Petrographical, petrochemical characteristics and condition of formation of granitoids in Chau Vien mountains, Long Hai area, Ba Ria – Vung Tau province
Abstract
On the basic of the investigation into materials composition, formation conditions, shows that:
1- Petrographical components consist of: The first phase: biotite granite, hornblende bearing biotite granite, The second phase: small-crystalled granite, and The vein phase are inclusive of aplitic granite and pegmatoid.
2- Most of the rocks are subjected to intensive post-magmatic alteration, mainly albitization and microlinization proccesses. Main mineral components are plagioclase, potassium feldspar, quartz, biotite and little hornblende.
3- The granitoid of Chau Vien mountain belong to calc - alkalin granite, type of I- granite or VAG. Magma were formed at 14,3km in depth at 9620C with pressure of PS 4,48 kbar and crytallised at 10,5 km in depth at 660 - 667 0C with pressure of PS 2,5 - 3 kbar.