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Characteristics and Genesis of Gold Mineralization in the Salu Bulo Prospect , Sulawesi, Indonesia
No full textCharacteristics and Genesis of Gold Mineralization in the Salu Bulo Prospect , Sulawesi, Indonesia
Get PDF秋田大学博士（工学）Several significant gold deposits hosted in metamorphic rocks have been discovered in Sulawesi, Indonesia, namely Paboya, Awak Mas, Palopo and Bombana. The Salu Bulo prospect is one of the gold prospects in the Awak Mas project in the central part of the Western Metallogenic Province, Sulawesi, Indonesia. The four domains in the Salu Bulo prospect (Biwa, Lelating, Bandoli and Freddie) has been explored by Placer Dome Inc., in 1999 and One Asia Resource Ltd., in 2011 to 2013 through 132 drilled holes with an average length of 100 m. The resource was measured and indicated about 5.6 million tons at 2.2 g/t Au with a cut-off grade at 0.5 g/t Au as well as an additional 0.5 million tons at 1.1 g/t Au as an inferred resource, reported by Tetra Tech in 2013. The Salu Bulo prospect is hosted by the cover sequence of Latimojong Metamorphic Complex. Within the prospect, the Latimojong Metamorphic Complex consists of meta-dark (graphitic), green (chloritic) and red (hematitic) mudstone, siltstone, sandstone and intercalated meta-volcanic and volcaniclastic rocks along with phyllite. The ore bodies in the Salu Bulo prospect are north-south trending and dipping steeply eastward, approximately three meters thick which are associated with veins, stockwork and breccias with an orientation sub-parallel and discordant to the foliation of the host rocks. The veins can be classified in three stages namely early, main and late stages and gold mineralization is related to the main stage. The veins formed during the main stage are composed of quartz, carbonate (mainly ankerite) and albite. The breccia formed mainly during the main stage of mineralization. The breccia is associated with quartz, carbonate (mainly ankerite), albite and pyrite.
Sulfide minerals, native gold and electrum are lesser abundant or absent in the veins and stockwork. High grade gold ores in the Salu Bulo prospect are accompanied with intense alteration along the main stage veins and breccia. Alteration mineral assemblage includes ankerite ± calcite, quartz, albite and pyrite along with minor sericite. Pyrite is the most abundant sulfide mineral, which is spatially related to gold (<2-42 μm in size). It is more abundant as dissemination in the altered host rocks than those in veins, suggesting that waterrock interaction played a role to precipitate pyrite and gold in the Salu Bulo prospect. Pyrite shows several different morphologies and textures: fine-grained, porous, deformed and massive pyrites. Lesser amounts of tennantite-tetrahedrite, chalcopyrite, bornite, galena, hematite and rutile are also present as inclusions in pyrites, and as discrete disseminated minerals in altered host rocks, veinlets and matrix of breccia. Covellite and chalcocite occur on the rim of some chalcopyrite.
Correlation coefficients of whole-rock Ag, Ni, Mo and Na contents to whole-rock Au content are above 0.5 indicating that they are strongly correlated with gold. The Mo, Ni, Sb, Hg, Se, Sr and W contents are relatively elevated in altered host rocks and ores than in unaltered host rocks, whereas the Cs, Rb and V contents are relatively depleted. The K₂O content is depleted in hydrothermally altered host rocks and ores indicating absence of potassic alteration and decomposition of K-bearing mineral in host rocks during hydrothermal alteration. Various elevated and depleted of MgO, Fe₂O₃, Al₂O₃ and MnO contents in hydrothermally altered host rocks and ores are related to inherited host rocks composition (i.e. mineral composition). PAAS normalized REE plots of unaltered and altered host rocks and ores are relatively similar patterns which are depleted of LREE and subhorizontal HREE with various Eu positive anomalous (Eu/Eu* varying from 0.1 to 0.9). ƩREE of unaltered host rocks is relatively similar and higher than hydrothermally altered host rocks and ore indicating evidence for mobility and fractionation of REE during hydrothermal alteration. Gold was introduced as electrum and native gold with Au / (Au + Ag) ratio ranging from 66.2 to 78.5 atomic % and from 81.4 to 82.3 atomic %, respectively as fracture filling and inclusion in pyrites. The Ni and Co concentrations of pyrite are high, 10 - 7780 ppm and 390 - 2710 ppm, respectively, in edges, cores and rims of pyrite with Co/Ni ratio of pyrite ranging from 0.09 to 63.
Fluid inclusions in quartz in the veins of the main stage and the matrix of breccia are mainly two-phase liquid-rich inclusions with minor two-phase vapor-rich and single-phase liquid or vapor inclusions. CO₂ and N₂ are detected in the fluid inclusions by Laser Raman microspectrometry. Raman spectrum of CO₂ clearly shows strong bands at ∼ 1285 cm-1 (v1) cm−1 and ∼ 1388 cm−1 (2v2) in mineralized vein and at ∼ 1282 cm-1 (v1) and ∼ 1385 cm−1 (2v2) in the matrix of breccia, N₂ and graphite at ∼ 2328 cm−1 and ∼ 1617 cm−1 respectively in mineralized vein and at ∼ 2327 cm−1 and ∼ 1606 cm−1 respectively in matrix of breccia. Homogenization temperature (Th) of fluid inclusions in the veins ranges from 132 to 357 ℃ and that in the matrix of breccia ranges from 148 to 368 ℃, which homogenized into a liquid phase. Salinity of fluid ranges from 3.5 to 8.0 wt% (average 6.3 wt%) NaCl equivalent in the veins and from 3.9 to 8.5 wt% (average 6.0 wt%) NaCl equivalent in the matrix of breccia. The wide range of homogenization emperature of fluid inclusions and the co-existence of two-phase liquid-rich and two-phase vapor-rich inclusions suggest boiling of fluid when they were trapped. The trapping temperature was 190 to 210 ℃. Fluid boiling probably occurred when the fluid was trapped at approximately 120 to 190 meters below the paleo water table. δ¹⁸Osmow values of fluid, +5.8 ‰ and +7.6 ‰ calculated from δ¹⁸Osmow of quartz (+17.2 ‰ and +19 ‰) at 205 ℃ from the main stage vein indicate oxygen isotopic exchange with wall rocks during deep circulation. δ³⁴Scdt of pyrite narrowly ranges from -2.0 to +3.4 ‰ suggesting a single source of sulfur. Gold mineralization in the Salu Bulo prospect occurred in an epithermal condition, after the metamorphism of the Latimojong Metamorphic Complex and emplacement of Palopo Granite or Enrekang Volcanic Series in the Late Miocene to Pliocene. It was formed at relatively shallow depth from CO₂-bearing sodic mineralizing fluid with low to moderate salinity (3.0 - 8.5 wt% NaCl equiv.). Temperature and pressure of ore formation range from 190 to 210 ℃ and 1.2 to 1.9 MPa, respectively
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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