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Recognition of the importance of chlorine complexing in enhancing the solubility of metal sulfides in aqueous solutions has led to the view that the chlorine content of intrusive rock could govern the ability of a magma to separate a metal-rich hydrothermal phase. This article presents the chlorine and fluorine contents of apatites in the granitic rocks of the Barren, Tungsten, and Molybdenum provinces of Southwest Japan.The abundance of Cl in apatites correlates negatively with rock D.I. (differentiation indices), and the abundance of F in apatites correlates positively with rock D.I. The abundance of Cl in apatites of the Molybdenum province is generally higher than that of the Tungsten and Barren provinces, and the abundance of F in apatites in the Molybdenum province is generally lower than that of F in apatites of the Tungsten and Barren provinces.Apatites in the granitic rocks associated with tungsten and fluorite mineralization and granite pegmatite formation, and from the Barren province are mostly F-OH apatites 相似文献
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Hitoshi Onuki Masahide Akasaka Takeyoshi Yoshida Munetomo Nedachi 《Contributions to Mineralogy and Petrology》1982,80(2):183-188
Ti-rich hydroandradite often occurs, though usually as a minor constituent, in serpentinized ultramafic rocks and associated gabbroic rocks of the Sanbagawa metamorphic belt. The chemistry of the host rocks is commonly characterized by undersaturation with SiO2. Two Ti-rich hydroandradites from metasomatized gabbroic rocks of the Shibukawa area have been chemically analysed by the wet method. Mössbauer experiments indicate the presence of Fe3+ and Fe2+ in the octahedral sites of these Ti-rich hydroandradites. Wet chemical analyses for total reducing capacity of the present garnets by two different methods together with Mössbauer data imply the presence of octahedral Ti3+ in their structure. Ti-rich hydroandratites, apart from their hydrous property, have a similar crystal chemistry to natural Ti-rich andradites. Ti-rich hydroandradites were probably formed in rocks with unusual chemical compositions within a P-T region of 300–400° C and 4–7 kb under limited conditions of relatively low oxygen fugacity and low μCO2. 相似文献
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Kohei SATO Anatoly A. VRUBLEVSKY Sergei M. RODIONOV Nikolai P. ROMANOVSKY Munetomo NEDACHI 《Resource Geology》2002,52(1):1-14
Abstract: Age of magmatism and tin mineralization in the Khingan‐Okhotsk volcano–plutonic belt, including the Khingan, Badzhal and Komsomolsk tin fields, were reviewed in terms of tectonic history of the continental margin of East Asia. This belt consists mainly of felsic volcanic rocks and granitoids of the reduced type, being free of remarkable geomagnetic anomaly, in contrast with the northern Sikhote‐Alin volcano–plutonic belt dominated by oxidized‐type rocks and gold mineralization. The northern end of the Khingan‐Okhotsk belt near the Sea of Okhotsk, accompanied by positive geomagnetic anomalies, may have been overprinted by magmatism of the Sikhote‐Alin belt. Tin–associated magmatism in the Khingan‐Okhotsk belt extending over 400 km occurred episodically in a short period (9510 Ma) in the middle Cretaceous time, which is coeval with the accretion of the Kiselevka‐Manoma complex, the youngest accretionary wedge in the eastern margin of the Khingan‐Okhotsk accretionary terranes. The episodic magmatism is in contrast with the Cretaceous‐Paleogene long–lasted magmatism in Sikhote–Alin, indicating the two belts are essentially different arcs, rather than juxtaposed arcs derived from a single arc. The tin‐associated magmatism may have been caused by the subduction of a young and hot back‐arc basin, which is inferred from oceanic plate stratigraphy of the coeval accre‐tionary complex and its heavy mineral assemblage of immature volcanic arc provenance. The subduction of the young basin may have resulted in dominance of the reduced‐type felsic magmas due to incorporation of carbonaceous sediments within the accretionary complex near the trench. Subsequently, the back‐arc basin may have been closed by the oblique collision of the accretionary terranes in Sikhote–Alin, which was subjected to the Late Cretaceous to Paleogene magmatism related to another younger subduction system. These processes could have proceeded under transpressional tectonic regime due to oblique subduction of the paleo‐Pacific plates under Eurasian continent. 相似文献
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Fluorite Deposits at Voznesenka in the Khanka Massif, Russia: Geology and Age of Mineralization 总被引：1，自引：0，他引：1
Kohei Sato Kazuhiro Suzuki Munetomo Nedachi Shigeru Terashima Margarita D. Ryazantseva Anatoly A. Vrublevsky + Alexander I. Khanchuk ++ 《Resource Geology》2003,53(3):193-211
Abstract. A huge fluorite deposit at Voznesenka in the Khanka massif, Far East Russia is concluded to have formed at ca. 450 Ma in Late Ordovician time based on the K‐Ar ages for Li‐micas in the fluorite ore and greisenized leucogranite within the deposit. This conclusion is inconsistent with the current view of Devonian mineralization that stemmed from widely scattered whole‐rock Rb‐Sr isotope data for the heterogeneous leucogranite stocks influenced by strong alteration. The Voznesenka and neighboring fluorite deposits may have formed in Cambrian limestone in relation to the intrusion of the Li‐F‐rich felsic magma which has a similar chemistry to representative Li‐F‐rich felsic rocks including topaz granite and ongonite or topaz rhyolite; these rocks may be classified as a specific group of highly fractionated felsic magmas. Biotite granite plutons exposed in the Voznesenka district are divided in age into two groups based on the CHIME age data for zircon, monazite and xenotime: Ordovician and Permian. The Ordovician plutons seem to be coeval to the fluorite deposits and are characterized by F‐rich chemistry, reduced nature and association of tin mineralization with the deposition of fluorite and tourmaline. The biotite granite magmas of initially enhanced F contents could have been highly fractionated to form Li‐F‐rich leucogranite cupolas that provided fluorite deposits within the host limestone. Future prospecting for similar fluorite deposits is to be focused on areas of intersection between Ordovician Li‐F‐rich granite and Cambrian carbonate sequences. The Permian granite of southeastern margin of the Grodekovo batholith is characterized by lesser F content, oxidized nature and the lack of tin and fluorite mineralization in contrast to the Ordovician granite. The result of Permian age does not support the current view of Silurian age for the batholith and requires overall chronological reinvestigation in connection with the tectonic history of the Khanka massif because the Grodekovo is a representative of Paleozoic batholiths in Primorie. 相似文献
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Takashi Tomiyasu Tomomi Eguchi Masahiko Yamamoto Katsuro Anazawa Hayao Sakamoto Tetsuo Ando Munetomo Nedachi Katsumi Marumo 《Marine Chemistry》2007
To estimate the influence of mercury emitted from submarine fumaroles, the horizontal and vertical distribution of mercury in sediment of Kagoshima Bay was studied. The fumaroles are located in the northern bay head area, and the sediment samples had been taken from 52 points throughout the bay with a gravity core sampler. The core samples obtained were cut at a thickness of 1–2 cm and used for measurements. The total concentration of mercury in surface sediment in the northern and central areas of the bay was 51–679 μg kg− 1 (average 199 μg kg− 1, n = 22) and 23–100 μg kg− 1 (average 55 μg kg− 1, n = 30), respectively. The highest value was obtained in the vicinity of the fumaroles. The mercury concentration in sediment near the fumaroles varied with depth, which may reflect the variation in fumarolic activity. A successive extraction method was applied to the speciation of mercury in the sediment. The results showed that sediment taken in the vicinity of submarine fumaroles contained a higher percentage of mercury bound with organic matter. 相似文献
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