NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Proximal impact deposits at the Cretaceous-Tertiary boundary in the Gulf of Mexico: a restudy of DSDP Leg 77 Sites 536 and 540Restudy of Deep Sea Drilling Project Sites 536 and 540 in the southeast Gulf of Mexico gives evidence for a giant wave at Cretaceous-Tertiary boundary time. Five units are recognized: (1) Cenomanian limestone underlies a hiatus in which the five highest Cretaceous stages are missing, possibly because of catastrophic K-T erosion. (2) Pebbly mudstone, 45 m thick, represents a submarine landslide possibly of K-T age. (3) Current-bedded sandstone, more than 2.5 m thick, contains anomalous iridium, tektite glass, and shocked quartz; it is interpreted as ejecta from a nearby impact crater, reworked on the deep-sea floor by the resulting tsunami. (4) A 50-cm interval of calcareous mudstone containing small Cretaceous planktic foraminifera and the Ir peak is interpreted as the silt-size fraction of the Cretaceous material suspended by the impact-generated wave. (5) Calcareous mudstone with basal Tertiary forams and the uppermost tail of the Ir anomaly overlies the disturbed interval, dating the impact and wave event as K-T boundary age. Like Beloc in Haiti and Mimbral in Mexico, Sites 536 and 540 are consistent with a large K-T age impact at the nearby Chicxulub crater.
Document ID
20040090169
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Alvarez, W.
(University of California Berkeley 94720, United States)
Smit, J.
Lowrie, W.
Asaro, F.
Margolis, S. V.
Claeys, P.
Kastner, M.
Hildebrand, A. R.
Date Acquired
August 21, 2013
Publication Date
August 1, 1992
Publication Information
Publication: Geology
Volume: 20
Issue: 8
ISSN: 0091-7613
Subject Category
Exobiology
Funding Number(s)
CONTRACT_GRANT: EAR-91-05297
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Exobiology
NASA Program Exobiology
Non-NASA Center
NASA Discipline Number 52-40

Available Downloads

There are no available downloads for this record.
No Preview Available