Primary Sn-rich titianite in the Qitianling granite, Hunan Province, southern China: An important type of tin-bearing mineral and its implications for tin exploration

Xie, Lie‐Wen; Wang, Rucheng; Zhu, Junjiang; Zhang, Wenlan; Dezi, Wang; Yu, Aibing

doi:10.1007/s11434-008-0557-1

Cited by 15 publications

(1 citation statement)

References 16 publications

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“…The exposed pluton, which is inferred to have been incrementally built (Liu et al, ), constitutes three main rock types (phases; Xie et al, ; Zhu et al, ): (1) porphyritic, medium‐ to coarse‐grained amphibole‐biotite‐rich monzonitic granite (Phase 1, ~45% of the exposure); (2) medium‐grained biotite ± amphibole‐bearing granite (Phase 2; ~40% of the exposure); and (3) a fine‐grained, biotite‐bearing granite (Phase 3; ~15% of the exposure; Figure b). Mafic microgranular enclaves (MMEs) with sizes between several centimeters to decimeters also locally occur, mostly in the Phase 1 granite (Zhao et al, ).…”

Section: Geological Settingmentioning

confidence: 99%

Experimental Constraints on Intensive Crystallization Parameters and Fractionation in A‐Type Granites: A Case Study on the Qitianling Pluton, South China

et al. 2019

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Phase equilibrium experiments are essential for robustly and accurately constraining the intensive parameters of magma systems and their fractionation history, which is particularly true for A-type granites crystallized from H 2 O-rich melts and at reducing conditions. Here, we constrain the crystallization conditions of the ferroan (A-type), Sn-mineralized Qitianling granite of South China, which formed during a major event of crustal formation and reorganization in the Mesozoic. To characterize the magma system conditions and fractionation, we have carried out a series of experiments on three representative, amphibole-bearing samples. The experiments were performed at 100-700 MPa (mainly at 200 and 300 MPa), at an fO 2 of~NNO−1.3 (1.3 log unit below the Ni-NiO buffer) or~NNO+2.4, at 660 to 900°C , and at variable H 2 O melt (~3-9 wt %). They show that the Qitianling magmas last crystallized at ≥300-350 MPa, at a H 2 O melt ≥ 6.5-8.0 wt %, and that magmatic fO 2 was~NNO−1.3 ± 0.5 at above-solidus conditions. Amphibole texture in the rocks suggests an early crystallization of this mineral, hence that water-rich (≥4 wt % H 2 O in melt) conditions prevailed early during the magmatic evolution, prior to amphibole crystallization. At all investigated conditions, amphibole crystallization requires at least 5-6 wt % dissolved H 2 O, being even absent in the more potassic composition. We interpret this as resulting from the elevated K 2 O content of the investigated compositions that inhibits amphibole crystallization in metaluminous granitic systems. The experimental liquid line of descent obtained at 200-300 MPa mimics the geochemical trend expressed by the pluton suggesting that fractionation occurred in the upper crustal reservoir. Key Points: • A-type Qitianling magmas were produced at high temperature (>900°C ) and with initial H 2 O melt ≥ 4 wt % • Crystallization of Qitianling granites occurred at ≥300-350 MPa, NNO −1.3 ± 0.5, and near-solidus H 2 O melt ≥ 6.5-8.0 wt % • Fractionation of the magmas occurred at or close to the level of final emplacement and crystallization Supporting Information: • Supporting Information S1granite evolution, we have carried out phase equilibrium experiments to robustly constrain the intensive parameters of crystallization for the A-type granites. We present (1) a petrological and geochemical overview on the Qitianling pluton; and (2) results from our phase equilibrium experiments; followed by a discussion of (3) the intensive crystallization parameters; and (4) processes underlying the geochemical variation of the pluton. We highlight that phase equilibrium constraints are crucial for deriving reliable estimates for crystallization temperatures, melt H 2 O content, and fO 2 for ferroan A-type granites, and thus for unraveling Mesozoic crust formation and evolution in South China.

