Geology and stratigraphy of the Sri Racha area, Chonburi Province, Eastern Thailand

Abstract

The Sri Rac ha area in so uth western Chonburi provi nce is underlain by late Palaeozoic sedim ent ary or metasedimentary rocks, Triass ic granit es, and Quaternary sediment s. The late Pala eo­ zoic rocks occupy 30 percent of the western portion of th e area while gran ites dom in ate the eastern portion and underli e approximately 20 percent of th e area. The late Palaeozoic rocks are beli eved to be of Permi an and Carboniferous age and poss ibl y as old as Devoni an. The Carboniferous rocks are Jo wgrade metamorphics consistin g of both foliated and non­ fo li ated varieties. They are d ivided int o 3 dist inctive uni ts, in order of descendin g age, namely in ter­ bedded schi st and quartzite, quartzite, and metacarbonate. Afte r correction for possible thjckenin g due to fo lding, th e overa ll thicknes of th ese rocks does not exceed 1,000 m. The Permian rocks are rath e r lim ited in distribution, comprisin g less than 50 m of clastic and non-clastic rocks . Foraminifera found in th e li mestone in dicate a Permian age. The late Palaeozoic sedimentary rocks have been fo lded. The fo ld is interpreted to be a westerly­ dipping overturned anti c line. It i located principall y in the western and central portions of th e area. ln d1 e northeastern porti on th e area is intruded by fi ne to coarse-grained granites.