Flower structures in sandstones of the Paleozoic Inkisi Group (Brazzaville, Republic of Congo): evidence for two major strike-slip fault systems and geodynamic implications
View/ Open
Discipline
Earth and related Environmental sciences
Subject
Geodynamics and mineral resources
Audience
Scientific
Date
2020Metadata
Show full item recordDescription
Few studies have reported field descriptions of flower structures associated with strike-slip faults. This study describes and illustrates flower structures near Brazzaville (Republic of Congo) and explains their implication for the tectonic history of the Paleozoic Inkisi Group. Field observations show that the Inkisi Group is affected by two major strike-slip fault systems. The oldest system is dominated by north-northwest south-southeast striking sinistral strike-slip faults and minor east west striking dextral strike-slip faults. The youngest system consists of dominant northeast southwest striking dextral strike-slip faults and minor northwest southeast striking sinistral strike-slip faults. Flower structures within these major strike slip faults show four types of arrangements that likely depend on fault growth, propagation and damage zones: (i) flower structures associated with wall damage zones; (ii) flower structures associated with linking damage zones; (iii) flower structures associated with tip damage zones; and (iv) hourglass flower structures. Paleostress analysis reveals that both major fault systems originated from two differently oriented pure strike-slip regime stress stages. The first stage, which engendered the first major fault system, developed under northwest southeast compression (i.e, s1 = 322°). This phase probably coincided with north south collision in the southern part of Gondwana in the Permo-Triassic and the Late Cretaceous compression times. The second stress stage, creating the second major fault system, developed under east west (i.e, s1 = 078°) compression. This phase is correlated with compression from the east west opening of the Atlantic Ocean in the Miocene times.
Citation
Nkodia, H.M.D; Miyouna, T.; Delvaux, D.; Boudzoumou, F. (2020). Flower structures in sandstones of the Paleozoic Inkisi Group (Brazzaville, Republic of Congo): evidence for two major strike-slip fault systems and geodynamic implications. , South African Journal of Geology, Vol. 123(4), 531-550, DOI: 10.25131/sajg.123.0038.Identifiers
Type
Article
Peer-Review
Yes
Language
eng