Thrust faults and fold vergence in the Palaeozoic middle and upper Witteberg Group, Cape Supergroup (Cape Fold Belt), Steytlerville: an interpretation of their relationship

Abstract

Research Article| March 01, 2002 Thrust faults and fold vergence in the Palaeozoic middle and upper Witteberg Group, Cape Supergroup (Cape Fold Belt), Steytlerville: an interpretation of their relationship P.W.K. Booth P.W.K. Booth Department of Geology, University of Port Elizabeth, P.O Box 1600, Port Elizabeth, 6000, Republic of South Africa., e-mail: glapwb@upe.ac.za Search for other works by this author on: GSW Google Scholar Author and Article Information P.W.K. Booth Department of Geology, University of Port Elizabeth, P.O Box 1600, Port Elizabeth, 6000, Republic of South Africa., e-mail: glapwb@upe.ac.za Publisher: Geological Society of South Africa First Online: 07 Mar 2017 Online ISSN: 1996-8590 Print ISSN: 1012-0750 © 2002 Geological Society of South Africa South African Journal of Geology (2002) 105 (1): 25–38. https://doi.org/10.2113/1050025 Article history First Online: 07 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation P.W.K. Booth; Thrust faults and fold vergence in the Palaeozoic middle and upper Witteberg Group, Cape Supergroup (Cape Fold Belt), Steytlerville: an interpretation of their relationship. South African Journal of Geology 2002;; 105 (1): 25–38. doi: https://doi.org/10.2113/1050025 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySouth African Journal of Geology Search Advanced Search Abstract Four sections through middle and upper Witteberg Group strata north of Steytlerville were investigated in detail to ascertain the phenomenon of opposite vergence of folds, as well as the relationship between folding and thrusting. Strata of the middle Witteberg Group are thinly-bedded and predominantly arenaceous, whereas those of the upper Witteberg Group show variation in bed thickness, lithological composition and proportion of arenaceous to argillaceous material. East-southeast striking thrust faults are commonly developed throughout the study area, and have a complex history of development. They display characteristic ramp and flat geometry, with south-southwest-dipping forethrusts predominating over north-northeast-dipping backthrusts. Thrust/fold relationships show that thrust faults formed prior to, during and after folding. Fold styles vary from gentle to tight, and fold axes of folds plunge shallowly east-southeast and west-northwest. The orientation of east-southeast-striking axial planes of folds and their predominantly northward vergence indicate that folds formed during a north-northeastward-directed compression event, during the Cape orogeny. The few examples of southward vergence of fold structures are explained in some cases by formation of folds during backthrusting, and in other cases folds formed prior to fore-and backthrusting. The implications of these findings are that strata of the middle and upper Witteberg Group have inherent structural complexities that make it difficult to define the lithostratigraphy. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.