Paleontology and Petrology of Late Paleozoikum Age in West Sumatera of Silungkang Formation

Abstract

Carbonate rock revealed in West Sumatra is one of the very old carbonate sedimentary rocks where most of these carbonate rocks have been transformed into metamorphic rocks in the form of Marble, which are still in the form of carbonate rocks which can still show age and depositional environment, whereas in Marble metamorphic rocks no fossils have been found. This paper will discuss paleontology and petrology in the Silungkang Formation which is widespread in West Sumatra. The purpose of this study is to study the recorded geological history of rock samples of Late Paleozoic age by identifying the presence of fossils. The research method is geological field observation and sampling from outcrops, the samples taken were micropaleontology and petrographic analyzes of thin incisions. The results of this study are on carbonate rocks found in the large foraminifera consisting of Fusulina, Fusulinella, Verbeekina, and Loftusia. Sp, Climacumminaantiqua, Bigerina, ProninanElenella, Koskinotextularia.Sp, PaleoeoxtulairaLongiseptata, the presence of fusulinaforaminifera fossils shows evidence of the age of rock formation is Central Pennsylvania to the Late Permian. From the results of the petrological analysis most of the carbonate-derived rocks have been converted into Marble which shows that the metamorphic process has been very intense, occurring at least during the Mesozoic Period to the Cenozoic.