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Journal : Bulletin of Scientific Contribution : Geology

KARAKTERISTIK BATUAN METAMORF BAYAH di DESA CIGABER, KABUPATEN LEBAK, PROVINSI BANTEN Aton Patonah; Ildrem Syafri
Bulletin of Scientific Contribution: GEOLOGY Vol 12, No 2 (2014): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (355.497 KB) | DOI: 10.24198/bsc geology.v12i2.8369

Abstract

Metamorphic rocks in Bayah Complex included by Bayah mountain zone. Purpose of this research is to know characteristic of this rock with using petrography methods, that is, identify texture, structure, mineral contain, and metamorphic facies of the rocks. The result showed that kind of the rock is dominated by biotite schist, some actinolite schist, hornblend schist and chlorite schist. Almost all them have retrograde metamorphism, is characterized by biotite altered to chlorite and muscovite, hornblende to actinolite, and actinolite to chlorite. This proses probably associated by uplift processes in Eocene – Oligocene.
EKLOGIT TERUBAH DAN BATUAN ASOSIASINYA SEBAGAI INDIKATOR SUBDUKSI PURBA SELAMA EOSEN ATAS HINGGA OLIGOSEN BAWAH DI SABUK METAMORFIK SULAWESI TENGAH BAGIAN TIMUR - INDONESIA Ildrem Syafri
Bulletin of Scientific Contribution: GEOLOGY Vol 12, No 3 (2014): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (906.641 KB) | DOI: 10.24198/bsc geology.v12i3.8374

Abstract

Eclogite is a metamorphic of rock derived from the continental crust or oceanic crust that can provide important information about the early stages of the orogenic process. In the Sulawesi island, eclogite or eclogite facies known expose in several places (Tectonic Complex of Bantimala, Palu valley and Bongka River Valley). In addition to these locations, eclogite have been also decouvert in the melange complex of Wasuponda. Wasuponda Eclogites shows a different textural and mineralogical composition than Bantimala eclogite or eclogite facies of Palu valley on the response of different processes occured. These rocks formed in a different geological times which provides information about two ancient subduction zones in the western and eastern parts of Central Sulawesi metamorphic belt.This study aims to obtain meaningful information about the chronology of the Sulawesi island in the Cretaceous and post Cretacepous periods. Some selected examples of eclogite and its associated rocks have been observed in petrographic and rock forming minerals of these rocks have been analyzed chemically using Microprobe Camebax and SX 50. The results of chemical analysis allows us to classify minerals appropriately used in the pressure and temperature condition of the rock formation. The maximum pressure and temperature conditions obtained from the application of geotermobarometer is 21.6 kbar for a temperature in 580 °C, while the application Thermocalc program provides pressure with an average of 20.7 ± 2.6 kbar at temperature in 500 ± 29 ° C. The pressure and temperature are very similar to the P-T conditions of eclogite formation of complex tectonic of Bantimala. Taking into account the uncertainty of the values for pressure, then the pressure obtained indicate that the eclogite formation was in depth of 61 to 80 km.Altered eclogite from Wasuponda undergone retromorphose towards the amphibolite - and green schist facies, while in stability field of amphibolite facies, these rocks are associated with garnet quartz, rutile, phengit, epidote schist and garnet, hornblende, quartz, rutile, muscovite, epidote schist and they have emerged to the surface and presented as a component melange of Wasuponda. Pressure and temperature conditions obtained from the study indicates that the direction of the P-T path of Wasuponda eclogite is clockwise. This condition is contrary to the results obtained by Parkinson (1991) of the blue schist and rock associations derived from Melange Peleru.Eclogite from Wasuponda Melange Complex likely originated from the ancient oceanic crust and are classically referred to layer 3 which is expected a gabbroic by composition. Magmatic paragenesis on this rock observed under the microscope are: clinopyroxene, plagioclase and opaque minerals, while eclogitic paragenesis are garnet, omphasite, phengite and rutile. Mineral paragenesis indicating retromorphose stage are calco-sodic amphibole, sphene and plagioclase, and they are present in the matrix.When a rock undergones a retrograde stage (toward the surface), the eclogite experienced an oceanic metamorphism indicated by the presence of edenite, edenitic hornblende, also hematite, quartz and chlorite showing the amphibolitation process, while minerals like zoisite, albite, white mica, calcite and zeolite states sausuritisation process that occured at high temperature and low pressure.
KARAKTERISTIK BATUAN SEDIMEN BERDASARKAN ANALISIS PETROGRAFI PADA FORMASI KALIBENG ANGGOTA BANYAK Novianti Wahyuni Purasongka; Ildrem Syafri; Lia Jurnaliah
Bulletin of Scientific Contribution: GEOLOGY Vol 13, No 1 (2015): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1482.72 KB) | DOI: 10.24198/bsc geology.v13i1.8382

