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AGU: Journal of Geophysical Research, Solid Earth

 

Keywords

  • acoustic properties
  • thermal properties
  • carbonate rocks
  • suevitic breccia
  • log interpretation
  • porosity

Index Terms

  • Exploration Geophysics: Downhole methods
  • Physical Properties of Rocks: Acoustic properties
  • Physical Properties of Rocks: Thermal properties
  • Physical Properties of Rocks: Permeability and porosity
  • Tectonophysics: Impact phenomena
Abstract
Cited By (0)
 

Abstract

Integrated interpretation of physical properties of rocks of the borehole Yaxcopoil-1 (Chicxulub impact structure)

S. I. Mayr

Angewandte Geophysik, Technische Universitaet Berlin, Berlin, Germany

A. Wittmann

Lunar and Planetary Institute, Houston, Texas, USA

H. Burkhardt

Angewandte Geophysik, Technische Universitaet Berlin, Berlin, Germany

Y. Popov

Russian State Geological Prospecting University, Moscow, Russia

R. Romushkevich

Russian State Geological Prospecting University, Moscow, Russia

I. Bayuk

Russian State Geological Prospecting University, Moscow, Russia

P. Heidinger

Geophysikalisches Institut, Universitaet Karlsruhe, Karlsruhe, Germany

H. Wilhelm

Geophysikalisches Institut, Universitaet Karlsruhe, Karlsruhe, Germany

The borehole Yaxcopoil-1, drilled within the Chicxulub meteoritic impact structure (Mexico), was completely cored from 404 to 1511 m through postimpact Tertiary limestones underlain by impactites. The impactites comprise impact melt-rich, suevitic breccia followed by megablocks of Cretaceous limestones, calcarenites, dolomites, and anhydrites. Measurements of porosity, density, and thermal parameters on 450 samples (equidistant sampling, complete depth range) and of ultrasonic velocities and electric resistivity on 80 representative samples are used to investigate the physical properties of carbonate rocks and to study the influence of the impact. Experiments under elevated pressure, calculations using frequency-dependent Biot-Gassmann theory, and cross-checking with borehole logs, where available, show that ultrasonic laboratory and sonic in situ data correspond. Sonic and electric quasi-continuous logs are obtained from empirical correlations with thermal conductivity, density, and porosity and consideration of mineralogical composition and microstructure. These data give constraints on interpretation and geophysical modeling of, e.g., seismic and gravity data. In the Tertiary postimpact limestone section, the rock fabric (porosity) influences the physical properties. The upper boundary of the impactites is distinctly determined by the high inhomogeneity factor and anisotropy coefficient of thermal conductivity and by the temperature gradient from high-resolution borehole temperature measurements. All physical properties indicate that the upper part of the suevitic breccia can be distinguished from the lower suevite unit. In the Cretaceous megablocks, a high variability of all properties (particularly, thermal conductivity, density of solid material, and temperature gradient) due to the high variability in the mineral composition (calcite, dolomite, anhydrite) is observed.

Received 4 October 2007; accepted 27 March 2008; published 3 July 2008.

Citation: Mayr, S. I., A. Wittmann, H. Burkhardt, Y. Popov, R. Romushkevich, I. Bayuk, P. Heidinger, and H. Wilhelm (2008), Integrated interpretation of physical properties of rocks of the borehole Yaxcopoil-1 (Chicxulub impact structure), J. Geophys. Res., 113, B07201, doi:10.1029/2007JB005420.

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