Johan Arif, Johan
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The mineralogy of gold-copper skarn related porphyry at the Batu Hijau deposit, Sumbawa, Indonesia Thwee Aye, May; Pramumijoyo, Subagyo; Idrus, Arifudin; Setijadji, Lucas Donny; Imai, Akira; Araki, Naoto; Arif, Johan
Journal of Applied Geology Vol 3, No 1
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2275.214 KB) | DOI: 10.22146/jag.7177

Abstract

Clacic gold-copper bearing skarn in the Batu Hijau porphyry deposit is located in the western part of Sumbawa Island, Indonesia. Skarn mineralizations were found at the deep level of the deposit (-450m to -1050mL) by drilling program 2003. No evidence around Batu Hijau has limestone although most skarn are metasomatiz ed from carbonate-rich rock as limestone or marble. Most skarn-type metasomatic alteration and mineralization occurs at the contact of andesitic volcanic rock and intermediate tonalite porphyry intrusion and within intermediate tonalite in some. Although both endoskarn and exoskarn can be developed, it has no clear minerals to known the endoskarn. Exoskarn is more principle skarn zone. The formation of skarn occurred two min stages: (1) prograde and (2) retrograde. The prograde stage is temporally and spatially divided into two sub-stages as early prograde (sub-stage I) and prograde metasomatic (sub-stage II). Sub-stage I begin immediately after the intrusion of the tonalite stock into the calcium rich volcanic rocks. Then, sub-stage II originated with segregation and evolution of a fluid phase in the pluton and its invasion into fractures and micro-fractures of host rocks developed during sub-stage I. The introduction of considerable amount of Fe, Si and Mg led to the large amounts of medium- to coarse-grained anhydrous calc-silicates. From the texture and mineralogy, the retrograde metasomatic stage can be divided into two sub-stages: (a) early retrograde and (sub-stage III) and (b) late retrograde (sub-stage IV). During sub-stage III, the previously formed skarn zones were affected by intense multiple hydro-fracturing phases in the gold-copper bearing stocks. Therefore, the considerable amounts of hydrous calc-silicates (epidote), sulfides (pyrite, chalcopyrite, sphalerite), oxides (magnetite, hematite) and carbonates (calcite) replaced the anhydrous calc-silicates. Sub-stage IV was coexisting with the intrusion of relatively low temperature, more highly oxidizing fluids into skarn system, bringing about partial alteration of the early-formed calc-silicates and developing a series of very fine-grained aggregrates of chlorite, clay, hematite and calcite.
ANALISIS KANDUNGAN FLUORINE (F) DI DALAM FOSIL TULANG DAN GIGI: KASUS DARI GUA PAWON, SANGIRAN, DAN KALITIDU Arif, Johan; Siregar, Darwin
Forum Arkeologi Volume 27, No 3, November 2014
Publisher : Balai Arkeologi Bali

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1692.585 KB) | DOI: 10.24832/fa.v27i3.30

Abstract

Bones will undergo diagenesis process when buried in soil which will decrease organic content and increase inorganic content coming from outside, such as F (fluorine). This research discusses about F (fluorine) content in fossilized bones and teeth coming from Pawon Cave in West Java, Sangiran in Central Java, and Kalitidu in East Java, which are in situ and not in situ. The content of F (fluorine) in fossilized bones and teeth can be used to determine their origin which are not in situ and lacking of stratigraphy information. The result of this research can be described as follows. F (fluorine) content in materials coming from Pawon Cave are varied. Materials coming from Kalitidu which are in situ have relatively the same F (fluorine) content, while material which is not in situ has the highest F (fluorine) content. Materials coming from Sangiran have different relation between F (fluorine) content and formation age, compared to materials coming from Pawon Cave and Kalitidu, that is the lesser the content of F (fluorine), the older the age of material. One of the fossilized materials, namely the molar of Homo erectus (JA-41), is the youngest tooth fossil of Homo erectus ever found in Sangiran. Tulang akan mengalami proses diagenesa ketika terkubur dalam tanah yang menyebabkan unsur organik makin berkurang dan unsur anorganik makin bertambah kadarnya karena masuknya unsur kimia anorganik dari luar, salah satunya adalah unsur F (fluorine). Penelitian ini membahas tentang kandungan F (fluorine) pada fosil-fosil tulang dan gigi yang bersifat insitu dan tidak insitu yang berasal dari Gua Pawon di Jawa Barat, Sangiran di Jawa Tengah, dan Kalitidu di Jawa Timur. Kandungan F (fluorine) pada fosil tulang dan gigi dapat digunakan untuk menentukan sumber asal fosil yang berstatus tidak insitu dan tidak diketahui kedudukan stratigrafinya. Hasil yang diperoleh adalah material yang berasal dari Gua Pawon mempunyai kadar F (fluorine) yang bervariasi. Material fosil dari Kalitidu yang berstatus insitu mempunyai kadar F (fluorine) yang relatif sama, sedangkan material fosil yang berstatus tidak insitu mempunyai kadar F (fluorine) paling tinggi. Material fosil dari Sangiran memiliki hubungan kandungan F (fluorine) dengan usia formasi yang berbeda dengan Gua Pawon dan Kalitidu, yaitu semakin kecil kadar F (fluorine) pada fosil tulang dan gigi, maka semakin tua umur fosil. Salah satu material fosil, yaitu gigi geraham Homo erectus (JA-41), merupakan fosil gigi Homo erectus termuda yang pernah ditemukan di Sangiran. 
GEO-ARKEOLOGI TERAS PURBA BENGAWAN SOLO DI SEKITAR KABUPATEN BOJONEGORO, JAWA TIMUR Arif, Johan; Nugroho, Harry
PURBAWIDYA: Jurnal Penelitian dan Pengembangan Arkeologi Vol 4, No 2 (2015): November 2015
Publisher : BALAI ARKEOLOGI JAWA BARAT

