Contact - Great Dyke to Granite
Contact between Great Dyke and country rock granites, striking 022 and dipping 60 degrees East. Mafic intrusion along the contact in places.
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Atlas
Domboshawa
The Chinamora Igneous Complex, some 1 500 sq km in extent, is an area of granitoid rocks north of Harare which is almost completely enveloped by ancient volcanic and metasedimentary rocks of the Harare-Shamva Greenstone Belt. The clear distinction between these two terrains, as one drives north towards Domboshawa, is a change from heavy red-brown loams to pale yellow-grey sandy soils. The plutonic complex is roughly elliptical in shape and it comprises a variety of gneisses, migmatites and granites of different age and composition.
Kaburi anticlinal fold structure
Makuti Group quartzo-feldspathic gneiss.
The Kaburi anticlinal fold structure with axis parallel to the NW regional trend, which can be traced over many tens of kilometres. The strongly deformed alternating lithologies comprising feldspathic gneiss, biotite gneiss, pelitic schist, quartzite, calc silicate rock and amphibolite are sometimes thrown into refolded interference patterns.
Stop 5 on the attached field guide
Porphyritic granite
The outcrop is part of the Chinamora Porphyritic Granite which Baldock (1991) assigned to the Chinamora Igneous Complex. This was first described by Snowden (1976) who recognised some 45 different granitic types and Snowden and Bickle (1976) later grouped these into old gneisses, gneissic granites and late granites. The Chinamora Porphyritic Granite is part of the “late granites”.
Malaputese Group at Gwayi River Mine (dumps around the Adder adit).
The Gwayi River Mine (formerly Gwaai River Mine) was operated by Messina (Transvaal) Development Corporation from 1970 until 1975, when the mine was closed for economic reasons. The mines have been dormant ever since, but since 2010, a Chinese company, Sino-Mining, has been doing exploration in the area.
Charleswood Diamonds
Following discovery of alluvial gold at Tarka Forest in 2004 and subsequent acquisition of a Special Grant over the area by the Zimbabwe Mining Development Corporation, a lot of interest was roused on the gold potential of the Chimanimani area. This resulted in DTZ-Ozgeo, a company specialised in alluvial minerals, securing a Special Grant (SG 4955) in 2007 to explore for gold in an area encompassing Charleswood Farm adjacent to Tarka Forest, about 15 km east of Chimanimani.
Kariba biotite gneiss overlain by basal red mudstone of the Lower Karoo Group
Kariba biotite gneiss at the Nyanyana bridge foundation overlain by basal red mudstone of the Lower Karoo Group.
The Nyanyana River bridge, crossed just prior to passing the turnoff to Kariba Airport, is founded on strongly foliated and folded biotite gneiss. The basal unit to the Karoo Supergroup, as in adjacent parts of Zambia, is a red mudstone with basal conglomerate in places.
Umwindsi Shear Zone
The Umwindsi Shear (Figures 2 and 3) is a major dislocation cutting through the Harare Greenstone Belt and separating the north-trending Passaford Limb from the north-easterly trending Arcturus Limb in the southern part of the Belt. It dies out to the southwest but continues over 90 km to the northeast and north. It is bounded by two zones of intense deformation which are up to 7 km apart and these are more widely spaced where it passes through the Greenstone Belt.
Palaeoproterozoic (ca. 2.03 Ga) granitoid intrusive into the Malaputese Group
This is a K-feldsparphyric porphyritic granite, cut by aplitic dykes. It has a weak fabric. It has yielded a simple population of zircons which give an age of 2.03 Ga (Master et al., 2013a,b)
Marange Diamonds
De Beers discovered the Marange fossil placer diamond deposit in 2003 during the tenure of their exploration licence (EPO 1523) covering the Marange area. The exploration was targeted at discovering kimberlitic diamonds, but the recovery of rounded diamonds in some heavy mineral samples collected from local streams led to suspicions of a secondary source for the diamonds. A search for the possible source led to the discovery of a mineralized conglomerate.
The discovery attracted informal miners from all over the country and abroad.
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