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最終更新日:2017年1月3日
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図3. 豪州の鉱石種別生産推移(1965年〜2008年)(O'Brien, 2009に加筆) |
図4. ハマスレー地域の地質概略と鉱床分布(Ramanaidou and Morris, 2010に加筆) |
図13. ハマスレー地域のチャンネル鉄鉱床分布と探鉱地域(Dalstra et al.,2010) @カリウィンギナ、Aセレニティ、Bソロモン・イースト、Cビーズリー・リバー |
図12. チャンネル鉄鉱床生成メカニズム(Dalstra et al.,2010) |
図11. 国内鉄鉱石および輸入粉鉱の品質(稲角, 2008) |
中山(2012)による『豪州ハマスレー地域のチャンネル鉄鉱床と我国製鉄技術の貢献』から |
Fig. 1. Distribution of Neoproterozoic iron formations: (A) World map showing the locations and age of major Neoproterozoic IFs, data sources are Breitkopf (1988), Klein and Beukes (1993), Lottermoser and Ashley (2000), Pelleter et al. (2006), Mukherjee (2008), Ali et al. (2009), Ilyin (2009), Bekker et al. (2010), Pecoits (2010); Basta et al.(2011)による『Petrology and geochemistry of the banded iron formation (BIF) of Wadi Karim and Um Anab, Eastern Desert, Egypt: Implications for the origin of Neoproterozoic BIF』から |
図1. 主要成分(アロケム粒子、鉄ミクライト、チャート)に基づくIFの分類及び命名(Beukes and Gutzmer, 2008) 図2. 原生代中期末までのグリーンストーン帯及びクラトンでのIFの時間分布。 Aは総量(百万t)、Bは総数を示す(Beukes and Gutzmer, 2008) 図3. IFを含む先カンブリア紀のクラトン及びサクセッションの世界分布。グリーンストーン帯の表示は、それらが断片的に多数分布していることを示すためのものであり、あくまで概略である。最も興味深い点は、IFを胚胎するクラトン及びサクセッションは限られており、世界的に見れば露頭は非常に少ないことである。また、広域的に分布する原生代後期の氷河堆積物と関連したラピタン型IFの分布も少ない(Beukes and Gutzmer, 2008) 図19. 高品位赤鉄鉱層の浅成変成モデル。A:酸化及び鉱化前、B〜F:電気化学過程による地下深部の酸化作用が、地表に向かって上昇・発達する過程(薄灰色)と、深部の赤鉄鉱.針鉄鉱鉱石の形成(濃灰色)を示す。地下構造に沿って浸透した地下水によりシリカの溶脱が生じた。H:埋没変成作用による針鉄鉱からのマイクロプレート赤鉄鉱の形成を示す。I:残された針鉄鉱の溶脱が生じ、品位向上した低P含有の赤鉄鉱鉱石が形成された(Morris, 1980、1985に加筆) 図25. WA州高品位鉄鉱石鉱床形成モデル(5段階)を示す。A〜C:一般的なBIF形成。D及びE:“チャートを含まないBIF”形成及び高品位赤鉄鉱.針鉄鉱鉱石に変換する最終段階の浅成作用を示す(Lascelles, 2006) 図26. Mt. Whaleback鉱床、Mt. Tom Price鉱床、Paraburdoo鉱床の高品位( Fe品位63 w %以上)マータイト−マイクロプレート赤鉄鉱鉱床形成に関する成因モデル。岩質ユニットは各鉱床図のとおり。熱水温度及び流体経路は本文を参照。(Thorne et et al., 2008) Hagemann(2011)による『鉄鉱石資源(4)WA 州のBIF に胚胎する鉄鉱石鉱床及び高品位深成鉱化作用の規制要因』から IF=鉄鉱層(Iron Formation) |
FIGURE 1. Global occurrence of Precambrian BIFs (after Trendall 2002). The map emphasizes the wide distribution of BIF and shows only a selection of well-known occurrences of different ages and kinds. BIFs that are discussed in this paper are shown in italics. |
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FIGURE 2. Highly schematic diagram showing the relative abundance of Precambrian BIFs vs. time, with several of the major BIFs or major BIF regions identitified. Estimated abundances are relative to the Hamersley Group BIF volume taken as a maximum (adapted from Gole and Klein 1981a; also based on tabulation of BIF dates in Walker et al. 1983, their table 11.1). The most recent age evaluations for the Hamersley Basin (2.8 to 2.2 Ga) are available from Trendall et al. (2004); for the Labrador Trough BIFs (1.88 Ga) from Findlay et al. (1995), and for the BIFs in the Frere Formation, Western Australia (1.9 to 1.8 Ga) from Williams et al. (2004). |
FIGURE 29. Relative abundance curve for BIF in the Precambrian (taken from Fig. 2) as well as calculated curves for the atmospheric evolution of oxygen and carbon dioxide from Kasting (2001, 2004), Kasting and Catling (2003), and Pavolv and Kasting (2002). |
FIGURE 10. Relative stabilities of minerals in metamorphosed ironformations as a function of metamorphic zones. From Klein (1983). |
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FIGURE 25. Schematic depositional environment for iron-formation and that of associated lithofacies in a marine system with a stratified water column in (a) a regressive stage, and (b) a transgressive stage. In a, the photic zone reaches the floor of the deep shelf, allowing for cryptalgalaminated limestone deposition. In b, the photic zone is considerably above the floor of the deep shelf, causing the deposition of various iron-formation types and chert. The thick arrows labeled C (carbon) in a represent high carbon productivity and supply, and the narrow arrows in b represent less carbon productivity and supply. From Klein and Beukes (1989). |
FIGURE 26. Schematic depositional environment for iron-formation and associated lithofacies in a marine system with a stratied water column. The thick arrows labeled C (organic carbon) represent high productivity (as in Fig. 25) whereas the thinner arrows represent lesser carbon productivity and supply. Banded siderite iron-formation precipitates along the chemocline where there is some organic carbon supply. Magnetite- and hematite-rich iron-formation precipitate where the organic matter supply is low and some oxygen is available. The well-mixed and near-shore water masses, where limestone deposition took place had a 13C composition similar to that of present-day oceans, close to 0. The deeper waters, where siderite-rich iron-formation was a primary precipitate (with δ13C on average, negative at .5.3.) as a result of signiT cant hydrothermal input, is shown as stratiT ed with δ13C (carb) ≒-5‰. (from Beukes et al. 1990). |
FIGURE 27. Paleoceanographic models for iron-formation deposition from the Archean to the Middle Proterozoic. (a) Archean to Early Proterozoic: stratiT ed ocean system with predominantly deep water deposition of microbanded iron-formation. (b) Middle Early Proterozoic: Breakdown of the stratiT ed ocean system and deposition of oolitic ironformation in shoal areas. (c) Middle Proterozoic: Fe-depleted, well mixed ocean system that is somewhat oxygenated but depleted in Fe. From Beukes and Klein (1992). |
manganese-formations. From Beukes and Klein (1992). |
Klein(2005)による『Some Precambrian banded iron-formations (BIFs) from around the world: Their age, geologic setting, mineralogy, metamorphism, geochemistry, and origin』から 【鉄鉱床中の代表的な鉄珪酸塩鉱物】〔リンクはウィキペディア〕 |
エヴァンズ(1989)による『鉱床地質学序説』から |
第15章 先カンブリア縞状鉄鉱層(梶原良道)
立見(編)(1977)による『現代鉱床学の基礎』から |