THE GEOLOGY AND STRUCTURE OF THE MASVINGO GREENSTONE BELT AND ADJACENT GRANITE PLUTONS FROM GEOPHYSICAL DATA, ZIMBABWE CRATON

Abstract

Research Article| December 01, 2009 THE GEOLOGY AND STRUCTURE OF THE MASVINGO GREENSTONE BELT AND ADJACENT GRANITE PLUTONS FROM GEOPHYSICAL DATA, ZIMBABWE CRATON O. GWAVAVA; O. GWAVAVA Department of Physics, University of Zimbabwe, P. O. Box MP167, Mt Pleasant, Harare., Present Address: Department of Geology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa. Corresponding author: e-mail: ogwavava@ufh.ac.za Search for other works by this author on: GSW Google Scholar R.T. RANGANAI R.T. RANGANAI Department of Physics, University of Zimbabwe, P. O. Box MP167, Mt Pleasant, Harare., Present Address: Physics Department, University of Botswana, Private Bag UB 0704, Gaborone, Botswana. e-mail: ranganai@mopipi.ub.bw Search for other works by this author on: GSW Google Scholar South African Journal of Geology (2009) 112 (3-4): 277–290. https://doi.org/10.2113/gssajg.112.3-4.277 Article history first online: 09 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 O. GWAVAVA, R.T. RANGANAI; THE GEOLOGY AND STRUCTURE OF THE MASVINGO GREENSTONE BELT AND ADJACENT GRANITE PLUTONS FROM GEOPHYSICAL DATA, ZIMBABWE CRATON. South African Journal of Geology 2009;; 112 (3-4): 277–290. doi: https://doi.org/10.2113/gssajg.112.3-4.277 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 structure and subsurface configuration of the Masvingo Greenstone Belt (MGB) in the Zimbabwe Craton (ZC), were investigated using aeromagnetic and gravity data. Gravity data from 158 new and 202 old gravity stations were combined to produce a Bouguer gravity map covering the greenstone belt and surrounding granites. The greenstone belt and ultramafic complexes are characterised by Bouguer gravity highs, whereas the granitic terrain are lows, with the lowest values over the post-volcanic plutons. Gravity modelling, constrained by surface geology and density measurements, was carried out on a profile crossing the greenstone belt. The modelling results indicate a depth extent of around 6 km for the dense greenstone belt with a thickness of about 8.5 km for the adjacent younger granite plutons, which are significantly less dense. Granite-greenstone contacts along the profile are near-vertical.Magnetic maps compiled from the Zimbabwe Geological Survey national aeromagnetic data set show the bulk of the greenstone belt to have low magnetic anomaly values, but with high magnetic anomaly values along its northern and western margins over ultramafic units and banded iron formations. The younger granites generally have higher magnetic anomaly values compared to both the greenstone belt and the older gneisses. In particular, a pronounced east-northeast-trending broad magnetic high is observed over the Charumbira pluton, and its edges mark the boundaries with the greenstone belt to the north, and the Limpopo belt to the south; with the latter characterised by low magnetic values. Several linear, small amplitude magnetic lows, which are mostly due to faults, trend northwest to southeast and north to south, with some revealing an apparent dextral movement. Derivative maps for both gravity and magnetic data bring out some of the linear features and the edges of the greenstone belt and granite plutons. Shallow and deep depth slices of the magnetic field allow separation of high and low frequency anomalies; such as the east-northeast-trending Limpopo dyke swarm of Karoo age.The information obtained from modelling, derivative maps and depth slicing suggest a trough-shaped configuration for the MGB, which is consistent with other known greenstone belts on the ZC and elsewhere. This information is consistent with an intracratonic, extensional rift environment for emplacement of the greenstone belt. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.