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Tuwu Yandong

Xinjiang, China

Main commodities: Cu Au
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The Tuwu, Yandong (6 km west of Tuwu), Chichu (30 km ENE of Tuwu) and Linglong porphyry Cu-Au deposits are located within eastern Xinjiang in western China, some 500 km ESE of the provincial capital of Urumqi and 80 km directly southwest of the city of Hami (#Location: Tuwu - 42° 6' 53"N, 92° 36' 17"E; Yandong - 42° 4' 1"N, 92° 32' 18"E.

They were deposited at 330 Ma during the Carboniferous, within the Kazakh-Mongol magmatic arc and occur immediately to the north of the major Kangguer Fault which marks the northern margin of the broad, transitional suture zone between the arc and the Tarim micro-continent to the south. To the south of this fault, a 10 km wide belt is characterised by an ophiolite bearing ductile shear deformed melange. The Carboniferous island arc succession that hosts the deposits is bounded to the north by a Devonian arc assemblage (Wang et al., 2001a; 2001b, Mao et al., 2003).

The Tuwu-Yandong cluster of deposit is quoted as containing 7.5 Mt of Cu metal (Kirkham and Dunne, 2000). Han et al., (2003), quote a resource at the main Tuwu deposit alone of 144.5 Mt @ 0.72% Cu, 0.16 g/t Au at a 0.5% Cu cut-off, or 292 Mt @ 0.49% Cu at a 0.2% Cu cut-off.

Geology

The arc and overlying sequence north of the Kangguer Fault comprises the Carboniferous (Han et al., 2003; Wang et al., 2001a, 2001ba), or Devonian (Qin et al., 2002) Qi'eshan Group, which has been subdivided into the following units, from the base: i). Unit 1 - light grey-brown, grey and grey-green medium to coarse-grained schistose greywacke - >100 m thick. ii). Unit 2 - purple-red andesitic volcanic breccia and grey-green tuff - 100 m thick. iii). Unit 3 - grey-green amygdaloidal basalt - 130 m thick. iv). Unit 4 - grey-green and light grey to grey-white pebbly-lithic sandstone, locally grading into polymictic conglomerate, lithic sandstone and bedded tuff, with intercalated basalt, andesite and dacite flows - 170 m thick. v). Unit 5 - grey-green amygdaloidal spilite-keratophyre lavas and brecciated flows, including intercalated trachy-basalt, basaltic trachy-andesite, trachy-andesite, dacite and rhyolite. This unit is the principal wall rock and host to the mineralised intrusives of the Tuwu porphyry Cu-Au deposit - 200 m thick. vi). Unit 6 - grey-green polymict conglomerate with granite, basalt and felsic porphyry clasts, with intercalated fine-grained lithic sandstone - 25 m thick.

The Qi'eshan Group is unconformably overlain by Middle Triassic sandstone and conglomerate of the Xishanyao Formation and by Quaternary sand and gravel cover (Han et al., 2003).

Diorite porphyry and at least 23 individual small stocks of plagiogranite porphyry have been intruded into the Qi'eshan Group in the Tuwu district. The plagiogranite intrusives are massive in appearance and have a porphyritic texture with phenocrysts of quartz, plagioclase and biotite in a subhedral matrix and comprise the mineralised porphyries of the district hosting the Tuwu, Yandong, Linglong and Chichu porphyry Cu-Au deposits (Han et al., 2003).

While Han et al., (2003) describe the deposit as lying within a consistent south dipping succession as described above, Wang et al., (2001a; 2001b) concluded that the mineralised diorite and plagiogranite porphyries have intruded the core of an east-west trending anticline of Qi'eshan Group sediments and volcanics, the limbs of which comprise an outward succession of siltstones, to tuffs and then basalt. This would imply a thinner host succession with only four units. Wang et al., (2001a; 2001b) also observe that the intersection of east-west strike slip faulting and cross trending NNW structures control the localisation of mineralisation. The diorite porphyry, which trends ENE and covers an area of 4 sq km, precedes the less extensive plagiogranite porphyry.

