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Mpinge section – Exposures of the Upper African Surface, Chikonyora hill

At this stop (in the axis of the Great Dyke towards the northern end of the Mpinge section) can be seen the principal regolith stratigraphy of the Upper African Surface exposed around and above old chromite workings on the southern slopes of Chikonyora hill (1729m). 
 
On the way, after the turn-off from the Mvurwi - Guruve tarred road, and to the right of the dirt road, look out for soil-mining areas and the mill and slimes dam of the old Mpinge eluvial chromite operation (1970s); also a good example of a butte (isolated hill with steep sides and a flat top similar to

Inyantue Formation paragneisses, and Pb claims near Elbas Mine

Exposures of isoclinally folded Inyantue Formation paragneisses in the Inyantue River, near Elbas Pb Mine. The gneisses were interpreted as metamorphosed argillaceous sediments and greywackes Lockett, 1979a,b). These gneisses are also invaded by tourmaline-bearing muscovite pegmatites. Alongside the dirt track on the far side of the Inyantue River, there are prospecting pits dug for argentiferous galena, which was mined at the Elbas Mine some 2 km away.

Mtshingwe Dyke View

The dominant feature of the view is the distant peak of the uppermost ironstone of the Bend Formation known as Mberengwa. The smaller “false” peak to west is one of the lower ironstones which cap the ultramafic to mafic lava sequence constituting the Bend Formation. The Peak marks the axis of a steeply plunging, NE trending syncline which affects all formations up to the lower parts of the Zeederbergs.

 

Above the Bend Formation is a locally developed conglomerate and agglomerate of the Koodoovale Formation, which is unconformably succeeded by the upper greenstones.

 

View of Chikonyora Ridge, Mpinge Section

A road-side stop between Mvurwi and Guruve to view the ridge of Chikonyora hill from the west side.

Note the following:

1.       This stop shows, in the distance, the (several tens of metres) thick, wooded silica cap of the Upper African Surface on the ca. 3km-long Chikonyora ridge with intermittently exposed cliffs of horizontally-fractured serpentinite at a lower elevation. The ridge is terminated at its northern end by the north northeast-trending, dextral Gurungwe fault.

Field Guide:-

View of Nyamaneche Hill, Horseshoe Section

A road-side stop between Mvurwi and Guruve to view Nyamaneche hill from the west side.

 

Note the following:

1.       This stop shows, in the distance, Nyamaneche hill at the southern end of the Horseshoe section which is offset from the Mpinge section by the Gurungwe fault.

2.       Nyamaneche hill is a rounded serpentinite massif with intermittently exposed cliffs at elevations of ca. 1640m beneath a tree-less silica cap of the Upper African Surface.

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).

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