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Structural features of Shamvaian Metasediments, Glendale

Where the main road crosses the Mazowe River, There is an excellent exposure of Shamviain metasediments (1a - S17.481002, E30.985577) The rocks, mainly a metagreywacke, show well developed foliations. Deformation increases in a northerly direction, to the sheared contact with the Glendale Pluton (not exposed) (1b - S17.480267, E 30.984390). It is a favourite site for teaching students to take basic structural measurments.

Deweras Aeolianites

Large-scale  planar  crossbedded  arkosic  sandstones of  the Deweras Group  display small-scale features that are diagnostic of aeolianites, including em-scale inversely-graded ripple-cross-laminated "subcritically-climbing translatent strata" (Hunter,  1976),  wedge-shaped  massive grainflows (avalanche  deposits),  and  pinstripe lamination. These are among the oldest authenticated aeolianites in the world (Master, 1995).

View of The Upper and Lower African Surfaces, Mvurwi Section

A road-side stop between Mvurwi and Guruve to view the topography of the Mvurwi section from the south side.

 

Note the following:

1.       On the left is the markedly planar Lower African Surface dominated by a dissected mesa terrain at a cliff-top elevation of ca. 1525m.

Ngulube Kimberlite, Mphoengs

The Ngulube kimberlite was discovered in 1998 by aeromagnetic survey by Debeers Zimbabwe. It is intruded into the Zimbabwean Archean craton a few kilometres from the Botswana border. Surface exposure of the kimberlite is poor, however, the central parts are presently exposed by trenching and shafts. Its mineralogy is typical of Group I kimberlites including abundant macrocrysts of olivine, picroilmenite, Cr-diopside, pyrope garnet; phenocrysts of olivine and microphenocrysts of spinel. Notably phlogopite is present though not abundant.

Ripple Creek Iron Ore Deposit

The Ripple Creek orebody lies near the base of the western limb of the Lannes Sedimentary Formation and is separated from the underlying lavas of the Ingwenya Formation only by a thin (± 5 metre) bed of felsitic shales and narrow lenticular horizons of dolomitic limestone.
The Ripple Creek iron ore deposit comprises the thickest portion of a long gossanous orebody that strikes northwest – southeast and forms a part of a 35km strike of gossanous rocks.

Hurungwe Gneiss

The Hurungwe Gneiss,ZMB13/8B, collected on the Karoi-Chirundu road is a biotite garnet granitic gneiss, containing quartz, K-feldspar, plagioclase, biotite, garnet. Biotite schlieren 2-4 mm wide help to define a gneissic foliation in the rock. The zircons have yielded ages of 2020.7 ± 6.6 Ma, which is regarded as the age of the intrusion (Master et al., 2015). No inherited zircons were found in this sample. 

Stop 1 on attached field guide

Traverse of Mvurwi Section of the Great Dyke to examine the Upper and Lower African Surfaces

Field Guide:-

A full-day, circular traverse of part of the Mvurwi section, principally to examine the heavily-eroded Upper African Surface towards the east and the better-preserved mesa terrain of the Lower African Surface towards the west. The route is ca. 6-7km long with a moderate ascent of ca. 300m at the start.

Chewore Dinosaur Footprints

There are 14 footprints of a large bipedal dinosaur in the dry bed of the Ntumbe (locally Mufuraninga) River in the Chewore Safari Area (Tim Broderick, 1985). A small trackway is 218cm long and consists of ten footprints set close to the midline. The average pace length is 24.6cm and average stride length 45.8cm. Height at hip is calculated at 22.5cm. The speed of the dinosaur was calculated at walking pace of ~1.98km/hour. A second theropod trackway (203cm long), the tracks are 7cm long and pace and stride lengths 39cm and 80cm, respectively.

Orpheus Mine

Orpheus Mine lies in the Iron-formation of the western limb of the Redcliff Jaspilite Formation. The ore is a hard, dense, grey haematite enclosed by, and derived from, a finely banded grey and red Iron-formation. It is believed that the ore is of hypogene origin although supergene processes have not been ruled out. The ore has formed by the leaching of silica-rich bands and possible infilling of iron. Faulting of the Iron-formation and associated clastic sediments has taken place and separates the orebody from the nearby Beacon Tor deposit.

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