian Rotalia-Lockhartia assemblages. Based on the composition of LBF assemblages and sedimentological characteristics, five distinct microfacies are identified, which represent different paleoenvironments within the inner-outer ramp. The initial phase of the post-K/Pg period is characterized by the presence of the Rotalia-Lockhartia wackstone, which indicates a rise in sea level. This rise is accompanied by a significant increase in glauconite mineral and fecal pellets, indicating a high rate of sedimentation during the earliest Danian. The K/Pg boundary event had a significant impact on the composition of LBF assemblages in shallow marine deposits globally. This event led to the extinction of several LBF Maastrichtian species, including Omphalocyclus macroporus, Lepidorbitoides blanfordi, Lepidorbitoides minor, Orbitoides media, and Orbitoides apiculate, followed by the appearance of important Danian LBF species such as Rotalia hensoni, Rotalia orientalis, Smoutina cruysi, Lockhartia cushmani, and Lockhartia diversa. The presence of a 1.5-meter-thick laterite band below the Maastrichtian Omphalocyclus-Orbitoides-Lepidorbitoides assemblages provides strong evidence for the onset of the collision between the Indian and Eurasian plates in this region of the Neo-Tethys. Based on detailed and accurate biostratigraphic data, we speculate that the Indian-Eurasian plate collision commenced during the middle Maastrichtian age rather than at the Maastrichtian/Danian boundary as previously suggested in studies conducted in the Himalayas, Eastern Neo-Tethys.

The Earth’s climate was marked by a pronounced warming at the onset of the Eocene Epoch, followed by successive short-lived warmings in the later part of the early Eocene. The carbon isotope (δ 13 C) excursions, the fingerprints of the Eocene hyperthermal events, have been established in the geological sections in India that lay across the equator in the early Eocene. The present study examines how shallow-marine foraminifera responded to the thermal events. The hyperthermal events, identified in sections of Kutch and Cambay basins corresponding to Shallow Benthic Zones (SBZs) between SBZ 5/6 to SBZ 11, have been examined for their foraminiferal assemblages, which indicate a shallow-marine environment. A significant change in the foraminiferal assemblage occurs from SBZ 5/6 to SBZ 11. The SBZ 5/6 to SBZ 10 interval (corresponding to Paleocene–Eocene Thermal Maximum, Eocene Thermal Maximum 2 and Eocene Thermal Maximum 3) is characterized by (i) low diversity and dwarfed foraminifera, (ii) rectilinear benthic foraminifera, and (iii) biserial and triserial planktic foraminifera that are known to survive in areas of high runoff, upwelling or otherwise eutrophic conditions. The stressed environments of the SBZ 5/6 to SBZ 10 appear to have ameliorated in SBZ 11 (corresponding to Early Eocene Climatic Optimum) with significant increase in abundance and diversity of foraminifera, dominance of K- strategists, and a switch from eutrophic to oligotrophic environments.

Larger benthic foraminiferal assemblages and their response to Middle Eocene Climate Optimum in the Kohat Basin (Pakistan, eastern Tethys)

