TY - JOUR
T1 - Depositional processes of impactites from the YAX-1 drill core in the Chicxulub impact structure inferred from vertical profiles of PDF orientations and grain size distributions of shocked quartz
AU - Chang, Yu
AU - Goto, Kazuhisa
AU - Sekine, Yasuhito
AU - Tajika, Eiichi
N1 - Funding Information:
Acknowledgments—This research is based on samples and data provided by the Chicxulub Scientific Drilling Program (CSDP) sponsored by the International Continental Scientific Drilling Program (ICDP) and Universidad Nacional Autonoma de Mexico (UNAM). We thank J. U. Fucugauchi for his support during sampling. Constructive reviews by Carl Alwmark, an anonymous reviewer, and Christian Koeberl (associate editor) have significantly improved the manuscript. This work was supported by MEXT KAKENHI Grant Number JP17H06456, and Grant in Aid from Astrobiology Center of the National Institutes of Natural Sciences (NINS).
Funding Information:
This research is based on samples and data provided by the Chicxulub Scientific Drilling Program (CSDP) sponsored by the International Continental Scientific Drilling Program (ICDP) and Universidad Nacional Autonoma de Mexico (UNAM). We thank J. U. Fucugauchi for his support during sampling. Constructive reviews by Carl Alwmark, an anonymous reviewer, and Christian Koeberl (associate editor) have significantly improved the manuscript. This work was supported by MEXT KAKENHI Grant Number JP17H06456, and Grant in Aid from Astrobiology Center of the National Institutes of Natural Sciences (NINS).
Publisher Copyright:
© The Meteoritical Society, 2018.
PY - 2018/7
Y1 - 2018/7
N2 - Core samples from the Chicxulub impact structure provide insights into the formation processes of a shallow-marine-target, complex crater. Although previous studies investigated the impactites (generally suevitic and polymict breccias) of the Yaxcopoil-1 (YAX-1) drill core in the Chicxulub impact structure, the interpretation of its deposition remains controversial. Here, we analyze planar deformation features (PDFs), grain size, and abundance of shocked quartz throughout the YAX-1 impactite sequence (794–895 m in depth). PDF orientations of most quartz grains in YAX-1 impactites show a distribution of both low angles ({10 (Formula presented.) 4}, {10 (Formula presented.) 3}, {10 (Formula presented.) 2}) and high angles (orientations higher than 55° to c-axis), while the lower part of the impactite sequence contains quartz showing only PDF orientations of low angles. High-abundance, coarse-grained shocked quartz is found from the lower to middle parts of the impactites, whereas it abruptly changes to low-abundance, fine-grained shocked quartz within the upper part. In the uppermost part of the impactites, repeated oscillations in contents of these two components are observed. PDF orientation pattern suggests most of the shocked quartz grains experienced a range of shock pressure, except two samples in the lower part of impactites, which experienced only a high level of shock. We suggest that the base and lower part of the impactite sequence were formed by ejecta curtain and melt surge deposits, respectively. Our results are also consistent with the interpretation that the middle part of the impactite sequence is fallback ejecta from the impact plume. Additionally, we support the contention that massive seawater resurges into the crater occurred during the deposition of the upper and uppermost part of the impactites.
AB - Core samples from the Chicxulub impact structure provide insights into the formation processes of a shallow-marine-target, complex crater. Although previous studies investigated the impactites (generally suevitic and polymict breccias) of the Yaxcopoil-1 (YAX-1) drill core in the Chicxulub impact structure, the interpretation of its deposition remains controversial. Here, we analyze planar deformation features (PDFs), grain size, and abundance of shocked quartz throughout the YAX-1 impactite sequence (794–895 m in depth). PDF orientations of most quartz grains in YAX-1 impactites show a distribution of both low angles ({10 (Formula presented.) 4}, {10 (Formula presented.) 3}, {10 (Formula presented.) 2}) and high angles (orientations higher than 55° to c-axis), while the lower part of the impactite sequence contains quartz showing only PDF orientations of low angles. High-abundance, coarse-grained shocked quartz is found from the lower to middle parts of the impactites, whereas it abruptly changes to low-abundance, fine-grained shocked quartz within the upper part. In the uppermost part of the impactites, repeated oscillations in contents of these two components are observed. PDF orientation pattern suggests most of the shocked quartz grains experienced a range of shock pressure, except two samples in the lower part of impactites, which experienced only a high level of shock. We suggest that the base and lower part of the impactite sequence were formed by ejecta curtain and melt surge deposits, respectively. Our results are also consistent with the interpretation that the middle part of the impactite sequence is fallback ejecta from the impact plume. Additionally, we support the contention that massive seawater resurges into the crater occurred during the deposition of the upper and uppermost part of the impactites.
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U2 - 10.1111/maps.13082
DO - 10.1111/maps.13082
M3 - Article
AN - SCOPUS:85045465497
VL - 53
SP - 1323
EP - 1340
JO - Meteoritics and Planetary Science
JF - Meteoritics and Planetary Science
SN - 1086-9379
IS - 7
ER -