Miocene Ultrapotassic, High-Mg Dioritic, and Adakite-like Rocks from Zhunuo in Southern Tibet: Implications for Mantle Metasomatism and Porphyry Copper Mineralization in Collisional Orogens

Sun, Xiang; Lu, Yongjun; McCuaig, T. Campbell; You, Zheng; Chang, Hui; Guo, Feng; Xu, Lina

doi:10.1093/petrology/egy028

Cited by 92 publications

(73 citation statements)

References 151 publications

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“…Felsic magmas may form either by fractional crystallization processes from basaltic magmas (Grove & Donnelly‐Nolan, ; Haase, Stroncik, Garbe‐Schonberg, & Stoffers, ; Lu, Loucks, Fiorentini, Yang, & Hou, ; McCulloch, Kyser, Woodhead, & Kinsley, ) or by partial melting of granulite and amphibolite in the lower crust (Beard, ; Hacker, Kelemen, & Behn, ; Lu et al, ; Smith, Stewart, & Price, ; X. Sun et al, ; S. Wu et al, ; S. Wu, Zheng, & Sun, ). Both processes were also confirmed by experimental work (Juster, Grove, & Perfit, ).…”

Section: Discussionmentioning

confidence: 99%

“…Fractionation trends are from Richards and Kerrich () and X. Sun et al () [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Discussionmentioning

confidence: 99%

“…Enrichment of Ba, Rb, Sr, U, and Pb is generally attributed to slab‐derived fluids, whereas melts of subducted sediment are thought to have high Th and Nb contents and high Th/Yb and Nb/Y ratios (Hawkesworth, Turner, Peate, McDermott, & Van Calsteren, ; Kelemen, Hanghøj, & Greene, ; X. Sun et al, ; Woodhead, Hergt, Davidson, & Eggins, ; Z. D. Zhao et al, ). Thus, high Ba contents (195–2247 ppm) and low Nb/Y ratios (0.3–0.9) for the Early Cretaceous igneous rocks (Figure b) indicate that subduction‐related metasomatism beneath the Yongxin area was related to fluids likely released from the subducting Pacific oceanic slab during the Early Cretaceous.…”

Section: Discussionmentioning

confidence: 99%

“…High Sr/Y intrusions could be produced by partial melting of slab melts (Defant & Drummond, ), thickened juvenile lower crust (H. Y. Wu, Zhang, et al, ; X. J. Zhang, Zhang, et al, ), or fractional crystallization of a hornblende‐dominated assemblage (Castillo, Janney, & Solidum, ; Z. Q. Hou, Gao, Qu, Rui, & Mo, ; Macpherson, Dreher, & Thirlwall, ; Richards & Kerrich, ; X. Sun et al, ). With differentiation, igneous rocks derived from hydrous magmas typically show decreasing trends in Yb, Dy/Yb, and increasing trends in Sr, Sr/Y, and Eu/Eu * , due to hornblende and/or titanite fractionation and/or suppression of plagioclase on the liquidus (Richards & Kerrich, ).…”

Section: Discussionmentioning

confidence: 99%

“…Mesozoic igneous rocks in North China Craton (Guo et al, 2010;H. F. Zhang et al, 2004) and Pacific and North Atlantic MORB (Hart, 1984) are also shown for comparison [Colour figure can be viewed at wileyonlinelibrary.com] FIGURE 9 Th vs. Th/Sm diagram (Allègre & Minster, 1978) to address the partial melting for the igneous rocks at Yongxin [Colour figure can be viewed at wileyonlinelibrary.com] Calsteren, 1997; Kelemen, Hanghøj, & Greene, 2003;X. Sun et al, 2018;Woodhead, Hergt, Davidson, & Eggins, 2001;Z.…”

Section: Implication For Tectonic Settingmentioning

confidence: 99%

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Zircon U–Pb geochronology and Sr–Nd–Pb–Hf isotopic constraints on the timing and origin of the Early Cretaceous igneous rocks in the Yongxin gold deposit in the Lesser Xing'an Range, NE China

