DECCAN VOLCANISM AND MASS EXTINCTION

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

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

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

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

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

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

SPE505: Volcanism, Impacts, and Mass Extinctions: Causes and Effects

TitleSPE505: Volcanism, Impacts, and Mass Extinctions: Causes and Effects
Publication TypeBook
Year of Publication2014
AuthorsKeller, G, Kerr, AC
Series TitleGSA Special Papers
Volume505
PublisherGeological Society of America
CityBoulder
ISBN978-0-8137-2505-5
Abstract

The 26 chapters of this symposium volume encompass reviews of special topics, summaries of particular datasets and original research contributions. Together they span age intervals ranging from the Neoproterozoic, Mesozoic to Paleogene and Recent addressing a variety of stratigraphic, paleoecologic, environmental and paleoclimatic events. These contributions are organized under four themes: 1. Applications, 2. Paleoecology—Recent, 3. Global bioevents—PE and KTB, and 4. Biodiversity and Stratigraphy in Deep Time. 

URLhttp://specialpapers.gsapubs.org/content/current
DOI10.1130/9780813725055

Atmospheric halogen and acid rains during the main phase of Deccan eruptions: Magnetic and mineral evidence

TitleAtmospheric halogen and acid rains during the main phase of Deccan eruptions: Magnetic and mineral evidence
Publication TypeBook Chapter
Year of Publication2014
AuthorsFont, E, Fabre, S, Nedelec, A, Adatte, T, Keller, G, Veiga-Pires, C, Ponte, J, Mirao, J, Khozyem, H, Spangenberg, JE
Book TitleGeological Society of America Special Papers
Pagination353–368
PublisherGeological Society of America Special Papers
Abstract

 

Environmental changes linked to Deccan volcanism are still poorly known. A major limitation resides in the paucity of direct Deccan volcanism markers and in the geologically short interval where both impact and volcanism occurred, making it hard to evaluate their contributions to the mass extinction. We investigated the low-magnetic-susceptibility interval just below the iridium-rich layer of the Bidart (France) section, which was recently hypothesized to be the result of paleoenvironmental perturbations linked to paroxysmal Deccan phase 2. Results show a drastic decrease of detrital magnetite and presence of scarce akaganeite, a hypothesized reaction product formed in the aerosols derived from reaction of a volcanic plume with water and oxygen in the high atmosphere. A weathering model of the consequences of acidic rains on a continental regolith reveals nearly complete magnetite dissolution after ~31,000 yr, which is consistent with our magnetic data and falls within the duration of the Deccan phase 2. These results highlight the nature and importance of the Deccan-related environmental changes leading up to the end- Cretaceous mass extinction.  PDF

URLhttps://doi.org/10.1130/2014.2505(18)
DOI10.1130/2014.2505(18)

Effects of Deccan volcanism on paleoenvironment and planktic foraminifera: A global survey

TitleEffects of Deccan volcanism on paleoenvironment and planktic foraminifera: A global survey
Publication TypeJournal Article
Year of Publication2014
AuthorsPunekar, J, Mateo, P, Keller, G
JournalGeological Society of America Special Papers
Volume505
Abstract

Deccan volcanism, one of Earth's largest flood basalt provinces, erupted  80% of its total volume (phase 2) during a relatively short time in the uppermost Maastrichtian paleomagnetic chron C29r and ended with the Cretaceous-Tertiary boundary mass extinction. Full biotic recovery in the marine realm was delayed at least 500 k.y. or until after the last Deccan eruptions in C29n (phase 3, 14% of the total Deccan volume). For over 30 yr, the mass extinction has been commonly attributed to the Chicxulub impact, and the delayed recovery remained an enigma. Here, we demonstrate that the two phases of Deccan volcanism can account for both the mass extinction and delayed marine recovery.In India, a direct correlation between Deccan eruptions (phase 2) and the mass extinction reveals that  50% of the planktic foraminifer species gradually disappeared during volcanic eruptions prior to the first of four lava megaflows, reaching  1500 km across India, and out to the Bay of Bengal. Another 50% disappeared after the first megaflow, and the mass extinction was complete with the last megaflow. Throughout this interval, blooms of the disaster opportunist Guembelitria cretacea dominate shallow-marine assemblages in coeval intervals from India to the Tethys and the Atlantic Oceans to Texas. Similar high-stress environments dominated by blooms of Guembelitria and/or Globoconusa are observed correlative with Deccan volcanism phase 3 in the early Danian C29n, followed by full biotic recovery after volcanism ended. The mass extinction and high-stress conditions may be explained by the intense Deccan volcanism leading to rapid global warming and cooling in C29r and C29n, enhanced weathering, continental runoff, and ocean acidification, resulting in a carbonate crisis in the marine environment.  PDF

URLhttp://specialpapers.gsapubs.org/content/early/2014/08/21/2014.2505_04.abstract
DOI10.1130/2014.2505(04)

Late Maastrichtian–early Danian high-stress environments and delayed recovery linked to Deccan volcanism

TitleLate Maastrichtian–early Danian high-stress environments and delayed recovery linked to Deccan volcanism
Publication TypeJournal Article
Year of Publication2014
AuthorsPunekar, J, Keller, G, Khozyem, H, Hamming, C, Adatte, T, Tantawy, AAAM, Ponte, J
JournalCretaceous Research
Volume49
Pagination63 - 82
Date PublishedJan-05-2014
ISSN01956671
Abstract

Deccan volcanism occurred in three intense phases of relatively short duration: phase 1 spanning the paleomagnetic chron C30r/C30n boundary (planktic foraminiferal CF4), phase 2 in the latest Maastrichtian C29r (zones CF1–CF2), and phase 3 in the early Danian C29n (P1b). This study explores the nature of paleoenvironmental changes correlative with the three volcanic phases in central Egypt and the Sinai based on planktic foraminifers, stable carbon and oxygen isotopes.

