Yoga Aribowo
Program Studi Teknik Geologi UNDIP

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GEOLOGI, ALTERASI HIDROTERMAL, DAN MINERALISASI DAERAH ONTO DAN SEKITARNYA, KECAMATAN HU’U, KABUPATEN DOMPU, PROVINSI NUSA TENGGARA BARAT Alif Febriansyah; Yoga Aribowo; Dian Agus Widiarso
Geological Engineering E-Journal Vol 6, No 2 (2014): Wisuda Periode Juli - Oktober 2014
Publisher : Program Studi Teknik Geologi, Fakultas Teknik, Universitas Diponegoro

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Abstract

The use of metallic minerals as raw materials is increasing. Therefore, Indonesia needs to improve metallic mineral reserves for the needs of the country and internationally to explore maximally. This can be done because some parts of Indonesia has huge reserves of metallic minerals.. This research purposed to learn about geological condition of research area involve morphology, lithology, and structure geology, determine alteration zone, and learn distribution of Copper (Cu) that contained in research area.Methodology used in this research is survey method and analysis method. Survey methos by doing surface geological mapping. Analytical method by doing petrology analyisis, petrography analysis, mineragraphy analysis, ASD analysis (Analytical Spectral Device) and sturcture geology analysis.Geomorphology of Onto and the surrounding divided into two units are volcanic very steep hill unit and volcanic steep hill unit. Lithology of research area from older  to younger are tuff, volcanic breccia and breached by porphyrytic andesite. Structure geology in research area in the form of alignment pattern by Dem Map (Digital Elevation Model) in period I direction of structure is west-east and northwest-southeast, whereas in period III direction is north-south. The alteration zone of research area are divided into advanced argillic zone associated with dickite, alunite, and kaolinite minerals; argllic zone associated with kaolinite, palygorskite, and siderite minerals; and intermediet argillic associated with palygorskite and Chlorite minerals. Mineralization of research area is in the form of stockwork and disseminated whick mineralized by pyrite and chalcopyrite as ore mineral. Type of mineralization deposition in research area is Porphyry depoosition type. The value levels of Copper in research area are potential with 1132,79 ppm in tuff unit STA. 33, STA. 35 with value levels of copper is 130,01 ppm, STA. 55 is 390,37 ppm, STA. 56 is 499,9 ppm and STA. 73 is 288,95 ppm.
MIKROFASIES BATUGAMPING FORMASI BULU DAN KUALITAS BAHAN BAKU SEMEN, PADA LAPANGAN GUNUNG “PAYUNG”, KECAMATAN BOGOREJO, KABUPATEN BLORA JAWA TENGAH Ajidityo Putro Fadhlillah; Yoga Aribowo; Dian Agus Widiarso
Geological Engineering E-Journal Vol 6, No 2 (2014): Wisuda Periode Juli - Oktober 2014
Publisher : Program Studi Teknik Geologi, Fakultas Teknik, Universitas Diponegoro

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Abstract

Bulu Formation is one of formation which is sedimented at Tertiary age in The North East Java Basin. Bulu Formation has a lithological composition of limestones with kalkarenit. Bulu Formation is located in Gandu village, Tahunan Village, and the surrounding areas, District Bogorejo, Blora, Central Java, with a particular study on the "Gunung Payung".The study aimed to determine microfasies, facies zone, the relative age, and standart of quality limestone as materials cement on data petrographic, paleontologist, and chemical analysis of limestone samples in the study area. Development of Limestone Bulu Formation Unit microfacies is Bioclast Red Algae Packstone, Bioclast Large Foram Grainstone, Bioclast Large Foram Packstone, Bioclast Planktonic Foram Packstone, Bioclast Grainstone with dolomitation, Planktonic Forams Grainstone, Planktonic Wackstone, Peloidal Wackestone, Packstone with dolomitation, Bioclast Wackstone with microspar, Bioclast Planktonic Foram Wackstone, Bioclast Wackstone with dolomitation, Bioclast Packstone with dolomitation, and Dolomite limestone.Based on the analysis microfacies and foraminifera on the areas of research, there are 3 types of facies zoning based on the model of Wilson (1975), namely: FZ 5 Platform - Margin Reefs, Marine Open 7 FZ, FZ 8 Platform and Interior - Restricted to the age of rocks between N9 to N12 is the Middle Miocene. From the chemical analysis, the potential limestones in the study area can be used as raw material for cement and relationships microfacies analysis and chemical analysis showed that the pitch "Gunung Payung" has a great potential in terms of good quality which is spread of West to East direction. The west area of “Gunung Payung” has better quality of limestone as a raw material for cement than east area.
GEOLOGI DAN ALTERASI HIDROTERMAL DAERAH BANTAR KARET DAN SEKITARNYA, KECAMATAN NANGGUNG, KABUPATEN BOGOR, PROVINSI JAWA BARAT Rizal Dwi Febriyana; Yoga Aribowo; Dian Agus Widiarso
Geological Engineering E-Journal Vol 6, No 1 (2014): Volume 6, Nomor 1, Tahun 2014
Publisher : Program Studi Teknik Geologi, Fakultas Teknik, Universitas Diponegoro

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Abstract

Alteration type at zone of mineralization has its own properties and characteristics that often characterized by the presence of mineral assemblage. The existence of alteration zone occurred due to changes mineral composition of rocks as a result of interaction between fluida of hydrothermal and wall-rocks. Alteration of hydrothermal is very closely linked with mineralization. Mineralization is an assembly and accumulation process of valuable rare minerals in the rocks to form ore deposits. Geological studies related to the characteristics and distribution of alteration and mineralization will assist in the planning of exploration process in the area. The aim of this study is to know the condition of geological research area that include variation of morphology, stratigraphy, structural of geology, alteration types are develop in the study area, as well as the relationship between altered minerals the result of hydrothermal alteration to precipitate epithermal mineralization in the study area.The methods used in this study include field mapping, followed by the method of sample analysis. Method of field mapping carried out by observing the lithology, structural of geology, geomorphology and alteration at Bantar Karet and surrounding areas, Nanggung subdistrict, Bogor Regency, West Java . Method of analysis carried out by analysis of petrology, petrography, mineralgraphy , X - ray diffractometer and the structure analysis of the lineament pattern.Lithology of the research area, beginning Early Miocene with sequence from old to young are unit of laminated tuff, unit of volcanic breccia, unit of andesite lava, unit of lapilli tuff, unit of tuff and unit of dacite intrusion. Structural of geology that develop in the study area are joint, fault that related with the lineament pattern, the main direction are Southwest-Northeast and Northwest-Southeast. Geomorphology of the study area was divided into two : the unit of volcanic landforms are very steep mountains and the unit of volcanic landforms are steep hilly. Alteration zones are contained in the study area, becoming three zones, there are Chlorite ± Smectite Alteration Zone (Propylitic), Smectite Alteration Zone - Kaolinite ± Montmorillonite (Argillic) and Silicified Zones. The mineralization exist are dessiminated Pyrite as ore mineral and oxide mineral such as Hematite which is the alteration of Magnetite and Feromagnesian on temperature conditions < 260oC. Characteristics of deposition types that developed in the study area based on the identification of geology, included alteration and mineralization is low sulphidation epithermal.