Zhong-hai

Sun

Li³

et al. 2019

Geological Journal

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The Lesser Xing'an Range in NE China is an important gold district. However, the age and genesis of Early Cretaceous magmatic rocks that are coeval with gold mineralization remain obscure. A suite of Early Cretaceous igneous rocks in a newly discovered gold deposit at Yongxin was conducted zircon U–Pb dating and Hf isotope and bulk‐rock geochemistry and Sr–Nd–Pb isotope analyses. A dacite of the Guanghua Formation and an andesite of the Longjiang Formation have zircon U–Pb ages of 111.7 ± 1.5 Ma and 119.7 ± 1.9 Ma, respectively. The dacite has zircon εHf(t) values of 5.4 to 12.0 and depleted bulk‐rock Sr–Nd–Pb isotopes ((87Sr/86Sr)i = 0.7049 to 0.7056, εNd(t) = 1.2 to 2.5, (206Pb/204Pb)i = 18.202 to 18.320). The andesite has zircon εHf(t) values of 5.6 to 13.6, (87Sr/86Sr)i of 0.7049 to 0.7051, εNd(t) of 1.0 to 1.6, and (206Pb/204Pb)i of 18.199 to 18.297. The ~120 Ma diorite porphyry and granite porphyry have zircon εHf(t) values of 3.7 to 10.0 and 3.6 to 10.2, respectively. These two units show large variations of 87Rb/86Sr ratios (<1) and similar Sr–Nd–Pb isotopes compositions. All rock units are enriched in light rare earth elements and large‐ion lithophile elements and depleted in high‐field‐strength elements. The formation of Yongxin Early Cretaceous igneous rocks was related to variable degrees of partial melting from Jurassic basalt in the lower crust with significant contribution from ancient continental materials. The low Sr/Y ratios (2–24) and negative correlations between Sr, Eu/Eu, and SiO2 indicate that magmas of the Early Cretaceous igneous rocks at Yongxin have low water content and thus have low potentiality for porphyry copper mineralization.

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Section: Discussionmentioning

confidence: 99%

“…Fractionation trends are from Richards and Kerrich () and X. Sun et al () [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Implication For Tectonic Settingmentioning

confidence: 99%

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Zircon U–Pb geochronology and Sr–Nd–Pb–Hf isotopic constraints on the timing and origin of the Early Cretaceous igneous rocks in the Yongxin gold deposit in the Lesser Xing'an Range, NE China

Zhong-hai

Sun

Li³

et al. 2019

Geological Journal

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Geochemistry and zircon trace elements composition of the Miocene ore‐bearing biotite monzogranite porphyry in the Demingding porphyry Cu‐Mo deposit, Tibet: Petrogenesis and implication for magma fertility

et al. 2019

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MS zircon U-Pb dating, whole-rock geochemistry, and zircon trace elemental data for the mineralization related biotite monzogranite porphyry in Demingding. Zircon U-Pb dating shows that the weighted mean 206 Pb/ 238 U ages of the Miocene biotite monzogranite porphyry is 20.36 ± 0.46 Ma (MSWD = 2.6, n = 21). The Miocene biotite monzogranite porphyry is characterized by high SiO 2 , K 2 O, and Al 2 O 3 contents and shows adakite-like signatures. These rocks have high Sr/Y ratios, fractionated REE patterns with low HREE abundances, enrichment in LILE compared with HFSE, and have ( 87 Sr/ 86 Sr) i values of 0.7059 to 0.7062, ε Nd (t) values of −2.35 to −1.67 and (-206 Pb/ 204 Pb) i ratios of 18.50-18.55. These features are similar to other Miocene adakite-like intrusions in the Gangdese belt. We propose that the biotite monzogranite porphyry shares the same petrogenesis with other Miocene ore-bearing adakite-like intrusions in the Eastern Gangdese belt and was derived from remelting of the subduction-modified, eclogitized Tibetan lower crust and mixing with hydrous mafic magmas from metasomatized Tibetan mantle. The zircons from biotite monzogranite porphyry have only minimal negative Eu anomalies (Eu N /Eu N * > 0.3), and exhibit large ratios of Ce 4+ /Ce 3+ (average value of 113), 10,000*(Eu N /Eu N *)/Y (3.94-8.14, >1), Ce/Nd (9-58, Average value of 30), (Ce/Nd)/Y (0.008-0.127, >0.003), and low value of Dy/Yb (0.15-0.24, <0.3), indicating that the biotite monzogranite porphyry is relatively hydrous and oxidized. The biotite monzogranite porphyry, therefore, is believed to be a relatively fertile intrusion with certain exploration potential.

