Abstract

A backarc basin represented by a mafic/ultramafic magmatic ophiolitic sequence has been discovered first time within Vietnam territory. Backarc basin/forearc basin and other features of a convergent tectonic system are being considered as a location of the two geological blocks that almagamated together and preferred as a geological suture. The middle Triassic suture resulted from the welding of the Indochina and Sibumasu blocks has been studied in details and traced from northen Thailand as Nan-Attaradit suture southward to Cambodia as Sra Kaeo suture. After a gap comparable to the territory of Vietnam it reappears in the northern Malaysia and being recognized as Bentong-Raub suture. With this new discovery of a back arc basin of this suture system located within Vietnam, the complete geographical location of the suture between the Indochina and Sibumasu block has been clearly verified and would be valuable information for geological studies in the area.