The Iorokhan Complex of Minor Intrusions in the Eastern Part of the Bureya Massif: Geology, Age, and Gold Mineralization

In this paper we analyze and summarize some recently acquired data coupled with the findings of previous geological, geochronological and metallogenic studies on igneous rocks of the Iorokhan gold-bearing complex in the eastern part of the Bureya massif. Four phases, whose rocks are of hypabyssal and subvolcanic intrusive facies, are shown to define the structure of the Iorokhan complex of minor intrusions; characteristic features of their composition and structural and tectonic settings of localization are given; geological and geochronological data are reported on their age (103 ± 1.0–97.4 ± 6.5 Ma), i.e. late Albian–early Cenomanian. By the ratio of alumina, calcium and alkalis, most of their compositions correspond to I-type high-alumina magnesia and magnesia-ferruginous varieties (A/CNK < 1.1) with low concentrations of HFSE, including HREE. Melting of an amphibolitic source rock produced a melt that could be a deep source of the Iorokhan diorites. A brief description of the Noni deposit is given and the main factors contributing to the localization of gold mineralization are considered. The ranges of the Iorokhan magmatites in the East Bureya volcano-plutonic zone can be considered as one of the fragments of the boundary structure between the continental margin of the eastern part of the Bureya massif and the accretionary wedges of the Sikhote-Alin orogenic belt. The Iorokhan complex of minor intrusions is assumed to be a small fragment of the wide belt of Late Albian–Early Cenomanian magmatite occurrence in the southern Far East of Russia, which formed in a setting of transform continental margin and zones of compression associated with extension resulting in the development of pull-apart basins typical of such margins.

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Studi Awal Geologi di Daerah Beruang Kanan Kabupaten Gunung Mas Propinsi Kalimantan Tengah

PROMINE ◽

10.33019/promine.v6i1.710 ◽

2018 ◽

Vol 6 (1) ◽

pp. 1-11

Author(s):

Retno Anjarwati ◽

Arifudin Idrus ◽

Lucas Donny Setijadji

Keyword(s):

Gold Mineralization ◽

Volcanic Rocks ◽

Gold Deposits ◽

Central Kalimantan ◽

Magmatic Arc ◽

Tertiary Sediment ◽

Copper Gold ◽

Regional Tectonic ◽

Mineralization Processes ◽

High Yields

The regional tectonic conditions of the KSK Contract of Work are located in the mid-Tertiary magmatic arc (Carlile and Mitchell, 1994) which host a number of epithermal gold deposits (eg, Kelian, Indon, Muro) and significant prospects such as Muyup, Masupa Ria, Gunung Mas and Mirah. Copper-gold mineralization in the KSK Contract of Work is associated with a number of intrusions that have occupied the shallow-scale crust at the Mesozoic metamorphic intercellular junction to the south and continuously into the Lower Tertiary sediment toward the water. This intrusion is interpreted to be part of the Oligocene arc of Central Kalimantan (in Carlile and Mitchell 1994) Volcanic rocks and associated volcanoes are older than intrusions, possibly aged Cretaceous and exposed together with all three contacts (Carlile and Mitchell, 1994) some researchers contribute details about the geological and mineralogical background, and some papers for that are published for the Beruang Kanan region and beyond but no one can confirm the genesis type of the Beruang Kanan region The mineralization of the Beruang Kanan area is generally composed by high yields of epithermal sulphide mineralization. with Cu-Au mineralization This high epithermal sulphide deposition coats the upper part of the Cu-Au porphyry precipitate associated with mineralization processes that are generally controlled by the structure

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