Site M0077: introduction

Gulick, Sean P. S.; Morgan, J. V.; Mellett, Claire L.; Green, S.L.; Bralower, Timothy J.; Chenot, Elise; Christeson, G. L.; Claeys, Philippe; Cockell, Charles S.; Coolen, Marco J. L.; Ferrière, L.; Gebhardt, Catalina; Goto, Kei; Jones, H.; Kring, D. A.; Lofi, Johanna; Lowery, Christopher M.; Ocampo-Torres, R.; Pérez‐Cruz, Ligia; Pickersgill, A. E.; Poelchau, M. H.; Rae, A.; Rasmussen, Cornelia; Rebolledo-Vieyra, M.; Riller, Ulrich; Sato, H.; Smit, Jan; Tikoo, S. M.; Tomioka, Naotaka; Urrutia‐Fucugauchi, J.; Whalen, Michael T.; Wittmann, A.; Yamaguchi, Kentaro; Xiao, Li; Zylberman, W.

doi:10.14379/iodp.proc.364.103.2017

Cited by 6 publications

(19 citation statements)

References 4 publications

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“…Velocities are ~2800-3300 m/s in the suevite from ~617 to 706 mbsf, where a sharp increase in borehole sonic P-wave values is observed to average velocities of ~3700 m/s (Figure 3c). This velocity increase correlates at 706 mbsf with the first observation of significant impact melt rock as up to 60-cm-thick intercalations in suevite, and with an increase in average maximum clast size from ~5 cm to ~13 cm in its host suevite [Morgan et al, 2017]. This velocity increase is also close to the boundary between subunits 2B and 2C at 713 mbsf, which is characterized by a change in suevite color from green, gray, and black in subunit 2B (Figure 4c) to brown in subunit 2C (Figure 4d).…”

Section: Hole M0077a Physical Propertiessupporting

confidence: 71%

“…The base of the suevite section, identified from core data at 722 mbsf in Hole M0077A, is not associated with a clear change in physical properties; instead, the major change in physical properties (increase in velocity and density, and a decrease in porosity) is observed at ~706 mbsf ( Figure 3) where coherent bodies of impact melt rock >10 cm thick first occur. The physical properties (Figure 3) of the lowest part of the suevite (706-722 mbsf) in Hole M0077A ( Figure 4d) are similar to those of the underlying impact melt rock units 3A and 3B at 722-747 mbsf (Figure 4e), which suggests that values are dominated by the melt clasts which range in size from a few mm to >10 cm at depths 706-722 mbsf [Morgan et al, 2017].…”

Section: Suevitementioning

confidence: 73%

“…Program (IODP/ICDP) Expedition 364 drilled and cored the Chicxulub peak ring and overlying post-impact sedimentary rock from depths 505.7-1334.7 m below the seafloor (mbsf) [Morgan et al, 2017]. Hole M0077A (Figure 1) provides the ground-truth information calibrating our geophysical data and interpretations.…”

Section: The International Ocean Discovery Program and International mentioning

confidence: 89%

“…The suevite (unit 2, Figures 4b-d) consists of clasts of impact melt, sedimentary rock, and basement lithologies, embedded in a fine-grained dominantly calcitic matrix, with maximum clast size increasing with depth from 0.2-1.0 cm to >20-25 cm [Morgan et al, 2017]. Suevite discrete sample measurements of velocities, porosities, and densities display an increase in variability at depths >678 mbsf (Figure 3).…”

Section: Hole M0077a Physical Propertiesmentioning

confidence: 99%

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

Christeson

Gulick

Morgan

et al. 2018

Earth and Planetary Science Letters

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Highlights  Chicxulub peak-ring rocks have low velocities and densities, and high porosities.  Physical property values indicate considerable damage of granitoid peak-ring rocks.  Suevite flowed downslope during and after peak-ring formation Abstract. 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/cm 3 , 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/cm 3 , 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/cm 3 , 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.

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Section: Hole M0077a Physical Propertiessupporting

confidence: 71%

Section: Suevitementioning

confidence: 73%

Section: The International Ocean Discovery Program and International mentioning

confidence: 89%

Section: Hole M0077a Physical Propertiesmentioning

confidence: 99%

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

Christeson

Gulick

Morgan

et al. 2018

Earth and Planetary Science Letters

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“…In 2016, ECORD conducted IODP-ICDP Expedition 364, Drilling the K-Pg Chicxulub Crater, as an MSP operation aboard Liftboat Myrtle (see photo in Spotlight 11) in <20 m water depth. The liftboat was outfitted with an ICDPprovided DOSECC drilling rig to drill into the peak ring of the Chicxulub impact structure (Morgan et al, 2017;Lowery et al, 2019, in this issue). The resultant 835 m of core represented the first offshore drilling into the crater and included basement rocks that were uplifted 8-10 km during crater formation (Morgan et al, 2016; Figure 1).…”

Section: Chicxulub Cratermentioning

confidence: 99%

Scientific Drilling Across the Shoreline

Gulick¹,

Miller²,

Keleman³

et al. 2019

Oceanog

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individuals to read, download, copy, distribute, print, search, and link to the full texts of Oceanography articles. Figures, tables, and short quotes from the magazine may be republished in scientific books and journals, on websites, and in PhD dissertations at no charge, but the materials must be cited appropriately (e.g., authors, Oceanography, volume number, issue number, page number[s], figure number[s], and DOI for the article). Republication, systemic reproduction, or collective redistribution of any material in

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Multiscale Geoelectrical Properties of the Rochechouart Impact Structure, France

Quesnel

Sailhac

Lofi

et al. 2021

Geochem Geophys Geosyst

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Terrestrial mid-size (apparent diameter D = 10-60 km) complex impact structures are usually heavily eroded, and often buried below a post-impact sediment cover or filled by a lake, thus precluding a clear estimate of the crater size (Melosh, 1989). The presence of a central structural uplift is systematic and characterizes this category of craters (Osinski & Pierazzo, 2013). Osinski et al. (2008) mentioned that massive impact melt rock (IMR) formations are usually observed for crystalline targets while for sedimentary targets, the melt appears more scattered in breccia. The distinction between clast-rich/clast-poor IMR, impact melt-rich/ melt-poor breccia, fractured/brecciated basement, and unaffected basement is however difficult for these highly eroded (or buried/underwater/covered by vegetation) structures. Thus the only way to distinguish between these types of units requires drilling and geophysics where impacts are buried. In those cases, geophysics provides a means of investigating the lateral and vertical extent of the impactite formations and of the brecciation/fracturing in the basement. Still numerical models of the sources of geophysical anomalies are limited by non-uniqueness and require additional geological data from drillings or trenches. This is particularly true for models built using potential-field data, which are the most widely used geophysical data for investigating impact structures, since the associated signatures are usually significant (e.g., a circular low gravity anomaly). Other geophysical methods (e.g., seismic reflection and refraction) suffer less from this issue. However, the few examples of electrical investigations over impact structures also reveal the necessity for additional constraints, from drilling to other geophysical data (see Henkel, 1992;Pilkington & Grieve, 1992), in order to reduce the ambiguity in the geological interpretations of the electrical contrasts.

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Site M0077: introduction

Cited by 6 publications

References 4 publications

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

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

Scientific Drilling Across the Shoreline

Multiscale Geoelectrical Properties of the Rochechouart Impact Structure, France

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