Part 2 - Eskom
Part 2 - Eskom
Part 2 - Eskom
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ENVIRONMENTAL SCOPING REPORT FOR THE PROPOSED 40MW OPEN CYCLE GAS TURBINE POWER<br />
PLANT IN THE AMERSFOORT AREA, MPUMALANGA<br />
7.1.5. Geology<br />
7.1.5.1. Regional Geology<br />
Bohlweki-SSI Environmental<br />
The majority of the study area is underlain by Karoo Supergroup sedimentary rocks<br />
of the Vryheid and Volksrust Formations of the Ecca Group. These are largely<br />
comprised of sandstone, mudstone, shale, siltstone, and coal seams.<br />
The available geological maps covering the study area did not indicate any major<br />
structural features such as faults or fractures. Limited tectonic activity is recognised<br />
within the study area, and the only evidence of secondary processes is outcrops of<br />
intrusive younger dolerite sills mapped in the Karoo sediments.<br />
Four generations of dolerite intrusions are recognised within the study area, based<br />
on olivine or plagioclase content, alteration, and texture. The intrusive dolerite has<br />
produced large-scale devolatilisation and structural displacement of the coal. These<br />
adverse geological conditions caused the closure of the Majuba Colliery in 1993. The<br />
lithostratigraphy of the study area is presented in Table 7.2 below.<br />
Table 7.2: Lithostratigraphy of the study area<br />
Age Supergroup Group Subgroup Formation Lithology<br />
Jurassic Dolerite<br />
Permian Karoo Ecca Volksrust Mudstone,<br />
siltstone,<br />
shale<br />
Permian Karoo Ecca Vryheid Sandstone,<br />
siltstone,<br />
shale, coal<br />
7.1.5.2. Geology of the farm Roodekopjes 67HS<br />
The general geology of the farm Roodekopjes 67HS from surface downwards is<br />
illustrated in Figure 7.8. The B8 dolerite sill outcrops at surface on the site and<br />
averages in the order of 30m thick. A sandstone and siltstone interval of between 5<br />
and 25m is followed by two to three stages of sill intrusion of the B4 dolerite totalling<br />
approximately 120m in thickness. Below this composite dolerite sill are sequences of<br />
sandstones, siltstones and mudstones containing minor coal seams. The main coal<br />
seams namely the Alfred and Gus seams are at an average depth of 280m below<br />
surface. They total about 5m in thickness with a small parting between them that<br />
thickens and becomes more prominent towards the east.<br />
Below this is a sequence of bioturbated siltstones, sandstone and mudstone with<br />
minor coal seams. The B6 dolerite sill underlies the whole farm. This dolerite has<br />
indurated the coal and the coal seams volatile content is well below the required<br />
average for Majuba. The seam elevation and attitude for farm Roodekopjes is flat<br />
and consistent.<br />
E02.JNB.000308<br />
ESKOM HOLDINGS LIMITED<br />
01<br />
45<br />
08/10/2009