Abstract

SALGUERO-HERNANDEZ, Eduardo; URRUTIA-FUCUGAUCHI, Jaime  and  RAMIREZ-CRUZ, Luis. Fracturing and deformation in the Chicxulub crater - Complex trace analysis of instantaneous seismic attributes. Rev. mex. cienc. geol [online]. 2010, vol.27, n.1, pp.175-184. ISSN 2007-2902.

Large complex impact craters form by collapse from initial excavation stage of a deep narrow bowl-shaped transient cavity. Fracturing and shattering of solids with finite tensile shear limits occur related to shock-induced damage of target material, with fracturing and fragmentation occurring during transient cavity crater collapse processes. Geophysical studies of subsurface crater structure may assist in studying shock-induced effects of deformation and fracturing of target rocks. Here we present initial results of a study of subsurface fracturing/deformation in the Chicxulub crater from seismic reflection data. The analysis is based on the instantaneous seismic attributes envelope amplitude, instantaneous frequency and Q factor, at selected sectors of the crater by looking at petrophysical properties and seismic attenuation. Shock effects with shattering and fracturing of Mesozoic target rocks show a trend to decrease away from the rim zone. Cretaceous carbonates show less attenuation inside the crater than in exterior sectors. The relative attenuation quality factor Q is lower in sections outside the crater rim as compared with higher Q values inside the rim, and particularly at depth within the Cretaceous sequence. Carbonates in the western sector are characterized by slightly larger attenuation than in the eastern sector, suggesting radial asymmetries in fracturing/deformation within Chicxulub.

Keywords : cratering; geophysical modeling; instantaneous seismic attributes; Chicxulub crater; Mexico.