GERTA KELLER PUBLICATIONS

Environmental changes during the Cretaceous-Paleogene mass extinction and Paleocene-Eocene Thermal Maximum: Implications for the Anthropocene

TitleEnvironmental changes during the Cretaceous-Paleogene mass extinction and Paleocene-Eocene Thermal Maximum: Implications for the Anthropocene
Publication TypeJournal Article
Year of Publication2018
AuthorsKeller, G, Mateo, P, Punekar, J, Khozyem, H, Gertsch, B, Spangenberg, J, Bitchong, AMbabi, Adatte, T
JournalGondwana Research
Volume56
Pagination69–89
Date Publishedapr
Abstract

The Cretaceous-Paleogene boundary (KPB) mass extinction (~66.02 Ma) and the Paleocene-Eocene Thermal Maximum( PETM)(~55.8Ma) are two remarkable climatic and faunal events in Earth's history that have implications for the current Anthropocene global warming and rapid diversity loss. Here we evaluate these two events at the stratotype localities in Tunisia and Egypt based on climatewarming and environmental responses recorded in faunal and geochemical proxies. The KPBmass extinction is commonly attributed to the Chicxulub impact, but Deccan volcanism appears as amajor culprit.Newmercury analysis reveals thatmajor Deccan eruptions accelerated during the last 10 ky and reached the tipping point leading up to themass extinction. During the PETM, climatewarmed rapidly by ~5 °C,which is mainly attributed tomethane degassing from seafloor sediments during global warming linked to the North Atlantic Igneous Province (NAIP). Biological effectswere transient,marked by temporary absence ofmost planktic foraminifera due to ocean acidification followed by the return of the pre-PETM fauna and diversification. In contrast, the current rapid rise in atmospheric CO2 and climate warming are magnitudes faster than at the KPB or PETM events leading to predictions of a PETM-like response as best case scenario and rapidly approaching sixth mass extinction as worst-case scenario.  PDF

URLhttps://doi.org/10.1016/j.gr.2017.12.002
DOI10.1016/j.gr.2017.12.002

Deccan volcanism induced high-stress environment during the Cretaceous–Paleogene transition at Zumaia, Spain: Evidence from magnetic, mineralogical and biostratigraphic records

TitleDeccan volcanism induced high-stress environment during the Cretaceous–Paleogene transition at Zumaia, Spain: Evidence from magnetic, mineralogical and biostratigraphic records
Publication TypeJournal Article
Year of Publication2018
AuthorsFont, E, Adatte, T, Andrade, M, Keller, G, Bitchong, AMbabi, Carvallo, C, Ferreira, J, Diogo, Z, Mirão, J
JournalEarth and Planetary Science Letters
Volume484
Pagination53–66
Date Publishedfeb
Abstract

We conducted detailed rock magnetic, mineralogical and geochemical (mercury) analyses spanning the Cretaceous–Paleogene boundary (KPB) at Zumaia, Spain, to unravel the signature of Deccan-induced climate and environmental changes in the marine sedimentary record. Our biostratigraphic results show that Zumaia is not complete, and lacks the typical boundary clay, zone P0 and the base of zone P1a(1) in the basal Danian. Presence of an unusual ∼1m-thick interval spanning the KPB is characterized by very low detrital magnetite and magnetosome (biogenic magnetite) contents and by the occurrence of akaganéite, a very rare mineral on Earth in oxidizing, acidic and hyper-chlorinated environments compatible with volcanic settings. These benchmarks correlate with higher abundance of the opportunist Guembelitria cretacea species. Detrital magnetite depletion is not linked to significant lithological changes, suggesting that iron oxide dissolution by acidification is the most probable explanation. The concomitant decrease in magnetosomes, produced by magnetotactic bacteria at the anoxic–oxic boundary, is interpreted as the result of changes in seawater chemistry induced by surficial ocean acidification. Mercury peaks up to 20–50 ppb are common during the last 100 kyr of the Maastrichtian (zone CF1) but only one significant anomaly is present in the early Danian, which is likely due to the missing interval. Absence of correlation between mercury content (R2 = 0.009) and total organic carbon (R2 = 0.006) suggest that the former originated from the Deccan Traps eruptions. No clear relation between the stratigraphic position of the mercury peaks and the magnetite-depleted interval is observed, although the frequency of the mercury peaks tends to increase close to the KPg boundary. In contrast to Bidart (France) and Gubbio (Italy), where magnetite depletion and akaganéite feature within a ∼50cm-thick interval located 5 cm below the KPg boundary, the same benchmarks are observed in a 1m-thick interval encompassing the KPg boundary at Zumaia. Results reinforce the synchronism of the major eruptions of the Deccan Traps Magmatic Province with the Cretaceous–Paleogene (KPg) mass extinction and provide new clues to better correlate the Deccan imprint of the global sedimentary record.  PDF

