資源地質科学研究グループのセミナー発表内容

In the Sikkim Himalaya, India, a complete inverted Barrovian sequence of metamorphism is preserved. In this sequence metamorphic grade increases from chlorite zone to sillimanite zone towards dip direction of the foliation plane, that is towards higher structural levels. Detail petrological study establishes the sequence of metamorphic mineral reactions and increasing pressure & temperature of metamorphism towards higher structural levels. This sequence is therefore a coherent inverted sequence, and is different from many other parts of Himalaya. This work shows that models of thermal inversion, such as the hotiron model, can not explain the development of this sequence.

鹿児島県菱刈鉱山・山田鉱床成泉7,8-7脈について、鉱化ステージ区分・石英の結晶度測定・K-Ar年代測定の結果と共に、今後の研究課題の一部として菱刈産氷長石のEPMA分析についても発表を行う。

The Eastern Ghats Mobile Belt located east coast of India. It comprises khondalite (garnet-sillimanite gneiss), leptynite (quartzo-feldspathic gneiss), calc-silicate rocks, two-pyroxene gneiss and sapphirine granulites. This area has three deformation events (Sarkar et al., 1981; Sengupta et al., 1990a) and two major metamorphic events of granulite formation at 2200Ma and 1100Ma. The study area is Paderu, Anantagiri, Sunkarimetta, Shimliguda and Anakapalle around Araku and Vishakhapatnam. In this study, it is aimed to clarify the characteristics and detailed mode of occurrence of fluid inclusions from granulite facies metamorphic rocks and to discuss on the activity of the fluids through the metamorphism.

In consequence of heating and cooling experiments, the presence of CO₂ fluid and H₂O fluid were observed. The CO₂ fluids tend to separate high-density and low-density fluid, while the densities of H₂O fluids show wide range. It is assumed that CO₂ fluids had been bipolarly active in early and late stage of retrogressive metamorphism, and then H₂O fluids might become active continuously in the later stage of metamorphism.

P-T conditions were described in diagram by various geothermobarometry and the density of primary CO₂ fluid inclusions. The P-T conditions were estimated to be 450-650 degree in Celsius and 2.5-7kb (garnet-biotite geothermometry and GAPQ, GOPS geobarometry), 500-550 degree and 3.7-6.7kb (orthopyroxene-biotite geothermometry and GAPQ, GOPS geobarometry), 700-750 degree and 5.5-7.2kb (garnet-ilmenite geothermometry and GAPQ, GOPS geobarometry), 700-900 degree and 6.0-9.4kb (garnet-orthopyroxene geothermo-metry and GAPQ, GOPS geobarometry), and 850-1050 degree and 7.5-12kb (orthopyroxene-ilmenite geothermometry and GAPQ, GOPS geobarometry) and so on, which indicate the decompression process of these metamorphic rocks in Shimliguda area.

タイに産するコランダムは後期新生代のアルカリ玄武岩に関連して見つかる宝石質サファイアとされているが、コランダムが玄武岩中に発見されたという報告はほとんどされていない。本論文は玄武岩の記載岩石学及び地球化学、コランダム中の鉱物包有物の観点から、玄武岩とコランダムの関係とコランダムの形成環境の推定を目的としている。

Egyptian emerald occurs in the felsic injections, e.g. plagioclasite pegmatite and quartz veins and the associating alteration halos which are spatially and genetically related to emplacement to muscovite leucogranites in schist rocks of melange zones. Leucogranites and related emerald deposits are typically confined to the NW- tending Nugrus major shear zone.
The alteration halos are consistently composed of successive zones of tourmalinized (B-metasomatized, closest to the leucogranite exocontact), phlogopitized (K-metasomatized), tremolitized (Mg, Ca-metasomatized), and distal talc-carbonated (CO₂-metasomatized) wallrocks.

It is suggested that emeralds is formed as the result of interaction of mixed fluids with the ultramafic fragments embricated in the biotite schists of melange rocks. The interacting fluids were dominantly magmatic (rich in Al, Na, K, B and Be) derived from the leucogranites and related pegmatites and metamorphic (CO₂ and CH₄-rich) derived from the country schist rocks.

The leucogranites are fertile, post-collisional and not directly related to the crustal thrusting (thickening). There fertility can be deduced from the higher Be, B and Rb contents as well as higher Rb/Ba, and lower Zr/Hf, and Nb/Ta ratios. Textual heterogeneities and development of pegmatitic faces and potassic pegmatite aureoles and the existence of alteration halos of phlogopitization and tourmalinization are very conclusive exploration criteria. The elemental zonation of B (close to the leucogranite) contacts and Be in the distal phlogopitized zone is also an additional evidence for emerald occurrence.

