TITLE:
History Woyla Arc of the Garba Complex: Implications for Tectonic Evolution of the South Sumatra Region, Indonesia
AUTHORS:
Idarwati, Heru Sigit Purwanto, Edy Sutriyono, Carolus Prasetyadi, Stevanus Nalendra Jati
KEYWORDS:
Basement High, Crystalline Sequence, Structure, Tectonics
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.12,
December
29,
2021
ABSTRACT: Studies on outcrop-scale structures have been conducted at the Garba
complex. This study aims to add the high-resolution of the South Sumatra region
to reconstruct the structural geology and implications of tectonics for the
region. The study area is commonly referred to as crystalline basement highs
forming the southwestern boundary of the Paleogene South Sumatra basin. The
structures commonly show the NW-SE, NNW-SSE, and ENE-WSW trends. The
methodology used includes field mapping, analysis of Digital Elevation Model
(DEM), petrography, and X-ray fluorescence (XRF). The major fractures include
wrench slip, reverse, and normal faults, while the observable microstructures
comprise pull-apart calcite veins, shear joints, boudins, parasitic folds, and
the augens. The earlier structuring episode was probably related to crustal
extension, perhaps associated with the Paleogene rifting that occurred along
the western margin of Sundaland. In the Late Neogene, tectonic compression took
place in the entire region, allowing inversion of the Pre-Tertiary sequence. As
compression waned in the Pleistocene, extension commenced, and a number of the
ENE-WSW tensional block faulting developed and intersected the older NNW-SSE
alignments. It is important to note that the latest tectonic event in
conjunction with deep erosional denudation had likely exhumed the terrain and
eventually shaped the present-day fractured and rough landforms in the study
area.