Results show that high-stress assemblages dominated by Guembelitria blooms are prominent in, but not exclusive to, all three volcanic phases. These blooms are well known from the aftermath of this mass extinction in zones P0–P1a, the intertrappean interval between volcanic phases 2 and 3. Guembelitria blooms in CF4 (phase 1) are relatively minor (<45%) although they comprise a substantial component of the planktic foraminiferal assemblages. Maximum Guembelitria blooms (>80% of the total assemblage) are observed in CF1, which spans the last 160 ka of the Maastrichtian marked by rapid global climatic warming and cooling correlative with phase 2. Major Guembelitria blooms (50–75%) are also observed in P1b, which is marked by climate warming (Dan-C2 event) and a major negative carbon isotope excursion correlative with phase 3. This high-stress event precedes full marine biotic recovery after the mass extinction.  PDF

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0195667114000056
DOI10.1016/j.cretres.2014.01.002
Short TitleCretaceous Research

Deccan volcanism, the Chicxulub impact, and the end-Cretaceous mass extinction: Coincidence? Cause and effect?

TitleDeccan volcanism, the Chicxulub impact, and the end-Cretaceous mass extinction: Coincidence? Cause and effect?
Publication TypeBook Chapter
Year of Publication2014
AuthorsKeller, G
Book TitleVolcanism, Impacts, and Mass Extinctions: Causes and Effects
Volume505
EditionGSA Special Papers
PaginationPp. 29-55
PublisherGeological Society of America
CityBoulder
Abstract

The recent discovery of the direct link between Deccan volcanism and the end-Cretaceous mass extinction also links volcanism to the late Maastrichtian rapid global warming, high environmental stress, and the delayed recovery in the early Danian. In comparison, three decades of research on the Chicxulub impact have failed to account for long-term climatic and environmental changes or prove a coincidence with the mass extinction. A review of Deccan volcanism and the best age estimate for the Chicxulub impact provides a new perspective on the causes for the end­Cretaceous mass extinction and supports an integrated Deccan-Chicxulub scenario. This scenario takes into consideration climate warming and cooling, sea-level changes, erosion, weathering, ocean acidification, high-stress environments with opportunistic species blooms, the mass extinction, and delayed postextinction recovery.The crisis began in C29r (upper CF2 to lower CF1) with rapid global warming of 4 °C in the oceans and 8 °C on land, commonly attributed to Deccan phase 2 eruptions. The Chicxulub impact occurred during this warm event (about 100–150 k.y. before the mass extinction) based on the stratigraphically oldest impact spherule layer in NE Mexico, Texas, and Yucatan crater core Yaxcopoil-1. It likely exacerbated climate warming and may have intensified Deccan eruptions. The reworked spherule layers at the base of the sandstone complex in NE Mexico and Texas were deposited in the upper half of CF1,  50–80 k.y. before the Cretaceous-Tertiary (K-T) boundary. This sandstone complex, commonly interpreted as impact tsunami deposits of K-T boundary age, was deposited during climate cooling, low sea level, and intensified currents, leading to erosion of nearshore areas (including Chicxulub impact spherules), transport, and redeposition via submarine channels into deeper waters. Renewed climate warming during the last  50 k.y. of the Maastrichtian correlates with at least four rapid, massive volcanic eruptions known as the longest lava flows on Earth that ended with the mass extinction, probably due to runaway effects. The kill mechanism was likely ocean acidification resulting in the carbonate crisis commonly considered to be the primary cause for four of the five Phanerozoic mass extinctions.  PDF

URLhttp://specialpapers.gsapubs.org/content/early/2014/06/10/2014.2505_03.1.abstract
DOI10.1130/2014.2505(03)

Multiproxy evidence of main Deccan Traps pulse near the Cretaceous-Tertiary boundary

TitleMultiproxy evidence of main Deccan Traps pulse near the Cretaceous-Tertiary boundary
Publication TypeBook Chapter
Year of Publication2013
AuthorsAdatte, T, Keller, G
Book TitleProceedings of XXIII Indian Colloquium on Micropaloentology and Stratigraphy and International Symposium on Global Bioevents in Earth's History
Volume1
ChapterPart III, Pp. 243
EditionSpecial Publication
PublisherGeological Society of India
CityBangalore
ISBN978-93-80998-08-4
KeywordsGlobal Bioevents, KTB, PE
Abstract

Recent studies indicate that the bulk (80%) of Deccan trap eruptions occurred over a relatively short time interval in magnetic polarity C29r, whereas multiproxy studies from central and southeastern India place the Cretaceous-Tertiary (KT) mass extinction near the end of this main phase of Deccan volcanism suggesting a cause-and-effect relationship. Beyond India multiproxy studies also place the main Deccan phase in the uppermost Maastrichtian C29r below the KTB (planktic foraminiferal zones CF2-CF1), as indicated by a rapid shift in 187Os/188Os ratios in deep-sea sections from the Atlantic, Pacific and Indian Oceans, coincident with rapid climate warming, coeval increase in weathering, a significant decrease in bulk carbonate indicative of acidification due to volcanic SO2, and major biotic stress conditions expressed in species dwarfing and decreased abundance in calcareous microfossils (planktic foraminifera and nannofossils). These observations indicate that Deccan volcanism played a key role in increasing atmospheric CO2 and SO2 levels that resulted in global warming and acidified oceans, respectively, increasing biotic stress that predisposed faunas to eventual extinction at the KTB.

URLhttp://www.geosocindia.com/index.php?page=shop.product_details&flypage=flypage-ask.tpl&product_id=227&category_id=20&option=com_virtuemart&Itemid=6

Volcanism, impacts and mass extinctions (Long Version)

TitleVolcanism, impacts and mass extinctions (Long Version)
Publication TypeWeb Article
Year of Publication2012
AuthorsKeller, G, Armstrong, H, Courtillot, V, Harper, D, Joachimski, M, Kerr, A, MacLeod, N, Napier, W, Palfy, J, Wignall, P
Access Year2012
Access DateNovember
PublisherThe Geological Society
CityLondon
Type of MediumOnline version
Keywordsclimate change, Impacts, Mass extinctions, ocean anoxia, Phanerozoic, Volcanism
Abstract

The nature and causes of mass extinctions in the geological past have remained topics of intense scientific debate for the past three decades.  Central to this debate is the question of whether one or several large bolide impacts, the eruption of large igneous provinces (LIPS), or a combination of the two were the primary mechanism(s) driving the environmental and habitat changes that are universally regarded as the proximate causes for four of the five major extinction events.  Recent years have seen a revolution in our understanding of both the interplanetary environment and LIPS eruptions and their environmental effects such that the current impact-kill scenario no longer seems adequate for the KT (KPg) or any other mass extinction.  Massive sequential volcanic eruptions and the breakup of giant comets leading to rapid climate change, ocean anoxia and ozone destruction emerge as the leading causes in major mass extinctions.  PDF

URLhttp://www.geolsoc.org.uk/Geoscientist/Archive/November-2012/Volcanism-impacts-and-mass-extinctions-2
Alternate TitleVolcanism, impacts and mass extinctions (long version)

The Cretaceous–Tertiary Mass Extinction, Chicxulub Impact, and Deccan Volcanism

TitleThe Cretaceous–Tertiary Mass Extinction, Chicxulub Impact, and Deccan Volcanism
Publication TypeBook Chapter
Year of Publication2012
AuthorsKeller, G
Book TitleEarth and Life
Pagination759 - 793
PublisherSpringer Netherlands
CityDordrecht
ISBN Number978-90-481-3427-4
KeywordsChicxulub impact, Cretaceous, Danian, deccan volcanism, Foraminifers, Maastrichtian, Mass extinctions, Paleogene
Abstract

After three decades of nearly unchallenged wisdom that a large impact (Chicxulub) on Yucatan caused the end-Cretaceous mass extinction, this theory is facing its most serious challenge from the Chicxulub impact itself, as based on evidence in Texas and Mexico and from Deccan volcanism in India. Data generated from over 150 Cretaceous–Tertiary (KT) boundary sequences to date make it clear that the long-held belief in the Chicxulub impact as the sole or even major contributor to the KT mass extinction is not supported by evidence. The stratigraphic position of the Chicxulub impact ejecta spherules in NE Mexico and Texas and the impact breccia within the crater on Yucatan demonstrate that this impact predates the KTB by about 300,000 years. Planktic foraminiferal and stable isotope analyses across the primary impact ejecta layer reveal that not a single species went extinct as a result of this impact and no significant environmental changes could be determined. The catastrophic effects of this impact have been vastly overestimated. In contrast, recent advances in Deccan volcanic studies indicate three volcanic phases with the smallest at 67.5 Ma, the main phase at the end of the Maastrichtian (C29r), and the third phase in the early Danian C29r/C29n transition (Chenet et al. 2007). The main phase of eruptions occurred rapidly, was marked by the longest lava flows spanning 1500 km across India, and ended coincident with the KT boundary. The KT mass extinction may have been caused by these rapid and massive Deccan lava and gas eruptions that account for ∼80% of the entire 3500 m thick Deccan lava pile.

URLhttp://link.springer.com/content/pdf/10.1007/978-90-481-3428-1_25
DOI10.1007/978-90-481-3428-110.1007/978-90-481-3428-1_25

Nature and timing of extinctions in Cretaceous-Tertiary planktic foraminifera preserved in Deccan intertrappean sediments of the Krishna–Godavari Basin, India

TitleNature and timing of extinctions in Cretaceous-Tertiary planktic foraminifera preserved in Deccan intertrappean sediments of the Krishna–Godavari Basin, India
Publication TypeJournal Article
Year of Publication2011
AuthorsKeller, G, Adatte, T, Bhowmick, PK, Upadhyay, H, Dave, A, Reddy, AN, Jaiprakash, BC
JournalEarth and Planetary Science Letters
Volume341-344
Pagination211 - 221
Date PublishedJan-08-2012
ISSN0012821X
Abstract

In C29r below the Cretaceous-Tertiary boundary (KTB) massive Deccan Trap eruptions in India covered an area the size of France or Texas and produced the world’s largest and longest lava megaflows 1500 km across India through the Krishna–Godavari (K–G) Basin into the Bay of Bengal. Investigation of ten deep wells from the K–G Basin revealed four lava megaflows separated by sand, silt and shale with the last megaflow ending at or near the KTB. The biologic response in India was swift and devastating. During Deccan eruptions prior to the first megaflow, planktic foraminifera suffered 50% species extinctions. Survivors suffered another 50% extinctions after the first megaflow leaving just 7–8 species. No recovery occurred between the next three megaflows and the mass extinction was complete with the last mega-flow at or near the KTB. The last phase of Deccan volcanism occurred in the early Danian C29n with deposition of another four megaflows accompanied by delayed biotic recovery of marine plankton. Correlative with these intense volcanic phases, climate changed from humid/tropical to arid conditions and returned to normal tropical humidity after the last phase of volcanism. The global climatic and biotic effects attributable to Deccan volcanism have yet to be fully investigated. However, preliminary studies from India to Texas reveal extreme climate changes associated with high-stress environmental conditions among planktic foraminifera leading to blooms of the disaster opportunist Guembelitria cretacea during the late Maastrichtian.  PDF

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0012821X12003056
DOI10.1016/j.epsl.2012.06.021
Short TitleEarth and Planetary Science Letters

Environmental effects of Deccan volcanism across the Cretaceous–Tertiary transition in Meghalaya, India

TitleEnvironmental effects of Deccan volcanism across the Cretaceous–Tertiary transition in Meghalaya, India
Publication TypeJournal Article
Year of Publication2011
AuthorsGertsch, B, Keller, G, Adatte, T, Garg, R, Prasad, V, Berner, Z, Fleitmann, D
JournalEarth and Planetary Science Letters
Volume310
Issue3-4
Pagination272 - 285
Date Published01/2011
ISSN0012821X
Abstract

The Um Sohryngkew section of Meghalaya, NE India, located 800–1000 km from the Deccan volcanic province, is one of the most complete Cretaceous–Tertiary boundary (KTB) transitions worldwide with all defining and supporting criteria present: mass extinction of planktic foraminifera, first appearance of Danian species, δ13C shift, Ir anomaly (12 ppb) and KTB red layer. The geochemical signature of the KTB layer indicates not only an extraterrestrial signal (Ni and all Platinum Group Elements (PGEs)) of a second impact that postdates Chicxulub, but also a significant component resulting from condensed sedimentation (P), redox fluctuations (As, Co, Fe, Pb, Zn, and to a lesser extent Ni and Cu) and volcanism. From the late Maastrichtian C29r into the early Danian, a humid climate prevailed (kaolinite: 40–60%, detrital minerals: 50–80%). During the latest Maastrichtian, periodic acid rains (carbonate dissolution; CIA index: 70–80) associated with pulsed Deccan eruptions and strong continental weathering resulted in mesotrophic waters. The resulting super-stressed environmental conditions led to the demise of nearly all planktic foraminiferal species and blooms (> 95%) of the disaster opportunist Guembelitria cretacea. These data reveal that detrimental marine conditions prevailed surrounding the Deccan volcanic province during the main phase of eruptions in C29r below the KTB. Ultimately these environmental conditions led to regionally early extinctions followed by global extinctions at the KTB.