The carbon cycle perturbations in geological history are preserved in the form of changes in stable carbon isotope ratios (δ13C values) in different carbon-bearing sedimentary archives. The carbon cycle perturbation that occurred across the Paleocene-Eocene boundary (~56 Ma) is known as the Paleocene Eocene thermal Maximum (PETM). After more than three decades of research, the exact magnitude of the negative carbon isotope excursion (CIE) is still fuzzy. The shallow marine sedimentary archive, deposited far above the lysocline, is considered to be the best archive to quantify the carbon cycle perturbation because the deep marine (carbonate) was likely to be affected by carbonate dissolution and terrestrial sedimentary records influenced by different climatic parameters. However, different biotic and abiotic processes could influence the magnitude of the CIE during the perturbed carbon cycle-climate state in a shallow marine environment. For this reason, the present study investigated the early Paleogene marine carbonate rocks deposited in the eastern Tethyan Sea (Ladakh, NW India) to check the possible presence of the PETM CIE and test whether shallow marine carbonate is a good archive for measuring the CIE magnitude. The presence of age-diagnostic larger benthic foraminifera and detailed micro-facies analysis indicates the investigated shallow marine carbonate rocks were deposited during the ~56 to 54 Ma (Shallow Benthic Zone - 4 to 7) and are likely to hold the PETM CIE. The secular variation in the δ13C values of unaltered bulk carbonate, screened through the cathodoluminescence microscopic study, reveals a PETM CIE magnitude of -3.6 ‰.  The observed CIE magnitude is similar to the globally accepted CIE magnitude (-4 ± 0.4 ‰) for PETM and suggests that shallow marine carbonate can be used to assess the magnitude of PETM and other carbon cycle perturbations.

The rich Eocene larger benthic foraminiferal (LBF) assemblages from the vicinity of Verona are well-known long since. However, they are described in detail only from the Ypresian to Bartonian interval. Here, we present the results of our morphometrically based study of Priabonian LBF. The lowermost part of the succession, just above the uppermost occurrence of giant Nummulites (N. biedai) is outcropping on Monte Cavro and contains Heterostegina reticulata multifida and Nummulites hormoensis as major constituents. These taxa clearly determine the earliest Priabonian SBZ 18C shallow benthic zone. Slightly younger strata could be studied in the three studied exposures on the northern side of Castel San Felice. These beds already represent the early Priabonian SBZ 19A Zone based on the first appearing Spiroclypeus sirottii and on the presence of Heterostegina reticulata mossanensis and Nummulites fabianii (replacing H. r. multifida and N. hormoensis, respectively). The most abundant LBF in these beds are the very diverse and well-preserved orthophragmines represented both by family Discocyclinidae (genus Discocyclina and Nemkovella) and Orbitoclypeidae (genus Orbitoclypeus and Asterocyclina). They determine the OZ 14 orthophragminid zone. The distinction of six species of the genus Discocyclina (especially that of D. euaensis from D. dispansa) is discussed in detail. The exposures around Castel San Felice are considered as key localities for the SBZ 19A and OZ 14 Zones containing their key LBF assemblages. Late Lutetian–Priabonian range charts for LBF and separately also for orthophragminid taxa are updated.

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 derivedn-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 derivedn-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.

Abstract. The early Paleogene is marked by multiple negative carbon isotope excursions (CIEs) that reflect massive short-term carbon cycle perturbations that coincide with significant warming during a high-pCO2 world, affecting both marine and terrestrial ecosystems. Records of such hyperthermals from the marine–terrestrial interface (e.g., estuarine swamps and mire deposits) are therefore of great interest as their present-day counterparts are highly vulnerable to future climate and sea level change. Here, we assess paleoenvironmental changes of midlatitudinal late Paleocene–early Eocene peat mire records along the paleo-North Sea coast. We provide carbon isotope data of bulk organic matter (δ13CTOC), organic carbon content (%TOC), and palynological data from an extensive peat mire deposited at a midlatitudinal (ca. 41∘ N) coastal site (Schöningen, Germany). The δ13CTOC data show a carbon isotope excursion of −1.3 ‰ (mean decrease in δ13CTOC; −1.7 ‰ at the onset of CIE) coeval with a conspicuous Apectodinium acme. Due to the exceptionally large stratigraphic thickness of the CIE at Schöningen (10 m of section) we established a detailed palynological record that indicates only minor changes in paleovegetation leading into and during this event. Instead, paleovegetation changes mostly follow natural successions in response to changes along the marine–terrestrial interface. The available age constraints for the Schöningen Formation hamper a solid assignment of the detected CIE to a particular hyperthermal such as the Paleocene–Eocene Thermal Maximum (PETM) or any succeeding hyperthermal event such as the Eocene Thermal Maximum 2 (ETM2). Compared to other nearby peat mire records (Cobham, UK; Vasterival, F) it appears that wetland deposits around the Paleogene North Sea have a consistent CIE magnitude of ca. −1.3 ‰ in δ13CTOC. Moreover, the Schöningen record shares major characteristics with the Cobham Lignite PETM record, including evidence for increased fire activity prior to the CIE, minor plant species change during the hyperthermal, a reduced CIE in δ13CTOC, and drowning of the mire (marine ingressions) during much of the Schöningen CIE event. This suggests that either the Schöningen CIE reflects the PETM or that early Paleogene hyperthermals similarly affected paleoenvironmental conditions of a major segment of the paleo-North Sea coast.

