Deep seismic reflection profiles across the Chicxulub Crater

Snyder, David B.; Hobbs, R. W.

doi:10.1130/0-8137-2339-6.263

Cited by 17 publications

(30 citation statements)

References 14 publications

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“…The seismic reflection data include regional profiles over the northern half of the crater, a constant‐radius profile exterior of the crater rim at ~85 km radial distance from the crater center, and a grid over the PR in the northwest quadrant of the crater (Figure ). The processing sequence of these data is summarized by Snyder and Hobbs [] and Gulick et al . [], and the processed data image impact features from the seafloor down to the base of the crust at ~35 km depth [ Morgan et al ., ; Gulick et al ., ].…”

Section: Methodsmentioning

confidence: 99%

Geophysical Characterization of the Chicxulub Impact Crater

Gulick

Christeson

Barton

et al. 2013

Reviews of Geophysics

106

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[1] Geophysical data indicate that the 65.5 million years ago Chicxulub impact structure is a multi-ring basin, with three sets of semicontinuous, arcuate ring faults and a topographic peak ring (PR). Slump blocks define a terrace zone, which steps down from the inner rim into the annular trough. Fault blocks underlie the PR, which exhibits variable relief, due to target asymmetries. The central structural uplift is >10 km, and the Moho is displaced by 1-2 km. The working hypothesis for the formation of Chicxulub is: a 50 km radius transient cavity, lined with melt and impact breccia, formed within 10 s of the impact, and within minutes, weakened rebounding crust rose kilometers above the surface, the transient crater rim underwent localized deformation and collapsed into large slump blocks, resulting in a inner rim at 70-85 km radius, and outer ring faults at 70-130 km radius. The overheightened structural uplift collapsed outward, buried the inner slump blocks, and formed the PR. Most of the impact melt was ultimately emplaced as a coherent <3 km thick melt sheet within the central basin that shallows within the inner regions of the PR. Smaller pockets of melt flowed into the annular trough. Subsequently, slope collapse, ejecta, ground surge, and tsunami waves infilled the annular trough and annular basin with sediments up to 3 km and 900 m thick, respectively. Testing this working hypothesis requires direct observation of the impactites, within and adjacent to the PR and central basin.

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Section: Methodsmentioning

confidence: 99%

Geophysical Characterization of the Chicxulub Impact Crater

Gulick

Christeson

Barton

et al. 2013

Reviews of Geophysics

106

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“…Utilizing seismic velocity information from the seismic reflection and refraction experiments (Brittan et al 1999;Christeson et al 1999;Mackenzie et al 2001;Morgan et al 2002aMorgan et al , 2002b, a uniform velocity of ∼2.5 km/s can be chosen as a representative average for the entire post-impact succession at Chicxulub, and has been used for depth-conversion in our analysis. A variable classification has been used over the years to describe the discernible impact-induced structural ring features within and in the near vicinity of Chicxulub (e.g., Morgan and Warner 1999;Snyder and Hobbs 1999a). However, it seems that a consensus has recently been reached defining a prominent peak ring within the crater, which is bounded by the crater rim, with an outer ring and a weak exterior ring in the crater vicinity (e.g., Morgan et al 2002b).…”

Section: Post-impact Infillingmentioning

confidence: 99%

Post‐impact structural crater modification due to sediment loading: An overlooked process

