T147 The Paleocene–Eocene Thermal Maximum Recorded in Continental Margin Sections: Constraining Timing and Cause of Carbon Injection

Monday, 23 September 2019
1:30 PM - 5:30 PM
Room 228AB, North Building

40AR-39AR AGES OF THE PALEOCENE-EOCENE BOUNDARY EXTRATERRESTRIAL IMPACT SPHERULES

Paper number: T147-7
Program: Technical Sessions
Time: 2:55 PM – 3:15 PM

Authors

Abstract

We report 40Ar-39Ar step-heating ages of P-E boundary impact spherules from Atlantic Margin coastal plain and open ocean sites. We test the hypothesis that the P-E spherules are reworked from an earlier event (e.g., K-Pg impact at ~66 Ma), which predicts a cooling age discordant from their depositional age of 55.93 ± 0.05 Ma at the P-E boundary. Isochrons from the step heating analyses yield 40Ar-36Ar intercepts in excess of the modern in most cases, indicating that the spherules have inherited radiogenic Ar (40Ar*), typical of impact glasses incompletely degassed before solidification. The weighted mean of the isochron-corrected plateau age is 54.1 ± 3.4 Ma (1s), and their isochron age is 55.4 ± 4.0 Ma, both indistinguishable from their P-E depositional age, not supporting the K-Pg reworking hypothesis. This is consistent with all other stratigraphic and geochemical evidence for an impact at the P-E boundary and ejecta distribution by air-fall.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-339611

© Copyright 2019 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.