Research Article| August 01, 2018 Response of larger benthic foraminifera to the Paleocene-Eocene thermal maximum and the position of the Paleocene/Eocene boundary in the Tethyan shallow benthic zones: Evidence from south Tibet Qinghai Zhang; Qinghai Zhang † 1Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, and CAS Centre for Excellence in Tibetan Plateau Earth Sciences, Lincui Road 16-3, 100101 Beijing, China2Department of Geosciences, University of Bremen, Klagenfurter Straße 4, 28359 Bremen, Germany †zhang@itpcas.ac.cn Search for other works by this author on: GSW Google Scholar Helmut Willems; Helmut Willems 2Department of Geosciences, University of Bremen, Klagenfurter Straße 4, 28359 Bremen, Germany3Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, East Beijing Road 39, 210008 Nanjing, China Search for other works by this author on: GSW Google Scholar Lin Ding; Lin Ding 1Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, and CAS Centre for Excellence in Tibetan Plateau Earth Sciences, Lincui Road 16-3, 100101 Beijing, China Search for other works by this author on: GSW Google Scholar Xiaoxia Xu Xiaoxia Xu 2Department of Geosciences, University of Bremen, Klagenfurter Straße 4, 28359 Bremen, Germany Search for other works by this author on: GSW Google Scholar GSA Bulletin (2019) 131 (1-2): 84–98. https://doi.org/10.1130/B31813.1 Article history received: 24 Mar 2017 rev-recd: 21 May 2018 accepted: 19 Jun 2018 first online: 01 Aug 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation Qinghai Zhang, Helmut Willems, Lin Ding, Xiaoxia Xu; Response of larger benthic foraminifera to the Paleocene-Eocene thermal maximum and the position of the Paleocene/Eocene boundary in the Tethyan shallow benthic zones: Evidence from south Tibet. GSA Bulletin 2018;; 131 (1-2): 84–98. doi: https://doi.org/10.1130/B31813.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Paleocene-Eocene thermal maximum (PETM) is one of the most pronounced global warming events in the Cenozoic. This event was associated with a large negative carbon isotope excursion (CIE) and with major changes in the atmosphere, hydrosphere, and biosphere. However, how the larger benthic foraminifera (LBFs) in the shallow Tethyan Ocean responded to the PETM remains controversial. In this study, we investigate two shallow-marine, LBF-rich carbonate sections from south Tibet, aiming to locate the position of the Paleocene/Eocene (P/E) boundary in the Tethyan shallow benthic zones (SBZs) and to examine the response of the LBFs to the PETM. Carbon isotope compositions of bulk carbonate were measured to constrain the stratigraphic position of the CIE onset marking the P/E boundary in the sections, and the LBFs were studied in rock thin sections in order to assess their biostratigraphy and to construct the SBZs. The combination of the carbon isotope data and constructed SBZs shows that the P/E boundary is located within SBZ5, not at the SBZ4/SBZ5 transition as proposed in the Western Tethyan domain. At the P/E boundary, no evident compositional change in LBF assemblages can be observed. However, a major compositional change in LBF assemblages occurs in the CIE recovery, characterized by the sudden disappearance of Miscellanea, Ranikothalia, Setia, Orbitosiphon, and the initial dominance of porcellaneous-walled Alveolina and Orbitolites together with small miliolids and rotaliids. We tentatively speculate that this compositional change in LBF assemblages may be related to a eutrophication event, likely resulting from intensified continental weathering during the CIE recovery of the PETM. You do not currently have access to this article.