URLhttps://doi.org/10.1016/j.epsl.2017.11.055
DOI10.1016/j.epsl.2017.11.055

Post-impact event bed (tsunamite) at the Cretaceous-Palaeogene boundary deposited on a distal carbonate platform interior

TitlePost-impact event bed (tsunamite) at the Cretaceous-Palaeogene boundary deposited on a distal carbonate platform interior
Publication TypeJournal Article
Year of Publication2017
AuthorsFont, E, Keller, G, Sanders, D, Adatte, T
JournalTerra Nova
Volume29
Pagination329–331
Date Published08/2018
Abstract

Korbar, McDonald, Fućek, Fuček, and Posilović (2017) report a tsunamite, triggered by the Chicxulub impact on Yucatan, from the Likva Cove carbonate platform of the Island of Brač, Croatia, which is similar to that in an earlier report from the nearby Island of Hvar (Korbar et al., 2015). If true, such deposits in the Adriatic Sea would be truly anomalous given that no tsunamites are identified in well-preserved Cretaceous–Palaeogene (K–Pg) sections from the Basque-Cantabric Basin (Bidart, Zumaia, Hendaye and Sopelana sections), which are located more proximal and towards the hypothetical tsunami wave propagation front. We strongly question the authors’ criteria for identifying the presumed “tsunamite” as well as the K–Pg boundary (KPB) age attributed to these deposits based on planktic foraminifera.  PDF

URLhttp://onlinelibrary.wiley.com/doi/10.1111/ter.12282/full
DOI10.1111/ter.12282

Environmental changes during the Cetaceous-Paleogene mass extinction and Paleocene-Eocene thermal maximum: Implications for the Anthropocene

TitleEnvironmental changes during the Cetaceous-Paleogene mass extinction and Paleocene-Eocene thermal maximum: Implications for the Anthropocene
Publication TypeJournal Article
Year of Publication2017
AuthorsKeller, G, Mateo, P, Punekar, J, Khozyem, H, Gertsch, B, Spangenberg, J, Bitchong, A, Adatte, T
JournalGondwana Research
Date Publisheddec
Abstract

The Cretaceous-Paleogene boundary (KPB) mass extinction (~ 66.02 Ma) and the Paleocene-Eocene Thermal Maximum (PETM) (~ 55.8 Ma) are two remarkable climatic and faunal events in Earth's history that have implications for the current Anthropocene global warming and rapid diversity loss. Here we evaluate these two events at the stratotype localities in Tunisia and Egypt based on climate warming and environmental responses recorded in faunal and geochemical proxies. The KPB mass extinction is commonly attributed to the Chicxulub impact, but Deccan volcanism appears as a major culprit. New mercury analysis reveals that major Deccan eruptions accelerated during the last 10 ky and reached the tipping point leading up to the mass extinction. During the PETM, climate warmed rapidly by ~ 5 °C, which is mainly attributed to methane degassing from seafloor sediments during global warming linked to the North Atlantic Igneous Province (NAIP). Biological effects were transient, marked by temporary absence of most planktic foraminifera due to ocean acidification followed by the return of the pre-PETM fauna and diversification. In contrast, the current rapid rise in atmospheric CO2 and climate warming are magnitudes faster than at the KPB or PETM events leading to predictions of a PETM-like response as best case scenario and rapidly approaching sixth mass extinction as worst-case scenario.

