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All Journal IJOG : Indonesian Journal on Geoscience Jurnal RISET Geologi dan Pertambangan Jurnal Pengabdian Kepada Masyarakat (Indonesian Journal of Community Engagement) Journal of Geoscience, Engineering, Environment, and Technology Jurnal Geologi dan Sumberdaya Mineral (Journal of Geology and Mineral Resources) Jurnal Geomine Jurnal Geosains dan Teknologi Indonesian Journal on Geoscience Indonesian Journal on Geoscience Journal of Applied Geology Prosiding Seminar Nasional Rekayasa Teknologi Industri dan Informasi ReTII Jurnal Geologi dan Sumberdaya Mineral (Journal of Geology and Mineral Resources)
Anastasia Dewi Titisari
Departemen Teknik Geologi, Fakultas Teknik, Universitas Gadjah Mada, Yogyakarta
Aerospace Engineering Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Environmental Science Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Physics Transportation

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Geologi Dan Mineralisasi Endapan Emas Orogenik Di Gunung Lipan, Kecamatan Rorowatu, Kabupaten Bombana, Sulawesi Tenggara, Indonesia Hidayatullah Hidayatullah; Arifudin Idrus; Anastasia Dewi Titisari
Jurnal Geomine Vol 10, No 3 (2022): Edisi Desember 2022
Publisher : Universitas Muslim Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33536/jg.v10i3.1297

Abstract

The prospect of Gunung Lipan is located in Rorowatu District, Bombana Regency, Southeast Sulawesi Province.  Physiographically it is situated in the Rumbia mountains, which is occupied by the metamorphic rocks of Pompageo complex. The Gunung Lipan is a prospect which has potential to produce gold mineralization in the Rumbia Mountains. However, a detailed research has never been carried out, in which the latest research is still on regional scale. Therefore, this study aims to understand more details about the geological conditions, alteration types and mineralization characteristics of the prospect and its surroundings. The research methods include geological mapping, petrographic analysis to determine type of hostrock, ore microscopy analysis to determine sulfide minerals in rocks/veins, and ore geochemistry to determine metal content in rocks and veins. Gold mineralization in the Gunung Lipan is hosted by mica schist, and controlled by sinistral shear fault in form of shear zone. The fault movement in the field is indicated by the presence of a milonite structure in the rock and the texture of mica fish on microscopic observations. The hydrothermal alteration appears at the study area is a typical type of alteration found in orogenic gold deposits such as silicification, carbonatization, and carbonization, argillic and propylitic. The sulfide minerals of orogenic type of gold deposit occurred in this study consist of stibnite, sinnabar, tripuhyite, pyrite, arsenopyrite, and hematite. Sulphide minerals are present in rocks and veins in disseminated form. Based on the results of geochemical analysis of gold content ranging from 0.005 ppm to 1.25 ppm, high grade gold was found in quartz veins that cross-cut foliation and veins with brecciated texture. Correlation of metallic elements using multivariate statistical methods shows that gold is positively correlated with As, Sb, and Hg, negatively correlated with Ag, and base metal elements (Pb, Zn, and Cu) are not abundant and are depleted when there is an increase in degree of metamorphism, which obviously implies a typical characteristics of orogenic gold deposit.
Genesa Marmer Daerah Mata Wawatu dan Sanggula, Kecamatan Moramo Utara, Konawe Selatan Berdasarkan Karakteristik Tekstur, Struktur, dan Asosiasi Batuannya Muhammad Arba Azzaman; Anastasia Dewi Titisari
Jurnal Geosains dan Teknologi Vol 6, No 1 (2023): Maret 2023
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jgt.6.1.2023.17-26