Alteration and Mineralisation

The main Tuwu porphyry Cu-Au deposit is a steeply dipping, east-west elongated body with a surface length of 1400 m, a maximum width of 175 m (20 m at surface, thickening with depth) and down-dip extent of more than 600 m. Its hangingwall and footwall both dip south at 60 to 65° and 65 to 80° respectively, while the orebody tends to plunge to the east. A lower grade deposit, Tuwu East, which is 1300 m long and varies from 32 to 85 m in width, occurs 200 m to the east of the main Tuwu orebody (Han et al., 2003; Wang et al., 2001a; 2001b).

Mineralisation occurs as veinlet, disseminated and less commonly nodular sulphides, principally chalcopyrite and pyrite, with minor bornite, sphalerite, magnetite and rickardite. Molybdenite is also present at Tuwu East. Chalcocite and digenite are found in the supergene enriched ore, while malachite occurs in the oxide zone. Gangue minerals within, and as selvages to veinlets, are quartz, plagioclase, sericite, chlorite and biotite with minor pyroxene, epidote, zoisite and calcite.

Mineralisation is hosted by plagiogranite porphyry which occurs in the deposit area as large dykes, in the adjacent diorite porphyry and in basaltic wall rocks. Within the plagiogranite, sulphides are predominantly disseminated, with the principal copper sulphide being medium- to coarse-grained chalcopyrite (or chalcopyrite aggregates) while in the volcanics and diorite porphyry, mineralisation takes the form of well-developed disseminations, veinlets and aggregates of chalcopyrite with associated disseminated bornite (Han et al., 2003).

A number of hypogene mineralised stages are recognised, as follows: i). Stage 1 is characterised by biotite alteration, accompanied by albite and K feldspar, with disseminated chalcopyrite + bornite mineralisation; ii). Stage 2 comprises phyllic alteration with associated quartz + pyrite + chalcopyrite assemblages occurring as veins; iii). Stage 3 is represented by quartz-molybdenite veining and molybdenite disseminations; iv). Stage 4 is composed of sulphates (gypsum and anhydrite) with some accompanying sulphide veinlets; v). Stage 5, late stage carbonate (calcite), laumontite and minor sulphides.

The hypogene mineralisation has been subjected to oxidation at surface with the formation of malachite and limonite with brochantite and black copper-wad, underlain by some supergene enrichment to produce chalcocite and digenite (Han et al., 2003). There is an outward alteration zonation of alteration as follows: i). siliceous core; ii). biotite; iii). phyllic; iv). argillic; and v). propylitic outer halo.

In practice however, only three alteration styles are recognised. Phyllic alteration (including an intensely siliceous zone) predominates in the plagiogranite porphyry in the core of the deposit, and is associated with the main orebody, comprising quartz-sericite (muscovite and hydro-muscovite), with minor albite and chlorite. The chlorite-biotite zone is found in the more extensive diorite porphyries (and basalts ?) into which the plagiogranite porphyry dykes were intruded, and as such is on either side of the phyllic zone. It accompanies the outer sections of the main orebody and is characterised by mafic biotite with minor accompanying K feldspar. The outer propylitic zone is mainly composed of chlorite, epidote and albite and is only accompanied by low grade mineralisation on the periphery of the orebody (Han et al., 2003; Wang et al., 2001a; 2001b).

The most recent source geological information used to prepare this summary was dated: 2005.    
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.


