A model of the Chicxulub impact structure (Yucatan, Mexico) based on its gravity and magnetic signatures

Espíndola, J. M.; Mena, M.; Fuente, Mauricio de la; Campos-Enríquez, J. O.

doi:10.1016/0031-9201(95)03022-6

Cited by 29 publications

(34 citation statements)

References 12 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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“…A 1978 aeromagnetic survey of the northwestern part of the Yucatán peninsula delineated a circular zone of high amplitude anomalies, which was suggested to be caused by a large buried impact crater (Penfield and Camargo 1981). Subsequent to the establishment of Chicxulub as the K/T boundary crater (Hildebrand et al 1991;Sharpton et al 1992), interpretation of magnetic data has provided useful constraints on defining the crater morphology (Pilkington et al 1994;Espindola et al 1995;Pilkington and Hildebrand 2000;Rebolledo-Vieyra 2001). Modeling of the magnetic field over Chicxulub is greatly simplified since magnetization contrasts of three to four orders of magnitude exist between the target rocks and several of the impact lithologies.…”

Section: Introductionmentioning

confidence: 99%

“…Based on modeling, these anomalies require magnetizations of ~5 A/m (Pilkington et al 1994;Espindola et al 1995) compared to average measured values at least ten times smaller. Hence, a mechanism is required to produce such elevated magnetization levels.…”

Section: Introductionmentioning

confidence: 99%

Magnetic mineralogy of the Yaxcopoil‐1 core, Chicxulub

Pilkington

Ames

Hildebrand

2004

Meteorit & Planetary Scien

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Abstract-Core from the Yaxcopoil-1 (Yax-1) hole, drilled as a result of the Chicxulub Scientific Drilling Project (CSDP), has been analyzed to investigate the relationship between opaque mineralogy and rock magnetic properties. Twenty one samples of suevite recovered from the depth range 818-894 m are generally paramagnetic, with an average susceptibility of 2000 × 10 −6 SI and have weak remanent magnetization intensities (average 0.1 A/m). The predominant magnetic phase is secondary magnetite formed as a result of low temperature (<150 °C) alteration. It occurs in a variety of forms, including vesicle infillings associated with quartz and clay minerals and fine aggregates between plagioclase/diopside laths in the melt. Exceptional magnetic properties are found in a basement clast (metamorphosed quartz gabbro), which has a susceptibility of >45000 × 10 −6 SI and a remanent magnetization of 77.5 A/m. Magnetic mafic basement clasts are a common component in the Yax-1 impactite sequence. The high susceptibility and remanence in the mafic basement clasts are caused by the replacement of amphiboles and pyroxenes by an assemblage with fine <1 µm magnetite, ilmenite, K-feldspar, and stilpnomelane. Replacement of the mafic minerals by the magnetic alteration assemblage occurred before impact. Similar alteration mechanisms, if operative within the melt sheet, could explain the presence of the high amplitude magnetic anomalies observed at Chicxulub.

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“…Estimates ranged from ~170 to ~295 km for the final crater diameter (e.g., Hildebrand et al 1991Hildebrand et al , 1995Sharpton et al 1993;Pilkington et al 1994;Espindola et al 1995). Some degree of consensus was only reached after Chicxulub had been imaged by a marine reflection seismic survey ( Fig.…”

Section: Chicxulub Mexicomentioning

confidence: 99%

“…The interpretative models derived from these data, however, are very different in detail (cf. Pilkington et al 1994;Espindola et al 1995;Sharpton et al 1996). Nevertheless, the interpretation of offshore reflection seismic data leaves no doubt as to the existence of an inner topographic peak ring with a diameter of ~80 km at Chicxulub Warner 1999a and1999b;Turtle et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Observations and interpretations at Vredefort, Sudbury, and Chicxulub: Towards an empirical model of terrestrial impact basin formation

Grieve

Reimold

Morgan

et al. 2008

Meteorit & Planetary Scien

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Abstract-The structural, topographic and other characteristics of the Vredefort, Sudbury, and Chicxulub impact structures are described. Assuming that the structures originally had the same morphology, the observations/interpretations for each structure are compared and extended to the other structures. This does not result in any major inconsistencies but requires that the observations be scaled spatially. In the case of Vredefort and Sudbury, this is accomplished by scaling the outer limit of particular shock metamorphic features. In the case of Chicxulub, scaling requires a reasoned assumption as to the formation mechanism of an interior peak ring. The observations/interpretations are then used to construct an integrated, empirical kinematic model for a terrestrial peak-ring basin. The major attributes of the model include: a set of outward-directed thrusts in the parautochthonous rocks of the outermost environs of the crater floor, some of which are pre-existing structures that have been reactivated during transient cavity formation; inward-directed motions along the same outermost structures and along a set of structures, at intermediate radial distances, during transient cavity collapse; structural uplift in the center followed by a final set of radially outward-directed thrusts at the outer edges of the structural uplift, during uplift collapse. The rock displacements on the intermediate, inward and innermost, outward sets of structures are consistent with the assumption that a peak ring will result from the convergence of the collapse of the transient cavity rim area and the collapse of the structural uplift.

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A model of the Chicxulub impact structure (Yucatan, Mexico) based on its gravity and magnetic signatures

Cited by 29 publications

References 12 publications

Structural uplift beneath the Chicxulub impact structure

Structural uplift beneath the Chicxulub impact structure

Magnetic mineralogy of the Yaxcopoil‐1 core, Chicxulub

Observations and interpretations at Vredefort, Sudbury, and Chicxulub: Towards an empirical model of terrestrial impact basin formation

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