Abstract

Salah satu daerah penghasil marmer di Provinsi Sulawesi Tenggara adalah Desa Mata Wawatu dan Sanggula, Kecamatan Moramo Utara, Kabupaten Konawe Selatan. Penelitian ini dilakukan untuk menginterpretasi genesa marmer yang meliputi tipe dan fasies metarmorfisme berdasarkan karakteristik tekstur, struktur, dan asosiasi batuannya. Ketiga parameter tersebut diketahui dengan melakukan observasi geologi, deskripsi singkapan dan sampel batuan, dan analisis petrografi. Hasilnya menunjukkan bahwa lokasi penelitian tersusun oleh tiga satuan batuan, yaitu Satuan Marmer, Satuan Filit, dan Satuan Konglomerat dengan struktur geologi berupa kekar, sesar geser sinistral, dan sesar geser sinistral diperkirakan yang terbentuk oleh gaya utama berarah relatif utara timur laut – selatan barat daya. Filit memperlihatkan stuktur foliasi tipe filitik dan tekstur hipidioblastik, kristaloblastik, dan lepidoblastik serta tekstur khusus berupa augen dan mortar. Mineralogi filit terdiri dari kuarsa, muskovit, grafit, klorit, dan mineral opak. Sementara itu, marmer di daerah penelitian menunjukkan struktur non foliasi. Namun, di beberapa tempat marmer menunjukkan retakan–retakan intensif dan struktur syn-genetic berupa perlapisan yang diduga merupakan struktur batuan asalnya, dengan variasi tekstur berupa hipidioblastik, xenoblastik, kristaloblastik, nematoblastik, granoblastik, granuloblastik serta tekstur khusus yang terdiri tekstur augen, saccaroidal, dan mortar.  Komposisi marmer tersusun oleh mineral kalsit, dolomit, kuarsa, muskovit, klorit dan mineral opak. Karakteristik tekstur dan struktur pada marmer serta asosiasi batuan termasuk himpunan mineralnya mengindikasikan bahwa marmer di lokasi penelitian terbentuk oleh proses metamorfisme regional, bersama dengan filit, pada fasies sekis hijau.
Aplikasi Principle Component Analysis dan Directed Principal Component untuk Pemetaan Alterasi Hidrotermal menggunakan Citra ASTER di Kecamatan Kokap, Kulon Progo Bayu Raharja; Agung Setianto; Anastasia Dewi Titisari
Jurnal Geologi dan Sumberdaya Mineral Vol. 20 No. 3 (2019): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v20i3.437

Abstract

Endapan emas di daerah Kokap, Kabupaten Kulon Progo yang berasosiasi dengan endapan tipe epitermal terbentuk akibat adanya proses alterasi hidrotermal. Pemanfaatan data penginderaan jauh untuk pemetaan alterasi telah berhasil dilakukan diberbagai lokasi. Penelitian ini bertujuan untuk mengkaji kemampuan citra ASTER saluran visible near infrared (VNIR) dan saluran shortwave infrared (SWIR) dalam memetakan jenis alterasi menggunakan metode Principle Component Analysis (PCA) dan Directed Principal Component (DPC). Klasifikasi multispektral selanjutnya dilakukan untuk membedakan tipe alterasi hidrotermal menggunakan kombinasi saluran hasil PCA dan DPC. Keberhasilan pemetaan alterasi hidrotermal dievaluasi secara statistik menggunakan confusion matrix. Tingkat akurasi yang dapat diterima adalah sebesar 85% dengan koefisien kappa lebih besar dari 0.8. Hasil penelitian menunjukkan metode DPC memiliki akurasi lebih baik dari PCA dalam memetakan tipe alterasi meskipun tingkat akurasi keduanya dibawah batas yang ditentukan. Saluran ASTER yang paling baik digunakan untuk memetakan tipe alterasi hidrotermal di lokasi penelitian adalah 1, 2, 4, dan 6.
Application of Landsat 8 Image in An Assessment of Hydrothermal Alteration Mapping in Dense Vegetation: A Case Study from Kokap Area, Kulon Progo Agung Setianto; Bayu Raharja; Anastasia Dewi Titisari
Indonesian Journal on Geoscience Vol. 9 No. 1 (2022)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.9.1.45-60

Abstract

DOI:10.17014/ijog.9.1.45-60Several researchers through geochemical analysis have proven the presence of gold mineralization in Kokap, Kulon Progo, as a result of hydrothermal alteration. Alteration mapping with optical remote sensing images in tropical areas is very difficult due to atmospheric conditions, dense vegetation cover, and rapid weathering. This study aims to assess the ability of Landsat 8 images in the mapping of hydrothermal alteration in Kokap, Kulon Progo, with the Principles Component Analysis (PCA) method. Three conventional machine learning methods, including artificial neural network (ANN), maximum likelihood classification (MLC), and support vector machine (SVM) were compared to find an optimal classifier for hydrothermal alteration mapping. The experiment revealed that the MLC method offered the highest overall accuracy. Two alteration zones were mapped, i.e. argillic zone and propylitic zone. The comparison results showed that the MLC classification of band ratio images of 5:2 and 6:7 yielded a classification accuracy of 56.4% and kappa coefficient of 0.36, which was higher than those of other machine learning methods and band combinations. The combination of Landsat 8 with DEM succeeded in increasing accuracy to 59.5% with kappa coefficient of 0.4.
Estimasi Sumberdaya Skarn Logam Dasar Dengan Metode Geostatistik Ordinary Kriging Blok A Ruwai Kabupaten Lamandau Provinsi Kalimantan Tengah Riyadi, Hasan; I Wayan Warmada; Anastasia Dewi Titisari; Arifudin Idrus
Retii Vol 18 No 1 (2023): Prosiding Seminar Nasional ReTII ke-18 (Edisi Penelitian)
Publisher : Institut Teknologi Nasional Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