Tsikalas

Faleide

2007

Meteorit & Planetary Scien

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Abstract-Post-impact crater morphology and structure modifications due to sediment loading are analyzed in detail and exemplified in five well-preserved impact craters: Mjølnir, Chesapeake Bay, Chicxulub, Montagnais, and Bosumtwi. The analysis demonstrates that the geometry and the structural and stratigraphic relations of post-impact strata provide information about the amplitude, the spatial distribution, and the mode of post-impact deformation. Reconstruction of the original morphology and structure for the Mjølnir, Chicxulub, and Bosumtwi craters demonstrates the long-term subsidence and differential compaction that takes place between the crater and the outside platform region, and laterally within the crater structure. At Mjølnir, the central high developed as a prominent feature during post-impact burial, the height of the peak ring was enhanced, and the cumulative throw on the rim faults was increased. The original Chicxulub crater exhibited considerably less prominent peakring and inner-ring/crater-rim features than the present crater. The original relief of the peak ring was on the order of 420-570 m (currently 535-575 m); the relief on the inner ring/crater rim was 300-450 m (currently ∼700 m). The original Bosumtwi crater exhibited a central uplift/high whose structural relief increased during burial (current height 101-110 m, in contrast to the original height of 85-110 m), whereas the surrounding western part of the annular trough was subdued more that the eastern part, exhibiting original depths of 43-68 m (currently 46 m) and 49-55 m (currently 50 m), respectively. Furthermore, a quantitative model for the porosity change caused by the Chesapeake Bay impact was developed utilizing the modeled density distribution. The model shows that, compared with the surrounding platform, the porosity increased immediately after impact up to 8.5% in the collapsed and brecciated crater center (currently +6% due to post-impact compaction). In contrast, porosity decreased by 2-3% (currently −3 to −4.5% due to post-impact compaction) in the peak-ring region. The lateral variations in porosity at Chesapeake Bay crater are compatible with similar porosity variations at Mjølnir crater, and are considered to be responsible for the moderate Chesapeake Bay gravity signature (annular low of −8 mGal instead of −15 mGal). The analysis shows that the reconstructions and the long-term alterations due to post-impact burial are closely related to the impact-disturbed target-rock volume and a brecciated region of laterally varying thickness and depthvarying physical properties. The study further shows that several crater morphological and structural parameters are prone to post-impact burial modification and are either exaggerated or subdued during post-impact burial. Preliminary correction factors are established based on the integrated reconstruction and post-impact deformation analysis. The crater morphological and structural parameters, corrected from post-impact loading and modification effects, can be used to better const...

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“…The knowledge of the internal structure of the Chicxulub crater mainly rests on seismic reflection studies (Fig. 1b) (Morgan et al 1997(Morgan et al , 2000Hildebrand et al 1998;Brittan et al 1999;Christeson et al 1999;Snyder and Hobbs 1999) and gravimetric data (Pilkington et al 1994;Hildebrand et al 1998). The dominant features in models of the Chicxulub crater are a collapsed central uplift of ~50 km-diameter with a ~18 km stratigraphic uplift (Christeson et al 2001), covered by a ~3 km-thick and 90 km-wide impact melt rock sheet (Pilkington et al 1994).…”

Section: Introductionmentioning

confidence: 99%

Structure and impact indicators of the Cretaceous sequence of the ICDP drill core Yaxcopoil‐1, Chicxulub impact crater, Mexico

Kenkmann

Wittmann

Scherler

2004

Meteorit & Planetary Scien

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Abstract-As part of the ICDP Chicxulub Scientific Drilling Project, the Yaxcopoil-1 (Yax-1) bore hole was drilled 60 km south-southwest of the center of the 180 km-diameter Chicxulub impact structure down to a depth of 1511 m. A sequence of 615 m of deformed Cretaceous carbonates and sulfates was recovered below a 100 m-thick unit of suevitic breccias and 795 m of post-impact Tertiary rocks. The Cretaceous rocks are investigated with respect to deformation features and shock metamorphism to better constrain the deformational overprint and the kinematics of the cratering process. The sequence displays variable degrees of impact-induced brittle damage and post-impact brittle deformation. The degree of tilting and faulting of the Cretaceous sequence was analyzed using 360°-core scans and dip-meter log data. In accordance with lithological information, these data suggest that the sedimentary sequence represents a number of structural units that are tilted and moved with respect to each other. Three main units and nine sub-units were discriminated. Brittle deformation is most intense at the top of the sequence and at 1300-1400 m. Within these zones, suevitic dikes, polymict clastic dikes, and impact melt rock dikes occur and may locally act as decoupling horizons. The degree of brittle deformation depends on lithology; massive dolomites are affected by penetrative faulting, while stratified calcarenites and bituminous limestones display localized faulting. The deformation pattern is consistent with a collapse scenario of the Chicxulub transient crater cavity. It is believed that the Cretaceous sequence was originally located outside the transient crater cavity and eventually moved downward and toward the center to its present position between the peak ring and the crater rim, thereby separating into blocks. Whether or not the stack of deformed Cretaceous blocks was already displaced during the excavation process remains an open question. The analysis of the deformation microstructure indicates that a shock metamorphic overprint is restricted to dike injections with an exception of the so called "paraconglomerate." Abundant organic matter in the Yax-1 core was present before the impact and was mobilized by impact-induced heating and suggests that >12 km 3 of organic material was excavated during the cratering process.

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Deep seismic reflection profiles across the Chicxulub Crater

Cited by 17 publications

References 14 publications

Geophysical Characterization of the Chicxulub Impact Crater

Geophysical Characterization of the Chicxulub Impact Crater

Post‐impact structural crater modification due to sediment loading: An overlooked process

Structure and impact indicators of the Cretaceous sequence of the ICDP drill core Yaxcopoil‐1, Chicxulub impact crater, Mexico

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