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Exploring volcanic-intrusive connections and chemical differentiation of high silica magmas in the Early Cretaceous Yanbei caldera complex hosting a giant tin deposit, Southeast China

Exploring volcanic-intrusive connections and chemical differentiation of high silica magmas in the Early Cretaceous Yanbei caldera complex hosting a giant tin deposit, Southeast China
Exploring volcanic-intrusive connections and chemical differentiation of high silica magmas in the Early Cretaceous Yanbei caldera complex hosting a giant tin deposit, Southeast China

Study of the origin and chemical differentiation of silicic magmas can provide important insights into crustal evolution and rare metal metallogeny. Tin mineralization always tends to form in relatively reduced, highly fractionated granite systems. Recognition of distinctions between fertile and barren magmas is of enormous benefit to mineral exploration. The Yanbei caldera complex (YCC), is a typical inland volcanic-intrusive complex that also hosts a giant porphyry-type tin ore deposit in Southeast China. To study the origin and chemical differentiation of the YCC and constrain its relationship with tin mineralization, a comprehensive petrological, whole-rock major and trace element geochemical data, along with zircon U–Pb ages, trace element and Hf isotopic data of the Yanbei caldera complex (YCC) and the Xiaoji granite (XG) near the YCC are carried out. LA-ICP-MS zircon U–Pb dating indicates that the generation and evolution of the YCC and the XG took place in a short time (4 M.y.) of between 142.4 and 138.4 Ma. Distinct zircon Hf isotopic compositions of the volcanic and intrusive units from the YCC suggest that they were derived from different magma sources. The volcanic rocks and the XG have consistent and low zircon Hf isotopic compositions (ε Hf(t) = −14.9 ~ −9.0), implying that they were almost exclusively derived from melting of Paleoproterozoic crustal rocks. But the magma source of the intrusive units (the granite porphyry, GP and the biotite granite, BG) (ε Hf(t) = −6.0 ~ −0.8) contains a significant mantle-derived component input. The whole-rock and zircon compositions suggest that the compositionally zoned volcano of the YCC can be interpreted in terms of the “crystal mush model”. The rhyolite has the geochemical characteristics of highly evolved magmas which undergo crystal fractionation, while the dacite displays a complementary geochemical signature implying that it represents the residual crystal mush after extraction of the rhyolitic melts. The XG displays similar chronological, compositional, and isotopic features to the rhyolite, suggesting that it is the intrusive equivalent of the rhyolite. The intrusive units (GP and BG) of the YCC are highly-evolved granites with elevated tin contents, responsible for tin mineralization. By comparison of fertile and barren systems in the YCC, we suggest that simple crystal fractionation for the high-evolved/extracted granitic melt does not necessarily lead to tin mineralization. A tin-bearing and volatile-rich melt originated under high-temperature partial melting of crustal source induced by underplating/input of a hot mantle magma is an essential precondition for some magmatic-hydrothermal tin mineralization systems.

An extensional arc-back setting, Crystal mush, Fractionated magmatism, Partial melting, Tin mineralization
0009-2541
120501
Li, Qian
b70cbe19-fa41-4d5f-b6f7-ec6a4d4e29b3
Zhao, Kui-dong
bd5bd864-d7d0-40b4-ae43-37cdc7632a37
Palmer, Martin R.
d2e60e81-5d6e-4ddb-a243-602537286080
Chen, Wei
9904232f-e5c4-45f2-ae48-f6f0505ada51
Jiang, Shao-yong
dc929006-69ac-4366-bf2b-dc97527602d3
Li, Qian
b70cbe19-fa41-4d5f-b6f7-ec6a4d4e29b3
Zhao, Kui-dong
bd5bd864-d7d0-40b4-ae43-37cdc7632a37
Palmer, Martin R.
d2e60e81-5d6e-4ddb-a243-602537286080
Chen, Wei
9904232f-e5c4-45f2-ae48-f6f0505ada51
Jiang, Shao-yong
dc929006-69ac-4366-bf2b-dc97527602d3

Li, Qian, Zhao, Kui-dong, Palmer, Martin R., Chen, Wei and Jiang, Shao-yong (2021) Exploring volcanic-intrusive connections and chemical differentiation of high silica magmas in the Early Cretaceous Yanbei caldera complex hosting a giant tin deposit, Southeast China. Chemical Geology, 584, 120501, [120501]. (doi:10.1016/j.chemgeo.2021.120501).