Tuwu

Yandong

  References & Additional Information
   Selected References:
Gao, J., Qin, K., Zhou, M.-F. and Zaw, K.,  2018 - Large-scale porphyry-type mineralization in the Central Asian Metallogenic Domain: Geodynamic background, magmatism, fluid activity and metallogenesis: in    J. of Asian Earth Sciences   Online, https://doi.org/10.1016/j.jseaes.2018.08.023.
Han, C., Rui, Z., Mao, J., Yang, J., Wang, Z. and Yuan, W.,  2003 - Geological characteristics of the Tuwu copper deposit, Hami, Xionjiang: in Mao, Goldfarb, Seltmann, Wang, Xiao and Hart (Eds.), 2003 Tectonic Evolution and Metallogenesis of the Chinese Altay and Tianshan, Proceedings Volume of the International Symposium of the IGCI-473 Project in Urumqi and Guidebook of the Field Excursion in Xinjiang, China: August 9-21, 2003 IAGOD Guidebook Series 10: CERCAMS/NHM London,    pp 249-260
Han, C., Xiao, W., Zhao, G., Mao, J., Li, S., Yan, Z. and Mao, Q.,  2006 - Major types, characteristics and geodynamic mechanism of Upper Paleozoic copper deposits in northern Xinjiang, northwestern China: in    Ore Geology Reviews   v28 pp 308-328
Han, C., Xiao, W., Zhao, G., Mao, J., Li, S., Yan, Z. and Mao, Q.,  2006 - Major types, characteristics and geodynamic mechanism of Upper Paleozoic copper deposits in northern Xinjiang, northwestern China: in    Ore Geology Reviews   v.28, pp. 308-328.
Han, C., Xiao, W., Zhao, G., Mao, J., Yang, J., Wang, Z. Yan, Z. and Mao, Q.,  2006 - Geological characteristics and genesis of the Tuwu porphyry copper deposit, Hami, Xinjiang, Central Asia: in    Ore Geology Reviews   v29 pp 77-94
Han, C., Xiao, W., Zhao, G., Mao, J., Yang, J., Wang, Z., Yan, Z. and Mao, Q.,  2005 - Geological characteristics and genesis of the Tuwu porphyry copper deposit, Hami, Xinjiang, Central Asia: in    Ore Geology Reviews   v29 pp 77-94
Han, C., Xiao, W., Zhao, G., Su, B., Sakyi, P.A., Ao, S., Zhang, J. and Zhang, Z.,  2014 - Late Paleozoic Metallogenesis and Evolution of the East Tianshan Orogenic Belt (NW China, Central Asia Orogenic Belt): in    Geol. of Ore Deposits (Pleiades Publishing)   v.56, pp. 493-512.
Mao J, Goldfarb R J, Wang Y, Hart C J, Wang Z, and Yang J,  2005 - Late Paleozoic base and precious metal deposits, East Tianshan, Xinjiang, China: Characteristics and geodynamic setting: in    Episodes   v.28 pp. 23-36
Pirajno, F., Seltmann, R. and Yang, Y.,  2011 - A review of mineral systems and associated tectonic settings of northern Xinjiang, NW China: in    Geoscience Frontiers   v.2, pp. 157-185.
Seltmann R and Porter T M,  2005 - The Porphyry Cu-Au/Mo Deposits of Central Eurasia: 1. Tectonic, Geologic & Metallogenic Setting and Significant Deposits: in Porter, T.M. (Ed), 2005 Super Porphyry Copper & Gold Deposits - A Global Perspective, PGC Publishing, Adelaide,   v.2 pp. 467-512
Seltmann, R., Porter, T.M. and Pirajno, F.,  2014 - Geodynamics and metallogeny of the central Eurasian porphyry and related epithermal mineral systems: A review: in    J. of Asian Earth Sciences,   v.79, pp. 810-841.
Shen, P., Pan, H. and Dong, L.,  2014 - Yandong porphyry Cu deposit, Xinjiang, China - Geology, geochemistry and SIMS U-Pb zircon geochronology of host porphyries and associated alteration and mineralization: in    Ore Geology Reviews   v.80, pp. 404-425.
Shen, P., Pan, H., Hattori, K., Cooke, D.R. and Seitmuratova, E.,  2018 - Large Paleozoic and Mesozoic porphyry deposits in the Central Asian Orogenic Belt: Geodynamic settings, magmatic sources, and genetic models: in    Gondwana Research   v.58, pp. 161-194.
