Geological Field Report Of Mazabeko Area

Abstract

In the location of Mazabeko south of KwaZulu-Natal, preserves one the geological stratigraphic units in the world dating 2.5 billion years ago. The type of work carried out at this place was field mapping, aiming to collect and process geological data from a specified area. The goal at the end of field mapping was to establish stratigraphic sequence, recognizing geological structure and also interpret the geology of Mazabeko. Throughout the mapping exercise, many results were obtained, including completion of stratigraphic columns and geological maps.

Geotectonically there are few and observable tectonic features, including faults and folding. Geomorphologically, the area has various meandering streams and alluvium fans. The study area also various small scale folds, faults and fractures. Geologically, the area is very complex and it is highly deformed.

Introduction

The geological stratigraphic unit of Mazabeko forms part of the Pongola Supergroup, deposited on the south eastern side of the Kaapvaal Craton in Swaziland and South Africa. The mapping exercise conducted at Mazabeko took place for two weeks, from the first of July till 14th of July with three distinct groups covering most geological field of the area.

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The topography of the study area consists of more vegetation and it is surrounded by homesteads.

STRATIGRAPHIC SUCCESSION

Ntabamhlophe Formation

The Ntabamhlophe formation contains rare ultramafic volcanic rock known as Komatiite, which occurs in Greenstonebelt, and also the heavily veined volcanic rock. Both Komatiite and the heavily vein volcanic rock are fine-grained, with grain-size ranging from 0.0625mm and below. Certain features are observed on a highly foliated Komatiite, including spinefix texture, irregular fractures and also quartz veins of about 6cm in length (Photo 1, stop 25).

The exposed weathered surface of Komatiite is grey-green in colour, while the fresh surface is green, as a result of serpentinization. Weak secondary foliations on Komatiite are vertical, dipping at an angle of approximately 90. Heavily vein volcanic rock consists of tectonic foliations and randomly orientated quartz veins. It is also veining dark soft material and has an aphanitic texture.

There is an observed contact between diamictite and quartzite, with the bearing of 098. The diamictite has a porphoritic texture and consists of fine muddy matrix. It also consists of different sub-rounded clasts of different sizes, including clasts of quartzite and komatiite. Quartzite clasts range in from 0.5mm to 10mm, whereas the komatiite clasts ranges from 1mm to 32cm. Clasts of komatiite in diamictite, indicates that the diamictite is older than quartzite. The highly foliated diamictite has an orientation of 124/56 north east

Mgeni Formation

This formation consists mainly of fine to medium-grained quartzite, with grain-size ranging from 0.2mm to 2mm. This quartzite is characterized by few sedimentary structures, namely, planar cross-beds, planar laminations, and also the herring-bone cross stratification. Mgeni formation's quartzite has the average orientation of 125/40, dipping in north east direction. The exposed surface of this quartzite is grey in colour, and has few irregular cracks.

Aloe Marlothii Fomartion

The quartzite in this formation has a brown colour on the exposed surface. It tends to have fine to medium grain size, ranging from 0.2mm to 2mm. The planar laminated quartzite consists of ripple marks, indicating agitation by wind or water waves. Other sedimentary structures such as cross-bedding has been observed. This formation has an average orientation of 140/41 north east.

Buffels River Formation

There is an angular unconformity between diamictite and quartzite. The highly foliated diamictite consists of different clasts derived from metamorphic and ingneous rocks, indicating that it is extraformational. It also consist of fine muddy matrix

ACKNOWLEDGEMENTS

Recent mapping exercise at Mazabeko have been carried out by the co-operative efforts of the University of Witswatersrands and the geosciences staff members. We benefitted from the co-operation and assistance of countless individuals, including

I am greatly thankful to the department of Geology and professors (Dr G.Bybee, Dr Z.Jinnah and Dr Robert) for their outmost help and guidance. They were the foundation bricks of this fieldwork in terms of guidance for students and through the understanding of this area. This field work has been a memorable excursion for me in the comprehension enigmatic theoretical knowledge.