Putranto, Sapto
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Quantification Model of Qualitative Geological Data Variables for Exploration Risk Assessment in Prospect Cu-Au Porphyry Deposit Randu Kuning, Wonogiri, Central Java Nurkhamim, Nurkhamim; Idrus, Arifudin; Harijoko, Agung; Endrayanto, Irwan; Putranto, Sapto
UNEJ e-Proceeding 2016: Proceeding The 1st International Basic Science Conference
Publisher : UPT Penerbitan Universitas Jember

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Abstract

Almost geological data variable contain some degree of uncertainty. Most decisions in mineral exploration was based on geological reports, measurements, calculations as well as ignorance of the geological uncertainty underlies all natural risks of the exploration effort. Risks affecting mineral exploration activities, among others caused by several things. Inherent natural variability in the process of geology and geological objects. Uncertainty on the conceptual and models, associated with incomplete knowledge and subjective interpretations of processes and geological objects. Errors can also occur when observing, measuring or evaluating samples or mathematical analysis of geological data. Data from exploration activities, can be grouped into two types of data, namely quantitative data (e g; grade) and qualitative data (geological data). Geological data variables still largely a qualitative data, resulting between some geologists are not infrequent errors of judgment (assessment of subjective data). This leads to misinterpretation of results of exploration that will ultimately impact on the exploration risk assessment. Currently, the quantification of qualitative data variable is one parameter which is becoming a necessity, because it will be easier in terms of interpretation, communication and measurable. Porphyry Cu - Au deposit in the Randu Kuning Prospect, Wonogiri has the characteristic geometry and grade distribution are quite complex. It is characterized by the appearance of some kind of vein and stockwork with different characteristics. Quantification of geological variables will result in a value that allows the quantification in quantifying exploration risk. For quantitative variables data (grade) using geostatistical methods, while for qualitative variables geological data using canonical correlation and multivariable regression.
HYDROTHERMAL ALTERATION AND VEIN TYPES OF THE RANDU KUNING PORPHYRY CU-AU DEPOSIT AT SELOGIRI AREA, WONOGIRI Sutarto, Sutarto; Idrus, Arifudin; Putranto, Sapto; Harjoko, Agung; Setijadji, Lucas D; Meyer, Franz M; Danny, Rama
Buletin Sumber Daya Geologi Vol. 9 No. 1 (2014): Buletin Sumber Daya Geologi
Publisher : Pusat Sumber Daya Mineral Batubara dan Panas Bumi

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Abstract

Many Tertiary hydrothermal altered dioritic composition intrusive rocks were found at the Randu Kuning  area and its vicinity, Selogiri, including hornblende microdiorite, hornblende-pyroxene diorite and quartz diorite. The hydrothermal fluids which responsible for the alteration and mineralization at the area is associated with the occurence of the horblende microdiorite intrusion.The alteration zone at the Randu Kuning area and its vicinity can be divided into several hydrothermal alteration zones, such as potassic (magnetite-biotite-K feldspar), prophyllitic (chlorite-magnetite-epidote-carbonate), phyllic (quartz-sericite-chlorite) and argillic (clay mineral-sericite). The alteration pattern in the Randu Kuning porphyry Cu-Au deposit is tipically a diorite  model characterising by the domination of  potassic alteration and prophyllitic zone. Phyllic and argillic alteration types are  restrictive found within the fault zones.A lot of porphyry vein types were found and observed at the Randu Kuning area, and classified into at least seven  vein types.  The paragenetic sequence of those veins from the earliest to the latest respectively are 1). Magnetite-chalcopyrite±quartz-biotite veinlets, 2). Quartz±magnetite (A type) veins, 3). Banded/Laminated quartz-magnetite (M type) veins, 4). Quartz±K feldspar (B type)veins, 5). Quartz  with thin centre line sulphide (AB type) veins, 6). Pyrite±chalcopyrite (C type) veinlets, and 7). Pyrite-quartz+chalcopyrire+carbonate (Dtype) veins. Gold and copper mineralisation  of the Randu Kuning Porphyry Cu-Au deposit, mostly related to the presence of quartz veins/veinlets containing sulfide i.e. Quartz  with thin centre line sulphide veins, Pyrite±chalcopyrite veinlets, and Pyrite-quartz+chalcopyrire+ carbonate veins.