Palaeomagnetism of the Mississippian Barnett Shale, Fort Worth Basin, Texas
Published:January 01, 2013
Devin Dennie, R. D. Elmore, John Deng, Earl Manning, Johari Pannalal, 2013. "Palaeomagnetism of the Mississippian Barnett Shale, Fort Worth Basin, Texas", Remagnetization and Chemical Alteration of Sedimentary Rocks, R. D. Elmore, A. R. Muxworthy, M. M. Aldana, M. Mena
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A palaeomagnetic study of four oriented cores was conducted to better understand the timing of diagenetic events in the Mississippian Barnett Shale, a primary source rock and the unconventional gas reservoir in the Fort Worth Basin, Texas. Thermal demagnetization removes a present-field modern viscous remanent magnetization (VRM) as well as a chemical remanent magnetization (CRM) that has shallow inclinations and streaked south–SE-directed declinations. The VRM was used to orient the CRM data for one well and it produced a similar streak of directions. The streaking of directions could represent a mixing trend between two or more CRMs. Specimens from...
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Remagnetization and Chemical Alteration of Sedimentary Rocks
Chemical remagnetization is a very common phenomenon in sedimentary rocks and developing a greater understanding of the mechanisms has several benefits. Acquisition of a secondary magnetization is usually tangible evidence of a diagenetic event that can be dated by isolation of the chemical remanent magnetization and comparison of the pole position to the apparent polar wander path. This can be important because diagenetic investigations are frequently limited by the difficulty in constraining the time frames in which most past events have occurred. Remagnetization can commonly obscure a primary magnetization; developing a better understanding of remagnetization could improve our ability to uncover primary magnetizations. Many chemical remagnetization mechanisms have been proposed, including those associated with chemical alteration by a number of different fluids (orogenic, basinal and hydrocarbons), burial diagenetic processes (clay diagenesis and maturation of organic matter) or other processes. This paper summarizes our current knowledge of these chemical remagnetization mechanisms, with a focus on examples where there is a connection with chemical alteration.