Deformation and fluid flow in the Huab Basin and Etendeka Plateau, NW Namibia

Salomon, E., Koehn, D. , Passchier, C., Chung, P., Haeger, T., Salvona, A. and Davis, J. (2016) Deformation and fluid flow in the Huab Basin and Etendeka Plateau, NW Namibia. Journal of Structural Geology, 88, pp. 46-62. (doi: 10.1016/j.jsg.2016.05.001)

Abstract

The Lower Cretaceous Twyfelfontein sandstone formation in the Huab Basin in NW Namibia shows the effects of volcanic activity on a potential reservoir rock. The formation was covered by the Paraná-Etendeka Large Igneous Province shortly before or during the onset of South-Atlantic rifting. Deformation bands found in the sandstone trend mostly parallel to the continental passive margin and must have formed during the extrusion of the overlying volcanic rocks, indicating that their formation is related to South-Atlantic rifting. 2D-image porosity analysis of deformation bands reveals significant porosity reduction from host rock to band of up to 70 %. Cementation of the sandstone, linked to advective hydrothermal flow during volcanic activity, contributes an equal amount to porosity reduction from host rock to band when compared to initial grain crushing. Veins within the basaltic cover provide evidence for hot fluid percolation, indicated by spallation of wall rock and colloform quartz growth, and for a later low-temperature fluid circulation at low pressures indicated by stilbite growth sealing cavities. Sandstone samples and veins in the overlying volcanic rocks show that diagenesis of the Twyfelfontein sandstone is linked to Atlantic rifting and was affected by both hydrothermal and low-thermal fluid circulation.

• Item Type: Articles (Letter)
• Additional Information: This project was funded by the German Research Foundation (DFG; grant no. KO 2463/8-1) within the priority program SAMPLE (South AtlanticMargin Processes and Links with Onshore Evolution; SPP 1375). The Schürmann Foundation is thanked for several grants to CWP for field expenses.
• Keywords: Deformation Bands, cataclastic bands, syn-volcanic faulting, quartz veins, porosity analysis, South Atlantic rifting
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Chung, Mr Peter and Koehn, Dr Daniel
• Authors: Salomon, E., Koehn, D., Passchier, C., Chung, P., Haeger, T., Salvona, A., and Davis, J.
• Subjects: Q Science > QE Geology
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences > Earth Sciences
• Journal Name: Journal of Structural Geology
• Journal Abbr.: JSG
• Publisher: Elsevier
• ISSN: 0191-8141
• ISSN (Online): 1873-1201
• Published Online: 13 May 2016
• Copyright Holders: Copyright © 2016 Elsevier
• First Published: First published in Journal of Structural Geology 88:46-62
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher