3D gravity modelling of the Chicxulub impact structure

Ebbing, Jörg; Janle, P.; Koulouris, Jannis; Milkereit, B.

doi:10.1016/s0032-0633(01)00005-8

Cited by 35 publications

(37 citation statements)

References 15 publications

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“…Our final velocity models are consistent with previous geophysical models, which all contain a 40-50 km-wide dense and/or highly magnetized body [Espindola et al, 1995;Sharpton et al, 1996;Hildebrand et al, 1998;Campos-Enriquez et al, 1998;Pilkington and Hildebrand, 2000;Ebbing et al, 2001] close to the location of the zone of high velocity in Fig. 3 and 4.…”

Section: Discussionsupporting

confidence: 89%

Structural uplift beneath the Chicxulub impact structure

Vermeesch¹,

Morgan²

2008

J. Geophys. Res.

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Models of the central structure of large impact craters are poorly constrained, partly due to the lack of well-preserved terrestrial examples, and partly because of the extreme nature of impact events. Even large impact craters take only a few minutes to form, during which time rocks from the deep crust move upwards many kilometers, interacting with impact melts and breccias before settling to their final position. We construct a new model of central uplift beneath the Chicxulub crater, based upon a well-constrained 3D velocity model, obtained by jointly inverting seismic travel-time and gravity data. The input tomographic dataset has good resolution and many rays cross the central uplift in many directions. We use laboratory measurements to convert between velocity and density. Our velocity model possesses a highvelocity-zone near the crater center, and velocity gradually decreases outside this zone. We use regional refraction data to interpret these velocities in terms of a broad 80-km-wide zone of structural uplift, in which the central rocks originate from the lower crust, and the surrounding rocks from the mid and upper crust. This is in contrast with previous models in 2 2 which the zone of central uplift is either 40-50 km or 150 km wide. Our interpretation is consistent with: scaling laws, Yucatán basement lithology, other velocity data, observations at similar-sized terrestrial craters, and dynamic modeling of peak ring formation. Our model of the uplift at Chicxulub can be used to help distinguish between competing models of effective target strength in numerical models of crater formation.

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Section: Discussionsupporting

confidence: 89%

Structural uplift beneath the Chicxulub impact structure

Vermeesch¹,

Morgan²

2008

J. Geophys. Res.

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“…Threedimensional seismic tomography suggests that the Chicxulub central melt sheet has a maximum thickness of 3.5 km in the center of the crater (Morgan et al 2000). This approximation is also supported by the gravity modeling of Ebbing et al (2001), who estimate a central melt thickness of ~3 km, which is consistent with previous scaling approximations (Kring 1995). However, Christeson et al (2001) interpret the seismic and gravity data as suggestive of a melt sheet that is only 1 km thick.…”

Section: Central Melt Sheetsupporting

confidence: 80%

Numerical modeling of impact‐induced hydrothermal activity at the Chicxulub crater

Abramov

Kring

2007

Meteorit & Planetary Scien

105

112

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Abstract-Large impact events like the one that formed the Chicxulub crater deliver significant amounts of heat that subsequently drive hydrothermal activity. We report on numerical modeling of Chicxulub crater cooling with and without the presence of water. The model inputs are constrained by data from borehole samples and seismic, magnetic, and gravity surveys. Model results indicate that initial hydrothermal activity was concentrated beneath the annular trough as well as in the permeable breccias overlying the melt. As the system evolved, the melt gradually cooled and became permeable, shifting the bulk of the hydrothermal activity to the center of the crater. The temperatures and fluxes of fluid and vapor derived from the model are consistent with alteration patterns observed in the available borehole samples. The lifetime of the hydrothermal system ranges from 1.5 to 2.3 Myr depending on assumed permeability. The long lifetimes are due to conduction being the dominant mechanism of heat transport in most of the crater, and significant amounts of heat being delivered to the near-surface by hydrothermal upwellings. The long duration of the hydrothermal system at Chicxulub should have provided ample time for colonization by thermophiles and/or hyperthermophiles. Because habitable conditions should have persisted for longer time in the central regions of the crater than on the periphery, a search for prospective biomarkers is most likely to be fruitful in samples from that region.

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“…The Y6 borehole was terminated in evaporitic rocks, i.e., dolomite and anhydrite, at a depth of 1630 m, whereas the C1 and S1 boreholes ended in melt rocks and breccias at 1581 m and ~1530 m, respectively (Ward et al 1995;Sharpton et al 1996;Stöffler et al 2003b). Farther away from the center of the impact crater, the T1 borehole also intersected Cretaceous rocks at a shallower depth, i.e., ~900 m. The relative position of the Cretaceous rocks in the Yax-1 borehole is thought to be the result of slumping around the crater periphery, an area that is characterized by a prominent gravity low (Ebbing et al 2001). With respect to the correlation of impactites from other boreholes, i.e., the Y6 borehole, we correlate our units 1 to 3 with the units 1 to 3 of Claeys et al (2003).…”

Section: Stratigraphic Relationship With Other Boreholesmentioning

confidence: 99%

First petrographic results on impactites from the Yaxcopoil‐1 borehole, Chicxulub structure, Mexico

Tuchscherer¹,

Reimold²,

Koeberl³

et al. 2004

Meteorit & Planetary Scien

109

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Abstract-The ICDP Yaxcopoil-1 (Yax-1) borehole located 60 km south-southwest of the center of the Chicxulub impact structure intercepted an interval of allogenic impactites (depth of 795-895 m). Petrographic analysis of these impactites allows them to be differentiated into five units based on their textural and modal variations. Unit 1 (795-922 m) comprises an apparently reworked, poorly sorted and graded, fine-grained, clast-supported, melt fragment-bearing suevitic breccia. The interstitial material, similar to units 2 and 3, is permeated by numerous carbonate veinlets. Units 2 (823-846 m) and 3 (846-861 m) are groundmass-supported breccias that comprise green to variegated angular and fluidal melt particles. The groundmass of units 2 and 3 comprises predominantly fine-grained calcite, altered alkali element-, Ca-, and Si-rich cement, as well as occasional lithic fragments. Unit 4 (861-885 m) represents a massive, variably devitrified, and brecciated impact melt rock. The lowermost unit, unit 5 (885-895 m), comprises highly variable proportions of melt rock particles (MRP) and lithic fragments in a fine-grained, carbonate-dominated groundmass. This groundmass could represent either a secondary hydrothermal phase or a carbonate melt phase, or both. Units 1 and 5 contain well-preserved foraminifera fossils and a significantly higher proportion of carbonate clasts than the other units. All units show diagnostic shock deformation features in quartz and feldspar clasts. Our observations reveal that most felsic and all mafic MRP are altered. They register extensive K-metasomatism. In terms of emplacement, we suggest that units 1 to 3 represent fallout suevite from a collapsing impact plume, whereby unit 1 was subsequently reworked by resurging water. Unit 4 represents a coherent impact melt body, the formation of which involved a significant proportion of crystalline basement. Unit 5 is believed to represent an initial ejecta/ground-surge deposit.

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3D gravity modelling of the Chicxulub impact structure

Cited by 35 publications

References 15 publications

Structural uplift beneath the Chicxulub impact structure

Structural uplift beneath the Chicxulub impact structure

Numerical modeling of impact‐induced hydrothermal activity at the Chicxulub crater

First petrographic results on impactites from the Yaxcopoil‐1 borehole, Chicxulub structure, Mexico

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