.[1] A small-scale steep structure characterised by the rotation of the subhorizontal foliation of the Nababeep Granite Gneiss into subvertical attitude, Klondike, O'okiep Copper District, Namaqualand, South Africa. Pencil for scale.

A steep structure is a unique structural feature found in the O'okiep Copper District (OCD), Namaqualand, Northern Cape Province, South Africa. These structures occur as narrow, east-west trending, antiformal and/or monoclinal zones of high strain characterised by the rotation of regional foliation into subvertical attitude.[2][3] These structures commonly host plug- and dyke-like mafic- to intermediate cupriferous bodies of the Koperberg Suite in their central portions.[4] Steep structures are interpreted to have formed at the same time as the granulite-facies metamorphism during the waning stages of the Namaqua Orogeny.[2][5] Steep structures are also intimately related to megabreccias, a term coined by geologists in the OCD for granite-gneiss and metasedimentary country rocks cemented by granitic material [6]

References

  1. ^ Geology Explainer (23 August 2020). "Geology Facts - steep structures".
  2. ^ a b Kisters, Alexander F. M.; Guy Charlesworth, E.; Gibson, Roger L.; Anhaeusser, Carl R. (1996-06-01). "Steep structure formation in the Okiep Copper District, South Africa: bulk inhomogeneous shortening of a high-grade metamorphic granite-gneiss sequence". Journal of Structural Geology. 18 (6): 735–751. Bibcode:1996JSG....18..735K. doi:10.1016/S0191-8141(96)80008-3. ISSN 0191-8141.
  3. ^ Watkeys, M. K. (1996-06-01). "The Klondike steep structure, Okiep Copper District, South Africa". South African Journal of Geology. 99 (2): 169–183. ISSN 1012-0750.
  4. ^ Clifford, Tom N.; Barton, Erika S. (2012-12-01). "The O'okiep Copper District, Namaqualand, South Africa: a review of the geology with emphasis on the petrogenesis of the cupriferous Koperberg Suite". Mineralium Deposita. 47 (8): 837–857. Bibcode:2012MinDe..47..837C. doi:10.1007/s00126-012-0403-x. ISSN 1432-1866. S2CID 129735687.
  5. ^ Gibson, R. L.; Robb, L. J.; Kisters, A. F. M.; Cawthorn, R. G. (1996-06-01). "Regional setting and geological evolution of the Okiep Copper District, Namaqualand, South Africa". South African Journal of Geology. 99 (2): 107–120. ISSN 1012-0750.
  6. ^ Kisters, Alexander F. M.; Gibson, Roger L.; Charlesworth, E. Guy; Anhaeusser, Carl R. (1998-02-01). "The role of strain localization in the segregation and ascent of anatectic melts, Namaqualand, South Africa". Journal of Structural Geology. Structures and Properties of High Strain Zones in Rocks. 20 (2): 229–242. Bibcode:1998JSG....20..229K. doi:10.1016/S0191-8141(97)00081-3. ISSN 0191-8141.
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