Basement characteristics along South West Indian Margin

Abstract

Results from detailed analyses of multi-channel seismic reflection data in association with gravity anomalies and lithology data from drilled holes are used to find out the basement structure in the vicinity of the Laccadive Ridge and Laccadive basin along southwest Indian margin. Morphology and seismic interpretation results show the basement in the study area having faulted blocks with horst/graben pattern, and there are basement highs parallel to the coastal line. While the margin highs are sediment deprived, thick sediments are observed in surrounding areas of the margin highs, with thickness up to 2-3s (TWT), and these sedimentary layers usually pinch out suddenly at the lower wall of steep normal faults. A thin layer of sediments is observed on the Laccadive Ridge in this region which has several small ridge peaks (distributed along ridge extension direction), that sometimes outcrop the seafloor. The basement ridge peaks are usually several thousand meters wide, and show obvious high abnormal gravity anomaly. The basement in the Laccadive basin is highly faulted, and appears to has evolved as stretched margin. Key words: South western continental margin of India, Laccadive ridge, Laccadive basin, seismic interpretation, gravity anomaly, seaward dipping reflector