Typological study including paragenetic, morphological, textural, and chemical characteristics of zircon from 9 rare metal granitic stocks and associated greisens were examined in order to identify the metallogenetic processes of their host granitoids. The investigated zircon-bearing granitoids and types of occurrences can be categorized into magmatically- and metasomatically-specialized types. The magmatic type include i) Peralkaline, Zr+Nb-enriched, Al-granite (e.g. Um Hibal); ii) Metaluminous, Nb+Zr+Y-enriched, A2-type alkali granite (e.g. Hawashia and Ineigi); iii) Peraluminous, Ta≧Nb+Sn+Be±W-enriched, Li-albite granite (e.g. Nuweibe, Igla and Abu Dabbab). The metasomatized granites are Nb>>Ta+Sn+Zr+Y+U±Be±W-enriched and hydrothermally altered alkali feldspar granite (i.e. apogranite; e.g. Um Ara, Abu Rusheid, and Um Naggat).

Zircon of metaluminous alkali granite is of Zr_0.99Hf_0.01SiO₄ in composition and is associated with sub-to transolvus assemblage of K-feldspar, quartz, plagioclase and annite-siderophyllite mica. It is prismatic with length/width ratios in the range of 5:1-3:1, doubly terminated with small pyramidal faces.

Zircon of peralkaline granite is characteristically equant with well developed pyramidal faces and short prisms (i.e. pseudo-octahedral habit) with length/width ratios in the range of 2:1-1:1. It is of Zr_0.990Hf_0.007SiO₄ in composition and is associated with hypersolvus assemblage consiting of alkali feldspar, quartz, aegirine and minor reibeekite.

Compositionally, zircon of Li-albite granite is ranging between Zr_0.925Hf_0.075SiO₄ and Zr_0.705Hf_0.295SiO₄. It is isomorphic with a simple combination of prism and bipyramidal terminations with length/width ratio of 3:1-2:1. This zircon commonly exhibits a normal zoning with rims consistently higher in Hf than cores. The higher Hf content of this zircon coupled with its association with topaz, tantalite and lithian micas (e.g. zinnwaldite and Li-white mica) indicates a higher solubility of Hf-flouride complexes and their more stabilized state at the lower temperatures in Li- and F-rich sodic melts.

Zircon of apogranite association ranges in composition between Zr_0.967Hf_0.013SiO₄ in the lower unaltered alkali feldspar granite zone and Zr_0.805Hf_0.64(Y, U, Th, HREE)_0.125SiO₄ in the apical metasomatized (i.e. microclinzed, albitized, and greisenized) apogranite zones. This compositional changes appear to reflect a roofward increasing in μKF, μNaF, and μHF of the exsolves fluids. Columbite, xenotime, uranothorite, cassiterite, beryl and fluorite are common associates of this zircon. This zircon is of bipyramidal to typical octahedral habit with complete absence of prism concurrently with conspicuous development of pyramid thus, imparting zircon crystals a length/width ratio of 1:1-0.5:1, The neoformed hydrothermal zircon commonly exhibits either normal or reverse zoning with rims consistently different in Hf, U, Y and HREE than cores, reflecting disequilibrium conditions (e.g. sudden change in P, T, salinity and pH) between the growing crystals and the exsolves fluids.

Mineral chemistry and geochemical characteristics of beryl-bearing granitoids, Eastern Desert of Egypt, were examined in order to identify the metallogenic processes of the host granitoids. The investigated berylliferous granitoids and type occurrences can be categorized as; i) Peraluminous, Ta≧Nb+Sn+Be±W-enriched, Li-albite granite (e.g. Nuweibi and Abu Dabbab) and ii) metasomatized, Nb>>Ta+Sn+Be±W±Mo-enriched alkali feldspar granite (i.e. apogranite; e.g. Homr Akarem, Homr Mikpid and Qash Amir).

In these two associations, beryl mineralization exhibits one or more the following mode of occurrence; stockwork greisen veins, greisen bodies, beryl + cassiterite±wolframite quartz veins, dissemination, and berylliferous miarolitic pegmatites.

The magmatically specialize, Li-albite granites exhibit a pronounced fractionated nature reflected in their LCT geochemical signature (for their enrichment in Li, Cs, and Ta). On the other hand, the lower unaltered alkali feldspar granite zones of apogranites are marginally metaluminous to mildly peraluminous. Besides, they are characterized by possessing NYF geochemical signature (for their enrichment in Nb, Y, and F).

Although beryl of the berylliferous granitoids contains appreciable contents of Fe, Na, and H₂O (particularly those of miarolitic pegmatites) yet, if is of normal type.

