Seismic images of Chicxulub impact melt sheet and comparison with the Sudbury structure

Barton, P. J.; Grieve, R. A. F.; Morgan, J. V.; Surendra, A.; Vermeesch, P. M.; Christeson, G. L.; Gulick, Sean P. S.; Warner, Mike

doi:10.1130/2010.2465(07)

Cited by 21 publications

(49 citation statements)

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“…[], 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 ., ]. The seismic profiles have been presented in numerous studies focusing on crater morphology and ring structure [ Morgan et al ., ; Morgan and Warner , , ; Snyder et al ., ; Morgan et al ., ; Gulick et al ., ], the PR [ Brittan et al ., ; Morgan et al ., ; Morgan et al ., ], the melt sheet [ Barton et al ., ], Moho character [ Snyder and Hobbs , ], and post‐impact basin stratigraphy [ Bell et al ., ; Whalen et al ., ].…”

Section: Methodsmentioning

confidence: 99%

Geophysical Characterization of the Chicxulub Impact Crater

Gulick

Christeson

Barton

et al. 2013

Reviews of Geophysics

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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

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106

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“…1994; Vermeesch and Morgan 2008). Between this high‐velocity zone and the low velocity (4.1 km s −1 ), postimpact Tertiary sediments and the suevitic breccia, there is a zone where velocities increase with depth from 5.5 to 5.8 km s −1 , which is interpreted to be the zone of impact melt rocks, with a maximum thickness in the center of ∼3.5 km (Barton et al. 2010).…”

Section: Suevite and “Fallback” Brecciasmentioning

confidence: 99%

The evolution of the Onaping Formation at the Sudbury impact structure

Grieve

Ames

Morgan

et al. 2010

Meteorit & Planetary Scien

168

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Abstract-The 1.4-1.6 km thick Onaping Formation consists of a complex series of breccias and ''melt bodies'' lying above the Sudbury Igneous Complex (SIC) at the Sudbury impact structure. Based on the presence of shocked lithic clasts and various ''glassy'' phases, the Onaping has been described as a ''suevitic'' breccia, with an origin, at least in part, as fallback material. Recent mapping and a redefined stratigraphy have emphasized similarities and differences in its various vitric phases, both as clast types and discrete intrusive bodies. The nature of the Onaping and that of other ''suevitic'' breccias overlying impact melt sheets is reviewed. The relative thickness, internal stratigraphic and lithological character, and the relative chronology of depositional units indicate multiple processes were involved over some time in the formation of the Onaping. The Sudbury structure formed in a foreland basin and water played an essential role in the evolution of the Onaping, as indicated by a major hydrothermal system generated during its formation. Taken together, observations and interpretations of the Onaping suggest a working hypothesis for the origin of the Onaping that includes not only impact but also the interaction of sea water with the impact melt, resulting in repeated explosive interactions involving proto-SIC materials and mixing with pre-existing lithologies. This is complicated by additional brecciation events due to the intrusion of proto-SIC materials into the evolving and thickening Onaping. Fragmentation mechanisms changed as the system evolved and involved vesiculation in the formation of the upper two-thirds of the Onaping.

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“…The acquired seismic data show that the water was deeper and the Mesozoic sediments thicker in the northeast quadrant of the crater than in the other quadrants (Bell et al, 2004;Gulick et al, 2008) and that lateral variation in the target at the impact site might explain the current crater asymmetry (Collins et al, 2008). Velocities and densities of the rocks that form the peak ring are low (Morgan et al, 2000;Vermeesch and Morgan, 2008;Barton et al, 2010), and a high-resolution velocity model obtained using full-waveform inversion ( Figure F4) shows that the uppermost peak ring is formed from about 100-150 m of rocks with low P-wave velocity (3000-3200 m/s) (Morgan et al, 2011). Given the lack of intact peak rings exposed at the Earth's surface, there is no consensus as to either their geologic nature (of what material are they composed and from what stratigraphic location this material originates) or the mode of formation of a peak ring.…”

Section: Introductionmentioning

confidence: 99%

Volume 364: Chicxulub: Drilling the K-Pg Impact Crater

Morgan¹,

Gulick²,

Mellett³

et al. 2017

Proceedings of the International Ocean Discovery Program

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The Chicxulub impact crater, on the Yucatán Peninsula of Méx-ico, is unique. It is the only known terrestrial impact structure that has been directly linked to a mass extinction event and the only terrestrial impact with a global ejecta layer. Of the three largest impact structures on Earth, Chicxulub is the best preserved. Chicxulub is also the only known terrestrial impact structure with an intact, unequivocal topographic peak ring. Chicxulub's role in the Cretaceous/Paleogene (K-Pg) mass extinction and its exceptional state of preservation make it an important natural laboratory for the study of both large impact crater formation on Earth and other planets and the effects of large impacts on the Earth's environment and ecology. Our understanding of the impact process is far from complete, and despite more than 30 years of intense debate, we are still striving to answer the question as to why this impact was so catastrophic.During International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) Expedition 364, Paleogene sedimentary rocks and lithologies that make up the Chicxulub peak ring were cored to investigate (1) the nature and formational mechanism of peak rings, (2) how rocks are weakened during large impacts, (3) the nature and extent of post-impact hydrothermal circulation, (4) the deep biosphere and habitability of the peak ring, and (5) the recovery of life in a sterile zone. Other key targets included sampling the transition through a rare midlatitude Paleogene sedimentary succession that might include Eocene and Paleocene hyperthermals and/or the Paleocene/Eocene Thermal Maximum (PETM); the composition and character of suevite, impact melt rock, and basement rocks in the peak ring; the sedimentology and stratigraphy of the Paleocene-Eocene Chicxulub impact basin infill; the geo-and thermochronology of the rocks forming the peak ring; and any observations from the core that may help constrain the volume of dust and climatically active gases released into the stratosphere by this impact. Petrophysical properties measurements on the core and wireline logs acquired during Expedition 364 will be used to calibrate geophysical models, including seismic reflection and potential field data, and the integration of all the data will calibrate models for impact crater formation and environmental effects. The drilling directly contributes to IODP Science Plan goals:Climate and Ocean Change: How does Earth's climate system respond to elevated levels of atmospheric CO 2 ? How resilient is the ocean to chemical perturbations? The Chicxulub impact represents an external forcing event that caused a 75% species level mass extinction. The impact basin may also record key hyperthermals within the Paleogene.Biosphere Frontiers: What are the origin, composition, and global significance of subseafloor communities? What are the limits of life in the subseafloor? How sensitive are ecosystems and biodiversity to environmental change? Impact craters can create habitats fo...

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Seismic images of Chicxulub impact melt sheet and comparison with the Sudbury structure

Cited by 21 publications

References 0 publications

Geophysical Characterization of the Chicxulub Impact Crater

Geophysical Characterization of the Chicxulub Impact Crater

The evolution of the Onaping Formation at the Sudbury impact structure

Volume 364: Chicxulub: Drilling the K-Pg Impact Crater

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