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THE VOLCANIC DEPOSIT WEATHERED PRODUCT IN JATINANGOR AREA, WEST JAVA Raden Irvan Sophian; . Abdurrokhim; Iyan Haryanto; . Hendarmawan
Bulletin of Scientific Contribution: GEOLOGY Vol 15, No 2 (2017): Bulletin of Scientific Contribution GEOLOGY
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1242.17 KB) | DOI: 10.24198/bsc geology.v15i2.13396

Abstract

ABSTRAKPembangunan di Kawasan Jatinangor dalam beberapa waktu ini telah mengalami perkembangan yang cukup pesat. Jatinangor adalah daerah baru yang dikembangkan untuk Pendidikan dari beberapa kampus seperti Unpad, ITB, IKOPIN, dan IPDN. Hal ini menyebabkan peningkatan jumlah penduduk tiap tahunnya dan juga menyebabkan berkembangnya infrastruktur untuk mendukung kegiatan Pendidikan di daerah ini. Untuk mengetahui hambatan dan menghindari terjadinya bencana alam di masa depan, maka harus dipahami perilaku tanah permukaan sebagai pondasi bangunan berbagai sarana prasarana. Metode penelitian meliputi pemetaan geologi teknik, pengambilan sampel tanah tidak terganggu, uji tes pit, analisis sifat petrologi atau batuan. Kondisi Geologi daerah ini terdiri dari produk vulkanik muda yang tidak terpisahhkan, yang terdiri dari breksi tufan, tuf, lahar, tuf lapilli, dan abu vulkanik yang berumur kuarter (kurang dari 2 Ma). Kondisi geomorfologi daerah ini terdiri dari dataran hingga perbukitan landai di selatan Gn. Manglayang. Berdasarkan hasil penelitian, kawasan Jatinangor memiliki distribusi tanah terdiri dari lanau hingga lempung berplastisitas tinggi (MH dan CH). Kondisi ini menyiratkan produk vulkanik yang tidak terkonsolidasi dan tanah residu semi-konsolidasi sebagai produk pelapukan dari ash dan alterasi dari tuff. Kata Kunci: Jatinangor, Sifat Fisik Tanah, Tuff, Material Vulkanik Muda belum Terpisahkan ABSTRACTThe development of jatinangor area in recent time has experienced a very rapid development. Jatinangor is the new location for Education area from several campuses such as Unpad, ITB, IKOPIN, and IPDN. This results in an increase in the number of population each year and also led to a growing development of infrastructure to support educational activities in this area. To know the obstacles and avoid the occurrence of natural disasters in the future, it should be understood the behavior of surface soil as the building foundation of various infrastructure facilities. The research method includes engineering geologic mapping, undisturbed soil sampling, test pit, petrologic or rock properties analysis. The geology of this area consists of undifferentiated young volcanic product (Qyu), containing tuffaceous breccia, tuff, lava, lapilli tuff, and volcanic ash. This product is deposited on Quaternary geologic age (less than 2 Ma). The geomorphology of this area consists of plain to hilly land at the south of Mount Manglayang. Result of this study shows that around Jatinangor area the distribution of soils consists of high plasticity silt and clay (MH and CH). This condition implies to semiconsolidated-nonconsolidated volcanic product and semi-consolidated residual soil as the weathering product of ash and tuff alterations. Keywords: Jatinangor, physical properties soil, tuff, undifferentiated young volcanic product
STRATIGRAFI VULKANIK DI LERENG UTARA GUNUNG TANGKUBAN PARAHU, DAERAH CISALAK, KABUPATEN SUBANG, PROVINSI JAWA BARAT Yuyun Yuniardi; . Hendarmawan; Vijaya Isnaniawardhani; . Abdurrokhim; Panji Ridwan
Bulletin of Scientific Contribution: GEOLOGY Vol 17, No 3 (2019): Bulletin of Scientific Contribution : GEOLOGY
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2197.751 KB) | DOI: 10.24198/bsc geology.v17i3.24985