URLhttps://doi.org/10.1016/j.gr.2017.12.002
DOI10.1016/j.gr.2017.12.002

Early to Late Maastrichtian environmental changes in the Indian Ocean compared with Tethys and South Atlantic

TitleEarly to Late Maastrichtian environmental changes in the Indian Ocean compared with Tethys and South Atlantic
Publication TypeJournal Article
Year of Publication2017
AuthorsMateo, P, Keller, G, Punekar, J, Spangenberg, JE
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume478
Pagination121–138
Date Published07/2017
Abstract

Planktic foraminiferal analysis, including species populations, diversity trends, high-stress indices and stable isotopes of the latest Campanian through Maastrichtian in the South Atlantic, Tethys and Indian oceans reveal four major climate and faunal events that ended with the Cretaceous-Paleogene (K/Pg), formerly Cretaceous-Tertiary (K/T), mass extinction. The prelude to these events is the late Campanian cooling that reached minimum temperatures in the earliest Maastrichtian (base C31r) correlative with low primary productivity and species diversity. Event-1 begins during the persistent cool climate of the early Maastrichtian (lower C31r) when primary productivity rapidly increased accompanied by rapid species originations, attributed to increased nutrient influx from increased upwelling, erosion during the sea-level fall ~70.6 Ma, and Ninety East Ridge volcanism. During Event-2 (upper C31r to lower C30n), climate rapidly warmed by 2–3 °C in deep waters and peaked at 22 °C on land, primary productivity remained high and diversification reached maximum for the entire Cretaceous. We attribute this climate warming to intense Ninety East Ridge volcanic activity beginning ~69.5 Ma, accompanied by rapid reorganization of intermediate oceanic circulation. Enhanced greenhouse conditions due to the eruption of Deccan Phase-1 in India resulted in detrimental conditions for planktic foraminifera marking the end of diversification. Global cooling resumed in Event-3 (C30n), species diversity declined gradually accompanied by dwarfing, decreased large specialized species, increased small ecologically tolerant taxa, and ocean acidification. Event-3 is mainly the result of enhanced weathering and volcanogenic CO2 adsorption by the oceans during the preceding warm Event-2 that led to cooling and lower pH in the surface ocean. Event-4 marks the last 250 kyr of the Maastrichtian (C29r), which began with the largest Deccan eruptions (Phase-2) that caused rapid climate warming of 4 °C in deep waters and 8 °C on land, acid rain and ocean acidification leading to a major carbonate crisis preceding the K/T mass extinction.  PDF

URLhttps://doi.org/10.1016/j.palaeo.2017.01.027
DOI10.1016/j.palaeo.2017.01.027

Mercury anomaly, Deccan volcanism, and the end-Cretaceous mass extinction

TitleMercury anomaly, Deccan volcanism, and the end-Cretaceous mass extinction
Publication TypeJournal Article
Year of Publication2016
AuthorsFont, E, Adatte, T, Sial, ANobrega, de Lacerda, LDrude, Keller, G, Punekar, J
JournalGeology
Volume44
Pagination171–174
Date Published01/2018
Abstract

The contribution of the Deccan Traps (west-central India) volcanism in the Cretaceous-Paleogene (KPg) crisis is still a matter of debate. Recent U-Pb dating of zircons interbedded within the Deccan lava flows indicate that the main eruptive phase (>1.1 × 106 km3 of basalts) initiated ∼250 k.y. before and ended ∼500 k.y. after the KPg boundary. However, the global geochemical effects of Deccan volcanism in the marine sedimentary record are still poorly resolved. Here we investigate the mercury (Hg) content of the Bidart (France) section, where an interval of low magnetic susceptibility (MS) located just below the KPg boundary was hypothesized to result from paleoenvironmental perturbations linked to the paroxysmal Deccan phase 2. Results show Hg concentrations >2 orders of magnitude higher from ∼80 cm below to ∼50 cm above the KPg boundary (maximum 46.6 ppb) and coincident with the low MS interval. Increase in Hg contents shows no correlation with clay or total organic carbon contents, suggesting that the Hg anomalies resulted from higher input of atmospheric Hg species into the marine realm, rather than organic matter scavenging and/or increased runoff. The Hg anomalies correlate with high shell fragmentation and dissolution effects in planktic foraminifera, suggesting correlative changes in marine biodiversity. This discovery represents an unprecedented piece of evidence of the nature and importance of the Deccan-related environmental changes at the onset of the KPg mass extinction.  PDF

URLhttps://pubs.geoscienceworld.org/gsa/geology/article/44/2/171/132071/mercury-anomaly-deccan-volcanism-and-the-end
DOI10.1130/g37451.1

The Cretaceous-Palaeogene boundary at Gorgonilla Island, Colombia, South America

TitleThe Cretaceous-Palaeogene boundary at Gorgonilla Island, Colombia, South America
Publication TypeJournal Article
Year of Publication2016
AuthorsBermúdez, HD, García, J, Stinnesbeck, W, Keller, G, Rodríguez, JVicente, Hanel, M, Hopp, J, Schwarz, WH, Trieloff, M, Bolívar, L, Vega, FJ
JournalTerra Nova
Volume28
Pagination83–90
Date Published01/2016
Abstract

The discovery of a new Cretaceous/Palaeogene (K/Pg) bathyal marine sequence on Gorgonilla Island, SW Colombia, extends the presence of Chicxulub impact spherule deposits to the Pacific region of northern South America and to the Eastern Pacific Ocean. The Gorgonilla spherule layer is approximately 20 mm thick and consists of extraordinarily well-preserved glass spherules up to 1.1 mm in diameter. About 70–90% of the spherules are vitrified, and their chemical composition is consistent with Haiti (Beloc) impact glass spherules. Normal size-grading, delicate spherule textures, welded melt components and an absence of bioturbation or traction transport suggest that the Gorgonilla spherule layer represents an almost undisturbed settling deposit. PDF

URLhttp://onlinelibrary.wiley.com/doi/10.1111/ter.12196/abstract
DOI10.1111/ter.12196

Maastrichtian to Eocene subsurface stratigraphy of the Cauvery basin and correlation with Madagascar

TitleMaastrichtian to Eocene subsurface stratigraphy of the Cauvery basin and correlation with Madagascar
Publication TypeJournal Article
Year of Publication2016
AuthorsKeller, G, Jaiprakash, BC, Reddy, AN
JournalJournal of the Geological Society of India
Volume87
Pagination5–34
Date Published01/2016
Abstract

Late Maastrichtian through middle Eocene planktic foraminiferal biostratigraphy and erosion patterns from three Cauvery basin wells are compared with the Krishna-Godavari basin, Madagascar and South Atlantic Site 525A. Maastrichtian sedimentation appears continuous at DSDP site 525A and substantially complete in the Cauvery basin and Madagascar for the interval from ~70.3 to 66.8 Ma (zones CF6-CF3). But the latest Maastrichtian through early Paleocene record is fragmented, except for some Krishna-Godavari and Cauvery basin wells protected from erosion by Deccan traps or graben deposition, respectively. Hiatuses are observed correlative with sea level falls at 66.8, 66.25, 66.10, 65.7, 63.8 and 61.2 Ma with erosion amplified by local tectonic activity including doming and uplift due to Deccan volcanism.

Throughout this region the Cretaceous-Paleogene transition (magnetochron C29r-C29n, 66.25-65.50 Ma) is preserved only in deep wells of the Krishna-Godavari basin where Deccan Traps protected intertrappean sediments from erosion. The late Paleocene to middle Eocene marine record was recovered from two Cauvery basin wells with hiatuses correlative with low sea levels at ~49.0-56.5 Ma (zones P4c-E6) and ~53.0-55.3 Ma (zones E1-E4) at the ridge well KALI-H. A nearly complete record was recovered from well AGA, including the PETM event (zones E1-E2), which marks this an excellent reference section for India.

