Proximal impact deposits at the Cretaceous-Tertiary boundary in the Gulf of Mexico: A restudy of DSDP Leg 77 Sites 536 and 540

Journal Article · Sat Aug 01 00:00:00 EDT 1992 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1992)020<0697:PIDATC>2.3.CO;2· OSTI ID:6937696

Alvarez, W; Asaro, F ^[1]; Smit, J ^[2]; Lowrie, W ^[3]; Asaro, F ^[4]; Margolis, S V; Claeys, P ^[5]; Kastner, M ^[6]; Hildebrand, A R ^[7]

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1. Univ. of California, Berkeley (United States)
2. Free Univ. of Amsterdam (Netherlands)
3. Inst. fuer Geophysik, Zuerich (Switzerland)
4. Lawrence Berkeley Lab., CA (United States)
5. Univ. of California, Davis (United States)
6. Univ. of California, San Diego (United States)
7. Geological Survey, Ottawa, Ontario (Canada)

Restudy 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.

• OSTI ID: 6937696
• Journal Information: Geology; (United States), Vol. 20:8; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GEOLOGIC STRATA
AGE ESTIMATION
GEOCHEMISTRY
GULF OF MEXICO
GEOLOGIC DEPOSITS
METEORITES
IMPACT SHOCK
CHEMICAL COMPOSITION
CRATERS
CRETACEOUS PERIOD
GEOLOGIC HISTORY
IRIDIUM COMPOUNDS
LIMESTONE
OFFSHORE DRILLING
SANDSTONES
TEKTITES
TERTIARY PERIOD
TSUNAMIS
ATLANTIC OCEAN
CARBONATE ROCKS
CARIBBEAN SEA
CAVITIES
CENOZOIC ERA
CHEMISTRY
DISASTERS
DRILLING
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GRAVITY WAVES
MESOZOIC ERA
REFRACTORY METAL COMPOUNDS
ROCKS
SEAS
SEDIMENTARY ROCKS
SURFACE WATERS
TRANSITION ELEMENT COMPOUNDS
WATER WAVES
580000* - Geosciences