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0012821X11004791
DOI10.1016/j.epsl.2011.08.015
Short TitleEarth and Planetary Science Letters

Foraminifera from the early Danian intertrappean beds in Rajahmundry quarries, Andhra Pradesh

TitleForaminifera from the early Danian intertrappean beds in Rajahmundry quarries, Andhra Pradesh
Publication TypeJournal Article
Year of Publication2010
AuthorsMalarkodi, N, Keller, G, Fayazudeen, PJ, Mallikarjuna, UB
JournalJournal of the Geological Society of India
Volume75
Issue6
Pagination851 - 863
Date PublishedJan-06-2010
ISSN0016-7622
Abstract

Intertrappean beds exposed between upper and lower traps of the Government and Sunnamrayalu quarries of Rajahmundry were analyzed based on benthic and planktic foraminifera, ostracodes and algae observed in thin sections. Planktic foraminifera indicate deposition occurred in the early Danian Parvularugoglobigerina eugubina (P1a) zone shortly after deposition of the lower trap flows. The most diverse planktic assemblages were deposited in limestones of the middle intertrappean interval and indicate an upper P1a age, or subzone P1a(2), as marked by the co-occurrence of P. eugubina, Globoconusa daubjergensis, Parasubbotina pseudobulloides and Subbotina triloculinoides. Reworked late Maastrichtian planktic foraminifera are common in a limestone interval and suggest erosion of uplifted Cretaceous sediments. Benthic foraminiferal assemblages indicate deposition occurred predominantly in shallow inner shelf to brackish environments. Similarly, ostracodes indicate variable environments ranging from inner neritic to brackish with fresh water influx, as also indicated by the presence of fresh water algae. These data confirm an overall deepening from restricted shallow marine to estuarine, lagoonal and finally open marine conditions followed by abrupt emersion and paleosoil deposition prior to the arrival of the upper trap flows at or near the base of C29n.

URLhttp://link.springer.com/article/10.1007%2Fs12594-010-0066-0
DOI10.1007/s12594-010-0066-0
Short TitleJ Geol Soc India

Deccan volcanism, the KT mass extinction and dinosaurs

TitleDeccan volcanism, the KT mass extinction and dinosaurs
Publication TypeJournal Article
Year of Publication2009
AuthorsKeller, G, Sahni, A, Bajpai, S
JournalJournal of Biosciences
Volume34
Issue5
Pagination709 - 728
Date PublishedJan-11-2009
ISSN0250-5991
Abstract

Recent advances in Deccan volcanic studies indicate three volcanic phases with the phase-1 at 67.5 Ma followed by a 2 m.y. period of quiescence. Phase-2 marks the main Deccan volcanic eruptions in Chron 29r near the end of the Maastrichtian and accounts for ∼80% of the entire 3500 m thick Deccan lava pile. At least four of the world’s longest lava flows spanning 1000 km across India and out into the Gulf of Bengal mark phase-2. The final phase-3 was smaller, coincided with the early Danian Chron 29n and also witnessed several of the longest lava flows.

The KT boundary and mass extinction was first discovered based on planktic foraminifera from shallow marine intertrappean sediments exposed in Rajahmundry quarries between the longest lava flows of the main volcanic phase-2 and smaller phase-3. At this locality early Danian (zone P1a) planktic foraminiferal assemblages directly overlie the top of phase-2 eruptions and indicate that the masse extinction coincided with the end of this volcanic phase. Planktic foraminiferal assemblages also mark the KT boundary in intertrappean sediments at Jhilmili, Chhindwara, where freshwater to estuarine conditions prevailed during the early Danian and indicate the presence of a marine seaway across India at KT time.

Dinosaur bones, nesting sites with complete eggs and abundant eggshells are known from central India surrounding the hypothesized seaway through the Narmada-Tapti rift zone. A Maastrichtian age is generally assigned to these dinosaur remains. Age control may now be improved based on marine microfossils from sequences deposited in the seaway and correlating these strata to nearby terrestrial sequences with dinosaur remains.

URLhttp://link.springer.com/article/10.1007%2Fs12038-009-0059-6
DOI10.1007/s12038-009-0059-6
Short TitleJ Biosci

Late Maastrichtian Volcanism in the Indian Ocean: Effects on Calcareous Nannofossils and Planktic Foraminifera

TitleLate Maastrichtian Volcanism in the Indian Ocean: Effects on Calcareous Nannofossils and Planktic Foraminifera
Publication TypeJournal Article
Year of Publication2009
AuthorsTantawy, AAAM, Keller, G, Pardo, A
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume284
Issue1-2
Pagination63 - 87
Date PublishedJan-12-2009
ISSN00310182
KeywordsBiotic effects, High stress environments, Indian Ocean Maastrichtian, Volcanism
Abstract

The biotic effects of volcanism have long been the unknown factors in creating biotic stress, and the contribution of the Deccan volcanism to the K–T mass extinction remains largely unknown. Detailed studies of the volcanic-rich sediments of Indian Ocean Ninetyeast Ridge Sites 216 and 217 and Wharton Basin Site 212 reveal that the biotic effects of late Maastrichtian volcanism on planktic foraminifera and calcareous nannofossils are locally as severe as those of the K–T mass extinction. The biotic expressions of these high stress environments are characterized by the Lilliput effect, which includes reduced diversity by eliminating most K-strategy species, and reduction in specimen size (dwarfing), frequently to less than half their normal adult size of both r-strategy and surviving K-strategy species. In planktic foraminifera, the most extreme biotic stress results are nearly monospecific assemblages dominated by the disaster opportunist Guembelitria, similar to the aftermath of the K–T mass extinction. The first stage of improving environmental conditions results in dominance of dwarfed low oxygen tolerant Heterohelix species and the presence of a few small r-strategy species (Hedbergella, Globigerinelloides). Calcareous nannofossil assemblages show similar biotic stress signals with the dominance of Micula decussata, the disaster opportunist, and size reduction in the mean length of subordinate r-strategy species particularly in Arkhangelskiella cymbiformis and Watznaueria barnesiae. These impoverished and dwarfed late Maastrichtian assemblages appear to be the direct consequences of mantle plume volcanism and associated environmental changes, including high nutrient influx leading to eutrophic and mesotrophic waters, low oxygen in the water column and decreased watermass stratification.

