Title:

Downward-facing structures in the Khomas Trough of the Damara Orogen, Namibia

Publication Year:
1989
Abstract:

The Khomas Trough of the southern Damara Orogen comprises Upper Proterozoic Kuiseb Formation schists which have undergone prograde regional metamorphism and polyphase deformation. Bedding is easily identifiable and graded units allow younging to be readily determined. Three phases of deformation have been distinguished. Downward-facing D2 structures are documented from three localities about 5 km north of the Matchless Member amphibolite. Both synformal anticlines and antiformal synclines are recorded based on bedding - cleavage relationships. This contrasts with the usual upward-facing structures recognized elsewhere in the Khomas Trough. The downward-facing sequence appears to be related to a major thrust zone, which indicates that thrusting was pre- and syn-D2 phase in this area. Additional evidence for a D1 phase of deformation occurs in the form of an s1 metamorphic banding cleavage and early quartz-veins and calc-silicate layers are folded by D2 . The occurrence of the D1 deformation event implies a protracted deformational history in this part of the Khomas Trough which can be correlated with the D2 event in the Central Zone represented by recumbent, south-easterly verging and locally downward-facing D2 folds.

Publication Title:

Communications of the Geological Survey of Namibia

Publisher:
Geological Survey of Namibia
Volume:
5
Pages:
55-60
Item Type:
Journal Article
Language:
en
Keywords:

EIS custom tag descriptions