Abstract

• The Pane Chaung Formation exposes at the eastern part of the Indo-Myanmar Range. It overlies on the Kanpetlet Schist and underlies by ophiolites. The present study intends to petrography and whole rock geochemistry for tectonic and provenances of this formation. Thirty samples of sandstone were collected from Kalay-Tiddim Road, Webula Section and Gangaw Section along the eastern IndoMyanmar Range that were made thin sections for petrographic study. Sixteen sandstones samples were collected for whole-rock major and minor oxide analyses. This formation consists predominantly of turbidite sandstones, graywacke, mudstone and shale. Graywacke, sandstone and shale interbedded units are dominant. The Halobia sp. is found at the Kalay-Tiddim Road that indicated the Triassic depositional age and deep water condition of salted Tethys Sea. The sandstones are composed of a detrital framework of angular to subangular, poorly sorted sand-sized grains associated with high matrix. The petrographic characters show the lithic wacke or greywacke. In the chemical composition, the SiO2/Al2O3 ratio ranges from 1.97 – 7.943 and Al2O3/SiO2 also ranges from 0.163-0.559. The Na2O/K2O ratio range from 1.01- 23.09 and K2O/Na2O range 0.228- 2.619. The geochemical characters indicate that the sandstones are wacke to greywackes. These chemical data show the tectonic environment of active continental margin to oceanic island arc. Their source rocks indicated by chemical data are acid to basic igneous rocks. So, these turbidite sandstones may be deposited at trench near the collision-subduction boundary of southern Asian margin during the closing events of Meso-Tethys at Triassic Period.