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

G. L. Christeson, S. P.S. Gulick, J. V. Morgan, C. Gebhardt, D. A. Kring, E. Le Ber, J. Lofi, C. Nixon, M. Poelchau, A. S.P. Rae, M. Rebolledo-Vieyra, U. Riller, D. R. Schmitt, A. Wittmann, T. J. Bralower, E. Chenot, P. Claeys, C. S. Cockell, M. J.L. Coolen, L. FerrièreS. Green, K. Goto, H. Jones, C. M. Lowery, C. Mellett, R. Ocampo-Torres, L. Perez-Cruz, A. E. Pickersgill, C. Rasmussen, H. Sato, J. Smit, S. M. Tikoo, N. Tomioka, J. Urrutia-Fucugauchi, M. T. Whalen, L. Xiao, K. E. Yamaguchi

    研究成果: Article査読

    43 被引用数 (Scopus)

    抄録

    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.

    本文言語English
    ページ(範囲)1-11
    ページ数11
    ジャーナルEarth and Planetary Science Letters
    495
    DOI
    出版ステータスPublished - 2018 8月 1

    ASJC Scopus subject areas

    • 地球物理学
    • 地球化学および岩石学
    • 地球惑星科学(その他)
    • 宇宙惑星科学

    フィンガープリント

    「Extraordinary rocks from the peak ring of the Chicxulub impact crater: P-wave velocity, density, and porosity measurements from IODP/ICDP Expedition 364」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

    引用スタイル