Similarity in erosion and sedimentation patterns of the late Maastrichtian to middle Paleocene from India to Madagascar and South Atlantic is mainly attributed to climate changes and sea level falls, regional tectonic activity from the Bay of Bengal to Madagascar, and uplift and doming in the Cauvery and K-G basins as a result of Deccan volcanism. Directly correlative with Deccan volcanism are high stress environments for marine calcifiers, as observed by species dwarfing, reduced diversity and blooms of the disaster opportunist Guembelitria cretacea in magnetochron C30n (zones CF4-CF3) correlative with Deccan phase-1 and Ninetyeast Ridge volcanism, in C29r (zones CF2-CF1) correlative with Deccan phase-2 and in C29n (zone P1b) correlative with Deccan phase-3 marking volcanism as the most important stress factor in the end-Cretaceous mass extinction and delayed evolution of planktic foraminifera.  PDF

 

 

URLhttps://link.springer.com/article/10.1007/s12594-016-0370-4
DOI10.1007/s12594-016-0370-4

Mercury anomaly, Deccan volcanism and the end-Cretaceous Mass Extinction: (REPLY)

TitleMercury anomaly, Deccan volcanism and the end-Cretaceous Mass Extinction: (REPLY)
Publication TypeJournal Article
Year of Publication2016
AuthorsFont, E, Adatte, T, Keller, G, Abrajevitch, A, Sial, ANobrega, de Lacerda, LDrude, Punekar, J
JournalGeology
Volume44
Paginatione382–e382
Date Published02/2016
Abstract

We thank Jan Smit and colleagues (Smit et al., 2016) for giving us the opportunity to clarify some important points in our original manuscript (Font et al., 2016a) and to discuss the issues raised in their Comment. Their main critique centers on the origin of the mercury anomalies, which they argue are post-depositional and cannot be assigned to Deccan Traps activity. Their arguments center on the hypothesis of Lowrie et al. (1990) who invoked a process of downward infiltration by reducing waters to explain the origin of the white beds below the CretaceousPaleogene (KPg) boundary at Gubbio, Italy. Apparently Smit et al. are not aware of the work by Abrajevitch et al. (2015) or that this issue was addressed in our Geology paper. Here we provide more detailed explanations of why the comments by Smit et al. are out of date.  PDF

URLhttps://pubs.geoscienceworld.org/gsa/geology/article/44/3/e382/132066/mercury-anomaly-deccan-volcanism-and-the-end
DOI10.1130/g37717y.1

Upheavals during the Late Maastrichtian: Volcanism, climate and faunal events preceding the end-Cretaceous mass extinction

TitleUpheavals during the Late Maastrichtian: Volcanism, climate and faunal events preceding the end-Cretaceous mass extinction
Publication TypeJournal Article
Year of Publication2016
AuthorsKeller, G, Punekar, J, Mateo, P
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume441
Pagination137–151
Date Published01/2016
Abstract

The late Maastrichtian was a time of major climate, evolution and extinction extremes. Rapid climate warming of 2–3 °C in intermediate waters between 69.5 and 68 Ma (top C31r to base C30n) accompanied maximum evolutionary diversification (43% increase, zone CF5 to low CF4) in planktic foraminiferal history, followed immediately by a cluster of extinctions. During the last 250 ky of the Maastrichtian (C29r, zones CF2–CF1), rapid warming of 4 °C in intermediate waters and 8 °C on land resulted in high-stress environments ending in the mass extinction. The end-Cretaceous mass extinction is recorded in sediments between massive Deccan lava flows in India and attributed to SO2 and CO2 outgassing leading to ocean acidification. The early late Maastrichtian climate and faunal upheavals are not well known.