Abstract. Transient greenhouse warming events in the Paleocene and Eocene were associated with the addition of isotopically light carbon to the exogenic atmosphere–ocean carbon system, leading to substantial environmental and biotic change. The magnitude of an accompanying carbon isotope excursion (CIE) can be used to constrain both the sources and amounts of carbon released during an event and also to correlate marine and terrestrial records with high precision. The Paleocene–Eocene Thermal Maximum (PETM) is well documented, but CIE records for the subsequent warming events are still rare, especially from the terrestrial realm.Here, we provide new paleosol carbonate CIE records for two of the smaller hyperthermal events, I1 and I2, as well as two additional records of Eocene Thermal Maximum 2 (ETM2) and H2 in the Bighorn Basin, Wyoming, USA. Stratigraphic comparison of this expanded, high-resolution terrestrial carbon isotope history to the deep-sea benthic foraminiferal isotope records from Ocean Drilling Program (ODP) sites 1262 and 1263, Walvis Ridge, in the southern Atlantic Ocean corroborates the idea that the Bighorn Basin fluvial sediments record global atmospheric change. The ∼ 34 m thicknesses of the eccentricity-driven hyperthermals in these archives corroborate precession forcing of the ∼ 7 m thick fluvial overbank–avulsion sedimentary cycles. Using bulk-oxide mean-annual-precipitation reconstructions, we find soil moisture contents during the four younger hyperthermals that are similar to or only slightly wetter than the background, in contrast with soil drying observed during the PETM using the same proxy, sediments, and plant fossils.The magnitude of the CIEs in soil carbonate for the four smaller, post-PETM events scale nearly linearly with the equivalent event magnitudes documented in marine records. In contrast, the magnitude of the PETM terrestrial CIE is at least 5 ‰ smaller than expected based on extrapolation of the scaling relationship established from the smaller events. We evaluate the potential for recently documented, nonlinear effects of pCO2 on plant photosynthetic C-isotope fractionation to explain this scaling discrepancy. We find that the PETM anomaly can be explained only if background pCO2 was at least 50 % lower during most of the post-PETM events than prior to the PETM. Although not inconsistent with other pCO2 proxy data for the time interval, this would require declining pCO2 across an interval of global warming. A more likely explanation of the PETM CIE anomaly in pedogenic carbonate is that other environmental or biogeochemical factors influencing the terrestrial CIE magnitudes were not similar in nature or proportional to event size across all of the hyperthermals. We suggest that contrasting regional hydroclimatic change between the PETM and subsequent events, in line with our soil proxy records, may have modulated the expression of the global CIEs in the Bighorn Basin soil carbonate records.

Abstract. Situated at the southern edge of the proto-North Sea, the lower Eocene Schöningen Formation of the Helmstedt Lignite Mining District, Lower Saxony, Germany, is characterized by several lignite seams alternating with estuarine to brackish interbeds. Here, we present carbon isotope data for bulk organic matter (δ13CTOC), total organic carbon content (%TOC), and palynomorphs from a 98 m thick sequence of the Schöningen Formation in combination with a new robust age model, which is based on eustatic sea level changes, biostratigraphy, and a correlation with existing radiometric ages. Based on the δ13CTOC data we observe six negative carbon isotope excursions (CIEs) reflecting massive short-term carbon cycle perturbations. A strong CIE of −2.6 ‰ in δ13CTOC values in the Main Seam and the succeeding marine interbed can be related to the Paleocene–Eocene Thermal Maximum (PETM). The subsequent CIE of −1.7 ‰ in δ13CTOC values may be correlated with the Eocene Thermal Maximum 2 (ETM2) or slightly older events preceding the ETM2. High-amplitude climate fluctuations including at least four minor CIEs with a maximum negative shift of −1.3 ‰ in δ13CTOC in the upper part of the studied section are characteristic of the Early Eocene Climatic Optimum (EECO). Palynological analysis across the Main Seam proved that shifts in δ13CTOC values are correlated with changes in the peat-forming wetland vegetation, specifically the change from a mixed angiosperm and gymnosperm flora to angiosperm-dominated vegetation at the onset of the PETM. The PETM-related CIE shows a distinct rebound to higher δ13CTOC values shortly after the onset of the CIE, which is recognized here as a common feature of terrestrial and marginal marine PETM records worldwide and may reflect a stepwise injection of carbon into the atmosphere.

