GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 296-5
Presentation Time: 2:30 PM


KELLER, Gerta1, MATEO, Paula2, ADATTE, Thierry3, PUNEKAR, Jahnavi4, SPANGENBERG, Jorge5, SCHOENE, Blair1, EDDY, Michael P.6, SAMPERTON, Kyle Michael7, KHADRI, Syed F.R.8, MONKENBUSH, Johannes9 and THIBAULT, Nicolas10, (1)Department of Geosciences, Princeton University, Guyot Hall, Princeton, NJ 08544, (2)Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, (3)Institute of Earth Sciences, University of Lausanne, Géopolis, Lausanne, 1015, Switzerland, (4)Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India, (5)Institut des dynamiques de la surface terrestre, Université de Lausanne, Quartier UNIL-Mouline, Bâtiment Géopolis, Lausanne, 1015, Switzerland, (6)Department of Geosciences, Princeton University, Princeton, NJ 08544, (7)Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore CA, 94550-9698, (8)Department of Geology, Amravati University, Amravati, 444602, India, (9)Geology, University of Kopenhagen, Kopenhagen, 1350, Denmark, (10)Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, 1350, Denmark

Deccan volcanism in India and the Chicxulub impact in Mexico are both linked to the Cretaceous-Paleogene (KPB) mass extinction; however, the relative timing of the impact and volcanic eruptions remain controversial, precluding full assessment of their respective roles. Mercury (Hg) anomalies in sediments related to global distribution and atmospheric fallout of Deccan emissions provide a potential tool to directly assess the cause-and-effect relationship between Large Igneous Province (LIP) volcanism, climate change and mass extinctions. We report high-resolution Hg and paleoclimatic records for the most complete and expanded late Maastrichtian - early Danian section at Elles, Tunisia (auxiliary GSSP to El Kef), and correlate this section with similar sequences (e.g., Israel, Spain, France) to assess the global Hg distribution relative to Deccan eruptions. Results confirm Hg as a robust proxy for Deccan volcanism, with large Hg peaks correlated globally. Results also demonstrate maximum global climate warming closely related to peak Hg concentrations at the CF2/CF1 boundary (190 ky pre-KPB) and hyperthermal warming related to maximum Hg concentrations during the last 20 ky before the mass extinction. In contrast, early Danian cooling is associated with low Hg concentrations. We correlate the highresolution, astronomically tuned cyclostratigraphy of Elles with high-resolution U-Pb geochronology of Deccan Trap volcanism at the ca. ±40 ky-level. Results show excellent age correlation for the last 350 ky of the Maastrichtian, with high Deccan eruption rates coincident with global climate warming trends. Volcanically-induced environmental changes led to increased stress on marine life (planktic foraminifera), as evident by reduced species size (Lilliput effect), decreased species populations, and a carbonate crisis that ultimately led to the KPB mass extinction. Threshold life conditions were reached during paroxysmal volcanic eruptions in the last 20 ky before the mass extinction. The timing of the Chicxulub impact relative to Deccan volcanism remains enigmatic in the absence of cosmic evidence in the Deccan and the stratigraphic position of impact breccia in the Chicxulub crater and impact glass spherules in NE Mexico predating the KPB.