Proximal impact deposits at the Cretaceous-Tertiary boundary in the Gulf of Mexico; a restudy of DSDP Leg 77 sites 536 and 540; with Suppl. Data 92-25

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doi: 10.1130/0091-7613(1992)020<0697:PIDATC>2.3.CO;2
Author(s): Alvarez, Walter; Smit, Jan; Lowrie, William; Asaro, Frank; Margolis, Stanley V.; Claeys, Philippe; Kastner, Miriam; Hildebrand, Alan R.
Author Affiliation(s): Primary:
Univ. Calif. at Berkeley, Dep. Geol. and Geophys., Berkeley, CA, United States
Other:
Free Univ. Amsterdam, Netherlands
ETH Inst. Geophys., Switzerland
Geol. Surv. Can., Canada
Volume Title: Geology (Boulder)
Source: Geology (Boulder), 20(8), p.697-700. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613 CODEN: GLGYBA
Note: In English. Geol. Surv. Can., Contrib. No. 51591. 27 refs.; illus. incl. 1 table, sect.
Summary: 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.
Year of Publication: 1992
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 06 Petrology, Sedimentary; 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Biostratigraphy; Carbonate rocks; Cenomanian; Cenozoic; Chicxulub; Clastic rocks; Clastic sediments; Cretaceous; DSDP Site 536; DSDP Site 540; Danian; Deep Sea Drilling Project; Distribution; Foraminifera; Framework silicates; Geochemistry; Gulf of Mexico; IPOD; Impact craters; Impact features; Impacts; Invertebrata; Iridium; K-T boundary; Leg 77; Limestone; Lithostratigraphy; Lower Paleocene; Lower Tertiary; Marine sediments; Mesozoic; Metals; Metamorphism; Meteor craters; Microfossils; Mudstone; North Atlantic; Ooze; Paleocene; Paleogene; Paleomagnetism; Platinum group; Protista; Quartz; Sandstone; Sedimentary rocks; Sediments; Shock metamorphism; Silica minerals; Silicates; Stratigraphic boundary; Stratigraphy; Tektites; Tertiary; Upper Cretaceous; Yucatan Peninsula
Coordinates: N232900 N233000 W0851240 W0851300
N234900 N235000 W0842200 W0842300
Record ID: 1992035287
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