A preliminary investigation of the waters and bottom sediments in the Malacca Strait and southern portion of the Andaman Sea, made in 1961 by the U. S. Naval Oceanographic Office, resulted in the collection of bottom sediments as well as salinity, temperature, and water transparency observations at 23 stations. Current measurements were made at selected sites for periods of 24 to 36 hours. The Malacca Strait is a narrow, shallow passage between the Malay Peninsula and Sumatra with oceanographic and bottom sediment characteristics closely related to the strong currents, debouching rivers, climatic variation, and the close proximity of bordering land masses. The strait assumed its present configuration as a result of the post-glacial rise of sea level which drowned the Sund Shelf. The strait is located in a typical equatorial climate although the monsoonal effects are not as severe as in the more open neighboring areas. A northwest current flow, essentially tidal, prevails in the strait throughout the year, and is largely responsible for the hydrographic and oceanographic conditions in the area. Surface salinities and temperatures are found generally to be lower than in the surrounding seas. A wedge of cold, high-salinity bottom water extends from the Andaman Sea into the Strait. Bottom sediments primarily consist of muddy sands, with large areas of mud occurring in the vicinity of debouching rivers and in the Andaman Sea Basin. Calcium carbonate, primarily in the form of mollusk shells and foraminiferal tests, and organic carbon are found only in minor am unts in the Strait. Higher concentrations of calcium carbonate generally were associated with the finer sediments of the Andaman Sea, while the higher concentrations of organic carbon were found in the vicinity of debouching rivers. The noncalcareous detrital fraction is dominated by quartz, with minor amounts of orthoclase and plagioclase feldspars. The heavy mineral suite is complex due to the varied geology of the bordering land areas. The heavy minerals present consist primarily of leucoxene, ilmenite, magnetite, biotite, and amphiboles.

End_of_Article - Last_Page 346------------