Abstract
The newly discovered Shimensi deposit is a super-large tungsten-copper (W–Cu) deposit with a metal reserve of 742.55 thousand tonnes (kt) W and 403.6 kt Cu. The orebodies are hosted in Mesozoic granites, which intruded the poorly documented Shimensi granodiorite belonging to the Jiuling batholith, the largest intrusion (outcrop > 2500 km2) in South China. Our new SHRIMP (Sensitive High Resolution Ion MicroProbe) zircon dating revealed that the granodiorite at Shimensi (ca. 830–827 Ma) was formed coeval (within analytical uncertainty) or slightly earlier than those in many other places (ca. 819–807 Ma) of the Jiuling batholith. The Neoproterozoic Shimensi granodiorite is peraluminous and high-K calc-alkaline, and contains low P content with no S-type trend (positive P2O5 vs. SiO2 correlation) displayed, thus best classified as peraluminous I-type. The I-type classification is also supported by the zircon REE patterns, largely (93%) positive εHf(t) (−0.87 to 6.60) and relatively low δ18O (5.8–7.7‰). The Neoproterozoic Shimensi granodiorite was formed after the continental arc magmatism (ca. 845–835 Ma), but before the post-collisional S-type granite emplacement (ca. 825–815 Ma) in the Jiangnan Orogen. Therefore, we propose that the Shimensi granodiorite was formed in a collisional/early post-collisional setting. The δ18O increase from the Shimensi granodiorite to many younger (ca. 819–807 Ma) granodiorites (6.0–8.5‰) in the Jiuling batholith probably reflects an increase of supracrustal rock-derived melts with the progress of collision. The Shimensi granodiorite contains low zircon Ce4+/Ce3+ and Eu/Eu*, suggesting a relatively reducing magma that does not favor porphyry Cu–Au mineralization. This left a high background Cu concentration (avg. 196 ppm) in the Neoproterozoic granodiorite, which may have contributed to the Mesozoic W–Cu mineralization, when the granodiorite is intruded and assimilated by the Mesozoic granites.
Highlights
Northern Jiangxi in South China is a world-class tungsten province [1,2,3,4,5,6,7], with its total metal resource estimated to be 4.0 million tonnes (Mt)
Mesozoic Shimensi granites are from Wei et al [6]
Geochemistry of the Neoproterozoic Shimensi granodiorite is very different from the Mesozoic
Summary
Northern Jiangxi in South China is a world-class tungsten province [1,2,3,4,5,6,7], with its total metal resource estimated to be 4.0 million tonnes (Mt). Minerals 2018, 8, x FOR PEER REVIEW and Zhuxi) in recent years have highlighted significant potential of future prospecting in this region. W–Cu deposit has delineated metalprospecting reserve of 742.55 and Zhuxi) in recent have highlighted significant potential ofafuture in this thousand region. [6] suggested whereas the Proterozoic granodiorite they have intruded rarely studied. That the copper-rich nature of Shimensi may been are associated with theRecently, Proterozoic suggested that the nature ofintruded. U–Pb age, trace element isotopes of the Proterozoic granodiorite at Shimensi. With these new data we discuss the petrogenesis and. Well as any metallogenic implications petrogenesis and tectonic setting of the Shimensi granodiorite, as well as any metallogenic.
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