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Section: Geological Settingmentioning

confidence: 99%

Experimental Constraints on Intensive Crystallization Parameters and Fractionation in A‐Type Granites: A Case Study on the Qitianling Pluton, South China

et al. 2019

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Cassiterite exsolution with ilmenite lamellae in magnetite from the Huashan metaluminous tin granite in southern China

Wang

Chen

et al. 2012

Miner Petrol

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Sn 4+ is generally the dominant form of tin in magnetite-series granites as shown by the presence of cassiterite or its incorporation into Ti-bearing minerals such as biotite and titanite. Little is known about the behavior of tin in magnetite. The Huashan granite is an oxidized tin granite in the Nanling Range, southern China, where it contains magnetite as the dominant Fe oxide mineral. It is included in biotite as an early phase and also as interstitial grains spatially associated with ilmenite, cassiterite, Sn-rich titanite (SnO 2 up to 5.9 wt.%), fluorite and apatite. This association indicates that tin enrichment occurred during the late stage of magma crystallization. Ilmenite lamellae display a trellis structure consistent with features of the "oxy-exsolution" process of Sn-bearing titanomagnetite precursor. Microinclusions of cassiterite (<1 μm in size) are found only within ilmenite lamellae. This suggests that magnetite with cassiterite inclusions is likely an indicator mineral of oxidized tin granites. Although rare in nature, Sn-bearing magnetite from weathered granites where concentrated in stream sediments, may serve as a strategic tracer for tin exploration in granite districts and in placer deposits, in general.

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Polyphase scheelite and stanniferous silicates in a W-(Sn) skarn close to Felbertal tungsten mine, Eastern Alps

Ordosch

Raith

Schmidt³

et al. 2019

Miner Petrol

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The scheelite exploration target Messelingscharte (Eastern Tyrol, Austria) is located in vicinity of the world-class Felbertal tungsten deposit. W-(Sn) mineralisation occurs in Early Palaeozoic amphibolites (Basal Amphibolite unit) in the Tauern Window of the Eastern Alps. The most important mineralisation type is a Sn-bearing clinozoisite-scheelite skarn of pre-Alpine (Variscan?) age. It occurs as metre-sized irregular pods within amphibolites and amphibole schists. It is composed of major clinozoisite, quartz, plagioclase and scheelite with minor and accessory titanite, calcite and chlorite. Bulk chemical analyses reveal high concentrations of the granitophile elements W (≤7.74 wt% WO 3 ), Sn (≤1254 ppm SnO 2 ), Be (≤41 ppm) and base metals (Cu, Pb, Zn; ∑ ≤ 2500 ppm) in the skarn rock. Three scheelite types are distinguished based on micro-textures, zoning, Mo-content and UV-fluorescence. They show intriguing similarities to scheelite from the Felbertal tungsten deposit where pre-Alpine Mo-bearing scheelite was apparently overprinted by two stages of metamorphism. The unique feature of the investigated W-(Sn) skarn is the association of scheelite with Sn-bearing silicates. Stanniferous clinozoisite and stanniferous titanite were identified as the main Sn carriers (clinozoisite ≤3.00 wt% SnO 2 ; titanite ≤6.48 wt% SnO 2 ); both minerals evidence metamorphic re-crystallisation. Substitution of (Al, Fe) 3+ by (Sn, Ti) 4+ in clinozoisite is coupled with incorporation of Fe 2+ . The skarn formed by interaction of fluids of likely magmatic-hydrothermal origin with metabasites. The clinozoisite-dominated calcsilicate rocks are interpreted as a metamorphosed distal W-(Sn) skarn.

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Primary Sn-rich titianite in the Qitianling granite, Hunan Province, southern China: An important type of tin-bearing mineral and its implications for tin exploration

Cited by 15 publications

References 16 publications

Experimental Constraints on Intensive Crystallization Parameters and Fractionation in A‐Type Granites: A Case Study on the Qitianling Pluton, South China

Experimental Constraints on Intensive Crystallization Parameters and Fractionation in A‐Type Granites: A Case Study on the Qitianling Pluton, South China

Cassiterite exsolution with ilmenite lamellae in magnetite from the Huashan metaluminous tin granite in southern China

Polyphase scheelite and stanniferous silicates in a W-(Sn) skarn close to Felbertal tungsten mine, Eastern Alps

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