Gravity and magnetic field modeling and structure of the Chicxulub Crater, Mexico

Abstract

The Chicxulub crater is an ∼180‐km‐diameter peak‐ring crater based on drill hole logs and samples, potential fields, seismic reflection profiles, and surface fracture patterns. A structural cross section produced based on these constraints has the features expected for a large complex impact crater. The Bouguer‐gravity anomaly consists of a broad ∼90‐km radius, ∼30‐mGal low with a central ∼20‐km radius, ∼20‐mGal high and two <5‐mGal concentric lows at ∼35‐ and ∼60‐km radius. The gravity anomaly is disrupted by large‐scale basement anomalies and possibly by large‐scale slumping and backwash erosion effects. The magnetic field anomaly over the crater consists of three zones, an outer zone from ∼45‐ to ∼90‐km radius of low‐amplitude, short‐wavelength anomalies with an irregular perimeter, a middle zone from ∼20‐ to ∼45‐km radius of high‐amplitude, short‐wavelength anomalies slightly elongated NNW‐SSE, and an inner ∼20‐km‐radius single large‐amplitude anomaly. Magnetic field modeling indicates that the melt pool averages ∼90 km in diameter and the melt volume in the crater is estimated at ∼20,000 km3. The melt pool size constrains the collapsed transient cavity diameter to ∼90 km. Gravity and magnetic field modeling indicate that the structural uplift is irregular in shape but ∼40 km in diameter and underlies or protrudes into the melt pool. The preliminary structural cross section indicates that the inferred peak‐ring is decoupled from the structural uplift. The geometry and Bouguer gravity signature of the crater indicate that no significant uplift of the Moho or relaxation of the crater has occurred.