Stratigrafi Sikuen Formasi Jatiluhur di Cekungan Bogor, Jawa Barat

Abstrak

ABSTRACT
The Jatiluhur Formation that exposed in the northern part of the Bogor Trough consists of a mixture of carbonate and siliciclastic sedimentary rocks. The very well outcrops are exposed in some parts of the Cipamingkis and Cileungsi Rivers, about 20 km to the northeast from Bogor City. The formation is characterized by mudstone dominated facies that consist of interlaminated siltstones, claystone and thin-bedded sandstones, and locally interbedded with thick-bedded sandstone, thick-bedded limestone, slump deposits, slump scar-fill deposits and channel-fill deposits.
Thick-bedded sandstones and slump deposits common found in the lower part of succession, while carbonate intervals are developed in the middle and upper part of the formation. The formation is interpreted to have been developed during middle–late Miocene in slope and shelf margin settings.
Overall the succession that exposed in both the rivers represent shallowing upward of the formation, which where overlain, in turn, by a deeper succession in the middle part, as a response of single relative sea level fall and rise.

Keyword: Jatiluhur, Stratigraphy, Thick-bedded, sequence

ABSTRAK
Singkapan Formasi Jatiluhur di bagian utara Cekungan Bogor (utamanya pada Sungai Cipamingkis dan Sungai Cileungsi, Bogor) memberikan kesempatan untuk meneliti urut-urutan batuan ini. Formasi Jatiluhur pada daerah penelitian ini disusun oleh batulempung dan batulanau dengan sisipan tipis batupasir halus sampai sedang. Pada beberapa interval juga bersisipan dengan batupasir tebal sampai sangat tebal, batugamping tebal sampai sangat tebal, endapan slump, endapan pengisi slump-scar dan endapan channel.
Sisipan batupasir tebal sampai sangat tebal, endapan slump, endapan pengisi slump-scar dan endapan channel umumnya dijumpai di bagian bawah formasi ini. Sedangkan sisipan batugamping dijumpai di bagian tengah formasi, yang kemudian ditutup kembali dengan perselingan batulempung, batulanau dan lapisan tipis batupasir pada lingkungan yang lebih dalam.
Secara keseluruhan Formasi Jatiluhur dicirikan dengan urut-urutan litologi yang mendangkal ke atas, yang kemudian berubah kembali secara gradual mendalam, sebagai respon dari perubahan turun dan naiknya relative permukaan air laut (fall and rise of relative sea level)

Kata kunci: Jatiluhur, stratigrafi, Tebal sisipan, sekuen