Wan, B., Xiao, W., Windley, B.F., Gao, J., Zhang, L. and Cai, K.,  2017 - Contrasting ore styles and their role in understanding the evolution of the Altaids: in    Ore Geology Reviews   v.80,  pp. 910-922.
Wang, Y., Chen, H., Baker, M.J., Han, J., Xiao, B., Yang, J. and Jourdan, F.,  2019 - Multiple mineralization events of the Paleozoic Tuwu porphyry copper deposit, Eastern Tianshan: evidence from geology, fluid inclusions, sulfur isotopes, and geochronology: in    Mineralium Deposita   v.54, pp. 1953-1076.
Wang, Y.-H., Xue, C.-J., Liu, J.-J. and Zhang, F.-F.,  2018 - Origin of the subduction-related Carboniferous intrusions associated with the Yandong porphyry Cu deposit in eastern Tianshan, NW China: constraints from geology, geochronology, geochemistry, and Sr-Nd-Pb-Hf-O isotopes: in    Mineralium Deposita   v.53, pp. 629-647.
Wang, Y.-H., Xue, C.-J., Liu, J.-L., Wang, J.-P., Yang, J.-T., Zhang, F.-F., Zhao, Z.-N., Zhao, U.-J. and Liu, B.,  2015 - Early Carboniferous adakitic rocks in the area of the Tuwu deposit, eastern Tianshan, NW China: Slab melting and implications for porphyry copper mineralization: in    J. of Asian Earth Sciences   v.103, pp. 332-349.
Wang, Y.H., Zhang, F.-F. and Li, B.-C.,  2017 - Genesis of the Yandong porphyry Cu deposit in eastern Tianshan, NW China: Evidence from geology, fluid inclusions and isotope systematics: in    Ore Geology Reviews   v.86, pp. 280-296.
Xiao, B., Chen, H., Wang, Y., Han, J., Xu, C. and Yang, J.,  2018 - Chlorite and epidote chemistry of the Yandong Cu deposit, NW China: Metallogenic and exploration implications for Paleozoic porphyry Cu systems in the Eastern Tianshan: in    Ore Geology Reviews   v.100, pp. 168-182
Yang K, Lian C, Huntington J F, Peng Q and Wang Q  2005 - Infrared spectral reflectance characterization of the hydrothermal alteration at the Tuwu Cu-Au deposit, Xinjiang, China: in    Mineralium Deposita   v40 pp 324-336
Yuan, H. Shen, P. and Pan, H.,  2018 - Nature and evolution of hydrothermal fluids in the formation of the Tuwu porphyry copper deposit in the Eastern Tianshan Mountains, NW China: in    J. of Asian Earth Sciences   Online https://doi.org/10.1016/j.jseaes.2018.07.018
Yuan, H., Shen, P., Pan, H. and Liu, Y.,  2020 - Mineralogy and mineral geochemistry of the Tuwu porphyry Cu deposit, Eastern Tianshan, NW China: implication for the ore-forming condition and Cu mineralization: in    Arabian Journal of Geosciences,   v.13, 20p. doi.org/10.1007/s12517-019-4982-z
Zhang, F.-F., Wang, Y.-K., Xue, C.-J., Lui, J.-J. and Zhang, W.,  2019 - Fluid inclusion and isotope evidence for magmatic-hydrothermal fluid evolution in the Tuwu porphyry copper deposit, Xinjiang, NW China: in    Ore Geology Reviews   v.113, DOI: 10.1016/j.oregeorev.2019.103078, 23p.
Zhang, L., Xiao, W., Qin, K. and Zhang, Q.,  2006 - The adakite connection of the Tuwu-Yandong copper porphyry belt, eastern Tianshan, NW China: trace element and Sr-Nd-Pb isotope geochemistry: in    Mineralium Deposita   v41 pp 188-200

   References in PGC Publishing Books: Want any of our books ? Pricelist
Seltmann R and Porter T M, 2005 - The Porphyry Cu-Au/Mo Deposits of Central Eurasia: 1. Tectonic, Geologic & Metallogenic Setting and Significant Deposits,   in  Porter T M, (Ed),  Super Porphyry Copper and Gold Deposits: A Global Perspective,  v2  pp 467-512
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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 takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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