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Daixian |
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Shanxi, China |
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Ti
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Super Porphyry Cu and Au
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The Daixian group of rutile deposit is located 240 km to the north of Taiyuan City in the north of Shanxi Province, and 285 km west of Beijing in northern China (#Location: 39° 16'N, 113° 01'E).
These deposits are situated within the Palaeoproterozoic Trans-North China Orogen, a 100 to 300 km wide and ~1200 km long, north-south to NE-SW trending terrane that separates the eastern and western blocks of the North China craton. The Xingyang-Kaifeng-Shijiazhuang-Jianping and Huashan-Lishi-Datong-Duolun faults form the margins with the eastern and western cratonic blocks respectively (Zhao et al., 2007). The deposits lie on the southern limb of the Caoduoshan-Fenshuiling anticline of the Hengshan Mountains, <50 km from the western margin of the northern half of the Trans-North China Orogen.
The Trans-North China Orogen includes the Taihua, Fuping, Hengshan, Huai'an and Xuanhua high-grade metamorphic complexes, and the Dengfeng, Zhongtiao, Zanhuang, Lüliang and Wutai low- to intermediate-grade metamorphic complexes (Zhao et al., 2000). The orogen is characterised by linear structural belts with strike-slip ductile shear zones, large-scale thrusting and folding (Li and Qian, 1991; Dirks et al., 1997; Zhang et al., 2007), sheath folds and strong mineral lineations (Wu and Zhong, 1998; Zhang et al., 2007). High-pressure granulites and retrograde eclogites are present, as are ancient oceanic fragments and ophiolitic mélange (Li et al., 1991; Bai et al., 1992; Polat et al., 2005; Zhao and Kröner, 2007).
The Daixian deposit occurs in the Nianzigou Formation of the Archaean Wutai Complex, which comprises greenschists to amphibolite facies rocks and is divided, from the base to the top into the Taizidi, Nianzigou and Binlingou formations (Jia et al., 2006).
The rutile ores are hosted in anthophyllite- and vermiculite- gneisses, and albite-clinochlore- bearing anthophyllite gneisses and vermiculite-anthophyllite bearing quartzite of the Upper Nianzigou Formation. The wall rocks are amphibolite with minor granulite, with a sharp boundary between ore and amphibolite, although both share similar foliations.
Most of the rutile ore is hosted in garnet-free anthophyllite gneiss with minor Mg hornblende, feldspar, quartz, phlogopite, rutile, zircon and titanite. Rutile grains are euhedral, 0.02 to 0.50 mm in size, contain 98.65 to 99.78.wt % TiO2, and form chains, thin layers along the foliation and dense aggregates. Rutile grains are compositionally homogeneous and contain no detectable mineral inclusions except local ilmenite lamellae and zircon. Crystallisation temperatures of the rutile are estimated at ~640°C at 0.7 GPa. Nb and Cr variations in rutile indicates a mafic protolith (rather than from aluminous pelitic rocks). SIMS U-Pb analyses of rutiles from the deposit yield a mean 207Pb/207Pb age of 1780.2±9.6 Ma. The characteristics of the rutile suggest this is a recrystallisation age rather than peak metamorphism so the rutile deposit formed no later than ~1780 Ma.
The rutile ores occur as layers or lenses in the Nianzigou Formation trending east-west to the west, to NW-SE in the east. Individual bodies of ore are several hundred metres to >1 km long, several to more than 100 m thick, and extend to depths of several tens to several hundred metres. From west to east there are three mining areas: Hongtang, Nianzigou and Yangtingshi, each separated by ~500 m along strike and distributed over a strike length of ~4 km. The deposits contain ~300 Mt of rutile ore averaging ~2.0 wt.% TiO2, locally up to 6.11 wt.%. The deposit has been mined since 2005.
The most recent source geological information used to prepare this decription was dated: 2012.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Shi G, Li X, Li Q, Chen Z, Deng J, Liu Y, Kang Z, Pang E, Xu Y and Jia X, 2012 - Ion Microprobe U-Pb Age and Zr-in-Rutile Thermometry of Rutiles from the Daixian Rutile Deposit in the Hengshan Mountains, Shanxi Province, China : in Econ. Geol. v.107 pp. 525-535
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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