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GEOREF RECORD

Folding of the Rustenburg Layered Suite adjacent to the Steelpoort Pericline; implications for syn-Bushveld tectonism in the eastern Bushveld Complex

Brendan M. Clarke, Ron Uken, Mike K. Watkeys and Juergen Reinhardt
Folding of the Rustenburg Layered Suite adjacent to the Steelpoort Pericline; implications for syn-Bushveld tectonism in the eastern Bushveld Complex
South African Journal of Geology (September 2005) 108 (3): 397-412

Abstract

The northeastern Bushveld Complex contact aureole is characterised by numerous, subequally-spaced, kilometre-scale metasedimentary Pretoria Group floor rock domes that penetrate the overlying Rustenburg Layered Suite to varying stratigraphic levels. The origin of these floor domes has been the subject of much debate, with both regional folding and diapiric models invoked as causal processes. Of late, however, the diapiric model of deformation has gained support and has been successfully thermomechanically modelled. Here the Rustenburg Layered Suite adjacent to one of these floor domes, the Steelpoort pericline, is examined and high-strain zones in the magmatic rocks in close spatial proximity to the pericline are described. On the northeastern flank of the pericline, the lower part of the Rustenburg Layered Suite is gently folded but discordant to the floor rock structure against which it abuts. The folds are characterised by their curvilinear axial traces that are parallel to the contact between the metasediments of the floor dome and the encircling igneous rocks. On the southwestern flank, high strain shear zones, characterised by sheath folds and strong tectonic fabrics, indicate shedding of igneous material off the flanks of the dome. These deformation zones adjacent to the Steelpoort pericline add independent support to the diapiric model of deformation proposed for the domal structures. The folding on the northeastern flank is readily attributable to diapir-induced drag and compression associated with diapiric growth. The sheath folds on the southwestern flank formed by the gravity-induced shedding of partially crystallised igneous material off the dome flanks during diapiric uplift. In addition, the numerous transgressive and onlapping relationships observed between units of the Rustenburg Layered Suite adjacent to the floor domes is compatible with diapiric deformation of the floor rocks.


ISSN: 1012-0750
EISSN: 1996-8590
Coden: TGSAA3
Serial Title: South African Journal of Geology
Serial Volume: 108
Serial Issue: 3
Title: Folding of the Rustenburg Layered Suite adjacent to the Steelpoort Pericline; implications for syn-Bushveld tectonism in the eastern Bushveld Complex
Affiliation: University of KwaZulu-Natal, Pietermarizburg, South Africa
Pages: 397-412
Published: 200509
Text Language: English
Publisher: Bureau for Scientific Publications, Pretoria, South Africa
References: 41
Accession Number: 2006-034955
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps
S25°00'00" - S25°00'00", E30°00'00" - E30°00'00"
Country of Publication: South Africa
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, Copyright, Geological Society of South Africa. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200610
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