Here we document the faunal similarities of both events from the Indian Ocean through the Tethys and Gulf of Mexico. Results show that both extreme warm events are marked by high-stress environments characterized by decreased abundance and diversity of large specialized species and dwarfing, high abundance of low oxygen tolerant species, and disaster opportunist surface dweller Guembelitria blooms. The similarity in faunal response with the Deccan warming of C29r (CF2–CF1) suggests that volcanism was also responsible for the warming and faunal upheaval of the early late Maastrichtian. Major volcanic activity at this time included the onset of Deccan eruptions and Ninetyeast Ridge volcanism. The role of the Chicxulub impact appears to have been a contributing, rather than causal, factor in the mass extinction.   PDF

URLhttps://doi.org/10.1016/j.palaeo.2015.06.034
DOI10.1016/j.palaeo.2015.06.034

A multi-proxy approach to decode the end-Cretaceous mass extinction

TitleA multi-proxy approach to decode the end-Cretaceous mass extinction
Publication TypeJournal Article
Year of Publication2016
AuthorsPunekar, J, Keller, G, Khozyem, HM, Adatte, T, Font, E, Spangenberg, J
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume441
Pagination116–136
Date Publishedjan
KeywordsLow magnetic susceptibilityPlanktic foraminiferaCarbonate-dissolutionOcean acidificationDeccan volcanism
Abstract

Mass extinctions generally involve a complex array of interrelated causes and are best evaluated by a multi-proxy approach as applied here for the end-Cretaceous mass extinction. This study documents and compares the planktic foraminiferal records, carbonate dissolution effects, stable isotopes, and magnetic susceptibility in France (Bidart), Austria (Gamsbach) and Tunisia (Elles) in order to explore the environmental conditions during the uppermost Maastrichtian Plummerita hantkeninoides zone CF1 leading up to the mass extinction. Planktic foraminiferal assemblages at Bidart and Gamsbach appear to be more diverse than those at Elles, with unusually high abundance (20–30%) and diversity (~15 species) of globotruncanids in the two deep-water sections but lower abundance (b10%) and diversity (b10 species) at the middle shelf Elles section. Oxygen isotopes in zone CF1 of Elles record rapid climate warming followed by cooling and a possible return to rapid warming prior to the mass extinction. The onset of high stress conditions for planktic foraminifera is observed ~50–60 cm below the KTB at Bidart and Gamsbach, and ~4.5 m below the KTB at Elles due to much higher sediment accumulation rates. These intervals at Bidart and Gamsbach record low magnetic susceptibility and high planktic foraminiferal fragmentation index (FI) at Elles, Bidart and Gamsbach. An increased abundance of species with dissolution-resistant morphologies is also observed at Gamsbach. The correlative interval in India records significantly stronger carbonate dissolution effects in intertrappean sediments between the longest lava flows, ending with the mass extinction. Based on current evidence, this widespread dissolution event stratigraphically coincides with the climate cooling that follows the Late Maatrichtian global warming and may be linked to ocean acidification due to Deccan volcanism. The estimated 12,000–28,000 Gigatons (Gt) of CO2 and 5200–13,600 Gt of SO2 introduced into the atmosphere likely triggered the carbonate crisis in the oceans resulting in severe stress for marine calcifiers leading to mass extinction.  PDF

URLhttp://www.sciencedirect.com/science/article/pii/S0031018215004617
DOI10.1016/j.palaeo.2015.08.025

Mass wasting and hiatuses during the Cretaceous-Tertiary transition in the North Atlantic: Relationship to the Chicxulub impact?

TitleMass wasting and hiatuses during the Cretaceous-Tertiary transition in the North Atlantic: Relationship to the Chicxulub impact?
Publication TypeJournal Article
Year of Publication2016
AuthorsMateo, P, Keller, G, Adatte, T, Spangenberg, JE
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume441
Pagination96–115
Date Published01/2018
Abstract

