Brittle reactivation of ductile shear zones in NW Namibia in relation to South Atlantic rifting

Salomon E, Koehn D, Passchier C (2015)

Publication Status: Published

Publication Type: Journal article

Publication year: 2015

Journal

Tectonics American Geophysical Union (AGU)

Publisher: AMER GEOPHYSICAL UNION

Book Volume: 34

Pages Range: 70-85

Journal Issue: 1

DOI: 10.1002/2014TC003728

Abstract

Rifting has occurred worldwide along preexisting mobile belts, which are therefore thought to control rift orientation on a large scale. On a smaller scale, shear zones within mobile belts are reactivated as rift faults. In NW Namibia, shear zones of the Neoproterozoic Kaoko Belt run subparallel to the present-day continental passive margin and are inferred to have been reactivated during the opening of the South Atlantic Ocean. However, the extent of this reactivation and the influence of the reactivated shear zones on South Atlantic rifting are largely unknown. A combined remote sensing and field study was conducted to quantify offsets that are a direct function of shear zone reactivation. The shear zones of the Kaoko Belt are partly overlain by the Parana-Etendeka volcanic rocks, which were emplaced shortly before or simultaneously to the Atlantic rifting. Faulting within these volcanic rocks can be linked to synrift or postrift movements. Along the shear zones, downfaulting of the basalts is widespread along listric faults where half-graben form in the hanging wall. At three sites we could determine vertical offsets of similar to 1180m, similar to 470m, and similar to 70m. Although many shear zones were reactivated as faults, these are isolated, and offsets are small, suggesting that reactivation occurred only as a side effect of the rifting and that the Kaoko Belt shear zones have not exerted a significant influence on the rift orientation.

Authors with CRIS profile

Eric Salomon Lehrstuhl für Geologie (Exogene Dynamik)

Involved external institutions

University of Glasgow GB United Kingdom (GB) Johannes Gutenberg-Universität Mainz (JGU) DE Germany (DE)

How to cite

APA:

Salomon, E., Koehn, D., & Passchier, C. (2015). Brittle reactivation of ductile shear zones in NW Namibia in relation to South Atlantic rifting. Tectonics, 34(1), 70-85. https://dx.doi.org/10.1002/2014TC003728

MLA:

Salomon, Eric, Daniel Koehn, and Cees Passchier. "Brittle reactivation of ductile shear zones in NW Namibia in relation to South Atlantic rifting." Tectonics 34.1 (2015): 70-85.

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