Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
A vertical transition from carbonates to iron formation in the Griqualand West sequence from Finsch mine
Thesis (M.Sc.) -- University of Stellenbosch, 1997.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2012
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614101628256257 |
|---|---|
| access_status_str | Open Access |
| author | Lamprecht, Dirk Ferdinand |
| author2 | Hallbauer, D. K. |
| author_browse | Hallbauer, D. K. Lamprecht, Dirk Ferdinand |
| author_facet | Hallbauer, D. K. Lamprecht, Dirk Ferdinand |
| author_sort | Lamprecht, Dirk Ferdinand |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (M.Sc.) -- University of Stellenbosch, 1997. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/55409 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:41.344Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/55409 A vertical transition from carbonates to iron formation in the Griqualand West sequence from Finsch mine Lamprecht, Dirk Ferdinand Hallbauer, D. K. Halbich, I. W. Stellenbosch University. Faculty of Science. Dept. of Earth Sciences. Geology, Stratigraphic -- Precambrian Carbonate rocks Iron Transition metals Dissertations -- Geology Thesis (M.Sc.) -- University of Stellenbosch, 1997. The open cast Finsch diamond mine lies near Lime Acres, approximately 40km south of Danielskuil, in the Northern Cape (Fig. I , p2a). Fresh unaltered banded iron formation rocks of the Kuruman Iron Formation in the Asbesheuwels Subgroup, and the underlying limestones of the Gamohaan Formation in the Campbellrand Subgroup, as well as a gradual transition between the two types, are exposed in the mine. Several micro-facies were identified in the Finsch transition zone, viz. carbonaceous limestones with contorted algal mats, black shales, various mudstones and cherts, stilpnomelane lutites, as well as Fe-carbonate, Fe-silicate and Fe-oxide rhythmites. Within the cherts and rhythmites several subgroups exist. The stratigraphic profile at Finsch, based on a lithofacies classification on microband and larger scales, is subdivided from the upper contact of the GamohaanFormation downwards into units A to D, and from the base of the Kuruman Iron Formation upwards into units 1 to 5. Major and trace elements are compared with published analyses of similar BIF facies from boreholes in other parts of the Kuruman Iron Formation, as well as from other Proterozoic, and some Archaean iron formations. Using multivariate techniques the geochemical data representing different rock types in the Finsch profile were devided into meaningful groups. Applying factor analysis to these groups it was possible to interpret the data in terms of the palaeoenvironment, the sedimentary conditions and the inferred source materials. For the Fe-Mg carbonates, black shales and shaly carbonates, a shallow water microbial environment is envisaged. Clay minerals from the black shales and mudstones were apparently derived from a felsic source, or from intermediate alkaline igneous rocks. Si was rhythmically deposited by pH changes, while Fe-precipitation was slowed down by increased mud deposition and intermittent ash-falls. The stilpnomelane lutite composition suggests a provenance alien to all the other mineralogical facies, and could have been linked to calcalkaline, or a distant acid to intermediate volcanic source. Palaeoenvironmental factors also had an influence on the composition of stilpnomelane lutites. Although free Fe2+ was probably not available in early Proterozoic times, the deeply weathered palaeosols, together \\·ith the proliferation of algae in water saturated soils, allowed Fe to be produced and carried in a colloidal form. A sluggish surface run-off from a nearby lowlying hinterland such as a komatiitic province provided enough Fe to uphold BIF precipitation in a confined very quiet lagoonal environment with mixed waters. Sporadic volcanic ashfalls interrupted the biochemical/chemical precipitation. Masters 2012-08-27T11:37:02Z 2012-08-27T11:37:02Z 1997 Thesis http://hdl.handle.net/10019.1/55409 en_ZA Stellenbosch University 136 leaves : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Geology, Stratigraphic -- Precambrian Carbonate rocks Iron Transition metals Dissertations -- Geology Lamprecht, Dirk Ferdinand A vertical transition from carbonates to iron formation in the Griqualand West sequence from Finsch mine |
| title | A vertical transition from carbonates to iron formation in the Griqualand West sequence from Finsch mine |
| title_full | A vertical transition from carbonates to iron formation in the Griqualand West sequence from Finsch mine |
| title_fullStr | A vertical transition from carbonates to iron formation in the Griqualand West sequence from Finsch mine |
| title_full_unstemmed | A vertical transition from carbonates to iron formation in the Griqualand West sequence from Finsch mine |
| title_short | A vertical transition from carbonates to iron formation in the Griqualand West sequence from Finsch mine |
| title_sort | vertical transition from carbonates to iron formation in the griqualand west sequence from finsch mine |
| topic | Geology, Stratigraphic -- Precambrian Carbonate rocks Iron Transition metals Dissertations -- Geology |
| url | http://hdl.handle.net/10019.1/55409 |
| work_keys_str_mv | AT lamprechtdirkferdinand averticaltransitionfromcarbonatestoironformationinthegriqualandwestsequencefromfinschmine AT lamprechtdirkferdinand verticaltransitionfromcarbonatestoironformationinthegriqualandwestsequencefromfinschmine |