Geological Prospection of Placer Chromium Deposits in the Waropen Regency—Indonesia (New Guinea) Using the Method of Indicator Minerals

Karol Zglinicki,Adam Piestrzyński,Krzysztof Szamałek,Paweł Kosiński

doi:10.3390/min10020094

Karol Zglinicki, Adam Piestrzyński + Show 2 more

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https://doi.org/10.3390/min10020094

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Abstract

Indicator minerals (IM) have been used in the research of gemstone and base metals for over 100 years. IMs are a main source of information about the occurrence of deposits, hydrothermal and weathering changes, as well as bedrock source and type. Since 2013, base metal mineral exploration has taken place on New Guinea Island (the Indonesian part). The analysis of chromian spinels as IM in beach and river sediments led to the discovery of rich chromian-bearing deposits in the Botawa River sediments. The dominant detrital minerals include chromian spinels, olivine, pyroxenes and serpentine. The source of chromian spinels, olivine and pyroxenes are most likely peridotites from the Earth’s mantle zone of the ophiolite series, generated under supra-subduction conditions. The terrigenous deposits contain metamorphic minerals, such as staurolites, andalusites, epidotes, amphiboles and fragments of micas, quartz and chlorite schists. Using ICP-MS analysis of the beach sands, the concentration of Cr2O3 was determined to be at the level of 1.17%, while in the heavy minerals concentrate from the Botawa River sediment, the content of Cr2O3 amounts to 24.83%. The authors conclude that the west parts of the Van Rees Mountains are the probable parent rocks for chromium-bearing sediments.

Highlights

Indicator minerals (IM) are minerals that provide important information about potential occurrences of deposits [1], weathering and hydrothermal changes, as well as the source and type of parent rock [2,3].The IM are macroscopically recognizable and characterized by high density and physical resistance, silt and sand size and are transported over great distances [2]
The collision of the Indo-Australian and Euro-Asian plates, formation of numerous subduction zones and related extension processes led to a series of changes on the regional level in SE Asia, including New Guinea Island [38,39,52]
Cenozoic tectonic collisions with island-arc terranes (Tosem, Amanab, Weyland, Gauttier, Cyclops) and closing of marginal basins led to the formation of numerous ophiolites in a supra-subduction environment [46,47,53]

Summary

Introduction

Indicator minerals (IM) are minerals that provide important information about potential occurrences of deposits [1], weathering and hydrothermal changes, as well as the source and type of parent rock [2,3].The IM are macroscopically recognizable and characterized by high density and physical resistance, silt and sand size and are transported over great distances [2]. Geologists have been using IM in the mineral exploration of copper ores [4,5], chromium ores [6], as well as platinum [7,8], gold [9] and gemstones [10,11] for a long time. The presence of IM in the alluvial and sea deposits allows recognizing the type of mineral deposits on a regional scale [12]. The gradual depletion of mineral resources entails conducting extensive geological prospection using both the greenfield and brownfield exploration. One of the most promising world regions with the high geopotential is the area of the Malay Archipelago (Indonesia) situated in the south-east edge of the Eurasian Plate. The basement of the west part of the Malay Archipelago is represented by the continental crust, while the east part is dominated by the island arc, ophiolite sequences and younger ocean

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