Structural and petrophysical characterization of mixed conduit/seal fault zones in聽carbonates: Example from the Castellas fault (SE France)
- 作者：Christophe Matonti matonti.christophe@free.fr ; Juliette Lamarche ; Juliette.Lamarche@univ-provence.fr ; Yves Guglielmi ; Lionel Marié
- 关键词：Fault-zone ; Architecture ; Lateral variations ; Carbonates ; Porosity ; Sonic waves velocity
- 刊名：Journal of Structural Geology
- 出版年：2012
- 期刊代码：52_01918141
- 类别：ear
- 出版时间：June, 2012
- 卷：39
- 期：Complete
- 页码：103-121
- 文件大小：5960 K
摘要
The Castellas fault in SE France affects carbonate rocks with a plurimeter scale offset聽along 1.5聽km of outcrop. In order to decipher the structural control on fault petrophysical and hydraulic character, we performed high resolution field structural mapping, laboratory porosity-Vp measurements, and thin sections analysis of deformations and diagenesis. Field mapping shows that the fault zone architecture displays strong lateral variations at the hectometer scale characterized by core thicknesses of 0-5聽m, one or several slip planes, and varying fracture patterns within the damage zone. The fault zone heterogeneity may be related to the magnitude of the throw, the position along the fault and the affected rock facies. Laboratory measurements revealed a strong porosity reduction correlated to a Vp increase, related to the cementation of pore volumes within a decameter area around the fault plane. This fault-sealing occurred mainly through a chemical diagenesis related to fluid circulation within fault-zone heterogeneities. A 3D conceptual model of a mixed conduit/seal fault zone is proposed, characterized by sealed impermeable fault tips and more or less permeable units within which flow can occur either perpendicular or parallel to the fault strike.