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0031018209003496
DOI10.1016/j.palaeo.2009.08.025
Short TitlePalaeogeography, Palaeoclimatology, Palaeoecology

K–T transition in Deccan Traps of central India marks major marine Seaway across India

TitleK–T transition in Deccan Traps of central India marks major marine Seaway across India
Publication TypeJournal Article
Year of Publication2009
AuthorsKeller, G, Adatte, T, Bajpai, S, Mohabey, DM, Widdowson, M, Khosla, A, Sharma, R, Khosla, SC, Gertsch, B, Fleitmann, D
JournalEarth and Planetary Science Letters
Volume282
Issue1-4
Pagination10 - 23
Date PublishedJun-05-2011
ISSN0012821X
Abstract

Deccan intertrappean sediments in central India are generally considered as terrestrial deposits of Maastrichtian age, but the Cretaceous–Tertiary (K–T) position is still unknown. Here we report the discovery of the K–T transition, a marine incursion and environmental changes preserved within the intertrappean sediments at Jhilmili, Chhindwara District, Madhya Pradesh. Integrative biostratigraphic, sedimentologic, mineralogic and chemostratigraphic analyses reveal the basal Danian in the intertrappean sediments between lower and upper trap basalts that regionally correspond to C29r and the C29R/C29N transition, respectively. Intertrappean deposition occurred in predominantly terrestrial semi-humid to arid environments. But a short aquatic interval of fresh water ponds and lakes followed by shallow coastal marine conditions with brackish marine ostracods and early Danian zone P1a planktic foraminifera mark this interval very close to the K–T boundary. This marine incursion marks the existence of a nearby seaway, probably extending inland from the west through the Narmada and Tapti rift valleys. The Jhilmili results thus identify the K–T boundary near the end of the main phase of Deccan eruptions and indicate that a major seaway extended at least 800 km across India.

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0012821X09001034
DOI10.1016/j.epsl.2009.02.016
Short TitleEarth and Planetary Science Letters

Early Danian Planktic Foraminifera From Cretaceous-Tertiary Intertrappean Beds At Jhilmili, Chhindwara District, Madhya Pradesh, India

TitleEarly Danian Planktic Foraminifera From Cretaceous-Tertiary Intertrappean Beds At Jhilmili, Chhindwara District, Madhya Pradesh, India
Publication TypeJournal Article
Year of Publication2009
AuthorsKeller, G, Khosla, SC, Sharma, R, Khosla, A, Bajpai, S, Adatte, T
JournalThe Journal of Foraminiferal Research
Volume39
Issue1
Pagination40 - 55
Date PublishedJan-01-2009
ISSN0096-1191
Abstract

The main Deccan volcanic province erupted mainly in terrestrial to lacustrine environments of late Maastrichtian to early Paleocene age, and lack age diagnostic fossils to accurately place the Cretaceous-Tertiary (K-T) boundary. As a result, the precise position of the K-T event within the volcanic province has remained speculative, and no realistic assessment of the biotic consequences of Deccan volcanism at K-T time has been possible. Here, we report the discovery of early Danian Zone P1a planktic foraminifera within lacustrine to brackish-marine ostracod assemblages near Jhilmili, Chhindwara District, India. These foraminiferal assemblages identify the K-T boundary in intertrappean sediments bracketed by basalt traps that are regionally correlative with C29R (Ambenali Formation) and the C29R-C29N transition (Mahalabeshwar Formation). The Jhilmili sequence is thus correlative with the shallow-marine, intertrappean Zone P1a assemblage and C29R and C29N of the lower and upper basalt traps exposed in Rajahmundry quarries. The presence of planktic foraminifera in predominantly terrestrial intertrappean sediments some 800 km from the nearest ocean suggests the presence of a seaway along the Narmada and Tapti rift zones with Jhilmili located at the eastern margin.

URLhttp://jfr.geoscienceworld.org/cgi/doi/10.2113/gsjfr.39.1.40
DOI10.2113/gsjfr.39.1.40
Short TitleThe Journal of Foraminiferal Research

Main Deccan volcanism phase ends near the K–T boundary: Evidence from the Krishna–Godavari Basin, SE India

TitleMain Deccan volcanism phase ends near the K–T boundary: Evidence from the Krishna–Godavari Basin, SE India
Publication TypeJournal Article
Year of Publication2008
AuthorsKeller, G, Adatte, T, Gardin, S, Bartolini, A, Bajpai, S
JournalEarth and Planetary Science Letters
Volume268
Issue3-4
Start Page293
Date Published01/2008
ISSN0012821X
Keywordsdeccan volcanism, K–T mass extinction, paleoenvironment, Rajahmundry
Abstract

Recent studies indicate that the bulk (80%) of the Deccan trap eruptions occurred over less than 0.8 m.y. in magnetic polarity C29r spanning the Cretaceous–Tertiary (K–T) boundary. Determining where within this major eruptive phase the K–T mass extinction occurred has remained problematic. For this reason, models estimating the biotic and environmental consequences have generally underestimated the rate and quantity of Deccan gas emissions by orders of magnitude leading to conclusions that volcanism could not have been one of the major causes for the K–T mass extinction. In this study we report that the most massive Deccan trap eruption occurred near the K–T mass extinction.

These results are based on sedimentologic, microfacies and biostratigraphic data of 4–9 m thick intertrappean sediments in four quarry outcrops in the Rajahmundry area of the Krishna–Godavari Basin of southeastern India. In this area two Deccan basalt flows, known as the Rajahmundry traps, mark the longest lava flows extending 1500 km across the Indian continent and into the Bay of Bengal. The sediments directly overlying the lower Rajahmundry trap contain early Danian planktic foraminiferal assemblages of zone P1a, which mark the evolution in the aftermath of the K–T mass extinction. The upper Rajahmundry trap was deposited in magnetic polarity C29n, preceding full biotic recovery. These results suggest that volcanism may have played critical roles in both the K–T mass extinction and the delayed biotic recovery.

