Timing and kinematics of the Colenso Fault: The Early Paleozoic shift from collisional to extensional tectonics in the Pan-African Saldania Belt, South Africa

Abstract

Research Article| September 01, 2002 Timing and kinematics of the Colenso Fault: The Early Paleozoic shift from collisional to extensional tectonics in the Pan-African Saldania Belt, South Africa Alexander F.M. Kisters; Alexander F.M. Kisters Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] Search for other works by this author on: GSW Google Scholar Richard W. Belcher; Richard W. Belcher Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] Search for other works by this author on: GSW Google Scholar Reyno Scheepers; Reyno Scheepers Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] Search for other works by this author on: GSW Google Scholar Abraham Rozendaal; Abraham Rozendaal Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] Search for other works by this author on: GSW Google Scholar L. Smith Jordaan; L. Smith Jordaan Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] Search for other works by this author on: GSW Google Scholar Richard A. Armstrong Richard A. Armstrong Research School of Earth Sciences, Australian National University, Canberra ACT 0200, Australia, e-mail: [e-mail] Search for other works by this author on: GSW Google Scholar Author and Article Information Alexander F.M. Kisters Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] Richard W. Belcher Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] Reyno Scheepers Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] Abraham Rozendaal Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] L. Smith Jordaan Department of Geology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa, e-mail: [e-mail] Richard A. Armstrong Research School of Earth Sciences, Australian National University, Canberra ACT 0200, Australia, e-mail: [e-mail] Publisher: Geological Society of South Africa First Online: 07 Mar 2017 Online ISSN: 1996-8590 Print ISSN: 1012-0750 © 2002, The Clay Minerals Society South African Journal of Geology (2002) 105 (3): 257–270. https://doi.org/10.2113/1050257 Article history First Online: 07 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Alexander F.M. Kisters, Richard W. Belcher, Reyno Scheepers, Abraham Rozendaal, L. Smith Jordaan, Richard A. Armstrong; Timing and kinematics of the Colenso Fault: The Early Paleozoic shift from collisional to extensional tectonics in the Pan-African Saldania Belt, South Africa. South African Journal of Geology 2002;; 105 (3): 257–270. doi: https://doi.org/10.2113/1050257 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 The Colenso fault is a major northwest to southeast trending fault zone in the Pan-African Saldania Belt of the Western Cape Province in South Africa that is spatially closely associated with granitoids of the ~550 to 510 Ma Cape Granite Suite. Most of these granites were previously considered to be largely post-tectonic intrusions, but structural data presented in this study demonstrate the synkinematic emplacement of granitoids into, and along, the Colenso Fault. The kinematic analyses of shear zones and granite fabrics together with previously published and new geochronological data are combined to provide constraints on the complex kinematic history of the fault and the tectonic evolution of the hitherto poorly understood Saldania Belt.Early, strongly gneissose granitoids of the composite Darling batholith (547 ± 6 Ma) were emplaced during sinistral strike-slip movement along the Colenso fault. Both the timing of emplacement and penetrative deformation of the Darling batholith suggest an intrusion of the pluton during the main Pan-African collisional event in the Saldania Belt. The younger Trekoskraal granite intrudes synkinematically into dextral strike-slip faults related to deformation along the Colenso fault. Single-zircon ages from synkinematic aplites constrain the timing of dextral strike-slip shearing to 539 ± 4 Ma. The emplacement of the late-kinematic Cape Columbine granite during dextral strike-slip faulting indicates that dextral strike-slip kinematics along the Colenso fault continued at least until ~520 Ma.These results point to a reversal of strike-slip motion along the Colenso fault at ~540 Ma that coincides with the onset of uplift of rocks of the Saldania Belt. The final exhumation of the belt at ~515 to 520 Ma is marked by the near-surface emplacement of the last phases of the Cape Granite Suite, related subaerial volcanism, sedimentation of the coarse-clastic, fault-bounded Klipheuwel Group, and the overlying fluvial to shallow-marine sequence of the Mid-Cambrian Cape Supergroup. The temporal and spatial overlap between igneous activity and rift-type sedimentation indicates that a substantial part of the Cape Granite Suite was emplaced in an overall transtensional and/or extensional setting. During this time, the voluminous plutonism of the Cape Granite Suite most likely represented a significant heat input that also contributed to a thermal weakening of the crust. In view of the Early Paleozoic extensional setting suggested here, we interpret Ar-Ar mineral ages of ~500 Ma and post-orogenic plutonism that are widely documented from Pan-African belts throughout southwestern Africa to reflect a thermal event related to crustal thinning and associated mantle upwelling that follows the main phase of Pan-African collisional tectonics. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.