Bulletin of the Geological Society of Malaysia, Volume 19, April 1986, pp. 515 – 532
Geological Survey Division, Department of Mineral Resources, Rama VI Road, Bangkok 10400, Thailand
Abstract: The Quaternary alluvial and coastal plains in Thailand covered approximately forty percent of the whole area of the country. These deposits are principal areas for the production of rice, the staple food of the country. The capital and major cities are mainly located on these Quaternary sedimentary plains. The Quaternary deposits are also of importance for economic mineral exploration, construction materials, groundwater, for evaluation of land use and rural development planning and also for coastal development projects. A complete stratigraphic sequence of Quaternary age probably developed in the Central Plain and these sedimentary formations can be classified into four distinct categories based on their histories, lithology, morphology, fauna and depositional environments. These are the fluviatile environment, the coastal environment, aeolian deposits and laterite. Block-faulting appear to be controlled by tectonic movements which affected also the changes in base level and erosional processes. These were followed by infilling of Quaternary alluvial sediments into the larger valley basin systems. Changes in climate and environmental processes were involved during these tectonic movements. Aeolian activity possibly occurred during the glacial period which coincided with drier conditions in this region. Weathering in humid tropical climate is generally responsible for laterization. The marine transgression-regression during Late Pleistocene-Holocene is also acceptable according to the available evidences. Quaternary stratigraphy of Thailand is in an embryonic state of development therefore it seems most desirable that attempts to set up local time stratigraphic classifications based on various types of lithogenetic sequences be continued in a variety of geographic areas. Before a valid Quaternary stratigraphy of Thailand can be established, more detail studies together with accurate absolute age determinations are needed.