Project Details
Projekt
The petrology, geochemistry and age determination of impact melt from the USGS-ICDP drill core Eyreville-B from the late Eocene Chesapeake Bay impact structure
Applicant
Dr. Vera Assis Fernandes, Ph.D.
Subject Area
Mineralogy, Petrology and Geochemistry
Term
from 2011 to 2014
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 194425568
Large impact craters distribute material globally, and their ejecta layers present important horizon markers allowing inter-correlation of sediments from different sites, e.g. for late Eocene sediments pre-dating the tipping point of Earth’s climate at the Eocene Oligocene boundary. The Global Stratotype Section and Point (GSSP) in Massignano (Italy) contains three Iridium rich ejecta layers covering a 2 Ma time interval, with two being attributed to the Chesapeake Bay (85 km Ø) and Popigai (100 km Ø) impact structures, respectively. Current radiometric age determination for the Chesapeake Bay crater is based on total fusion Ar ages of tektites (distal impact glasses). In preliminary 40Ar-39Ar work, I have shown that precise Ar ages on these tektites cannot be acquired by total fusion experiments but require step heating measurements. I propose a systematic petrologic, geochemical and radiometric study of the first found impact melt rocks from within the Chesapeake Bay crater and refine the 40Ar-39Ar ages for the related tektites. The study will be complemented by 40Ar-39Ar age determinations of impact melt rocks from three other late Eocene impact structures, Popigai, Mistastin and Wanapitei. Radiometric and petrological results combined with new numerical models on impact ejecta distribution result in age, composition and distribution of global marker horizons in later Eocene sediments: a fundamental data set for investigations on the succession of events predating the tipping point of Earth’s climate. Only the USGS-ICDP Eyreville B drill core provides the sample material for the main focus of this research: dating the Chesapeake Bay crater.
DFG Programme
Infrastructure Priority Programmes
Participating Persons
Professor Dr. Wolf Uwe Reimold; Professor Dr. Mario Trieloff
