Porphyry Mo deposits are important suppliers of molybdenum for industrial applications, but the origin and source of metals in these deposits remain debated. Here, we present Mo isotope data for Miocene mineralized porphyritic monzogranites (MPMs) and Paleocene barren biotite monzogranites and tuffs (BMTs) from the Bangpu porphyry Mo (Cu) deposit in the Gangdese metallogenic belt. The results show that the MPMs display radiogenic Sr and Pb isotopes and elevated δ98/95Mo (relative to NIST SRM 3134; +0.07‰–1.2‰) and Mo contents, which exceed the range of the depleted mantle. These characteristics cannot be attributed to surface weathering, hydrothermal alteration, magmatic differentiation, or partial melting but rather reflect the incorporation of Mo from black shales into their magma sources, as evidenced by the significant correlations between δ98/95Mo and εNd(t) and aluminum saturation index (ASI) values. In contrast, the BMTs display lower Mo and δ98/95Mo values than the mineralized samples, and their δ98/95Mo values display no correlations with radiogenic isotopes or ASI values. The contrasting characteristics of mineralized and barren samples provide strong evidence that the addition of black shales played an important role in the formation of the Bangpu porphyry Mo deposit. Our study thus establishes a possible link between porphyry Mo deposits and organic-rich sediments and highlights the great potential of Mo isotopes in studying porphyry Mo deposits.
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Research Article|
May 19, 2023
Tracing black shales in the source of a porphyry Mo deposit using molybdenum isotopes
Qiqi Xue;
Qiqi Xue
1
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China2
Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China3
University of Chinese Academy of Sciences, Beijing 100049, China
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Lipeng Zhang;
Lipeng Zhang
1
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China2
Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China
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Shuo Chen;
Shuo Chen
1
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China2
Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China
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Kun Guo;
Kun Guo
4
Center for Isotope Geochemistry and Geochronology, Laoshan Laboratory, Qingdao 266237, China
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Tao Li;
Tao Li
5
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China
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Zhong Han;
Zhong Han
6
Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China
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Weidong Sun
Weidong Sun
1
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China2
Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China3
University of Chinese Academy of Sciences, Beijing 100049, China
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Qiqi Xue
1
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China2
Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China3
University of Chinese Academy of Sciences, Beijing 100049, China
Lipeng Zhang
1
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China2
Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China
Shuo Chen
1
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China2
Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China
Kun Guo
4
Center for Isotope Geochemistry and Geochronology, Laoshan Laboratory, Qingdao 266237, China
Tao Li
5
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China
Zhong Han
6
Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China
Weidong Sun
1
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China2
Laboratory for Marine Geology, Laoshan Laboratory, Qingdao 266237, China3
University of Chinese Academy of Sciences, Beijing 100049, China
Publisher: Geological Society of America
Received:
14 Dec 2022
Revision Received:
15 Mar 2023
Accepted:
27 Apr 2023
First Online:
19 May 2023
Online ISSN: 1943-2682
Print ISSN: 0091-7613
© 2023 Geological Society of America
Geology (2023)
Article history
Received:
14 Dec 2022
Revision Received:
15 Mar 2023
Accepted:
27 Apr 2023
First Online:
19 May 2023
Citation
Qiqi Xue, Lipeng Zhang, Shuo Chen, Kun Guo, Tao Li, Zhong Han, Weidong Sun; Tracing black shales in the source of a porphyry Mo deposit using molybdenum isotopes. Geology 2023; doi: https://doi.org/10.1130/G51240.1
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