The Mesozoic Caosiyao giant porphyry Mo deposit in Inner Mongolia, North China and Paleo-Pacific subduction-related magmatism in the northern North China Craton

H. Wu, L. Zhang, Franco Pirajno, Q. Shu, M. Zhang, M. Zhu, P. Xiang

Research output: Contribution to journalArticle

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Abstract

© 2016 Elsevier Ltd The Caosiyao giant porphyry Mo deposit is located in the Wulanchabu area of Inner Mongolia, within the northern North China Craton (NCC). It contains more than 2385 Mt of ore with an average grade of 0.075% Mo. In the Caosiyao mining district, Mo mineralization occurs mainly in a Mesozoic granite porphyry as disseminations and stockworks, with some Mo distributed in Archean metamorphic rocks and diabase as stockworks and veins. The host granite porphyry is composed of two different phases that can be distinguished based on mineral assemblages and textures: one phase contains large and abundant phenocrysts (coarse-grained), while the other phase is characterized by fewer and smaller phenocrysts (medium-grained). Zircon U–Pb–Hf analyses of the former phase yielded a concordant 206Pb/238U age of 149.8 ± 2.4 Ma with a 206Pb/238U weighted mean age of 149.9 ± 2.4 Ma and eHf(t) values ranging from -12.2 to 18.3, while the latter phase gave a concordant 206Pb/238U age of 149.0 ± 2.2 Ma with a 206Pb/238U weighted mean age of 149.0 ± 2.1 Ma and eHf(t) values ranging from -13.1 to 17.7. Five samples of disseminated molybdenite have a 187Re–187Os isochron age of 149.5 ± 5.3 Ma with a weighted average age of 149.0 ± 1.8 Ma, whereas six veinlet-type molybdenite samples have a well-constrained 187Re–187Os isochron age of 146.9 ± 3.1 Ma and a weighted average age of 146.5 ± 0.8 Ma. Thus, it is suggested that the Mo mineralization of the Caosiyao deposit occurred during the Late Jurassic (ca. 147–149 Ma), almost coeval with the emplacement of the host granite porphyry (ca. 149–150 Ma). The host granite porphyry is characterized by high silica (SiO2 = 71.52–74.10 wt%), relatively high levels of oxidation (Fe2O3/FeO = 0.32–0.94 wt%) and high alkali element concentrations (Na2O + K2O = 8.21–8.76 wt%). The host granite porphyry also shows enrichments in U and K, and depletion in Ba, Sr, P, Eu, and Ti, suggesting strong fractional crystallization of plagioclase, biotite, and accessory minerals. These observations, t
Original languageEnglish
Pages (from-to)281-299
JournalJournal of Asian Earth Sciences
Volume127
DOIs
Publication statusPublished - Sep 2016

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porphyry
craton
magmatism
subduction
granite
molybdenite
mineralization
accessory mineral
diabase
fractional crystallization
metamorphic rock
biotite
Archean
plagioclase
emplacement
zircon
silica
Jurassic
texture
oxidation

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@article{dcfb6bdfd57443009f26511e8c2a6251,
title = "The Mesozoic Caosiyao giant porphyry Mo deposit in Inner Mongolia, North China and Paleo-Pacific subduction-related magmatism in the northern North China Craton",
abstract = "{\circledC} 2016 Elsevier Ltd The Caosiyao giant porphyry Mo deposit is located in the Wulanchabu area of Inner Mongolia, within the northern North China Craton (NCC). It contains more than 2385 Mt of ore with an average grade of 0.075{\%} Mo. In the Caosiyao mining district, Mo mineralization occurs mainly in a Mesozoic granite porphyry as disseminations and stockworks, with some Mo distributed in Archean metamorphic rocks and diabase as stockworks and veins. The host granite porphyry is composed of two different phases that can be distinguished based on mineral assemblages and textures: one phase contains large and abundant phenocrysts (coarse-grained), while the other phase is characterized by fewer and smaller phenocrysts (medium-grained). Zircon U–Pb–Hf analyses of the former phase yielded a concordant 206Pb/238U age of 149.8 ± 2.4 Ma with a 206Pb/238U weighted mean age of 149.9 ± 2.4 Ma and eHf(t) values ranging from -12.2 to 18.3, while the latter phase gave a concordant 206Pb/238U age of 149.0 ± 2.2 Ma with a 206Pb/238U weighted mean age of 149.0 ± 2.1 Ma and eHf(t) values ranging from -13.1 to 17.7. Five samples of disseminated molybdenite have a 187Re–187Os isochron age of 149.5 ± 5.3 Ma with a weighted average age of 149.0 ± 1.8 Ma, whereas six veinlet-type molybdenite samples have a well-constrained 187Re–187Os isochron age of 146.9 ± 3.1 Ma and a weighted average age of 146.5 ± 0.8 Ma. Thus, it is suggested that the Mo mineralization of the Caosiyao deposit occurred during the Late Jurassic (ca. 147–149 Ma), almost coeval with the emplacement of the host granite porphyry (ca. 149–150 Ma). The host granite porphyry is characterized by high silica (SiO2 = 71.52–74.10 wt{\%}), relatively high levels of oxidation (Fe2O3/FeO = 0.32–0.94 wt{\%}) and high alkali element concentrations (Na2O + K2O = 8.21–8.76 wt{\%}). The host granite porphyry also shows enrichments in U and K, and depletion in Ba, Sr, P, Eu, and Ti, suggesting strong fractional crystallization of plagioclase, biotite, and accessory minerals. These observations, t",
author = "H. Wu and L. Zhang and Franco Pirajno and Q. Shu and M. Zhang and M. Zhu and P. Xiang",
year = "2016",
month = "9",
doi = "10.1016/j.jseaes.2016.06.014",
language = "English",
volume = "127",
pages = "281--299",
journal = "Journal of Asian Earth Sciences",
issn = "1367-9120",
publisher = "Elsevier",

}

The Mesozoic Caosiyao giant porphyry Mo deposit in Inner Mongolia, North China and Paleo-Pacific subduction-related magmatism in the northern North China Craton. / Wu, H.; Zhang, L.; Pirajno, Franco; Shu, Q.; Zhang, M.; Zhu, M.; Xiang, P.

