Abrupt climatic change during the latest Maastrichtian; establishing robust temporal links with the onset of Deccan volcanism and K/Pg mass extinction

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Author(s): Barnet, James; Littler, K.; Kroon, D.; Leng, M. J.; Westerhold, T.; Roehl, U.; Zachos, J. C.
Author Affiliation(s): Primary:
University of Exeter, Camborne School of Mines, Exeter, United Kingdom
University of Edinburgh, Edinburgh, United Kingdom
British Geological Survey, Nottingham, United Kingdom
MARUM - University of Bremen, Bremen, Germany
University of California Santa Cruz, Santa Cruz, CA, United States
Volume Title: AGU 2017 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2017; American Geophysical Union 2017 fall meeting, New Orleans, LA, Dec. 11-15, 2017. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: A transient period of climate change, characterized by a global warming of ≈2.5-5°C followed by a cooling to pre-excursion conditions, occurred during the last 300 kyr of the Maastrichtian (≈66.34-66.02 Ma). This instability may have played a role in destabilizing marine and terrestrial ecosystems, priming the system for abrupt extinction at the K-Pg boundary, likely triggered by a large bolide impact. This pre-K-Pg warming event has often been linked to the main phase of Deccan Trap volcanism, however large uncertainties associated with radio-isotopic dating methods of basalts, along with low sedimentation rates and hiatuses in many studied sedimentary sequences, have long hampered a definitive correlation. To complement recent advances in dating of the traps, we have generated the first complete and highest resolution (2.5-4 kyr) benthic stable δ13C and δ18O record for the final million years of the Maastrichtian using the epifaunal foraminifera species Nuttallides truempyi from ODP Site 1262, Walvis Ridge, South Atlantic, calibrated to an updated orbitally-tuned age model. We then compare our data to other previously published geochemical data from other sites in the high, middle, and low latitudes. Our data confirms that the onset of the warming event coincides with the onset of the main phase of Deccan volcanism, strongly suggesting a causal link. Furthermore, spectral analysis of our extended late Maastrichtian-Early Eocene record suggests that the onset of the warming event corresponds to a 405-kyr eccentricity minima, in contrast to many transient warming events (hyperthermals) of the Paleogene, suggesting a control by orbital forcing alone is unlikely. A peculiar feature of the event, compared to other hyperthermals, is a muted carbon cycle response during warming, which may be related to the comparatively heavier δ13C signature of volcanogenic CO2 (-7 ppm), compared to other sources of light carbon invoked to explain Paleogene hyperthermals. The warming event coincided with minor extinctions of thermocline-dwelling foraminifera, along with dwarfing and blooms of the opportunistic disaster genera Guembelitria, suggesting that Deccan-induced climatic instability may have played a role in priming high-stress ecosystems which were tipped over a threshold into mass extinction during bolide impact.
Year of Publication: 2017
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Cenozoic; Climate change; Cretaceous; Deccan Traps; K-T boundary; Leg 208; Lower Paleocene; Maestrichtian; Mass extinctions; Mesozoic; ODP Site 1262; Ocean Drilling Program; Paleocene; Paleoclimatology; Paleogene; South Atlantic; Stratigraphic boundary; Tertiary; Upper Cretaceous; Walvis Ridge
Coordinates: S271100 S271100 E0013500 E0013400
Record ID: 2018074794
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