Category: Mineral Article
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The modern seafloor topography of the Upper of Thailand is relatively smooth and has little relief, except on the southwestern and eastern-southeastern parts of the area where bathymetric depressions  were encountered The slope gradient has a break point between 12-15 m bathymetric. The delta front in front of the Chao Phraya River mouth is steeper (1:1,500) than in front of the Mae Klong and Tha Chin river mouths (1:2,000).

Interpretation of high-resolution seismic profiles in correlation with borehole data provided valuable information on offshore Quaternary sedimentation, tectonics as well as environmental and engineering geology of this area. Three main seismic units of late Quaternary strata formed during and since the last glacial maximum were identified; Unit 1, the lowermost unit directly overlying undifferentiated older complex sedimentary strata, displays mainly high amplitude aggrading seismic facies and moderate to high amplitude incised valley seismic configurations. It is composed of stiff alluvial silty clay alternated with silty sand and dense channel sand deposited during regression period of late Pleistocene lowst and sea level.