The Paleoproterozoic Waterberg Group, South Africa : provenance and its relation to the timing of the Limpopo orogeny

Show simple item record Corcoran, Patricia L. Bumby, Adam John Davis, D.W. 2014-06-04T08:43:23Z 2014-06-04T08:43:23Z 2013
dc.description.abstract Four Paleoproterozoic formations of the Waterberg Group in South Africa are composed of coarse clastic detritus derived from erosion of the Limpopo Belt. Timing of the Limpopo orogeny, an event involving the collision of the Kaapvaal and Zimbabwe cratons, has long been a contentious issue. The results of point counting, major and trace element geochemistry, and U–Pb detrital zircon geochronology indicate that the Waterberg sedimentary formations in the study area were primarily sourced by siliceous (rifted margin) sedimentary and minor mafic volcanic rocks of the Archean Beit Bridge Complex, Limpopo Central Zone. The volumetrically predominant beige/brown sandstones in the four studied formations are quartzrich with average QFR ratios of 80:7:13 (Blouberg), 70:19:11 (Setlaole), 88:5:7 (Makgabeng), and 89:3:8 (Mogalakwena). Chert and arenite account for >90% of lithic fragments in all formations, with minor siliceous gneiss fragments. Although all formations are silica enriched, the Makgabeng dune samples produce extremely high SiO2 abundances (92–99 wt%), which are attributed to the presence of silica cement and quartz within rock fragments. Geochemically, the stratigraphically highest Mogalakwena Formation is unique with elevated Ti and Zr values, and intra-formational differences in REE patterns; the latter feature is consistent with a mixed provenance. Volumetrically minor green and purple sandstones in the Waterberg formations contain the greatest Cr, Ni, Ti, and V abundances, which supports localized derivation from a mafic or ultramafic source. Chemical index of alteration (CIA) values range from 57 to 89, which could indicate significant chemical weathering of the source rocks, but a plot of Th/Sc versus Zr/Sc illustrates that the sandstones have undergone recycling, which was probably responsible for enrichments in Al2O3 relative to Na2O3, CaO and K2O. Combinations of well rounded and subangular quartz grains support a recycled origin. Detrital zircons in the lowermost Blouberg Formation produced a wide array of ages ranging from ca. 3379 to 2043 Ma. The youngest peak at 2046 Ma is also the largest, and represents the maximum age of deposition for the formation. Additional peaks at 3281 Ma, 3330 Ma, and 3379 Ma are consistent with ages previously determined from the Beit Bridge Complex, whereas peaks at 2578 Ma and 2649 Ma coincide with ages determined from gneisses of the Limpopo Central Zone. Derivation of detritus from the Beit Bridge Complex is directly indicated by sedimentary and siliceous gneiss fragments in the sandstones, subrounded quartz grains suggestive of relatively short transport distances, green and purple sandstone drapes derived from mafic volcanic units, and paleocurrent patterns consistent with south to southwest flow directions. Therefore the timing of deposition of the Blouberg Formation (2046 Ma) equates to the end stages of the Limpopo orogeny. This negates previous suggestions that the Limpopo orogeny occurred only during the Neoarchean. en_US
dc.description.librarian hb2014 en_US
dc.description.uri en_US
dc.identifier.citation Corcoran, PL, Bumby, AJ & Davis, DW 2013, 'The Paleoproterozoic Waterberg Group, South Africa : provenance and its relation to the timing of the Limpopo orogeny', Precambrian Research, vol. 230, no. 6, pp. 45-60. en_US
dc.identifier.issn 0301-9268 (print)
dc.identifier.issn 1872-7433 (online)
dc.identifier.other 10.1016/j.precamres.2012.12.009
dc.language.iso en en_US
dc.publisher Elsevier en_US
dc.rights © 2013 Elsevier B.V. All rights reserved.Notice : this is the author’s version of a work that was accepted for publication in Precambrian Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Precambrian Research, vol.230, no.6, pp. 45-60. 2013. doi : 10.1016/j.precamres.2012.12.009 en_US
dc.subject Limpopo belt en_US
dc.subject Waterberg group en_US
dc.subject Palaeoproterozoic en_US
dc.subject Geochemistry en_US
dc.subject Detrital zircon U–Pb geochronology en_US
dc.subject Provenance en_US
dc.title The Paleoproterozoic Waterberg Group, South Africa : provenance and its relation to the timing of the Limpopo orogeny en_US
dc.type Postprint Article en_US

Files in this item

This item appears in the following Collection(s)

Show simple item record