Geological, Geomechanical and Geochemical Analysis on Claystone Of The Warukin Formation

Abstract This study was conducted to determine the characteristics of Warukin claystone by carrying out 3G approach (geology – geomechanics and geochemistry). The aim of this is to provide the latest information on characteristics of Warukin claystone which may later be used for various purposes. Results of the study showed that the provenance of Warukin claystone was from recycled orogen. This was corroborated by the geochemical data which stated that the claystone was composed by clay-sized quartz minerals. Clay-sized quartz minerals indicate that there has been a long process of transport and weathering of the quartz minerals that have high resistance according to the Goldich series, until they become clay-sized. This finding has changed the paradigm so far that says that the Warukin claystone is composed of clay minerals, which is actually composed of clay-sized quartz minerals. The other geochemical data result is the absence of minerals from volcanic rocks that appear at the beginning of the Bowen series, which have fragile property. As a result of the recycled process, the fragile minerals were not found in claystone of the Warukin Formation. Mg is the fragile element that was not found and the mineral is an element binding in montmorillonite, so the presence of the montmorillonite in claystone of the Warukin Formation was also not found. Geomechanical data result shows that Warukin claystone had strength of around 100 kPa with internal friction angle of about 14° and cohesion of about 29 kPa. The results of 3G analysis had provided new answers that claystone of the Warukin Formations is composed by clay-sized quartz and the existence of montmorillonite is unlikely to be found in the Warukin Formation. Both of these corroborate the analysis that claystone of the Warukin Formation is from recycled orogen.