URLhttp://www.sciencedirect.com/science/article/pii/S0012821X08000344
DOI10.1016/j.epsl.2008.01.015
Short TitleEarth and Planetary Science Letters

Cretaceous climate, volcanism, impacts, and biotic effects

TitleCretaceous climate, volcanism, impacts, and biotic effects
Publication TypeJournal Article
Year of Publication2008
AuthorsKeller, G
JournalCretaceous Research
Volume29
Issue5-6
Pagination754 - 771
Date PublishedJan-10-2008
ISSN01956671
KeywordsBiotic effects, Cretaceous Impacts, Mass extinctions, Volcanism
Abstract

Cretaceous volcanic activities (LIPs and CFBPs) appear to have had relatively minor biotic effects, at least at the generic level. Major biotic stress during the Cretaceous was associated with OAEs and related to nutrient availability largely from weathering, greenhouse warming, drowning of platform areas, and volcanism. The biotic effects of OAEs were often dramatic at the species level, causing the extinction of larger specialized and heavily calcified planktonic foraminifera (rotaliporid extinction) and nannoconids (nannoconid crises), the temporary disappearances of other larger species, and the rapid increase in r-selected small and thin-walled species, such as the low oxygen tolerant heterohelicids and radially elongated taxa among planktic foraminifera and thin walled nannofossils. Biotic diversity increased during cool climates, particularly during the late Campanian and Maastrichtian, reaching maximum diversity during the middle Maastrichtian. High biotic stress conditions began during greenhouse warming and Deccan volcanism about 400 ky before the K-T boundary; it reduced abundances of large specialized tropical planktic foraminiferal species and endangered their survival. By K-T time, renewed Deccan volcanism combined with a large impact probably triggered the demise of this already extinction prone species group.

Evidence from NE Mexico, Texas, and the Chicxulub crater itself indicates that this 170 km-diameter crater predates the K-T boundary by ∼300,000 years and caused no species extinctions. The Chicxulub impact, therefore, can no longer be considered a direct cause for the K-T mass extinction. However, the K-T mass extinction is closely associated with a global Ir anomaly, which is considered too large, too widespread, and too concentrated in a thin layer to have originated from volcanic activity, leaving another large impact as the most likely source. This suggests that a second still unknown larger impact may have triggered the K-T mass extinction.  PDF

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0195667108000566
DOI10.1016/j.cretres.2008.05.030
Short TitleCretaceous Research

Planktonic Foraminiferal Biostratigraphy and Faunal Turnover across the Cretaceous-Tertiary Boundary in Southwestern Iran

TitlePlanktonic Foraminiferal Biostratigraphy and Faunal Turnover across the Cretaceous-Tertiary Boundary in Southwestern Iran
Publication TypeJournal Article
Year of Publication2007
AuthorsDarvishzad, B, Ghasemi-Nejad, E, Ghourchaei, S
JournalJournal of Sciences, Islamic Republic of Iran
Volume18
Issue2
Pagination39-149
Type of ArticleUniversity of Tehran
KeywordsCretaceous-Tertiary Boundary; Biostratigraphy; Plankton foraminifera
Abstract

The Kabirkuh section in the Ilam Province of southwestern Iran contains one of the most complete Late Maastrichtian to early Danian sequences similar to those known from the eastern Tethys realm. The Cretaceous-Tertiary boundary is marked by a 1-2 cm thick kidney-red shale in the uppermost Gurpi Formation. All Late Maastrichtian planktonic foraminiferal biozones CF1 to CF4 (equivalent to the Abathomphalus mayaroensis zone) and Danian zones P0 (Parvularugo-globigerina extensa), P1a (Parvularugoglobigerina eugubina) and Parasubbotina pseudobulloides are present. Faunal studies show that all but six of the Cretaceous species identified (22 of 29 species) disappeared at or below the K-T boundary in zone CF1 (P. hantkeninoides). Another 6 species (Heterohelix globulosa, H. navarroensis, H. dentata, Hedbergella monmouthensis, H. holmdelensis, Guembelitria cretacea) appear to have survived into the early Danian. Early disappearances appear to be environmen tally controlled. Coarse ornamented species with small populations disappeared first, whereas small species with little or no ornamentation and generally large populations tended to survive after the environment changing. This indicates a pattern of gradual and selective faunal turnover in planktonic foraminifera during the latest Maastrichtian and into the earliest Danian that is similar to that observed at the El Kef stratotype of Tunisia, as well as K-T sequences in Egypt, Italy, Spain and Mexico.  PDF

URLhttp://jsciences.ut.ac.ir

Biotic effects of late Maastrichtian mantle plume volcanism: implications for impacts and mass extinctions

TitleBiotic effects of late Maastrichtian mantle plume volcanism: implications for impacts and mass extinctions
Publication TypeJournal Article
Year of Publication2005
AuthorsKeller, G
JournalLithos
Volume79
Issue3-4
Pagination317 - 341
Date PublishedJan-02-2005
ISSN00244937
KeywordsBiotic effects, DSDP Site 216, Impacts, Late Maastrichtian, Planktic foraminifera Guembelitria, Volcanism
Abstract

During the late Maastrichtian, DSDP Site 216 on Ninetyeast Ridge, Indian Ocean, passed over a mantle plume leading to volcanic eruptions, islands built to sea level, and catastrophic environmental conditions for planktic and benthic foraminifera. The biotic effects were severe, including dwarfing of all benthic and planktic species, a 90% reduction in species diversity, exclusion of all ecological specialists, near-absence of ecological generalists, and dominance of the disaster opportunist Guembelitria alternating with low O2-tolerant species. These faunal characteristics are identical to those of the K–T boundary mass extinction, except that the fauna recovered after Site 216 passed beyond the influence of mantle plume volcanism about 500 kyr before the K–T boundary. Similar biotic effects have been observed in Madagascar, Israel, and Egypt. The direct correlation between mantle plume volcanism and biotic effects on Ninetyeast Ridge and the similarity to the K–T mass extinction, which is generally attributed to a large impact, reveal that impacts and volcanism can cause similar environmental catastrophes. This raises the inevitable question: Are mass extinctions caused by impacts or mantle plume volcanism? The unequivocal correlation between intense volcanism and high-stress assemblages necessitates a review of current impact and mass extinction theories.

