Abstract:
The Andaman Sea Basin, a well-known back-arc spreading centre and a mature
petroliferous basin, presents a unique and complex scenario for understanding the
interplay
of
sedimentary
processes
and
fault
tectonics
on
seafloor geomorphology evolution, particularly in the eastern shelf region. This study,
using high-resolution 3D seismic data and published exploratory well-seismic
interpretation results, aims to establish a comprehensive stratigraphic framework for the
Tanintharyi region, spanning the Lower Miocene, Middle Miocene, Upper
Miocene, Pliocene, and Quaternary. A submarine canyon system was identified and
investigated along the Tanintharyi continental slope within the East Andaman Basin,
comprising thirteen slope-confined canyons arranged predominantly in an east-west
vertical slope orientation. By analysing seismic reflection features, five distinct seismic
facies have been identified, including basal lag (BL), slump and debris-flow deposits
(SDFDs), canyon confined sheets (CCSs), laterally inclined packages (LIPs), and channel-levees (CLs). The evolution of this canyon system, a vital focus of this study, can be
categorised into three phases based on the morphology and sedimentary
structures observed: canyon initiation, canyon extension, and erosion-sedimentation. The
findings of this study highlight the critical controlling role of faults in canyon evolution,
with the intensity of fault activity displaying a negative correlation with canyon size,
indicating the direct impact of faults on geomorphological changes. In addition, the
geomorphological changes induced by fault activity have resulted in changes in sediment
supply, dispersal, and sedimentation rates, thus significantly impacting the spatial
distribution and dimensions of slope-confined canyons within the East Andaman Basin,
with far-reaching implications.