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (289.859 KB)

Abstract

Abstract The mapping of the existing ancient terrace of Bengawan Solo (Bengawan means big river) is the preliminary geo-archaeological research conducted in several sites in  Bojonegoro region of East Java. The subject found in these ancient terraces were the findings of several Paleolithic tools and vertebrate fossils. Therefore, the aim of the study was to find out the extension of the terrace and to provide a guidance for archaeologists in searching the remains of ancient human culture such as Paleolithic tools and vertebrate fossils. On behalf of the study, firstly the geological mapping was conducted in the studied area and were also to describe the sediment profile and to collect sediment samples (including vertebrate fossils) and also for sedimentary and chemical analysis. In the area studied there were three ancient terraces which were known as,  Menden, Jipangulu and Ngandong. Menden terrace (sub-Recent) was exposed at Payaman, Jipangulu terrace (Early Holocene) in Prangi and Wotangare, and Ngandong terrace at Prangi and Kedung village (Solo valley). In the context of stratigraphy, the whole ancient terraces were composed of gravel and coarse sand in the lower part to sandy clay in the upper part. This indicated that the whole terraces were formed by the meandering river of ancient Bengawan Solo. The position of those ancient terraces were relative to the position of recent Bengawan Solo is 2-3 m (Menden terrace), 5-7 m (Jipangulu terrace) and more than 8 m in length (Ngandong terrace). Based on this study, the archaeologists should focus on the gravel to coarse sedimentary strata of the quaternary fluvial system on behalf of searching the cultural artifact of paleolithic including the fossilized remains of human and other quaternary vertebrates within the ancient terrace of Bengawan Solo. 
Geomorphological survey at Padang Candi, Kuantan Singingi Regency, Central Sumatra, Indonesia Arif, Johan
PURBAWIDYA: Jurnal Penelitian dan Pengembangan Arkeologi Vol 8, No 1 (2019): Vol. 8(1) Juni 2019
Publisher : BALAI ARKEOLOGI JAWA BARAT

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (804.304 KB) | DOI: 10.24164/pw.v8i1.290

Abstract

Padang Candi site in the Kuantan Singingi Regency of Riau Province, located about 19.3 km southwest of Taluk city, and about 3 km northeast of Lubuk Jambi. In the year 2000s, some archaeological stuff have been found at Padang Candi, among others, various sized of bricks as a raw material for building construction, and some gold plate with scrip. It is presumed those stuffs had a connection with the Sriwijaya Kingdom between AD 800. The goal of the paper is to gain a spectrum of understanding about the assemblages of bricks as a raw material for building construction was found, on three sites that are at Sector-I (sec-I), and the others in small quantities were found at Sector-II (sec-II) and Sector-III (sec-III) on the basis of geomorphological study. This study involves the geomorphological investigation of the area at the scale of 1:2000. In terms of geomorphology, the landscape at Padang Candi consists of two units, namely, the Floodplain Unit formed by Quaternary river alluvium (Qal), and the Low Hilly Unit composed by Tuff Unit as a part of the Miocene Telisa Formation (Tmtu). Sector-I (sec-I) situated on the relatively higher isolated hilly than sec-II and sec-III. The area westward of sec-II might be remains of ancient settlement, and there is trench-like morphology found eastward of sec-I. In the matter of sec-1 which is situated on isolated hilly, evoke a curiosity about the status of building construction at sec-I. The presence of the trench-like morphology also gives arises of curiosity about its function. Those matter should be a consideration by archaeologist when do next excavation and study, including the area which is supposed as an ancient settlement.