| Title | Carboniferous-Permian tectonic transition envisaged in two magmatic episodes at the Kuruer Cu-Au deposit, Western Tianshan (NW China) |
| Authors | Yu, Jie Li, Nuo Qi, Nan Guo, Jian-Ping Chen, Yan-Jing |
| Affiliation | Peking Univ, Key Lab Orogen & Crust Evolut, Beijing 100871, Peoples R China. Chinese Acad Sci, Xinjiang Inst Ecol & Geog, Xinjiang Res Ctr Mineral Resources, Urumqi 830001, Peoples R China. Xinjiang Lab Mineral Resources & Digital Geol, Urumqi 830011, Peoples R China. Xinjiang Bur Nonferrous Met, Geol Team 703, Yili 835000, Peoples R China. |
| Keywords | Kuruer Western Tianshan Porphyry Cu-Au deposit Geochemistry Zircon U-Pb age and Lu-Hf isotopes Carboniferous-Permian ASIAN OROGENIC BELT U-PB GEOCHRONOLOGY IN-SITU ANALYSIS LA-ICP-MS VOLCANIC-ROCKS CONTINENTAL GROWTH SOUTH TIANSHAN YILI BLOCK TIEN-SHAN DAHALAJUNSHAN FORMATION |
| Issue Date | 2018 |
| Publisher | JOURNAL OF ASIAN EARTH SCIENCES |
| Citation | JOURNAL OF ASIAN EARTH SCIENCES. 2018, 153(,SI), 395-411. |
| Abstract | The Western Tianshan in NW China is one of the most important gold provinces in the Central Asian Orogenic Belt (CAOB). The recently discovered Kuruer Cu-Au deposit has been interpreted to represent a transition from high-sulfidation epithermal to porphyry mineralization system. In this study, we present new LA-ICP-MS zircon U-Pb ages for the many magmatic rock types at Kuruer, including the Dahalajunshan Formation andesitic tuff (333.2 +/- 1.6 Ma), diorite porphyry (269.7 +/- 2.0 Ma), slightly-altered (264.4 +/- 2.6 Ma) and intensively-altered (270.5 +/- 2.5 Ma) albite porphyry. These ages reveal two distinct magmatic episodes: The Early Carboniferous Dahalajunshan Formation (wall rocks) andesitic tuff samples contain narrow ranges of SiO2 (60.29-61.28 wt.%), TiO2 (0.96-0.98 wt.%), Al2O3 (16.55-16.57 wt.%) and Fe2O3T. (5.36-5.57 wt.%). The tuff is characterized by LREE enrichment and HFSE depletion, as well as LREE/HREE enrichment ((La/Yb)(N) = 8.31-8.76) and negative Eu anomalies (delta Eu = 0.64-0.76). Zircon epsilon(Hf) (t) values are 5.4-8.2, and two stage Hf model ages (T-DM2) are 821-1016 Ma, indicating partial melting of a moderately depleted mantle wedge with Precambrian continental crustal input. The ore-forming Middle Permian diorite porphyry and (quartz) albite porphyry have variable major oxide compositions (e.g., SiO2 = 53.09-53.12 wt.% for the diorite porphyry, 70.84-78.03 wt.% for the albite porphyry, and 74.07-75.03 wt.% for the quartz albite porphyry) but similar chondrite-normalized REE and primitive mantle-normalized multi-element patterns. These porphyries display LREE enrichment and HFSE depletion, as well as elevated LREE/HREE enrichment and negative Eu anomalies. The positive zircon epsilon(Hf)(t) values (11.7-15.9 for the diorite porphyry, 8.9-14.9 for the albite porphyry) and young two-stage Hf model ages (T-DM2) (282-542 Ma for the diorite porphyry, 337-717 Ma for the albite porphyry) indicate a major juvenile continental crustal involvement. We propose that the Carboniferous and Middle Permian magmatism was formed in a continental arc and post-collisional settings, respectively, with the latter episode responsible for the Cu-Au mineralization. |
| URI | http://hdl.handle.net/20.500.11897/512445 |
| ISSN | 1367-9120 |
| DOI | 10.1016/j.jseaes.2017.07.048 |
| Indexed | SCI(E) |
| Appears in Collections: | 造山带与地壳演化教育部重点实验室 |