An important feature exhibits by the berylliferous apogranites is the occurrence of white mica as the sole mafic mineral in their lower unaltered alkali feldspar granite zones. Presence of white mica (i.e. phengites) can be considered as a mineralogical evidence that the volatile-rich pockets of such specialized melt underwent disequilibrium crystallization, rapid nucleation rates leading to exsolving and expulsion of Be-enriched volatile phase.

インド、Eastern Ghats Mobile Beltの中でも比較的新しい年代（1.9Ga）を示すdomain4岩体のShimliguda地域における、leptyniteを母岩とするalumunous granuliteとそれを取り囲むcharnockite試料を用いて、その産状を観察し、流体包有物や地質温度・圧力計などを用いて、生成環境や流体の挙動とその役割を推測する。

豊羽鉱山石見ヒのボーリングコアから見出されたPb-Sn-Sb-S 系鉱物について，産状や EPMA 化学分析の結果を元に考察した．EPMA の結果からは franckeite serise の potosiite に相当すると考えられるが, 周辺脈で報告されている同系統の鉱物と比較すると, 化学組成や共生鉱物など異なる点もいくつか見受けられた．

ジュラ紀以降に形成したカムチャツカ半島の金属鉱床区とテクトニクスについて，Nokleberg et al. (2005)を参考に再検討する．
また，カムチャツカ半島全域の熱水鉱床を主な対象とした10鉱床から得られた硫化鉱物の硫黄同位体の分析結果，各地域の花崗岩系列・基盤岩のタイプと分布から，Sn鉱床区およびAu-Ag鉱床の鉱化金属種の差異をもたらした鉱床成因を考察する．

Fluid inclusions preserve important clues on the metamorphic process and conditions. Especially, they may contribute information about the retrogressive metamorphism due to the existence of a large amount of inclusions and their good preservation state. CO₂ fluid is known as one of the important fluid species of heat transport from deep interior of the Earth, and it is considered to be an agent of metamorphism.

Recently, very high density CO₂ fluid is reported from ultrahigh temperature granulites in India (e.g., Sarkar et al., 2003), southern Africa (Tsunogae & Reenen, 2007) and East Antarctica (Tsunogae et al., 2002). These reports suggested that CO₂ fluids were active during peak metamorphism.

This study reports the petrographic data, the mode of occurrences and characteristics of fluid inclusions related to granulite metamorphism in the Eastern Ghats Granulite Belt, India.

The Laloki massive sulphide deposit (latitude: 9º26'S, longitude: 147º20'E) near Port Moresby is a time and stratabound type. It was first mined from 1908 to 1926 and again from 1938 to 1942. Production during mining was about 40, 000 tonnes of sulphide ore. The mine ceased due to World War II. Further metallurgical and exploration data after the war have confirmed economic reserves up to 373, 000 tonnes, with average grades of 3.75g/t Au, 10.76g/t Ag, 3.93% Cu and 2.51% Zn (Williamson, 1982; Shedden, 1990).

The Laloki massive sulphide is hosted by siliceous to calcareous, carbonaceous mudstone (Williamson, 1982) and rare white/gray chert (Davies, 1961) within the latest Paleocene succession. The Paleocene-Eocene sequences underlay the mine area with the Sadowa Gabbro of 55.7±1.5-56.3±0.5 Ma, K-Ar dating, intruding these sequences. Faulting and shearing of the sedimentary sequences are generally parallel to bedding and have regional NW to NE trend; stratal repetition is common in the area. Contact metamorphism is limited to a few meters locally resulting in aureoles of calc-silicate hornfels (Joyce, 1965; Yates & De Ferranti, 1967). A primary mineralisation is characterised by colloform and botryoidal textures, and including framboidal pyrite; and secondary mineralization was a remobilisation and recrystallisation of the primary mineralisation with a higher degree of crystallinity. To date, a Cu-Fe bearing zinc sulphide mineral has recently been discovered from unmetamorphosed ore (Kulange et al., 2002). This mineral plots as a distinct natural phase on the CuS-FeS-ZnS ternary phase of the Cu-Fe-Zn-S quaternary system.

鈴木光郎 (1981) と Mark V. Sander (1988) の二つの論文を参考にして、細粒石英が沈殿した状況を推測した。個々の石英結晶をCL像で見たとき、内部にみられる樹枝状の発光部分は初期に沈殿したカルセドニー部分が再結晶化したものであり、粒界に近い発光性を示さない部分によって埋められている。

ソーダライトの亜種であるハックマナイトは, 露光すると退色し, 紫外線を照射すると色が復元されるテネブレッセンスを示す.
ここ最近, ラピスラズリ鉱山で知られるSare Sang周辺のKokcha渓谷で産出が報告された宝石質ハックマナイトの産状について, 他の地域に産するハックマナイトの産状と比較し, 考察を行う.

