| Penulis/Author |
THAWNG LIAN MUNG (1); Prof. Dr. Ir. Sugeng Sapto Surjono, S.T., M.T., IPU., ASEAN.Eng. (2) ; Ir. Salahuddin, S.T., M.Sc., Ph.D., IPM. (3); Dr.Ing. Ir. Donatus Hendra Amijaya, S.T., M.T., IPM. (4) |
| Abstrak/Abstract |
ABSTRACT
Upper Eocene Sedimentary rocks of Yaw Formation comprise of terrigenous sediments predominantly of thickly bedded, planar and trough-cross bedded sandstonealternating with shales and coal seams are well exposed in Tamu Township, Sagaing Region, Myanmar. Geologically, its lies within the Upper Chindwin Basin. The Yaw Formation sandstones were studied with a view to understand the nature of the study area in relation to provenance and tectonic setting. Eight representative samples of sandstone from Yaw Formations were examined for detrital mineralogy, petrology and tectonic implications. Petrographic analysis involves the examination of rock samples in thin section under reflected polarized microscope. Point counting technique was employed and 300 - 350 grains were measured in each thin section. For modal analysis, Qt F L, Qm F Lt diagrams (after Dickison et.al., 1983a) and Q F L, Qm F Lt diagrams (after Dickison and Suczek 1979 as modified by Dickinson 1982, Dickinson et.al.,1982) were used. These sandstones are medium to coarse grained, moderately to moderately well sorted, sub-angular to sub - rounded and of moderate sphericity and composed of several varieties of quartz, feldspar, rock fragments, mica and a suite of heavy minerals. Petrographically, the Yaw sandstones are subarkose and quartz arenite. On the Qm F Lt diagram, the sandstones of Yaw Formation are plot as “transitional continental” and “Recycled orogenic” provenance fields. Volcanic rocks fragments are generally scare in the sandstones the study area.
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