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- Title
Review and new insights on the significant unconformities related to the strati-structural evolution of NW Sabah within the Dangerous Ground, South China Sea.
- Authors
Das, Prabal Shankar; Choudhuri, Mainak; Zakaria, Noor Liyana; Tengku Hassan, Tengku Mohd Syazwan B; Rudiana, Cecep Wahyu; Mohd Idris, Jamin Jamil B
- Abstract
The NW Sabah Platform and Trough, located within the Dangerous Ground (DG), form the southern conjugate margin of the South China Sea (SCS). Since the Palaeocene, this area evolved through extensional tectonics followed by drifting and finally, collision during the Miocene, resulting in a number of unconformities dividing the sedimentary package into separate tectono-stratigraphic sequences. Available publications were solely based on 2D seismic data, as there was no well penetration. Based on recently acquired 3D seismic and four newly drilled wells, the current article attempts to correlate the different unconformities throughout the area in terms of their tectonic origin and provide an age bracket matching with the regional tectonic evolution. Four major unconformities can be identified from the seismic data, each with distinctive characteristics. From the lowermost, they are the rift onset unconformity (ROU), separating the basement/pre-rift sequences from the syn-rift; the intra-rift unconformity (IRU), separating the syn-rift into early and late syn-rift units; the breakup unconformity (BU), separating the late syn-rift from the post-rift drift sequences and the red unconformity (RU) separating the post-rift drift sequences from the post-drift sequences. Based on regional correlation and analysis from drilled wells, the ROU is approximated at around the Early Palaeocene age; the IRU is sporadically developed around the Middle Eocene age; the BU is dated around the later part of the Early Oligocene age in the study area, while the RU is correlated with the collision of the DG with Borneo and assigned a Middle Miocene age. Between the BU and the RU, there is a carbonate unit that acts as an important environmental and age marker and has been assigned a Late Oligocene-Early Miocene age based on biostratigraphy. Structural analysis of the faults in the basement and BU level indicates a rotation in the stress direction from N-S to NW-SE during the late phase of rifting, corresponding to the opening of the eastern and south-western sub-basin of the SCS.
- Subjects
BORNEO; URUGUAY; MIDDLE age; MIOCENE Epoch; OLIGOCENE Epoch; STATISTICAL correlation; BIOSTRATIGRAPHY
- Publication
Arabian Journal of Geosciences, 2024, Vol 17, Issue 1, p1
- ISSN
1866-7511
- Publication type
Article
- DOI
10.1007/s12517-023-11828-w