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Journal : Jurnal Geologi dan Sumberdaya Mineral

KONTROL SIRKULASI IKLIM DAN TEKTONIK TERHADAP ENDAPAN SEDIMEN SUNGAI PURBA BERUMUR PLISTOSEN DI DESA MULYASEJATI, KARAWANG DAN CILANGKAP, PURWAKARTA Moechtar, H.; Subiyanto, Subiyanto
Jurnal Geologi dan Sumberdaya Mineral Vol 21, No 2 (2011): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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Abstract

A study on the conglomeratic sandstone and siltstone unit (Qoa) in the Mulyasejati Village (Kabupaten Karawang) and Conglomeratic and tuffaceous sandstone unit (Qav) of Pleistocene age in the Cilangkap Village (Kabupaten Purwakarta) has been carried out. The objectives of this paper are to reconstruct the mechanism of Depositional Period Intervals (DPI) of each lithologic unit. Sedimentological and stratigraphical analyses were carried out in the field based on seven vertical measured section of 1:50 scales. The thickness of the sections range from 1.20 to 7.70 m. Based on the correlation, both of lithostratigraphic units belong to into fluvial systems, and can be divided into four DPI (A to D). The sedimentary facies pattern of each DPI is controlled by the thrust structure, and are shown by stacking channels (FAS) 1 to 4. Whereas, the vertical composition of sediment is controlled by the fluctuation humidity related to climate change following Milankovitch cycles. Changes in the colour and composition of the sediments of the fluvial systems during the depositional processes of DPI A-D, can be interpereted as the result of climate changes. The climate circulations starting from nearly climatic optimum to climatic minimum or even dry.Keywords: facies, fluvial, climate, Interval of Deposition Periods
SEDIMENTOLOGI DAN STRATIGRAFI ALUVIUM BAWAH PERMUKAAN DI PESISIR CIREBON DAN SEKITARNYA Hidayat, Suyatman; Mulyana, Herman; Moechtar, Herman; Subiyanto, Subiyanto
Jurnal Geologi dan Sumberdaya Mineral Vol 19, No 4 (2009): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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Abstract

This study was based on sedimentological analyses of seven boreholes located along the NW to SE traverse, approximately parallel to coastal line of Cirebon. The penetration of the bore head varies from 8 to 13 m. Holocene subsurface of alluvial deposits can be divided into seven environment systems, consisting of Gintung Formation and deposits of offshore, nearshore, beach sand, swamp, channel river, and floodplain. Based on stratigraphic aspects, the succession of that sediments can be divided into three sedimentary intervals (IP I-III). Each interval is typically for environment changes which is controlled by changes of sea level, such as high sea level (IP I), sea level falling (IP II), and low sea level (IP III). The Quaternary dynamics related to environment changes and changes of basin fill were influenced by universal of climatic circulation, regional tectonic, and local of sea level changes. Keywords: Aluvium deposits, sea level, tectonic, climate
KARAKTER WILAYAH GENANGAN LAKUSTRIN HOLOSEN BERDASARKAN ASPEK SEDIMENTOLOGI DAN STRATIGRAFI ENDAPAN RAWA DAN UNDAK SUNGAI (Studi Kasus Geologi Kuarter Daerah Air Molek dan Sekitarnya, Kab. Singingi dan Kab. Indragiri Hulu, Provinsi Riau) Hidayat, Suyatman; Basri, C; Subiyanto, Subiyanto; Mulyana, Herman; Moechtar, Herman
Jurnal Geologi dan Sumberdaya Mineral Vol 19, No 5 (2009): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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Abstract

This study was based on analyses of sedimentology and stratigraphy of nine sediment samples obtained from shallow boreholes. The boring was done of A - B traverse, southwest – northeast direction around Indragiri river, south of Rengat. The study was focus on river channel and lauctrin deposits under the swamp sediments and river terraces as the resent of penetration of the bore head varies from 3.80 to 9.95 m . Based on the correlation of lateral and vertical variation, the stratigraphic succession can be grouped into two depositional interval i.e. depositional interval I & II. (IP.I & IP II). Vertical changes on the lithologic composition can be related to changes on humidity conditions. It is shown from the changes in the character of the facies between lower and upper lacustrine. Changes in basin centre between lower and upper lacustrine environment, as the result of basement movement caused by tectonic activity, impected to up and down movement of the basin floor. Keywords : Quaternary sediments, lacustrine, climate, tectonic
GEOLOGI ALUVIUM DAN KARAKTER ENDAPAN PANTAI/PEMATANG PANTAI DI LEMBAH KRUENG ACEH, ACEH BESAR (PROV. NAD) Moechtar, Herman; Subiyanto, Subiyanto; Sugianto, D.
Jurnal Geologi dan Sumberdaya Mineral Vol 19, No 4 (2009): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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Abstract

The alluvium in the Krueng Aceh valley, suggests that it is deposited in floodbasin, fluvial system, transition, and linier clastic environments. The linier clastic enviroments consists of offshore (Fellp), nearshore (Fedp), beach/ beach-ridge (Fep/ Fepp), and marsh deposits. The research was carried out by surface geological mapping and analysed sedimentology and stratigraphy of ten boreholes trending west-east to southwest and west-east to south. Depths of the boreholes varies from 2.30 to 10 m at elevation of + 0.90 - + 10 m above sea level. Based on correlation of sedimentary environment in the linier clatic environment,sea level changes can be divided into three cycles that were controlled by active tectonic of the Seulimeum fault respectively. Keywords: sedimentology, stratigraphy, alluvium
PERKEMBANGAN LUAS LINGKUNGAN PENGENDAPAN SEDIMEN PLISTOSEN AKHIR HINGGA HOLOSEN DI DATARAN ALUVIAL RENGASDENGKLOK DAN SEKITARNYA, KAB. KARAWANG (JAWA BARAT) Moechtar, H.; Subiyanto, Subiyanto; Samodra, H.
Jurnal Geologi dan Sumberdaya Mineral Vol 21, No 3 (2011): Jurnal Sumber Daya Geologi
Publisher : Pusat Survei Geologi

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Abstract

Study of area development on depositional environments during the Late Pleistocene to Holocene in the alluvial plain of Rengasdengklok surroundings, Karawang Regency (West Java) based on sedimentology and stratigraphy aspects. The study was based on analyses of nine borehole informations obtained along the West to East with the thickness of sediments varied from 6.75 to 10.20 m.Study on Quaternary deposits from boreholes , revealed four depositional environments. These are swamp, floodbasin, floodplain, and river channel environments. Based on correlation of the lateral and vertical variation of the sediment bodies, three Interval of Deposition Periods were recognised. Each of the interval is characterized by increasingly and decreasingly of environments which was controlled by climatic changes and tectonic. The climatic changes were recorded as (1)minimum climate into climatic optimum under warming conditions during deposition of Interval of Deposition Period A into the middle of Interval of Deposition Period B, and (2)optimum climate into climatic minimum under cooling conditions during deposition the middle of Intreval of Deposition Period B into Interval of Deposition Period C. The tectonic activities which controlled the deposition processes were recorded as two stages. These were the change posisiton of river channel deposits 1 to river channel deposits 2 and shifting of river channel deposits 2 into Recent Citarum river (river channel deposits 3).Key words: Sediment, depositional environemnt, climate, tectonic, Rengasdengklok