Abstract

Administratively, the research areas included in the district of Semarang, Central Java Province. This research was conducted at Jeragung River with the object of claystone and sandstone. In physiographic, rocks in the study area are in Kendeng Basin, and parts of Anggota Banyak Kalibeng Formation. This study aims to determine the characteristics of sedimentary rocks mainly sandstones, based on petrographic analysis to determine the source of the sediment and diagenesis processes that formed. Based on observations of six sandstone samples from areas of research included in Feldspatic Wacke. Provenance analysis of six samples of sandstone with using Dickinson and Suczek triangles, shows the origin of sediment is arc magmatic. Diagenesis phase which occurs is eogenesis characterized by compacting and leaching, mesogenesis marked by cementation and recrystallization, as well as the replacement and deformation marks telogenesis process.
LINGKUNGAN PENGENDAPAN SATUAN BATULEMPUNG SISIPAN BATUPASIR PADA FORMASI KEREK DAERAH JUWANGI DAN SEKITARNYA, BERDASARKAN KARAKTERISTIK LITOLOGI, ANALISIS STRUKTUR SEDIMEN, DAN KANDUNGAN FOSIL BENTONIK Hana Morina; Ildrem Syafri; Lia Jurnaliah
Bulletin of Scientific Contribution: GEOLOGY Vol 12, No 3 (2014): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1031.812 KB) | DOI: 10.24198/bsc geology.v12i3.8375

Abstract

The research area is located in the Juwangi, Grobogan District, Central Java Province. Geographically located between 110o 44’ 19,536” BT – 110o 49’ 19,5384” BT dan 7o 13’ 53,2704” LS – 7o 8’ 53,2716” LS. Research using the method geological surface mapping. Determination of depositional environment unit based on the characteristic of lithology, sedimentary structures, and benthic foraminiferal. Based on the characteristic of lithology, this unit composed of mudstone and sandstone. Mudstone has a consideralable thickness, as sandstones insert. Sedimentary structures that are found in the form of parallel lamination and cross lamination shows that its transport medium is water. Benthic foraminiferal analysis result indicate that the bathymetry zone is outer neritic. So it can be estimated that the depositional environment of this unit are in the shallow marine.
POTENSI GEOWISATA DI KAWASAN TELUK CILETUH, SUKABUMI, JAWA BARAT Adi Hardiyono; Ildrem Syafri; Mega F. Rosana; Euis Y. Yuningsih; Herry -; Suci Sarah Andriany
Bulletin of Scientific Contribution: GEOLOGY Vol 13, No 2 (2015): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (853.992 KB) | DOI: 10.24198/bsc geology.v13i2.8396

Abstract

Ciletuh be local Geopark since August 2014, and now towards preparing to become a National Geopark. This geopark is proposed by the government of Sukabumi in 2014. Remains of the geology in this geopark is the emergence of ophiolite complex as a result of fossil tectonic subduction between the Eurasian plate and the Indo-Australian Plate at the age cretasius. Geomorphology tectonic activity form the shape known as the Ciletuh amphitheater, and also the unique shapes result of water erosion that formed the rocks that looks into unique shapes like dragon-stone, frogs-rock, buffalo-stone. etc. There is also the conservation of green turtles and other wild animals such as sea eagles, panthers also conservation Raflesia flowers, Cantigi and mangrove forests to support geopark Ciletuh. Geopark Ciletuh can be divided into four complexes, namely Geoarea Tamanjaya, Geoarea Ciwaru-Mount Rhinos, Geoarea Citisuk-Cikepuh and Geoarea Citirem Ujunggenteng.Some programs geotrek made to visit geoarea either road, or by sea with a boat, also made supporting facilities such as hotels, homestays, local guides and signs.
FASIES DAN LINGKUNGAN PENGENDAPAN BATUGAMPING FORMASI PARIGI DI DAERAH PANGKALAN, KARAWANG, JAWA BARAT Yogi Fernando; Ildrem Syafri; Moh. Ali Jambak
Bulletin of Scientific Contribution: GEOLOGY Vol 13, No 1 (2015): Bulletin of Scientific Contribution
Publisher : Fakultas Teknik Geologi Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2353.439 KB) | DOI: 10.24198/bsc geology.v13i1.8384

Abstract

Facies and depositional environments were studied to determine the growth of the carbonate rocks of Parigi Formation in Pangkalan District, Karawang, West Java. The study was conducted at nine outcrops to identify the characteristics of the macroscopic observations. Some thin section of limestone sample was taken at each location of the observations used to make microscopic analysis. Macroscopic and microscopic analysis of twenty one rock sample classified into six facies, namely: coral bafflestone facies, coral bindstone facies, algae - foraminifera packstone facies, foraminifera packstone facies, interbedded wackestone – grainstone facies, and mudstone facies. A composite log created on the outcrops around G.Guha to determine the stratigraphic of Parigi Formation in Pangkalan District. Facies succession in the composite log grouping facies into several depositional facies associations, namely: fore reef facies, offreef slope facies, reef front facies, and reef flat facies. Depositional environments are fore reef and core reef.