T104 Microfossil Proxies in Earth History

Monday, 26 September 2016
8:00 AM - 12:00 PM
Room 505

MICROFOSSIL δ11B AS A PROXY FOR ORBITAL-SCALE pCO2 CHANGE IN THE EARLY PLEISTOCENE

Paper number: T104-11
Program: Technical Sessions
Time: 10:40 AM – 11:00 AM

Authors

Abstract

Atmospheric CO2 concentrations in the late Pleistocene have been characterized from ancient air bubbles trapped within polar ice sheets which demonstrate the glacial-interglacial relationship between the global carbon cycle and climate. However, continuous ice core records are so far limited to the last 800 ky, when glacial cycles occurred approximately every 100-ky. Boron isotope ratios, (δ11B) recorded in the tests of fossil planktic foraminifera, offer an opportunity to extend the atmospheric pCO2 record to earlier time periods, when glacial cycles instead occurred approximately every 41-ky. We present new high-resolution records of planktic foraminiferal δ11B, Mg/Ca (a sea surface temperature proxy), and δ18O. Combined with reasonable assumptions for ocean alkalinity, these data allow us to estimate pCO2 over three of the 41-ky climate cycles at ~1.5 Ma. Our results provide new constraints for studies of long-term CO2 storage and release, regional controls on the early Pleistocene carbon cycle, and pCO2 variability before the mid-Pleistocene transition.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-284968

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