秋田県北鹿盆地には、多数の黒鉱鉱床（海底噴気堆積性塊状硫化物鉱床）が分布する事が知られている。そこでは過去に活発な鉱山開発が行われ、また世界的にもその成因や生成環境などが関係研究者によって注目されて来た歴史がある。

同盆地西部の大館市周辺には、特に多くの黒鉱鉱床(花岡、松峰、釈迦内、松木等)が密集して分布し、中でも松峰鉱床と隣接する釈迦内鉱床では礫状黄鉱質黒鉱鉱石が卓越する傾向が認められる。

本鉱床第８鉱体近傍の鉱床層準上盤の凝灰岩中から産出した斑銅鉱質礫状黄鉱は、著しく金に富む特徴を示し、外観上は激しく角礫化している。破砕状黄鉄鉱の粒間を充填して斑銅鉱を主とする各種銅鉱物が産出し、粗粒エレクトラムに富むと共に、各種含Ag,Bi,Te鉱物を伴う特異な産状と組織を示す。 今回は、特に本鉱石の産状、鉱物共生、化学組成、生成条件等について述べる。

Franckeite series minerals の type locality は, いわゆるボリビア型多金属鉱床であり, 本邦でも豊羽鉱山の他に別子鉱山, 豊栄鉱山から産出の報告がある.
Sugaki and Kitakaze(1988)の論文等を元に, 豊羽鉱山と他の地域との Franckeite series minerals の産状を比較し, 考察を行う.

北東ユーラシア地域（日本，モンゴル，カムチャツカ等）の熱水鉱床と現世の熱水活動について，これまでフィールドワークを行った地域を対象に概要を述べる．
このほか，レアメタル資源を含む金属価格の高騰や資源リサイクル等の消費社会の現状についての問題点を議論する．

インド、Eastern Ghats Mobile Belt 中の Shimliguda 産 alumunous granulite と周囲の岩相について、これまで得られたデータに加え、同一石切り場の別の採取地点から得られた試料を用い、その産状や特性を流体包有物などから明らかにし、生成環境を推測する。

A review of Kuroko deposits will basically cover their genetic history, geology, tectonic setting, depth of formation and their ages. Their T-P conditions, alteration types, mineral assemblages (ore and gangue) and textures will be also discussed. Other massive sulphide deposits from Pacific Ocean, Besshi-type, Cyprus-type and VMS-type will be also looked at for comparison purpose.

In conclusion, a preliminary comparison of the Laloki massive sulphide deposit will be made in reference to the Kuroko and other related massive sulphide deposits.

鹿児島県菱刈鉱床において、昨年12月に実施された調査について観察結果等を述べる。鉱床のほぼ全域において試料を採取できた。本鉱床、山神鉱床、山田鉱床のそれぞれにおいて、特徴的な脈構造が確認できた。特に、山田鉱床西部において新たに発見された脈については、脈構造が不明瞭であったり粘土鉱物が多く含まれている等の特徴が目立った。

上国石 (Jokokuite) は、北海道桧山郡上国鉱山の Mn 炭酸塩鉱脈型鉱床から発見された新鉱物で、Manganese Sulfate Pentahydrate (MnSO₄・5H₂O， Triclinic；Nambu, M. et al., 1978) である。本鉱物は合成実験によりその安定領域が検討され、天然での産出が予想されながらもそれまで未発見であったものである。

今回は、第2の産地として上国鉱山と同様な Mn 鉱脈型鉱床である稲倉石鉱山で発見された上国石について、その産状や鉱物学的性質並びに成因について紹介する。併せて、稲倉石鉱床における Mn 鉱石の産状や鉱物組織についても紹介する。

大黒島は，北海道東部・厚岸町の沖約 3km に位置する外周 6.1km，面積 1.1km²の無人島であり，周囲は標高約 80m の急崖に囲まれている．同島内陸部 の測線上 19 地点から土壌を採取し，植生・植被率の記載，植物の採取を行った．地球化学図，生物多様性マップをもとに，土壌の化学的性質と土壌動物の生息環境の関係について初期見解を述べる．

※この内容は，21世紀 COE 若手研究者共同研究プロジェクト (高橋亮平，舘卓司，大原昌宏，松枝大治，馬渡峻輔，吉田尚生，高橋英樹，小林快次) によるものです．

アフガニスタン,Badakhshan,Kokcha valleyに産するソーダライトの亜種であるハックマナイトについて、SEM-CL 分析で得られたデータを元に考察する。