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Miocene multi‐source magma system and magma mixing in the Zhunuo porphyry Cu deposit, southern Tibet, China

et al. 2020

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Zhuno is the only large porphyry copper deposit that preserves the complete magmatic system in the western part of Gangdese porphyry copper belt. Intrusions in the Zhunuo deposit include pre‐ore porphyritic monzogranite, syn‐ore monzogranite porphyry, and post‐ore quartz syenite‐normal granite porphyry, high‐Cr granite porphyry, normal diorite porphyry, high‐Mg diorite porphyry (diorite enclave), potassic lamprophyre, and ultrapotassic lamprophyre. Enriched Sr–Nd isotopic composition and high MgO, LILE, HFSE, LREE, and compatible element (Cr, Ni) contents of the ultrapotassic lamprophyre indicate that the magma derived from the enriched Lhasa lithospheric mantle, which had been metasomatized by fluids and sediment‐derived melts associated with Neo‐Tethyan oceanic subduction and subsequent Indian continental lithosphere subduction. The depletion of the Sr–Nd isotopic composition and MgO (or Mg#), Cr, and Ni content of the normal diorite porphyry manifest that the magma source is juvenile Lhasa lower crust instead of Indian mantle. Geochemical characteristics indicate that the magma sources of the quartz syenite‐normal granite porphyry, high‐Mg diorite porphyry‐diorite enclave, and potassic lamprophyre was derived from ancient Lhasa middle‐upper crust, crust‐mantle transition zone, and enriched Lhasa mantle without Indian lithosphere contribution, respectively. Their similar Sr–Nd isotopic compositions demonstrate a uniform Sr–Nd isotopic reservoir from crust to mantle in Zhunuo area. The major and trace element compositions suggest that the high‐Cr granite porphyry was formed by mixing of quartz syenite‐normal granite porphyry and ultrapotassic lamprophyre magmas. High Sr/Y values and low Y contents of the monzogranite and monzogranite porphyry display adakitic properties. The major and trace element contents and Sr–Nd isotopic composition indicate the monzogranite‐monzogranite porphyry are likely from mixing of the normal diorite porphyry magma with the quartz syenite‐normal granite porphyry magma, rather than with the high‐Mg dioritic (high‐Mg diorite porphyry‐diorite enclave) and/or potassic‐ultrapotassic magmas. According to the spatial and temporal consistency of the adakitic and potassic‐ultrapotassic rocks with the N–S‐trending rifts, Indo‐Asian convergence rate reduction, and uplifting model of Tibetan Plateau, we infer that the magma genesis of the Zhuno intrusions is attributed to decompressional partial melting of Lhasa crust‐mantle triggered by the tearing of the subducting Indian Plate.

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Miocene Ultrapotassic, High-Mg Dioritic, and Adakite-like Rocks from Zhunuo in Southern Tibet: Implications for Mantle Metasomatism and Porphyry Copper Mineralization in Collisional Orogens

Cited by 92 publications

References 151 publications

Zircon U–Pb geochronology and Sr–Nd–Pb–Hf isotopic constraints on the timing and origin of the Early Cretaceous igneous rocks in the Yongxin gold deposit in the Lesser Xing'an Range, NE China

Zircon U–Pb geochronology and Sr–Nd–Pb–Hf isotopic constraints on the timing and origin of the Early Cretaceous igneous rocks in the Yongxin gold deposit in the Lesser Xing'an Range, NE China

Geochemistry and zircon trace elements composition of the Miocene ore‐bearing biotite monzogranite porphyry in the Demingding porphyry Cu‐Mo deposit, Tibet: Petrogenesis and implication for magma fertility

Miocene multi‐source magma system and magma mixing in the Zhunuo porphyry Cu deposit, southern Tibet, China

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