Abstract

AbstrakGunung Tangkuban Parahu adalah gunung api aktif di Provinsi Jawa Barat yang merupakan  fase termuda dari kelanjutan sistem vulkanisme Sunda-Tangkuban Parahu yang memiliki sejarah geologi yang cukup rumit dan komplek, khususnya daerah Cisalak dan sekitarnaya, Kabupaten Subang. Metode Fasies Gunungapi dapat digunakan untuk merekonstruksi peristiwa erupsi yang terjadi masa lampau dan juga dapat digunakan untuk memprediksi arah aliran apabila terjadi erupsi berikutnya. Stratigrafi vulkanik daerah penelitian dapat dibagi menjadi enam satuan yang diurutkan dari muda ke tua, yaitu: Aliran Piroklastik 1  Bukittunggul (Ba1) Holosen; Jatuhan Piroklastik Tangkuban Parahu (Tj) Holosen; Aliran Piroklastik Tangkuban Parahu (Ta) Holosen; Aliran Piroklastik 2 Bukittunggul (Ba2) Plistosen awal; Aliran Lava Bukittunggul (Bl) Plistosen awal; dan Aliran Lava Sunda (Sl) Plistosen tengah. Setelah dilakukan analisis fasies diperoleh fasies dengan endapan paling muda yang memiliki material berupa konglomerat dan fasies debris flow, pada fase selanjutnya didapatkan fasies endapan jatuhan piroklastik, kemudian dilanjutkan dengan fasies aliran prioklastik atau ignimbrit, dan fasies berikutnya adalah berupa block dan ash deposit, serta fasies terakhir dengan meterial tertua yang berlitologikan lava adalah fasies lava koheren. Dampak erupsi berupa aliran lahar, awan panas, dan material jatuhan yang terjadi di masa lalu masih sangat mungkin terjadi pada masa yang akan datang. Katakunci: Tangkuban Parahu, Fasies Gunungapi, Erupsi. AbstractTangkuban Parahu Volcano is an active volcano in West Java Province which is the youngest phase of the continuation of the Sunda-Tangkuban Parahu volcanism system which has a fairly complex and complex geological history, especially the Cisalak and surrounding areas, Subang Regency. The Volcanic Facies Method can be used to reconstruct eruption events that have occurred in the past and can also be used to predict the direction of flow when the next eruption occurs. The volcanic stratigraphy of the study area can be divided into six units which are sorted from young to old, namely: Pyroclastic Flow 1 Bukittunggul (Ba1) Holocene; Holocene Tangkuban Parahu (Tj) Pyroclastic Fall; Pyroclastic Flow Tangkuban Parahu (Ta) Holocene; Bukittunggul 2 Pyroclastic Flow (Ba2) Early Plistocene; Bukittunggul Lava Flow (Bl) Early Plistocene; and Sunda Lava Flow (SL) Middle Plistocene. After facies analysis, facies was obtained with the youngest sediment which had material in the form of conglomerates and debris flow facies, in the next phase obtained facies of pyroclastic fall deposits, then proceed with prioclastic flow facies or ignimbrite, and the next facies were blocks and ash deposits, and facies the last with the oldest meterial lava is the coherent lava facies. The impact of the eruption in the form of lava flow, hot clouds, and falling material that occurred in the past is still very likely to occur in the future. Keywords: Tangkuban Parahu, Volcano Facies, Eruption.
Miocene Planktonic Foraminiferal Biozonation for South Sumatra Basin, Indonesia Djadjang Jedi Setiadi; . Hendarmawan; Edy Sunardi; Eddy Arus Sentani; Johanes Hutabarat
Journal of Geological Sciences and Applied Geology Vol 2, No 3 (2017): Journal of Geological Sciences and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v2i3.15615

Abstract

Planktonic foraminifera are widely utilized for marine sediments analysis and recent developments in the geochronology of planktonic foraminifera has improved their values as a tool for sedimentary basin analysis. Assessment on the applicability of the “standard” foraminiferal biozonations (e.g., Bolli, 1966; Blow, 1969; and Postuma, 1971) to the biostratigraphy data of the South Sumatra Basin suggests that the standard zones, which are mostly interval-zones defined by first occurrence events, are hardly applicable to the biostratigraphy data derived from the examination of well-cuttings routinely and continuously used in most sedimentary basin studies in Indonesia.The proposed biozonation in this paper were constructed based on two considerations, i.e. information on the biostratigraphy events as indicated in regional- and global-scale biozonation schemes and the occurrence of foraminifera species in the South Sumatra Basin. The correlation between the proposed zonation and that of Blow’s (1969) scheme suggests that the proposed zonation is basically a Blow’s zonation and, accordingly, may be perceived as a modified Blow’s zonation for South Sumatra Basin.