Deep-sea sections in the North Atlantic are claimed to contain the most complete sedimentary records and ultimate proof that the Chicxulub impact is Cretaceous-Tertiary boundary (KTB) in age and caused the mass extinction. A multi-disciplinary study of North Atlantic DSDP Sites 384, 386 and 398, based on high-resolution planktonic foraminiferal biostratigraphy, carbon and oxygen stable isotopes, clay and whole-rock mineralogy and granulometry reveals the age, stratigraphic completeness and nature of sedimentary disturbances. Results show a major hiatus across the KTB at Site 384 with Zones CF1, P0 and P1a missing, spanning at least ~ 540 ky, similar to other North Atlantic and Caribbean localities associated with tectonic activity and Gulf Stream erosion. At Sites 386 and 398, discrete intervals of disturbed sediments with mm-to-cm-thick spherule layers have previously been interpreted as the result of impact-generated earthquakes at the KTB destabilizing continental margins prior to settling of impact spherules. However, improved age control based on planktonic foraminifera indicates spherule deposition in the early Danian Zone P1a(2) (upper Parvularugoglobigerina eugubina Zone) more than 100 ky after the KTB. At Site 386, two intervals of white chalk contain very small (< 63 μm) early Danian Zone P1a(2) assemblages (65%) and common reworked Cretaceous (35%) species. In contrast, the in situ red-brown and green abyssal clays of this core are devoid of carbonate. In addition, high calcite, mica and kaolinite and upward-fining are observed in the chalks, indicating downslope transport from shallow waters and sediment winnowing via distal turbidites. At Site 398, convoluted red to tan sediments with early Danian and reworked Cretaceous species represent slumping of shallow water sediments as suggested by dominance of mica and low smectite compared to in situ deposition. We conclude that mass wasting was likely the result of earthquakes associated with increased tectonic activity in the Caribbean and the Iberian Peninsula during the early Danian well after the Chicxulub impact.  PDF

URLhttps://doi.org/10.1016/j.palaeo.2015.01.019
DOI10.1016/j.palaeo.2015.01.019

U-Pb geochronology of the Deccan Traps and relation to the end-Cretaceous mass extinction

TitleU-Pb geochronology of the Deccan Traps and relation to the end-Cretaceous mass extinction
Publication TypeJournal Article
Year of Publication2015
AuthorsSchoene, B, Samperton, KM, Eddy, MP, Keller, G, Adatte, T, Bowring, SA, Khadri, SFR, GERTSCH, BRIAN
JournalScience
Volume347
Pagination182–184
ISSN0036-8075
Abstract

The Chicxulub asteroid impact (Mexico) and the eruption of the massive Deccan volcanic province (India) are two proposed causes of the end-Cretaceous mass extinction, which includes the demise of nonavian dinosaurs. Despite widespread acceptance of the impact hypothesis, the lack of a high-resolution eruption timeline for the Deccan basalts has prevented full assessment of their relationship to the mass extinction. Here we apply uranium-lead (U-Pb) zircon geochronology to Deccan rocks and show that the main phase of eruptions initiated ~250,000 years before the Cretaceous-Paleogene boundary and that >1.1 million cubic kilometers of basalt erupted in ~750,000 years. Our results are consistent with the hypothesis that the Deccan Traps contributed to the latest Cretaceous environmental change and biologic turnover that culminated in the marine and terrestrial mass extinctions. PDF

URLhttp://science.sciencemag.org/content/347/6218/182
DOI10.1126/science.aaa0118

Early to late Maastrichtian environmental changes linked to Deccan Traps and Ninetyeast ridge volcanism: Case study of the Indian ocean

TitleEarly to late Maastrichtian environmental changes linked to Deccan Traps and Ninetyeast ridge volcanism: Case study of the Indian ocean
Publication TypeMiscellaneous
Year of Publication2015
AuthorsMateo, P, Keller, G, Punekar, J
Abstract