This research aims to determine the shape of the block model and the distribution of ore deposits and to determine the results of the resource estimation of base metal skarn. Mineral resource estimation reflects the shape and distribution of a mineral deposit so that it can be used as a basis for estimating reserves or mining activities. The data used in this study are the results of exploration drilling, namely collar, assay, survey and lithology. The estimation of base metal skarn resources in this study uses the ordinary kriging method with a block model measuring 10m x 5m x 3m. The results of the estimation of metal skarn resources of Block A Ruwai using the method obtained tonnage for inferred resources of 19,452 tons, indicated 29,542 tons and measured 16,546 tons with an average Pb-Zn content of 10.71%, 10.85% and 11.51%. The estimation results of the ordinary kriging method were compared with the composite data of Pb-Zn content (raw initial data) to determine its accuracy based on cross validation parameters. From the cross validation results, the RMSE (root mean square error) value is 0.40 which is close to 0 (zero), the correlation coefficient (r) is 0.83 and the coefficient of determination (r2) is 0.7 which is close to 1, so the estimation results are considered good enough.
Mineralogical and Geochemical Characteristics of Clays at Godean Hills, Yogyakarta – Indonesia (A Study Case at Gunung Patuk and Gunung Wungkal) Yoellanice, Diory; Titisari, Anastasia Dewi; Setiawan, Nugroho Imam
Journal of Applied Geology Vol 9, No 2 (2024)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.95164

Abstract

Gunung Patuk and Gunung Wungkal are part of the Godean Hills in Yogyakarta, Indonesia. The Godean Hills are isolated hills consisting of a series of hills surrounded by the Young Merapi Volcanics Deposits. A previous study reported that Gunung Patuk and Gunung Wungkal are porphyry andesite – micro diorite intrusions. Both hills are igneous rock intrusion and are found almost perfect soil profiles from the source/parent rock to the A horizon. However, another previous study suggests that at Gunung Wungkal has occurred hydrothermal alteration process. There is still a debate over the genesis of clay in that area, therefore this research needs to be carried out to provide a comprehensive understanding of mineralogical and geochemical characteristics of the clays at that area. The results of petrographic identification on the source/parent rock sample indicate that the rock sample is classified as andesite rock. Meanwhile, the results of mineralogy identification using the X-Ray Diffraction (XRD) method show that almost all types of soil profiles contain illite, kaolinite, and smectite. The calculation results of CIW (Chemical Index Weathering) and CIA (Chemical Index Alteration) values based on geochemical data show that CIW and CIA values increase steadily as they approach the ground surface. Based on the presence of illite (indicates a product relating to the relatively high temperatures) in horizon A with high values of CIW and CIA, therefore it can be interpreted that clay minerals at Gunung Patuk and Gunung Wungkal were the product of superimpose of hydrothermal alteration and weathering processes.
Co-Authors Agung Setianto Anita Yuliyanti Anita Yuliyanti Arifudin Idrus Atmoko, Didik Dwi Atmoko, Didik Dwi Bayu Raharja Bayu Raharja Bayu Raharja Bayu Raharja Cendi Diar Permata Dana David Phillips Didik Dwi Atmoko Didik Dwi Atmoko Hakim, Fahmi Hartono Hartono Hartono Hartono Hidayatullah Hidayatullah Hitznaiti Zaidini' Khul Husna I Gde Budi Indrawan I Wayan Warmada Ilham Dharmawan Putra Kha Yay Oo Koichiro Watanabe Muhammad Arba Azzaman Muhammad Arba Azzaman Myaing, Yu Yu Nugroho Imam Setiawan Nugroho, Yanuardi Satrio Permata Dana, Cendi Diar Phillips, David Pratomo, Septyo Uji Raharja, Bayu Riyadi, Hasan Selma Kurniawati Sia Pamela Dita Yanuardi Satrio Nugroho Yoellanice, Diory Yu Yu Myaing Yunie Wiyasri