 

 

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0024493704003111
DOI10.1016/j.lithos.2004.09.005
Short TitleLithos

Suche nach der Ursache des Massensterbens vor 65 Millionen Jahren

TitleSuche nach der Ursache des Massensterbens vor 65 Millionen Jahren
Publication TypeJournal Article
Year of Publication2004
AuthorsGerta, K
JournalWerdenberger Jahrbuch
Pagination189-200
Abstract

Seit der Entdeckung des ChicxulubAsteroidenkraters auf der südmexikanischen Halbinsel Yucatán im Jahr l990 (Abb. 1) wird dieser Krater für das Aussterben der Dinosaurier und zahlreicher weiterer Tiergruppen verantwortlich gemacht. Der Einschlag (Impakt2 ) vor rund 65 Millionen Jahren soll eine weltweite Feuerwalze und gigantische Flutwellen verursacht haben, und der aufgewirbelte Staub und Russ soll zur totalen Verdunkelung der Atmosphäre geführt haben. Zurück blieb der Todeskrater. – Ein wunderbares Skript, wie gemacht für Film und Fernsehen. Und so fand die Story in den letzten 15 Jahren Eingang in die öffentliche Meinung und wurde so auch in der wissenschaftlichen Literatur oft als Faktum dargestellt. Aber entspricht sie der Wahrheit? Reichen die wissenschaftlichen Belege aus, um diese Theorie zu untermauern?   PDF

URLhttp://www.sunorbit.net/Belege/K_23.pdf

Characterization of late Campanian and Maastrichtian planktonic foraminiferal depth habitats and vital activities based on stable isotopes

TitleCharacterization of late Campanian and Maastrichtian planktonic foraminiferal depth habitats and vital activities based on stable isotopes
Publication TypeJournal Article
Year of Publication2003
AuthorsAbramovich, S, Keller, G, üben, D, BERNER, ZSOLT
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume202
Issue1-2
Pagination1 - 29
Date PublishedJan-12-2003
ISSN00310182
Abstract

Depth habitats of 56 late Cretaceous planktonic foraminiferal species from cool and warm climate modes were determined based on stable isotope analyses of deep-sea samples from the equatorial Pacific DSDP Sites 577A and 463, and South Atlantic DSDP Site 525A. The following conclusions can be reached: Planoglobulina multicamerata (De Klasz) and Heterohelix rajagopalani (Govindan) occupied the deepest plankton habitats, followed by Abathomphalus mayaroensis (Bolli), Globotruncanella havanensis (Voorwijk), Gublerina cuvillieri Kikoine, and Laeviheterohelix glabrans (Cushman) also at subthermocline depth. Most keeled globotruncanids, and possibly Globigerinelliodes and Racemiguembelina species, lived at or within the thermocline layer. Heterohelix globulosa (Ehrenberg) and Rugoglobigerina, Pseudotextularia and Planoglobulina occupied the subsurface depth of the mixed layer, and Pseudoguembelina species inhabited the surface mixed layer. However, depth ranking of some species varied depending on warm or cool climate modes, and late Campanian or Maastrichtian age. For example, most keeled globotruncanids occupied similar shallow subsurface habitats as Rugoglobigerina during the warm late Campanian, but occupied the deeper thermocline layer during cool climatic intervals. Two distinct types of ‘vital effect’ mechanisms reflecting photosymbiosis and respiration effects can be recognized by the exceptional N13C signals of some species. (1) Photosymbiosis is implied by the repetitive pattern of relatively enriched N13C values of Racemiguembelina (strongest), Planoglobulina, Rosita and Rugoglobigerina species, Pseudoguembelina excolata (weakest). (2) Enriched respiration 12C products are recognized in A. mayaroensis, Gublerina acuta De Klasz, and Heterohelix planata (Cushman). Isotopic trends between samples suggest that photosymbiotic activities varied between localities or during different climate modes, and may have ceased under certain environmental conditions. The appearance of most photosymbiotic species in the late Maastrichtian suggests oligotrophic conditions associated with increased water-mass stratification.  PDF

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0031018203005728
DOI10.1016/S0031-0182(03)00572-8
Short TitlePalaeogeography, Palaeoclimatology, Palaeoecology

Late Maastrichtian paleoclimatic and paleoceanographic changes inferred from Sr/Ca ratio and stable isotopes

TitleLate Maastrichtian paleoclimatic and paleoceanographic changes inferred from Sr/Ca ratio and stable isotopes
Publication TypeJournal Article
Year of Publication2003
AuthorsStüben, D, Kramar, U, Berner, ZA, Meudt, M, Keller, G, Abramovich, S, Adatte, T, Hambach, U, Stinnesbeck, W
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume199
Issue1-2
Pagination107 - 127
Date PublishedJan-10-2003
ISSN00310182
Abstract

Milankovitch-scale cycles can be recognized in high-resolution δ13C, δ18O, Sr/Ca, mineralogical, and magnetic susceptibility data in hemipelagic sediments that span the last 700 kyr of the Maastrichtian at Elles, Tunisia. Oxygen isotope data reveal three cool periods between 65.50 and 65.55 Ma (21.5-23.5 m), 65.26 and 65.33 Ma (8-11 m), and 65.04 and 65.12 Ma (1.5-4 m), and three warm periods between 65.33 and 65.38 Ma (12-16 m), 65.12 and 65.26 Ma (4-8 m), and 65.00 and 65.04 Ma (0-1.5 m). The cool periods are characterized by small surface-to-deep temperature gradients that reflect intensive mixing of the water column. The surface-to-deep Sr/Ca gradient generally correlates with the oscillating ΔT trend (temperature difference between surface and bottom waters). The carbon isotope composition of planktonic foraminifera indicates a continuous decrease in surface bioproductivity during Late Maastrichtian. Decreasing Δ13C values (difference between the δ13C values of surface and bottom dwelling foraminifera) and the carbon isotope ratios of the planktonic species at the onset of gradual warming at 65.50 Ma reflect a reduction in surface productivity as a result of decreased upwelling that accompanied global warming and possibly increased atmospheric pCO2 related to Deccan Trap volcanism. Time series analysis applied to magnetic susceptibility, δ18O, and Sr/Ca data identifies the 20 kyr precession, 40 kyr obliquity, and 100 kyr eccentricity Milankovich cycles.  PDF

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0031018203004991
DOI10.1016/S0031-0182(03)00499-1
Short TitlePalaeogeography, Palaeoclimatology, Palaeoecology

