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Deformational features and impact-generated breccia from the Sierra Madera impact structure, West Texas

Sarah Huson, Michael Pope, A. John Watkinson and Franklin Foit
Deformational features and impact-generated breccia from the Sierra Madera impact structure, West Texas
Geological Society of America Bulletin (January 2011) 123 (1-2): 371-383

Abstract

Deformational features from the Sierra Madera impact structure, west Texas, were studied to estimate shock temperature and shock pressure values involved during its formation. Sandstone, limestone, and polymict impact-generated breccia samples occur within the central uplift. The sandstones host several shock-related deformational features including toasted quartz grains and planar microstructures (planar fractures and planar deformation features) in quartz. Zircon mineral grains separated from the sandstone samples provide evidence of shock deformation in the form of planar fractures and granular surface textures. Both sandstone and carbonate within the central uplift contain shatter cones, whereas polymict impact-generated breccia samples contain shatter cone fragments and clasts of mixed lithology. Most high-temperature features (e.g., high-temperature mineral phases and a melt sheet) typically associated with less eroded structures of similar size are lacking; however, some small (millimeter-size) possible devitrified glass clasts within polymict breccias occur at several locations. Deformational features within zircon mineral grains, shatter cones, and quartz grains with multiple planar microstructures record pressure and temperature conditions during the impact of approximately 3-20 GPa and postshock temperatures between 350 and >1000 degrees C. Deformational conditions during the impact event were almost certainly higher, given that erosion has presumably removed most of the more severely shocked rocks.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 123
Serial Issue: 1-2
Title: Deformational features and impact-generated breccia from the Sierra Madera impact structure, West Texas
Affiliation: Washington State University, School of Earth and Environmental Sciences, Pullman, WA, United States
Pages: 371-383
Published: 201101
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 54
Accession Number: 2011-012654
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, geol. sketch maps
N30°34'00" - N30°37'00", W102°57'00" - W102°52'00"
Secondary Affiliation: Texas A&M University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201108
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