Situated at the southern edge of the proto-North Sea the lower Eocene Schöningen Formation of the Helmstedt Lignite Mining District, Lower Saxony, Germany is characterized by several lignite seams alternating with estuarine to brackish interbeds. Here, we present carbon isotope data of bulk organic matter (δ13CTOC), organic carbon content (%TOC), and palynomorphs from a 98 m thick sequence of the Schöningen Formation embedded into a new robust age model. This is based on eustatic sea-level changes, biostratigraphy, and a correlation to existing radiometric ages. Based on the δ13CTOC data we observe six negative carbon isotope excursions (CIEs) reflecting massive short-term carbon cycle perturbations. A strong CIE of −2.6 ‰ in δ13CTOC values in the Main Seam and the succeeding marine interbed can be related to the Paleocene–Eocene Thermal Maximum (PETM). The subsequent CIE of −1.7 ‰ in δ13CTOC values may be correlated with the Eocene Thermal Maximum 2 (ETM2) or slightly older events preceding the ETM2. High-amplitude climate fluctuations including at least 4 minor CIEs with a maximum negative shift of −1.3 ‰ in δ13CTOC in the upper part of the studied section are characteristic for the EECO. Palynological analysis across the Main Seam proved that shifts in δ13CTOC values are correlated with changes in the peat forming wetland vegetation, specifically the change from a mixed angiosperm and gymnosperm flora to an angiosperm dominated vegetation at the onset of the PETM. The PETM-related CIE shows a distinct rebound to higher δ13CTOC values shortly after the onset of the CIE, which is here recognized as a common feature of terrestrial and marginal marine PETM-records worldwide and may be related to changes in the vegetation including different carbon isotope budgets of gymnosperms and angiosperms.

Situated at the southern edge of the proto-North Sea the lower Eocene Schöningen Formation of the Helmstedt Lignite Mining District, Lower Saxony, Germany is characterized by several lignite seams alternating with estuarine to brackish interbeds. Here, we present carbon isotope data of bulk organic matter (δ13CTOC), organic carbon content (%TOC), and palynomorphs from a 98 m thick sequence of the Schöningen Formation embedded into a new robust age model. This is based on eustatic sea-level changes, biostratigraphy, and a correlation to existing radiometric ages. Based on the δ13CTOC data we observe six negative carbon isotope excursions (CIEs) reflecting massive short-term carbon cycle perturbations. A strong CIE of −2.6 ‰ in δ13CTOC values in the Main Seam and the succeeding marine interbed can be related to the Paleocene–Eocene Thermal Maximum (PETM). The subsequent CIE of −1.7 ‰ in δ13CTOC values may be correlated with the Eocene Thermal Maximum 2 (ETM2) or slightly older events preceding the ETM2. High-amplitude climate fluctuations including at least 4 minor CIEs with a maximum negative shift of −1.3 ‰ in δ13CTOC in the upper part of the studied section are characteristic for the EECO. Palynological analysis across the Main Seam proved that shifts in δ13CTOC values are correlated with changes in the peat forming wetland vegetation, specifically the change from a mixed angiosperm and gymnosperm flora to an angiosperm dominated vegetation at the onset of the PETM. The PETM-related CIE shows a distinct rebound to higher δ13CTOC values shortly after the onset of the CIE, which is here recognized as a common feature of terrestrial and marginal marine PETM-records worldwide and may be related to changes in the vegetation including different carbon isotope budgets of gymnosperms and angiosperms.