Record type: Article

Abstract

Study of the origin and chemical differentiation of silicic magmas can provide important insights into crustal evolution and rare metal metallogeny. Tin mineralization always tends to form in relatively reduced, highly fractionated granite systems. Recognition of distinctions between fertile and barren magmas is of enormous benefit to mineral exploration. The Yanbei caldera complex (YCC), is a typical inland volcanic-intrusive complex that also hosts a giant porphyry-type tin ore deposit in Southeast China. To study the origin and chemical differentiation of the YCC and constrain its relationship with tin mineralization, a comprehensive petrological, whole-rock major and trace element geochemical data, along with zircon U–Pb ages, trace element and Hf isotopic data of the Yanbei caldera complex (YCC) and the Xiaoji granite (XG) near the YCC are carried out. LA-ICP-MS zircon U–Pb dating indicates that the generation and evolution of the YCC and the XG took place in a short time (4 M.y.) of between 142.4 and 138.4 Ma. Distinct zircon Hf isotopic compositions of the volcanic and intrusive units from the YCC suggest that they were derived from different magma sources. The volcanic rocks and the XG have consistent and low zircon Hf isotopic compositions (ε Hf(t) = −14.9 ~ −9.0), implying that they were almost exclusively derived from melting of Paleoproterozoic crustal rocks. But the magma source of the intrusive units (the granite porphyry, GP and the biotite granite, BG) (ε Hf(t) = −6.0 ~ −0.8) contains a significant mantle-derived component input. The whole-rock and zircon compositions suggest that the compositionally zoned volcano of the YCC can be interpreted in terms of the “crystal mush model”. The rhyolite has the geochemical characteristics of highly evolved magmas which undergo crystal fractionation, while the dacite displays a complementary geochemical signature implying that it represents the residual crystal mush after extraction of the rhyolitic melts. The XG displays similar chronological, compositional, and isotopic features to the rhyolite, suggesting that it is the intrusive equivalent of the rhyolite. The intrusive units (GP and BG) of the YCC are highly-evolved granites with elevated tin contents, responsible for tin mineralization. By comparison of fertile and barren systems in the YCC, we suggest that simple crystal fractionation for the high-evolved/extracted granitic melt does not necessarily lead to tin mineralization. A tin-bearing and volatile-rich melt originated under high-temperature partial melting of crustal source induced by underplating/input of a hot mantle magma is an essential precondition for some magmatic-hydrothermal tin mineralization systems.

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Accepted/In Press date: 20 August 2021
e-pub ahead of print date: 24 August 2021
Published date: 1 December 2021
Additional Information: Funding Information: The study was supported by the National Key R & D Plan (No. 2017YFC0601404 ), the National Natural Science Foundation of China Projects (No. 91755208 , No. 41673043 ), and a special fund from the State Key Laboratory of Geological Processes and Mineral Resources (No. MSFGPMR03-2 ). Qian Li is also grateful for the financial support by the Fundamental Research funds for National Universities , China University of Geosciences (Wuhan) , and a scholarship from the China Scholarship Council . Prof. Catherine Chauvel, Prof. Jean-François Moyen and an anonymous review are thanked for their constructive reviews, which improved this paper significantly. Publisher Copyright: © 2021 Elsevier B.V. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
Keywords: An extensional arc-back setting, Crystal mush, Fractionated magmatism, Partial melting, Tin mineralization

Identifiers

Local EPrints ID: 452056
URI: http://eprints.soton.ac.uk/id/eprint/452056
ISSN: 0009-2541
PURE UUID: 76de2483-851e-4fb9-b8e3-12f998c46fa2

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Date deposited: 10 Nov 2021 17:31
Last modified: 17 Mar 2024 06:51

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Contributors

Author: Qian Li
Author: Kui-dong Zhao
Author: Wei Chen
Author: Shao-yong Jiang

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