FACIES DETERMINATION OF Mg-BREARING CARBONATES, A CASE STUDY FROM GUNUNG BODAS, CIAMPEA, BOGOR

PROCEEDINGS PIT IAGI RIAU 2006
The 35^th IAGI Annual Convention and Exhibition
Pekanbaru – Riau, 21 – 22 November 2006

FACIES DETERMINATION OF Mg-BREARING CARBONATES, A CASE STUDY FROM GUNUNG BODAS, CIAMPEA, BOGOR

Adam D. Zeiza¹ , Heri Tanjung¹ , Krishna P. Laya^1
1Department of Geology, Padjadjaran University
ABSTRACT

The observed area is the limestone member of Bojongmanik Formation and it is occurred as lenses within the Bojongmanik Formation which is Middle Miocene in age. It is interesting that limestone from this area has been used extensively in steel industry. Further more it is discovered from the chemical analysis of MgO content.

From the field observation of this limestone hill, the eastern side of the hill is concluded as a reef build up and comprised of a more rigid body of carbonate rather than the western side. The eastern reef build up is considered to be developed in high energy environment and this is assumed to be related with the enriching distribution of MgO from western to eastern side of the carbonate body. The bedding trend with orientation N 265^o E/65^o that occured adjacent to the western side of the first mentioned reef build up give us explanation that the sediment is dumped at the confluence of the opposing sets of waves refracted around the reef front to form less rigid and finer grain carbonate sediment, which in this case is the carbonate on the western side that derived from the the eastern side.

All the statements above are strenghtened by the observation of carbonate body from the eastern part of the area which shows texture of reefal carbonate and finer grain size to the west. In conclusion, the reef build up on the eastern side developed at the seaward and high energy environment and eroded to form another carbonate sediment on the western side.

This study suggest that from the field observation combine with geochemical analysis, Gunung Bodas hill contain sufficient Mg-bearing carbonate which is assumed to be usefull in steel industry as steel fluxing agent for example. By this study, it is expected that the area with sufficient Mg content such as on the western side of Gunung Bodas Hill could be recognized as an eligible source of limestone to be used in steel industry.