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Hot atmospheric formation of carbonate accretionary lapilli at the Cretaceous-Paleogene boundary, Brazos River, Texas, from clumped isotope thermometry

David G. Burtt, Gregory A. Henkes, Thomas E. Yancey and Daniel Schrag
Hot atmospheric formation of carbonate accretionary lapilli at the Cretaceous-Paleogene boundary, Brazos River, Texas, from clumped isotope thermometry
Geology (Boulder) (March 2022) 50 (5): 636-640

Abstract

The Chicxulub impact (in the northern Yucatan Peninsula, Mexico) marks the Cretaceous-Paleogene (K-Pg) boundary and is implicated in one of the five major extinctions. Researchers have examined ejecta from the Chicxulub impact, and most recently a drill core from the crater itself, yet the processes and chemical reactions occurring in the impact vapor plume are poorly constrained. Rounded carbonate particles, identified as accretionary lapilli, have been found thousands of kilometers from the impact crater and may be a unique record of plume conditions. We present carbon (delta (super 13) C), oxygen (delta (super 18) O), and clumped (Delta (sub 47) ) isotope ratios of lapilli from the Brazos River, Texas (USA), as well as from foraminifera and a mudstone. Unaltered lapilli delta (super 13) C and delta (super 18) O values covary, ranging from -9.38 ppm to -2.10 ppm and from -7.72 ppm to -5.36 ppm, respectively, and they are distinct from mudstones, foraminifera, and secondarily altered lapilli in the same section. Clumped isotope temperatures [T(Delta (sub 47) )] from the lapilli range from 66 degrees C to 539 degrees C and average 155 + or - 46 degrees C (1 standard deviation), with sedimentary and fossil carbonates recording clement, shallow ocean-like T(Delta (sub 47) ). These data are consistent with petrography and hypothesized vapor plume formation, and we argue that the delta (super 13) C and delta (super 18) O values result from target rock decarbonation. Atmospheric temperatures >100 degrees C extending >1800 km from the Chicxulub crater imply an uninhabitable zone within seconds to minutes of the impact that was 10 times larger in diameter than the crater itself.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 50
Serial Issue: 5
Title: Hot atmospheric formation of carbonate accretionary lapilli at the Cretaceous-Paleogene boundary, Brazos River, Texas, from clumped isotope thermometry
Affiliation: Stony Brook University, Department of Geosciences, Stony Brook, NY, United States
Pages: 636-640
Published: 20220308
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 36
Accession Number: 2022-020506
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N32°39'41" - N32°39'41", W98°07'19" - W98°07'19"
Secondary Affiliation: Texas A&M University, College Station, TX, USA, United StatesHarvard University, Cambridge, MA, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, 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: 202217
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