The Maastrichtian (C31-C30n) was a time of major environmental changes that record evolutionary diversification in planktic foraminifera as well as a minor extinction associated with climate change and high carbonate dissolution. Although these changes have been observed worldwide, their cause(s) remain speculative. Here we report on these events based on Ninetyeast Ridge sites, Indian Ocean, investigate their links to Deccan and Ninetyeast Ridge volcanism and correlate the results with sections around the world. Methods include high-resolution quantitative planktonic foraminiferal biostratigraphy and oxygen and carbon stable isotopes analysis. The Campanian cooling reached its maximum near the Campanian-Maastrichtian boundary (planktic foraminifera zone CF8, base C31r) and was followed by species diversification and a gradual increase in δ13C marking enhanced primary productivity (Event I, zones CF8-CF7). Volcanism associated with the Ninetyeast Ridge may have been an important source of nutrients that created favorable environmental conditions that led to this diversification. Maximum δ13C and negative δ18O values in zone CF6 (top C31r) mark high productivity and climate warming correlative with a rapid increase in species diversity (Event II). The subsequent cooling and decrease in δ13C marks maximum Cretaceous diversity around the CF5-CF4 transition (Event III, C31r-C30n transition). In zone CF4, rapid warming (top C31n) followed by cooling (base C30n) led to a rapid increase in the relative abundance of the most robust planktic and benthic species (large, thick walls) and gradual extinctions of Campanian survivor species (Event IV, C31n-C30n transition). In zone CF3 (top C30n), an increase in the relative abundance of generalist and disaster opportunist species, a rapid decrease in diversity, species dwarfing, high fragmentation index and decreased primary productivity indicate enhanced environmental stress conditions (Event V). During this time, both Ninetyeast Ridge and Deccan phase-1 volcanism were active, suggesting that the environmental changes were likely linked to intense volcanic eruptions that released large amounts of volcanogenic SO2 and CO2 poisoning the environment, causing ocean acidification and ultimately extinctions.  PDF

New geochemical constraints on the Paleocene–Eocene thermal maximum: Dababiya (GSSP), Egypt

TitleNew geochemical constraints on the Paleocene–Eocene thermal maximum: Dababiya (GSSP), Egypt
Publication TypeJournal Article
Year of Publication2015
AuthorsKhozyem, H, Adatte, T, Spangenberg, JE, Keller, G, Tantawy, AAziz, Ulianov, A
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume429
Pagination117–135
Date Published07/2018
Abstract

The Paleocene-Eocene Thermal Maximum (PETM) shows an extraordinary drop in the δ13C of carbonate and organic matter across the globe, suggesting massive release of 13C-depleted carbon dioxide into the ocean and atmosphere over a very short time interval (probably < 20ky). We report a geochemical and mineralogical study of 106 samples spanning the most expanded PETM at the Dababiya Global Stratotype Standard section and Point (GSSP) near Luxor, Egypt. The field and laboratory observations reveal that the deposition occurred in a submarine channel extended laterally about 200 m with the deepest part (~ 0.88 m) at the designated GSSP, although all bio-zones are present. Stable isotope records of both carbonate and organic carbon show decreases starting 0.6 m below the Paleocene-Eocene boundary (PEB) and culminating at the erosion surface. A persistent shift in δ15Norg values to near zero reflects a gradual increase in bacterial activity. High Ti, K and Zr and low Si contents at the PEB coincide with increased kaolinite contents, which suggests intense chemical weathering under more humid conditions at the PETM onset. Two negative Ce-anomalies indicate intervals of anoxic conditions during the lower and middle PETM (base and top of zone E1). The first anoxic event is represented by a negative Ce-anomaly, high V/C rand V/V + Ni ratios, negative Mn* and an abundance of idiomorphic pyrite crystals that indicate anoxic to euxinic conditions. The anoxic event (middle PETM) is marked by high U, Mo, V, Fe and abundant small sized (2–5 μm) pyrite framboids, increased Cu, Ni, and Cd at the same level suggesting anoxic conditions linked to high surface water productivity. Above this interval, oxic conditions returned as indicated by the precipitation of phosphorus and barium. These data reveal an expanded PETM interval marked by intense weathering as a crucial parameter during the recovery phase.  PDF

URLhttps://doi.org/10.1016/j.palaeo.2015.04.003
DOI10.1016/j.palaeo.2015.04.003

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