In: Journal of Asian Earth Sciences, Vol. 127, 09.2016, p. 281-299.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The Mesozoic Caosiyao giant porphyry Mo deposit in Inner Mongolia, North China and Paleo-Pacific subduction-related magmatism in the northern North China Craton

AU - Wu, H.

AU - Zhang, L.

AU - Pirajno, Franco

AU - Shu, Q.

AU - Zhang, M.

AU - Zhu, M.

AU - Xiang, P.

PY - 2016/9

Y1 - 2016/9

N2 - © 2016 Elsevier Ltd The Caosiyao giant porphyry Mo deposit is located in the Wulanchabu area of Inner Mongolia, within the northern North China Craton (NCC). It contains more than 2385 Mt of ore with an average grade of 0.075% Mo. In the Caosiyao mining district, Mo mineralization occurs mainly in a Mesozoic granite porphyry as disseminations and stockworks, with some Mo distributed in Archean metamorphic rocks and diabase as stockworks and veins. The host granite porphyry is composed of two different phases that can be distinguished based on mineral assemblages and textures: one phase contains large and abundant phenocrysts (coarse-grained), while the other phase is characterized by fewer and smaller phenocrysts (medium-grained). Zircon U–Pb–Hf analyses of the former phase yielded a concordant 206Pb/238U age of 149.8 ± 2.4 Ma with a 206Pb/238U weighted mean age of 149.9 ± 2.4 Ma and eHf(t) values ranging from -12.2 to 18.3, while the latter phase gave a concordant 206Pb/238U age of 149.0 ± 2.2 Ma with a 206Pb/238U weighted mean age of 149.0 ± 2.1 Ma and eHf(t) values ranging from -13.1 to 17.7. Five samples of disseminated molybdenite have a 187Re–187Os isochron age of 149.5 ± 5.3 Ma with a weighted average age of 149.0 ± 1.8 Ma, whereas six veinlet-type molybdenite samples have a well-constrained 187Re–187Os isochron age of 146.9 ± 3.1 Ma and a weighted average age of 146.5 ± 0.8 Ma. Thus, it is suggested that the Mo mineralization of the Caosiyao deposit occurred during the Late Jurassic (ca. 147–149 Ma), almost coeval with the emplacement of the host granite porphyry (ca. 149–150 Ma). The host granite porphyry is characterized by high silica (SiO2 = 71.52–74.10 wt%), relatively high levels of oxidation (Fe2O3/FeO = 0.32–0.94 wt%) and high alkali element concentrations (Na2O + K2O = 8.21–8.76 wt%). The host granite porphyry also shows enrichments in U and K, and depletion in Ba, Sr, P, Eu, and Ti, suggesting strong fractional crystallization of plagioclase, biotite, and accessory minerals. These observations, t

AB - © 2016 Elsevier Ltd The Caosiyao giant porphyry Mo deposit is located in the Wulanchabu area of Inner Mongolia, within the northern North China Craton (NCC). It contains more than 2385 Mt of ore with an average grade of 0.075% Mo. In the Caosiyao mining district, Mo mineralization occurs mainly in a Mesozoic granite porphyry as disseminations and stockworks, with some Mo distributed in Archean metamorphic rocks and diabase as stockworks and veins. The host granite porphyry is composed of two different phases that can be distinguished based on mineral assemblages and textures: one phase contains large and abundant phenocrysts (coarse-grained), while the other phase is characterized by fewer and smaller phenocrysts (medium-grained). Zircon U–Pb–Hf analyses of the former phase yielded a concordant 206Pb/238U age of 149.8 ± 2.4 Ma with a 206Pb/238U weighted mean age of 149.9 ± 2.4 Ma and eHf(t) values ranging from -12.2 to 18.3, while the latter phase gave a concordant 206Pb/238U age of 149.0 ± 2.2 Ma with a 206Pb/238U weighted mean age of 149.0 ± 2.1 Ma and eHf(t) values ranging from -13.1 to 17.7. Five samples of disseminated molybdenite have a 187Re–187Os isochron age of 149.5 ± 5.3 Ma with a weighted average age of 149.0 ± 1.8 Ma, whereas six veinlet-type molybdenite samples have a well-constrained 187Re–187Os isochron age of 146.9 ± 3.1 Ma and a weighted average age of 146.5 ± 0.8 Ma. Thus, it is suggested that the Mo mineralization of the Caosiyao deposit occurred during the Late Jurassic (ca. 147–149 Ma), almost coeval with the emplacement of the host granite porphyry (ca. 149–150 Ma). The host granite porphyry is characterized by high silica (SiO2 = 71.52–74.10 wt%), relatively high levels of oxidation (Fe2O3/FeO = 0.32–0.94 wt%) and high alkali element concentrations (Na2O + K2O = 8.21–8.76 wt%). The host granite porphyry also shows enrichments in U and K, and depletion in Ba, Sr, P, Eu, and Ti, suggesting strong fractional crystallization of plagioclase, biotite, and accessory minerals. These observations, t

U2 - 10.1016/j.jseaes.2016.06.014

DO - 10.1016/j.jseaes.2016.06.014

M3 - Article

VL - 127

SP - 281

EP - 299

JO - Journal of Asian Earth Sciences

JF - Journal of Asian Earth Sciences

SN - 1367-9120

ER -