T89 The Cretaceous-Paleogene (K-Pg) Boundary Interval: From Large-scale Geological Events to Mass Extinction Mechanisms

Monday, 23 September 2024
8:00 AM - 12:00 PM
204C

RECALIBRATION OF PLANKTIC FORAMINIFERAL BIOZONE P0 WITH 3He DATA IMPLIES LIGHTNING-FAST SPECIATION AFTER THE K/PG BOUNDARY

Paper number: T89-6
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM

Authors

Abstract

The immediate aftermath of the Cretaceous/Paleogene (K/Pg) mass extinction in the marine realm is delimited in planktic foraminiferal biostratigraphy as Zone P0, defined as the interval between the extinction of Cretaceous species and the first appearance of the new Paleocene taxon Parvularugoglobigerina eugubina in the aftermath of the Chicxulub impact. Zone P0 includes the initial recovery of marine productivity, including bacteria and phytoplankton, and the first originations of new species. Constraining the age of this interval is crucial for understanding how quickly this initial recovery and diversification occurred. However, the duration of Zone P0 is calibrated from paleomagnetic reversal datums based on the flawed assumption of constant sedimentation rates across the K/Pg boundary. These magnetostratigraphic calibrations provide estimates from 6 to 40 kyr for the duration of P0, with 30 kyr currently canonized in both the Geologic Time Scale and the Cenozoic Planktonic Foraminiferal Biozonation of Wade et al. (2011, Earth Science Reviews) as the duration of P0. Here, we provide a new calibration for this interval using published records of 3He, a cosmic-dust derived isotope already used to estimate the duration of the K/Pg boundary clay (which lies within P0). Using 3He accumulation rates from six boundary sections with both planktic foraminiferal biostratigraphy and 3He data, we find a duration of Zone P0 of between 3.8 and 11.1 kyr, with an average of 7.0 kyr, significantly shorter than the currently defined duration of 30 kyr. This recalibration suggests that new planktic foraminiferal species which began to appear 50% of the way through P0 evolved within 3.5 kyr after the extinction, an order of magnitude faster than previously documented rapid speciation events of extant and fossil taxa in other groups, which range from 10-20 kyr or longer. Our results demonstrate how quickly evolution can occur in the aftermath of drastic change, and help bridge the gap between “ecological evolution” observable on human timescales and the evolution of new morphospecies in the fossil record.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-404807

© Copyright 2024 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.