Hiroharu Matsueda

Bio: Hiroharu Matsueda is an academic researcher from Hokkaido University. The author has contributed to research in topics: Mineralization (geology) & Sphalerite. The author has an hindex of 11, co-authored 48 publications receiving 395 citations. Previous affiliations of Hiroharu Matsueda include Russian Academy of Sciences & American Museum of Natural History.

Genesis of epithermal Au-Ag mineralization of the Koryu Mine, Hokkaido, Japan

Abstract: Koryu is an epithermal gold-silver quartz vein deposit in southwestern Hokkaido, Japan. The deposit occurs in an east-west shear zone within Miocene black mudstone. The deposit consists of eight major veins with a general east-west strike. The three major veins show variable internal structure and texture, in both vertical and horizontal directions. K-Ar ages for adularia from veins 1 and 3 are 0.8 to 1.2 Ma, indicating a Pleistocene age of mineralization. Based on crosscutting relationships and mineral parageneses, the veins appear to have formed during two mineralization epochs. The earlier event is further divided into three stages (E-I, -II, -III), whereas seven stages can be distinguished in the later event (L-I, -II, -III, -IV, -V, -VI, -VII). The wide veins consist of multiple mineralization stages. Most gold-silver mineralization is associated with the L-III stage.The earlier mineralization stages are characterized by manganocalcite, johannsenite, and small amounts of ore minerals, whereas the later stages are characterized by large amounts of ore minerals. Gangue minerals associated with later ore consist of interstratified chlorite-smectite and microcrystalline quartz alternately banded with adularia and comb-texture quartz. Gold-silver-bearing minerals include electrum, aeanthite- aguilarite, polybasite-pearceite, pyrargyrite-proustite, jalpaite, mckinstryite, hessite, an Ag-Te-Se-S mineral, and tetrahedrite.The presence of vapor-dominated fluid inclusions in several stages suggests that boiling occurred intermittently throughout ore deposition. The formation temperatures of the earlier mineralization epoch (263 degrees -283 degrees C) were slightly higher than those of the later mineralization epoch (246 degrees -260 degrees C) except for stages E-III-b (223 degrees C) and L-VII (206 degrees C). Salinities range from 0.5 to 6.0 wt percent NaCl equiv, although CO 2 concentrations up to 1.4 wt percent in some later stages account for a portion of the apparent salinity. These data indicate that maximum P total of the ore fluid was 31 to 68 bars, equivalent to 430 to 850 m below the paleowater table.Quartz morphology combined with fluid inclusion studies suggests that boiling of the fluid occurred repeatedly, leading to silica-supersaturated conditions with respect to quartz and resulting in the formation of the various silica textures. Recrystallization of silica to quartz occurred throughout vein formation.The stable isotope data combined with parageneses, quartz textures, and fluid inclusion studies suggest the following model for the Koryu gold-silver deposits. The veins show two distinct mineralization epochs, an earlier and a later one, which were responsible for type 1 and 2 hydrothermal fluids, respectively. Both types are dominantly meteoric water in origin. The early fluid is characterized by relatively heavy delta 18 O values (-5.3 to -4.7ppm) and a temperature of > or = 260 degrees C. The later fluid is characterized by relatively low delta 18 O values (-9.3 to -6.0ppm) and a temperature of > or = 250 degrees C. Type 1 fluids may have circulated deeply and leached Ca and Mn, which were precipitated as manganocalcite and johannsenite during the earlier mineralization epoch. Type 2 fluids mixed with shallower water, ascended through new conduits, and apparently carried large amounts of gold and silver, although the source of the metals cannot be determined at present. When the hydrothermal fluids ascended at discrete time intervals to the boiling zone (<850 m) during the later epoch, gold and silver were precipitated at 250 degrees C.

P-T evolution of the granulite-facies rocks of the Lützow-Holm Bay region, East Antarctica

Abstract: Petrographical evidence of relict minerals (kyanite, staurolite and sapphirine) enclosed in garnet in aluminous metapelites containing sillimanite suggests that the Lützow-Holm Bay (LHB) granulites have undergone prograde recrystallization in the kyanite stability field prior to peak temperature conditions in the sillimanite stability field during the late Proterozoic (c. 700–1100 Ma) followed by granite and pegmatite activity at 500 Ma. The clockwise P-T trajectory of the LHB granulites is distinctive from that of the neighbouring part of the Rayner Complex, which has been interpreted to be a reworked portion of the Archaean Napier Complex. The LHB region, East Antarctica, is a granulite- facies terrane metamorphosed probably during the late Proterozoic, c. 700–1100 Ma (Shibata et al. 1986). Subsequent granite and pegmatite activity has been dated at 500 Ma (Yanai & Ueda 1974, Shibata et al. 1985), an event extensively reported over East Antarctica (Grew 1982). The LHB region is underlain by pelitic to psammitic gneisses, basic to intermediate gneisses (including charnockitic rocks) with subordinate amounts of calc-silicate rocks and ultramafic rocks. Recent petrological studies have revealed the progressive increase of metamorphic grade from the Prince Olav Coast to LHB as shown in Fig. 1. According to Shibata et al. (1986), the initial 87Sr/86Sr ratios of metasedimentary gneisses from these areas are low (0.705–0.706) suggesting they did not have a long pre-metamorphic history. This contrasts with relatively high ratios (0.71–0.74) from the neighbouring Rayner Complex (Grew 1978, Black et al. 1987). In the LHB region, aluminous metapelites containing garnet and sillimanite as

