'n Petrogenetiese studie van 'n gedeelte van die Namaqualandse Metamorfe Kompleks langs die Oranjerivier tussen Ramansdrif en Homrivier, Warmbaddistrik, suidelike Suidwes-Afrika/Namibië

Abstract

Abstract provided by author:

Two metamorphic events (mostly isochemical), a regional progressive event and a later retrogressive event, weredistinguished. Only slight titanium enrichment is suspected during metamorphosis, with metasomatic alteration in the shearzones

The deformation history of the area under investigation seems to be as follows: D1 - F1-folding; D2 - F2-folding; D3 - Groothoek thrust; D4 - F3-folding; D5 - Tantalite Valley megashear zone caused rotation in the northern part of the study area in an easterly direction (clockwise); D6 - North-south shears (cut through the foliation as rotated by the Tantalite Valley megashear zone); D7 - West-northwest shears (cut through the north-south shears); D8 - Northeast-southwest shears (Jakkalswater shear seems to be the youngest structure)

The metavolcanites of the Haib Subgroup - Orange River Group are calc-alcaline rocks which are associated with a volcanic arc. These metavolcanites were intruded by the granitoids of the Vioolsdrif Suite during subduction from the south. The Houms-Revier Suite however, is a younger granite which originated as a within plate granite

Two metamorphic events (mostly isochemical), a regional progressive event and a later retrogressive event, were distinguished. Only slight titanium enrichment is suspected during metamorphosis, with metasomatic alteration in the shear zones