HR: 1340h
AN: T43C-1344 [Abstracts]
TI: The Chicxulub Impact - Connection to K/T Boundary Event Based on Petrophysical and Paleomagnetic
Investigations
AU: * Elbra, T
EM: tiiu.elbra@helsinki.fi
AF: Division of Geophysics, University of Helsinki, PO Box 64, Helsinki, 00014
Finland
AU: Pesonen, L J
EM: lauri.pesonen@helsinki.fi
AF: Division of Geophysics, University of Helsinki, PO Box 64, Helsinki, 00014
Finland
AB:
Establishing relationships between the Chicxulub impact crater and the K/T boundary event has been one of the main reasons
for Chicxulub Scientific Drilling what was carried out in framework of the International Continental Drilling Program (ICDP).
Drilling-site (Hacienda Yaxcopoil) was chosen on the basis of previous work achieved by drillings of the oil exploratory
program by Petr¢leos Mexicanos and more recently by the National University of Mexico (UNAM). The Yaxcopoil-1 borehole is
1511 m deep, and sampling started from 404 m. Drillcore runs through 3 intervals: the post-impact layer, the impact layer and
the pre-impact target rock. Samples of this study were gathered in collaboration of many institutions (Helsinki University,
UNAM, Vrije University of Amsterdam and Humboldt University of Berlin) and cover all these intervals.
Standard petrophysical and paleomagnetic measurements (including magnetostratigraphy) were carried out in order to clarify
some of the dating issues. Results show that paleomagnetic measurements of the drillcore, coupled with petrophysical data
provide a good tool of isolating various units including the impact layer, the K/T boundary- and the post-impact sequences.
NRM and susceptibility values of samples from pre- and post-impact layers show that most samples are very weakly magnetized,
with exception of the interval from 790 m to 900 m that includes the K/T boundary layer. Also our data show that
magnetostratigraphy of the impact layer is quite complex due to possible hydrothermal remagnetization process. Additionally
these data reveal that the Chicxulub impact event took probably place within the magnetic chron 29R and therefore can be
related to K/T boundary event.
DE: 8125 Evolution of the Earth
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1520 Magnetostratigraphy
DE: 1535 Reversals (process, timescale, magnetostratigraphy)
DE: 1540 Rock and mineral magnetism
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting