The Limestone Diagenesis in The Bojongmanik Formation Based on Petrographic Analysis

Abstrak

The Bojongmanik Formation is a deposit belonging to the Banten Block, has an age range from Middle Miocene to
early Pliocene, and is interspersed with sandstone, marl, shale claystone, and limestone (Sudana and Santosa, 1992).
The limestone members of the Bojongmanik Formation are limestones containing mollusks with age equivalent to the
Middle Miocene (Efendi, 1998). This research aims to know the microscopic labeling. This diagenetic process works
on the limestone in the Bojongmanik Formation to know the stages of diagenesis and the relationship between the
diagenetic process and the porosity of the limestone. The method used in this research is petrographic analysis. Based
on the results of research from 15 samples of thin incisions of the Bojongmanik Formation, there are three types of
limestone: packstone limestone, floatstone limestone, and wackestone limestone, which undergo a process of
diagenetic cementation, dissolution, neomorphism, microbial micritization, and compaction. The depositional
environment of the limestone diagenesis of the Bojongmanik Formation is in the marine phreatic, burial, meteoric
phreatic, and meteoric vadose environments. The dominant porosity was found to be vuggy and intraparticle types.
One factor that influences the process of diagenesis is the formation of secondary porosity in limestone. The lower
porosity value indicates that there is a little dissolving effect. The higher porosity value indicates much dissolving in
the phreatic zone.
Keyword: The Bojongmanik Formation, Petrography Analysis, Porosity, Limestone Diagenesis