- 1*7 - 



Profiles with the electrosonic profiler will he made at 5 knots in the 

 Straits , the Andaman Sea, and the Bay of Bengal. This program, coupled with 

 the sediment programs of Mr. Keller in the Straits and of Mr. Rodolfo in the 

 Andaman Sea, and with the hydrographic, magnetic, gravity, heat prole, and 

 camera operations, is directed toward providing data contrihuting to the 

 solution of several specific problems. In the Straits, the intent is to 

 check on features in a narrow strait which can he traceahle to features on 

 the bordering land. In this case it involves possible projection of the 

 Malayan anticlines and syuelines into the Straits, the possible extension 

 of the large northeastern Sumatra sedimentary basin, and extension of a 

 possible fault marking the eastward margin of the Andaman Sea basin. This 

 fault is traceable to the Irrawaddy delta from northern Burma and marks the 

 eastern limit of the Burmese oil basin. Sediment studies in the Irrawaddy 

 delta are to determine the basinward variations in sediment characteristics, 

 especially clay mineralogy, and for purposes of comparison with the Ganges 

 delta. It is hoped to trace the continuation of the volcanic belt from the 

 delta through the volcanic Narcondam and Barren Islands to the seaward ex- 

 tension of the Barisan Range of volcanoes of western Sumatra. This volcanic 

 ridge at its northern end is covered by deltaic sediments but apparently is 

 the inner volcanic arc of the island arc complex. This ridge will be investi- 

 gated together with the parallel trough just east of" the Andaman and Nicobar 

 Islands. This trough is probably a northern continuation of the inner trough 

 between Sumatra and the offshore islands to the west. At least two profiles 

 will be made across the Andaman- Nicobar Ridge and into deep water to the west. 

 These crossings will provide sediment samples to delineate the contract in 

 sedimentary environment between the Andaman Sea and the open ocean. Rock 

 dredging, bottom photography, electronsonic profiling, echo sounding, and 

 gravity and magnetic measurements will all be utilized in attempting to 

 understand the complex geology of the area. 



Additional projects will include (l) dredging midway between North Andaman 

 and the headland of the Arakan Range, where a few calcareous sandstone 

 pebbles were recovered from grab samples taken by SERRANO in 1961. (2) 

 Sediment sampling across the ridge foraminifera to correlate with the work 

 of Schwager on samples off Car Nicobar Island taken by the Austrian frigate 

 NOVARA in the last century, and (3) sediment sampling in the Gulf of Martaban 

 to permit comparison between Irrawaddy sediments and those from the Sittang 

 and Salween Rivers . 



Delineation of the detailed trackline through the Straits of Malacca and 

 Andaman Sea is not now possible. A tentative trackline will be available 

 only after further discussions with Fisher of Scripps on the results of the 

 ARGO's two crossings of the Andaman-Nicobar ridge in 1962. Three weeks are 

 tentatively programmed for the Malacca Straits - Andaman Sea work, and the 



