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Abstrak :
Penelitian ini merupakan langkah awal yang terbilang baru di Formasi Jatiluhur, Sungai Cibeet untuk menganalisis proses diagenesis, mengidentifikasi fitur diagenesis dan sejarahnya. Daerah penelitian tersusun oleh batuan silisiklastik berupa batupasir, batulanau, batulempung, terdapat pula batuan bersifat karbonatan. Sebanyak sepuluh sampel dilakukan analisis petrografi untuk menentukan karakterisasi tekstur dan mineralogi batuan. Selain analisis petrografi, analisis SEM dan XRD sebanyak masing-masing tiga sampel dapat digunakan untuk studi diagenesis. Beberapa proses diagenesis seperti kompaksi, sementasi, disolusi, dan penggantian mineral dapat memengaruhi keterbentukan batuan Formasi Jatiluhur. Proses kompaksi menghasilkan kontak antarbutir berupa point, long, concavo-convex, dan sutured serta semen yang ditemukan berupa semen kalsit dan mineral lempung seperti albit, ilit, kaolinit, dan smektit. Mineral kuarsa, mika, dan feldspar mengalami penggantian. Proses-proses diagenesis tersebut mengakibatkan perubahan porositas dari batuan. Tipe-tipe porositas didominasi oleh tipe intergranular dan intrapartikel dengan persentase antara 5-30%. Sejarah diagenesis pada daerah penelitian diawali oleh tahap eogenesis, mesogenesis, dan telogenesis. Dengan adanya pelaksanakan studi diagenesis, maka kualitas reservoar (misalnya) dapat ditentukan. Penelitian ini menunjukan bahwa proses diagenesis mengakibatkan adanya heterogenitas batuan Formasi Jatiluhur di sekitar aliran Sungai Cibeet. ......This research is a relatively new to conduct in the Jatiluhur Formation, especially Cibeet River that aimed to analyse the diagenesis process and identify diagenesis features and its history. The research area is composed of siliciclastic rocks in the form of sandstone, siltstone, and claystone but there are also carbonate rocks. A total of ten samples were subjected to petrographic analysis to determine the characterisation of rock textures and mineralogy. In addition to petrographic analysis, SEM and XRD analysis of three samples each are used for diagenesis studies. Several diagenesis processes such as compaction, cementation, dissolution, and mineral replacement affected the rock formation of the Jatiluhur Formation. The compaction process produced contact between grains in the form of point, long, concavo-convex, and sutured contacts as well as cement found in the form of calcite cement and clay minerals such as albite, illite, kaolinite, and smectite. Quartz, mica, and feldspar minerals underwent mineral replacement. These diagenesis processes resulted in changes in the rock porosity. The types of porosity are dominated by intergranular and intraparticle types with the percentage between 5-30%. The history of diagenesis in the research area began with the stages of eogenesis, mesogenesis, and telogenesis. With the implementation of a diagenesis study, the quality of the reservoir (for example) can be defined. This study shows that the diagenesis process resulted in the heterogeneity of the Jatiluhur Formation rocks around the Cibeet River streams.

Abstrak :
Penelitian terfokus pada Formasi Klapanunggal pada kala Miosen Tengah tersusun atas batugamping yang merupakan bagian dari Cekungan Jawa Barat dan Palung Bogor bagian Utara. Tujuan dari penelitian adalah menentukan karakteristik fasies, lingkungan pengendapan, dan sejarah diagenesis batugamping pada Formasi Klapanunggal, Jawa Barat. Metode penelitian yang dilakukan adalah pengumpulan data dan pengukuran penampang stratigrafi, analisis petrografi, X-ray Diffraction, dan Scanning Electron Microscope. Klasifikasi fasies yang didapatkan dari hasil deskripsi makroskopis dan analisis petrografi sebanyak enam (6) fasies, yaitu Skeletal Wackestone, Skeletal Packstone, Benthic Foram Grainstone, Skeletal Rudstone, Coral Rudstone, dan Bindstone. Kemudian, fasies-fasies tersebut diklasifikasikan menjadi asosiasi fasies berdasarkan makroskopis dan petrografi menghasilkan tiga (3) asosiasi fasies, yaitu Platform Interior (Open Marine), Platform Margin Reef, dan Slope. Selanjutnya, hasil analisis diagenesis dan paragenetik menghasilkan sejarah diagenesis batugamping pada Formasi Klapanunggal secara berurutan, yaitu tahapan eogenetik (marine phreatic dan meteoric phreatic), tahapan mesogenetik (burial), dan tahapan telogenetik (meteoric phreatic dan meteoric vadose). Kemudian, terdapat hubungan asosiasi fasies dengan diagenesis, yaitu fitur sementasi marine lebih intensif pada asosiasi fasies Platform Margin Reef dibandingkan dengan asosiasi fasies Slope dan Platform Interior (Open Marine). Selain itu, pengaruh kompaksi mekanik lebih kuat pada asosiasi fasies Platform Margin Reef dan Slope dibandingkan dengan asosiasi fasies Platform Interior (Open Marine). ......The research focused on the Klapanunggal Formation during the Middle Miocene which was composed of limestone which was part of the West Java Basin and the Northern part of the Bogor Trench. The purpose of this research is to determine facies characteristics, facies association, depositional environment and the history of limestone diagenesis in Klapanunggal Formation, West Java. Research method is data collection and measurement of stratigraphic sections, petrographic analysis, X-ray Diffraction, and Scanning Electron Microscope. The classification of facies obtained from the result of macroscopic description and petrographic analysis as many as six (6) facies, namely Skeletal Wackestone, Skeletal Packstone, Benthic Foram Grainstone, Skeletal Rudstone, Coral Rudstone, and Bindstone. Then, those facies classified into facies association based on macroscopic and petrographic analysis produces in three (3) facies association, namely Platform Interior – Open Marine, Platform Margin Reef, and Slope Furthermore, the results of diagenesis and paragenetic analysis produce a history of limestone diagenesis in the Klapanunggal Formation sequentially, namely the eogenetic stages (marine phreatic and meteoric phreatic), mesogenetic (burial) stages, and telogenetic stages (meteoric phreatic and meteoric vadose). Then, there is a relationship between facies associations with diagenesis, namely marine cementation features are more intensive in the Platform Margin Reef facies association than the Slope and Platform Interior (Open Marine) facies associations. In addition, the effect of mechanical compaction is stronger on the Platform Margin Reef and Slope facies association compared to the Platform Interior (Open Marine) facies association.