Petrography and geochemistry of granitic rocks at Chon Daen and bueng Sam Phan districts, Phetchabun province

Abstract

This study is aimed to investigate the petrography and geochemistry of granitic rocks at Chon Daen and Bueng Sam Phan districts, Phetchabun province. Moreover, the explanation and classification of tectonic setting which related to the occurrence of the granitic rocks are considered. There are 3 locations in the study. The first location is in Dongkui sub-district, Chon Daen district, Phetchabun province. The second and third locations are in Phaya Wang sub-district, Bueng Sam Phan district, Phetchabun province. The distance between second location and third location is approximately 5 kilometers. According to the study results, the granitic rocks at Chon Daen district can be classified into granite, and Bueng Sam Phan granitic rocks can be classified into diorite and quartz diorite. The geochemical result from X-Ray fluorescence spectrometry showed the variation of major oxides content in each rock unit. Granite has higher amount of SiO2 when compared with diorite and quartz diorite. Nevertheless, it contains lower amount of CaO, FeOtotal and MgO compared with Bueng Sam Phan granitic rocks. The alkali oxides (Na2O and K2O) amount are slightly different. Based on the discussion of petrogenesis and tectonic setting, these rock units are geochemically metaluminous originated in Calc-Alkaline to high-K Calc-Alkaline magma series. These qualities are matched with the volcanic arc magmatism. Furthermore, the geochemical evidence indicates these rock units as an I-type affinity. To summarize, these granitic rocks have occurred by the eastward subduction of Paleo-Tethys under Indochina terrane.