Cikidang hydrothermal gold deposit in western Java, Indonesia

Abstract: . The Cikidang gold deposit, discovered in 1991, is located within the Bayah dome, a Tertiary-Quaternary volcanic zone at west end of Java, which is well known as a gold district (e.g., Pongkor and Cikotok mines). Typical low-sulfidation quartz-adularia-sericite(-calcite) vein deposits represent the gold deposit in the district. The Cikidang vein system comprises four sub-parallel quartz-adularia-sericite(-calcite) veins that are rich in manganese oxide and limonite with very poor amount of sulfides. These vary from 0.5 to 2.7 m thick and extend for up to 1,000 m long. The vein trends roughly N-S and dip 60d to 86° toward west. The ore grades vary from trace to 74.9 g/t Au and 1.2 to 225.0 g/t Ag. A K/Ar age determination on adularia yielded 2.4 Ma for the Cikidang vein. The ore minerals are represented by electrum, argentite, aguilarite and pyrite. Electrum shows the compositional ranges of Ag (50–65 atom %). The gangue minerals are dominated by quartz with variable amounts of calcite, sericite, adularia, clay minerals, manganese oxide and limonite. The vein textures are so variable as banded, colloform, comb, brecciated and massive. Host rocks, composed of Miocene lapilli tuff and breccia, suffered from pervasive hydrothermal alterations. Wall rocks adjacent to the vein are characterized by argillic and propylitic alteration. The fluid inclusion study of the Cikidang vein shows homogenization temperatures ranging from 170 to 260°C. Salinities are low, generally below 3 wt% NaCl equivalent. Oxygen isotope results suggest meteoric water in origin for ore fluids responsible for the Cikidang deposit.

Mineral Chemistry of Albite-Enriched Granitoids at Um Ara, Southeastern Desert, Egypt

Abstract: Mineral chemistry and typomorphic characteristics are used to monitor the physicochemical evolution of late-magmatic to postmagmatic alteration processes that resulted in the development of a radioactive and albite-enriched microgranite stock. The mineral paragenesis indicates that postmagmatic fluids were enriched in Nb, Zn, Mn, U., Th, Zr, and Y, in addition to Rb, Li, and F Manganocolumbite with extremely high Nb/(Nb+Ta) (0.99), Mn/(Mn+Fe) (0.82), and zircon with high Zr/(Zr+Hf) (0.97) indicate crystallization under alkaline, relatively high-temperature conditions (>425° C). The close association of manganocolumbite, Nb-Mn-Zn- rich ilmenite (with 1.2 to 14.5 wt% ZnO), spessartine garnet (with 68.2-89.4 mol% spessartine), zircon, xenotime, zinnwaldite mica (up to 5.98 wt% F), and fluorite indicates the strong affinity of the elements of Nb, Y., Zr, Mn, and Zn for stable complexing by K+, Na+, Li+, and F− rich supercritical fluids during the course of extraction and transportation. The enrichment of the ...

Cambrian Orogenic Belt in East Antarctica and Sri Lanka: Implications for Gondwana Assembly

Abstract: Ion microprobe U-Pb dating of zircons from the Lutzow-Holm Complex (LHC) and the Yamato-Belgica Complex (YBC), East Antarctica indicate high-grade regional metamorphism and associated folding of LHC occurred between $$521 \pm 9$$ and $$553 \pm 6 Ma$$. This shows, for the first time, the existence of a Cambrian orogenic belt within the East Antarctic Shield. Many zircons from the LHC contain cores that record inherited ages from ~2900 to ~1500 Ma. Components of ~1000 Ma zircon have been identified in three locations. This may indicate the maximum age of the deposition of LHC. One metasedimentary gneiss from the YBC records a well-defined age at about 600 Ma, whereas another yields a dispersion of ages interpreted as the result of varied radiogenic Pb loss in ~1000 Ma zircons at about 500-600 Ma. These gneisses have inherited ages of up to ~2500 Ma. Our work enables an improved fit to the once contiguous fragments of Gondwana. The Highland/Southwestern Complex (HSWC) of Sri Lanka has remarkable petrological...