Karst bauxite deposits in the Zagros Mountain Belt, Iran

Zarasvandi, Alireza; Charchi, A; Carranza, Emmanuel John M.; Alizadeh, Bahram

doi:10.1016/j.oregeorev.2008.05.005

Cited by 78 publications

(37 citation statements)

References 18 publications

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“…Most of Iranian karst bauxites in the Zagros orogenic belts are low-grade, böhmitic, diasporic bauxites [14][15][16][17]. They contain 20-45 wt % Al 2 O 3 , 3-38 wt % Fe 2 O 3 , and in most cases appear red in outcrops.…”

Section: Introductionmentioning

confidence: 99%

The Role of Organic Matter in the Formation of High-Grade Al Deposits of the Dopolan Karst Type Bauxite, Iran: Mineralogy, Geochemistry, and Sulfur Isotope Data

Ellahi¹,

Taghipour²,

Nejadhadad³

2017

Minerals

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Mineralogical and geochemical analyses of the Dopolan karstic bauxite ore were performed to identify the characteristics of four bauxite horizons, which comprise from top to bottom, bauxitic kaolinite, diaspore-rich bauxite, clay-rich bauxite, and pyrite-rich bauxite. Diaspore, kaolinite, and pyrite are the main minerals; böhmite, muscovite, rutile, and anatase are the accessory minerals. The main minerals of the Dopolan bauxite deposit indicate slightly acidic to alkaline reducing conditions during bauxitization. Immobile elements (Nb, Ta, Zr, Hf, and rare earth elements) are enriched in the diaspore-rich horizon, which also has the highest alumina content, whereas redox sensitive elements (e.g., Cr, Cu, Ni, Pb, Zn, Ag, U, and V) are enriched in the lowest horizon of pyrite-rich bauxite. The presence of a high content of organic matter was identified in different horizons of bauxitic ore from wet chemistry. The presence of organic matter favored Fe bioleaching, which resulted in Al enrichment and the formation of diaspore-rich bauxite. The leached Fe 2+ reacted with the hydrogen sulfur that was produced due to bacterial metabolism, resulting in the formation of the pyrite-rich horizon towards the bottom of the Dopolan bauxite horizons. Biogeochemical activity in the Dopolan bauxitic ore was deduced from the reducing environment of bauxitization, and the deposition of framboidal and cubic or cubic/octahedral pyrite crystals, with large negative values of δ 34 S of pyrite (−10‰ to −34‰ ) and preserved fossil cells of microorganisms.

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Section: Introductionmentioning

confidence: 99%

The Role of Organic Matter in the Formation of High-Grade Al Deposits of the Dopolan Karst Type Bauxite, Iran: Mineralogy, Geochemistry, and Sulfur Isotope Data

Ellahi¹,

Taghipour²,

Nejadhadad³

2017

Minerals

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“…Based on the Al2O3-Fe2O3-SiO2 ternary diagram [50], organic-rich and clay-rich bauxite horizons show weak and moderate lateritization, respectively, whereas oolitic, pisolitic and iron-rich bauxites plot in the strong lateritization field ( Figure 6). Furthermore, the Dopolan bauxite samples plot in the bauxite and kaolinite bauxite fields on the Al2O3-Fe2O3-SiO2 ternary diagram ( Figure 7) suggesting tropical paleo-geographic conditions which favored bauxitization and the formation of bauxite horizons [9,51]. High content of trace elements such as Cr (132-1088 ppm), Zr (132-557 ppm) and Nb (28-77 ppm) is a significant and common feature of the Dopolan bauxite (Table 2).…”

Section: Major and Trace Elementsmentioning

confidence: 98%

“…Based on the Al 2 O 3 -Fe 2 O 3 -SiO 2 ternary diagram [50], organic-rich and clay-rich bauxite horizons show weak and moderate lateritization, respectively, whereas oolitic, pisolitic and iron-rich suggesting tropical paleo-geographic conditions which favored bauxitization and the formation of bauxite horizons [9,51].…”

Section: Major and Trace Elementsmentioning

confidence: 99%

“…Residual bauxite deposits are classified as karst bauxite and laterite type bauxite [1]. Karst bauxite deposits from the Mediterranean region and other worldwide bauxite formations have been investigated by a number of authors [2][3][4][5][6][7][8][9][10][11]. Karst bauxite genesis is related to paleo-weathering products derived from different rocks types including carbonate rocks, marl, volcanic and magmatic rocks [12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…The most important known bauxite deposits in Iran are distributed in four regions, namely: (1) Sanandaj-Sirjan belt, Permo-Triassic and late Triassic in Bukan and Kanshiteh; (2) The Zagros Fold belt, Upper Cretaceous, Triassic in Mandan, Deh-now, Sarfaryab and Dopolan [9]; (3) The Alborz mountains, Upper Triassic in Tilabad and Jajarm [31]; and (4) The central plateau of Iran, Upper Triassic, Permo-Triassic in Bazargan and Balbaloyeye [31] (Figure 1). The Triassic Dopolan bauxite deposit is located in the Chaharmahal and Bakhtiary province in a high Zagros structural zone.…”

Section: Introductionmentioning

confidence: 99%

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Mineralogy, Geochemistry and Stable Isotope Studies of the Dopolan Bauxite Deposit, Zagros Mountain, Iran

et al. 2016

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Abstract:The Dopolan deposit is a Mediterranean-type bauxite located in the Zagros Fold-Thrust Zone, Iran. This deposit consists of five lithological members including iron-rich, clay-rich, oolitic, pisolitic and organic matter-containing bauxites. The mineralogy of the deposit includes diaspore, boehmite, and kaolinite, nacrite, with minor pyrite, anatase and rutile. Geochemical studies show that light rare earth elements (LREEs) are enriched relative to heavy rare earth elements (HREEs) in all members, supporting an authigenic origin. Mass changes based on Ti as an immobile element indicate that conventionally-immobile elements (Al, Nb, Ta, Zr, Hf) are enriched in situ in the residual units, whereas mobile elements (K, Ca, Si) were depleted during bauxitization. This study shows that the Khaneh-Kat argillitic dolomite is the likely parent rock. The δ 18 O (7.63‰to 9.35‰) and δD values (´49.91‰to´66.49‰) for kaolinite in the bauxite samples suggest equilibration with meteoric waters which supports a supergene origin. Bauxitization occurred in a warm climate with relatively constant isotopic composition suggesting climate stability during the development of bauxite horizons and remobilization of Al (with formation of secondary boehmite). The δ 13 C values of calcite (´7.3‰) in the bauxite support the idea that the Khaneh-Kat Formation has experienced post-depositional isotope exchange with meteoric waters during the karstification process.

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