Situated at the southern edge of the proto-North Sea the lower Eocene Schöningen Formation of the Helmstedt Lignite Mining District, Lower Saxony, Germany is characterized by several lignite seams alternating with estuarine to brackish interbeds. Here, we present carbon isotope data of bulk organic matter (δ13CTOC), organic carbon content (%TOC), and palynomorphs from a 98 m thick sequence of the Schöningen Formation embedded into a new robust age model. This is based on eustatic sea-level changes, biostratigraphy, and a correlation to existing radiometric ages. Based on the δ13CTOC data we observe six negative carbon isotope excursions (CIEs) reflecting massive short-term carbon cycle perturbations. A strong CIE of −2.6 ‰ in δ13CTOC values in the Main Seam and the succeeding marine interbed can be related to the Paleocene–Eocene Thermal Maximum (PETM). The subsequent CIE of −1.7 ‰ in δ13CTOC values may be correlated with the Eocene Thermal Maximum 2 (ETM2) or slightly older events preceding the ETM2. High-amplitude climate fluctuations including at least 4 minor CIEs with a maximum negative shift of −1.3 ‰ in δ13CTOC in the upper part of the studied section are characteristic for the EECO. Palynological analysis across the Main Seam proved that shifts in δ13CTOC values are correlated with changes in the peat forming wetland vegetation, specifically the change from a mixed angiosperm and gymnosperm flora to an angiosperm dominated vegetation at the onset of the PETM. The PETM-related CIE shows a distinct rebound to higher δ13CTOC values shortly after the onset of the CIE, which is here recognized as a common feature of terrestrial and marginal marine PETM-records worldwide and may be related to changes in the vegetation including different carbon isotope budgets of gymnosperms and angiosperms.

Situated at the southern edge of the proto-North Sea the lower Eocene Schöningen Formation of the Helmstedt Lignite Mining District, Lower Saxony, Germany is characterized by several lignite seams alternating with estuarine to brackish interbeds. Here, we present carbon isotope data of bulk organic matter (δ13CTOC), organic carbon content (%TOC), and palynomorphs from a 98 m thick sequence of the Schöningen Formation embedded into a new robust age model. This is based on eustatic sea-level changes, biostratigraphy, and a correlation to existing radiometric ages. Based on the δ13CTOC data we observe six negative carbon isotope excursions (CIEs) reflecting massive short-term carbon cycle perturbations. A strong CIE of −2.6 ‰ in δ13CTOC values in the Main Seam and the succeeding marine interbed can be related to the Paleocene–Eocene Thermal Maximum (PETM). The subsequent CIE of −1.7 ‰ in δ13CTOC values may be correlated with the Eocene Thermal Maximum 2 (ETM2) or slightly older events preceding the ETM2. High-amplitude climate fluctuations including at least 4 minor CIEs with a maximum negative shift of −1.3 ‰ in δ13CTOC in the upper part of the studied section are characteristic for the EECO. Palynological analysis across the Main Seam proved that shifts in δ13CTOC values are correlated with changes in the peat forming wetland vegetation, specifically the change from a mixed angiosperm and gymnosperm flora to an angiosperm dominated vegetation at the onset of the PETM. The PETM-related CIE shows a distinct rebound to higher δ13CTOC values shortly after the onset of the CIE, which is here recognized as a common feature of terrestrial and marginal marine PETM-records worldwide and may be related to changes in the vegetation including different carbon isotope budgets of gymnosperms and angiosperms.