Age and paleoenvironment of the Maastrichtian to Paleocene of the Mahajanga Basin, Madagascar: a multidisciplinary approach

TitleAge and paleoenvironment of the Maastrichtian to Paleocene of the Mahajanga Basin, Madagascar: a multidisciplinary approach
Publication TypeJournal Article
Year of Publication2003
AuthorsAbramovich, S, Keller, G, Adatte, T, Stinnesbeck, W, Hottinger, L, Stueben, D, Berner, Z, Ramanivosoa, B, Randriamanantenasoa, A
JournalMarine Micropaleontology
Volume47
Pagination17–70
Date Publishedjan
Abstract

Lithology, geochemistry, stable isotopes and integrated high-resolution biostratigraphy of the Berivotra and Amboanio sections provide new insights into the age, faunal turnovers, climate, sea level and environmental changes of the Maastrichtian to early Paleocene of the Mahajanga Basin of Madagascar. In the Berivotra type area, the dinosaur-rich fluvial lowland sediments of the Anembalemba Member prevailed into the earliest Maastrichtian. These are overlain by marginal marine and near-shore clastics that deepen upwards to hemipelagic middle neritic marls by 69.6 Ma, accompanied by arid to seasonally cool temperate climates through the early and late Maastrichtian. An unconformity between the Berivotra Formation and Betsiboka limestone marks the K–T boundary, and juxtaposes early Danian (zone Plc? or Pld) and latest Maastrichtian (zones CF2–CF1, Micula prinsii) sediments. Seasonally humid warm climates began near the end of the Maastrichtian and prevailed into the early Danian, accompanied by increased volcanic activity. During the late Danian (zones P1d–P2), a change to seasonally arid climates was accompanied by deepening from middle to outer neritic depths.   PDF

URLhttps://doi.org/10.1016/s0377-8398(02)00094-4
DOI10.1016/s0377-8398(02)00094-4

Biotic effects of impacts and volcanism

TitleBiotic effects of impacts and volcanism
Publication TypeJournal Article
Year of Publication2003
AuthorsKeller, G
JournalEarth and Planetary Science Letters
Volume215
Issue1-2
Pagination249 - 264
Date PublishedJan-10-2003
ISSN0012821X
KeywordsBiotic effects, Cretaceous–Tertiary, DSDP Site 216, Impacts, Maastrichtian, Volcanism
Abstract

The biotic effects of late Maastrichtian mantle plume volcanism on Ninetyeast Ridge and Deccan volcanism mirror those of the Cretaceous–Tertiary (KT) mass extinction and impact event. Planktonic foraminifera responded to high stress conditions with the same impoverished and small-sized species assemblages dominated by the disaster/opportunists Guembelitria cretacea, which characterize the KT mass extinction worldwide. Similar high stress late Maastrichtian assemblages have recently been documented from Madagascar, Israel and Egypt. Biotic effects of volcanism cannot be differentiated from those of impacts, though every period of intense volcanism is associated with high stress assemblages, this is not the case with every impact. The most catastrophic biotic effects occurred at the KT boundary (65.0 Ma) when intense Deccan volcanism coincided with a major impact and caused the mass extinction of all tropical and subtropical species. The Chicxulub impact, which now appears to have predated the KT boundary by about 300 kyr, coincided with intense Deccan volcanism that resulted in high biotic stress and greenhouse warming, but no major extinctions. The unequivocal connection between intense volcanism and high stress assemblages during the late Maastrichtian to early Danian, and the evidence of multiple impacts, necessitates revision of current impact and mass extinction theories.  PDF

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0012821X0300390X
DOI10.1016/S0012-821X(03)00390-X
Short TitleEarth and Planetary Science Letters

High-stress paleoenvironment during the late Maastrichtian to early Paleocene in Central Egypt

TitleHigh-stress paleoenvironment during the late Maastrichtian to early Paleocene in Central Egypt
Publication TypeJournal Article
Year of Publication2002
AuthorsKeller, G, Adatte, T, Burns, SJ, Tantawy, AAziz
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume187
Issue1-2
Pagination35 - 60
Date PublishedJan-11-2002
ISSN00310182
Keywordshigh-stress late Maastrichtian paleoenvironment
Abstract

Biostratigraphic, mineralogical, geochemical and isotopic analyses of the Gebel Qreiya section in the Asyut Basin of central Egypt indicate a depositional environment interrupted by periods of erosion due to local tectonic activity exacerbated by eustatic sea-level fluctuations, and by high-stress environmental conditions akin to those normally experienced during the Cretaceous-Tertiary boundary transition. During the late Maastrichtian (66.8-65.4 Ma) this region experienced a breakdown of the biologically mediated surface to bottom gradient of the 13C/12C ratio with planktic N13C values 0.2-0.8x lighter than benthic values. Planktic foraminiferal species diversity was reduced by more than 50%, with faunal assemblages dominated (75-90%) by the opportunistic disaster species Guembelitria cretacea, which alternate with abundance of small, low oxygen-tolerant heterohelicids (Heterohelix navarroensis, H. dentata, H. globulosa). This prolonged breakdown in ocean primary productivity occurred during a time of global climate cooling and sea-level regressions (at 66.8 and 65.5 Ma), though clay mineralogy suggests that locally low seasonality warm, wet, tropical and subtropical conditions prevailed. The high detrital influx suggests that the biologically high-stress environment was primarily linked to the existing shallow shelf conditions in southern Egypt, and possibly to local tectonic activity and restricted circulation. A normal carbon isotope gradient was briefly reestablished during the short climate warming and rising sea level between 65.4 and 65.2 Ma, a time of increased species diversity, peak abundance of rugoglobigerinids and common heterohelicids. During the last 200 000 years of the Maastrichtian, increased precipitation and terrestrial runoff (increased phyllosilicates and kaolinite) and increasing total organic carbon values are associated with Heterohelix-dominated planktic foraminiferal assemblages. The K/T boundary is marked by a red clay layer and Ir anomaly of 5.4 ppb. During the early Danian, planktic foraminiferal populations and stable isotope data indicate that similarly fluctuating high-stress conditions prevailed in central Egypt as elsewhere in the marginal eastern Tethys.  PDF

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0031018202005047
DOI10.1016/S0031-0182(02)00504-7
Short TitlePalaeogeography, Palaeoclimatology, Palaeoecology