Extraordinary rocks from the peak ring of the Chicxulub impact crater; P-wave velocity, density, and porosity measurements from IODP/ICDP Expedition 364

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doi: 10.1016/j.epsl.2018.05.013
Author(s): Christeson, G. L.; Gulick, S. P. S.; Morgan, J. V.; Gebhardt, C.; Kring, D. A.; Le Ber, E.; Lofi, J.; Nixon, C.; Poelchau, M.; Rae, A. S. P.; Rebolledo-Vieyra, M.; Riller, U.; Schmitt, D. R.; Wittmann, A.; Bralower, T. J.; Chenot, E.; Claeys, P.; Cockell, C. S.; Coolen, M. J. L.; Ferrière, L.; Green, S.; Goto, K.; Jones, H.; Lowery, C. M.; Mellett, C.; Ocampo-Torres, R.; Perez-Cruz, L.; Pickersgill, A. E.; Rasmussen, C.; Sato, H.; Smit, J.; Tikoo, S. M.; Tomioka, N.; Urrutia-Fucugauchi, J.; Whalen, M. T.; Xiao, L.; Yamaguchi, K. E.
Author Affiliation(s): Primary:
University of Texas at Austin, Jackson School of Geosciences, Austin, TX, United States
Imperial College London, United Kingdom
Alfred Wegener Institute, Germany
Lunar and Planetary Institute, United States
University of Leicester, United Kingdom
Université de Montpellier, France
University of Alberta, Canada
University of Freiburg, Germany
Universität Hamburg, Germany
Arizona State University, United States
Pennsylvania State University, United States
Université de Bourgogne-Franche Comté, France
Vrije Universiteit Brussel, Belgium
University of Edinburgh, United Kingdom
Curtin University, Australia
Natural History Museum, Austria
British Geological Survey, United Kingdom
Tohoku University, Japan
United Kingdom Hydrographic Office, United Kingdom
Université de Strasbourg, France
Universidad Nacional Autónoma De México, Mexico
University of Glasgow, United Kingdom
University of Utah, United States
Japan Agency for Marine-Earth Science and Technology, Japan
Vrije Universiteit Amsterdam, Netherlands
Rutgers University, United States
University of Alaska, United States
China University of Geosciences, China
Toho University, Japan
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, Vol.495, p.1-11. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 50 refs.; illus., incl. sects., 1 table, sketch map
Summary: Joint International Ocean Discovery Program and International Continental Scientific Drilling Program Expedition 364 drilled into the peak ring of the Chicxulub impact crater. We present P-wave velocity, density, and porosity measurements from Hole M0077A that reveal unusual physical properties of the peak-ring rocks. Across the boundary between post-impact sedimentary rock and suevite (impact melt-bearing breccia) we measure a sharp decrease in velocity and density, and an increase in porosity. Velocity, density, and porosity values for the suevite are 2900-3700 m/s, 2.06-2.37 g/cm3, and 20-35%, respectively. The thin (25 m) impact melt rock unit below the suevite has velocity measurements of 3650-4350 m/s, density measurements of 2.26-2.37 g/cm3, and porosity measurements of 19-22%. We associate the low velocity, low density, and high porosity of suevite and impact melt rock with rapid emplacement, hydrothermal alteration products, and observations of pore space, vugs, and vesicles. The uplifted granitic peak ring materials have values of 4000-4200 m/s, 2.39-2.44 g/cm3, and 8-13% for velocity, density, and porosity, respectively; these values differ significantly from typical unaltered granite which has higher velocity and density, and lower porosity. The majority of Hole M0077A peak-ring velocity, density, and porosity measurements indicate considerable rock damage, and are consistent with numerical model predictions for peak-ring formation where the lithologies present within the peak ring represent some of the most shocked and damaged rocks in an impact basin. We integrate our results with previous seismic datasets to map the suevite near the borehole. We map suevite below the Paleogene sedimentary rock in the annular trough, on the peak ring, and in the central basin, implying that, post impact, suevite covered the entire floor of the impact basin. Suevite thickness is 100-165 m on the top of the peak ring but 200 m in the central basin, suggesting that suevite flowed downslope from the collapsing central uplift during and after peak-ring formation, accumulating preferentially within the central basin.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 05 Petrology, Igneous and Metamorphic; 23 Surficial Geology, Geomorphology; Atlantic Ocean; Body waves; Breccia; Chicxulub Crater; Density; Elastic waves; Expedition 364; Granites; Gulf of Mexico; IODP Site M0077; Igneous rocks; Impact breccia; Impact craters; Impact features; Impact melts; Impactites; International Continental Scientific Drilling Program; International Ocean Discovery Program; Melts; Metamorphic rocks; Metamorphism; Mexico; North Atlantic; P-waves; Physical properties; Plutonic rocks; Porosity; Ring structures; Sedimentary rocks; Seismic waves; Shock metamorphism; Suevite; Velocity
Coordinates: N212700 N212700 W0895700 W0895700
Record ID: 2018070195
Copyright Information: GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands