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Mapping the Chicxulub Impact Stratigraphy and Peak Ring Using Drilling and Seismic Data
Author(s) -
Christeson G. L.,
Morgan J. V.,
Gulick S. P. S.
Publication year - 2021
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1029/2021je006938
Subject(s) - geology , impact crater , seafloor spreading , trough (economics) , structural basin , drilling , stratigraphy , seismology , geomorphology , petrology , paleontology , tectonics , mechanical engineering , physics , astronomy , engineering , economics , macroeconomics
We integrate high‐resolution full‐waveform velocity models with seismic reflection images to map the peak ring and impactite stratigraphy at the Chicxulub structure. International Ocean Discovery Program/International Continental scientific Drilling Program Site M0077 provides ground truth for our interpretations. The peak ring is narrower (∼10 km width) where it is high relief (600–700 m below seafloor) and wider (∼15 km width) where it is lower relief (1,000–1,200 m below seafloor). Both target asymmetry and angle of impact could have contributed to observed differences in peak ring morphology. We interpret a layer of lowered velocities as a resurge layer formed from the ocean resurge, seiche, and returning tsunami flowing into the newly formed impact basin. This graded suevite layer has an average thickness of 187 ± 58 m with only local thickness differences within the annular trough, peak ring, and central basin. These observations suggest that the returning ocean was of substantial height and energetic enough to carry debris across the entire topographic peak ring. We map impact melt rock throughout the crater, with a thick impact melt sheet in the central basin (>500 m), thin intermittent melt rock capping the peak ring, and a ∼500‐m thick layer of melt rock in the annular trough near the peak ring that thins toward the crater rim. We estimate that ∼70%–75% of the melt rock volume is in the central basin. We image features above and adjacent to the central basin melt sheet that we interpret as upflow zones associated with a long‐lasting hydrothermal system.