Formation and geodynamic implication of the Early Yanshanian granites associated with W–Sn mineralization in the Nanling range, South China: an overview

ABSTRACT

The Nanling range (Nanling) is characterized by intense and widespread Mesozoic magmatism related large-scale W–Sn mineralization. A summary of geochemistry, geochronology, and petrogenesis for the W–Sn-bearing granites has been carried out in this study. A series of rock- and ore-forming ages in Nanling indicate that the W–Sn mineralization is closely related to the Early Yanshanian granitic magmatism both in temporal and spatial dimensions (165–150 Ma). Geochemical features show that both of the W- and Sn-bearing granites, which mainly belong to highly fractionated I-type granites with a few A-type granites, are characterized by high contents of SiO₂, Al₂O₃, Na₂O, and K₂O; enrichment in Rb, Th, U, Zr, Hf, and REE; depletion in Sr, Ba, P, and Ti; and high ratios of A/CNK. Furthermore, the different Sr–Nd–Hf isotopic compositions indicate that they are mainly originated from the partial melting of the Precambrian basement rocks of the Cathaysia Block at low oxygen fugacity, and the estimated temperatures for the tungsten-bearing and tin-bearing granites are ca. 700°C and ca. 800°C, respectively. The model of the mantle–crust interaction exhibits that different percentages of mantle-derived magma were likely involved in the generation of the tin-bearing granites and tungsten-bearing granites. In combination with previous studies, we propose that these granites in Nanling were emplaced in an extensional setting, as a response to the break-off and roll-back of the subducted Palaeo-Pacific Plate during 175–150 Ma.

KEYWORDS:

• I-type granites
• W–Sn mineralization
• Mesozoic magmatism
• extensional setting
• subducted Palaeo-Pacific plate
• Nanling

Highlights

• Most of the Early Yanshanian highly fractionated I-type granites and related W–Sn deposits in Nanling were formed in ca. 165 Ma–150 Ma.

• The tin- and tungsten-bearing granites were derived from partial melting of Precambrian basement of the Cathaysia Block with different amount of mantle-derived magmas.

• Magmas of these granites formed in an extension setting caused by break-off and roll-back of the subducted Palaeo-Pacific plate.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

This study is supported by the National Key R&D Program of China [No. 2016YFC0600404] and the National Natural Science Foundation of China [Nos. 41673040, 41502067].