The Micangshan terrane is located along the NW margin of the Yangtze block and contains the second oldest Precambrian basement in South China. It comprises the Beiba and the Wangcang-Nanjiang segments, while the oldest suites (similar to 2.1 Ga Houhe complex) occur in the Beiba. The Hekou and the Wangjiaping metamorphic volcano-sedimentary sequences in the Wangcang are characterized by intensive metamorphism and deformation, long being regarded as the equivalent of the Houhe suite. This contribution presents an integrated study of zircon U-Pb geochronology and Hf isotope, whole rock elemental and Sr-Nd isotope geochemistry on volcanic rocks of the metastrata. It reveals that they formed at similar to 865-860 Ma and underwent upper amphibolite facies metamorphism at similar to 815 Ma with lower limits in P-T conditions of similar to 5.0 kbar and similar to 650-660 degrees C. The Hekou metavolcanics comprise dacitic-rhyolitic and alkaline basaltic rocks with minor tholeiitic mafics, whereas those of the Wangjiaping are composed of dacitic and tholeiitic mafic rocks. The Hekou alkaline metamafics show affinity to high-Nb to Nb-enriched basalts (HNB-NEB) with epsilon(Nd)(t) values of + 5.80 to + 6.25, whereas tholeiitic metamafics of the both sequences display characteristics typifying high-Al basalt (HAB) with epsilon(Nd)(t) value similar to +2.66. The Hekou and the Wangjiaping metafelsics have epsilon(Nd)(t) ranges of -2.33 to + 5.60 and -0.82 to + 0.99 (except one + 2.29), respectively, and the dacitic rocks show features akin to the high Mg-number andesites. The similar to 865-860 Ma magmatism is suggested to have occurred in an extensional basin with a post-subduction affinity. It was induced by upwelling of convective asthenosphere succeed the ceased slab subduction: the Wangjiaping metafelsics were derived from partial melting of juvenile lower crust, the Hekou dacitic rocks were produced by partial melts of the relict of subducted oceanic crust interacted with mantle wedge; the Hekou HNB-BEB were sourced by metasomatized mantle wedge, whereas the HAB lavas were generated by anhydrous partial melts of the upwelling asthenosphere. The similar to 815 Ma metamorphism was caused by an amalgamation between the South Qinling belt and the proto margin of the northwestern Yangtze block. This event was followed by an expanding rift from the Micangshan successively to the South Qinling.

Lead-zinc ore deposits hosted by carbonatic strata are the most important ore type of Pb–Zn resources in South China and have long been studied. Although their metallogenic timing has been well constrained recently to the Caledonian, our understanding of the metal sources and mineralization mechanism remains controversial. This study aims to provide new insights to these contexts via a new Pb isotope tracing of the Xiangshuidong deposit in the western Hunan Province. The Xiangshuidong deposit is one of the typical deposits in the Huayuan-Tongren Pb–Zn ore-concentrated area in South China. Both ore-forming sulfides and carbonates of the host strata were analyzed by in situ analysis using MC-LA-ICPMS. Along with compiled data of other typical deposits of the same type in South China, it is revealed that: the ore-forming sulfides were distinctively different from the carbonates of the host strata in Pb isotopic signatures; the ore-forming metals were sourced mainly by regional high-grade crystalline basements, rather than host rocks or adjacent strata; the ores display metallogenic characteristics typical of Mississippi Valley Type (MVT) Pb–Zn deposits, rather than reworked sedimentary deposits. A metallogenic model for the Caledonian Pb–Zn ores is accordingly proposed and a new guidance on further ore exploration is suggested.

Here we report a new study of a gabbroic suite and its associated dioritic and monzogranitic plutons situated in the Yangtze continental interior, the unique continental core in South China, by means of integrated U-Pb dating and Hf isotope analysis of zircon and whole rock Sr-Nd isotope and elemental geochemistry. These intrusive suites are parts of a large batholith (similar to 970 km(2)) known as the Neoproterozoic Huangling intrusive complex, which is emplaced in the Archean to Paleoproterozoic high-grade terrain. The gabbro and diorite are dated at 812 +/- 3 Ma and 816 +/- 6 Ma, respectively, whereas the monzogranite is dated at 801 +/- 6 Ma. Trace element geochemistry of magmatic clinopyroxene, peritectic hornblende and petrography of the gabbro suggest that the mafic suite formed by anhydrous melt that had undergone the early stages of crystalline fractionation of plagioclase, clinopyroxene and/or garnet. Zircon Hf isotope and whole-rock Sr-Nd isotopic and elemental compositions infer that the gabbro was sourced by slightly enriched lithospheric mantle modified by previous subduction; the diorite is likely to have been derived from similar to 850 Ma igneous rocks by anatexis and admixing variably with mantle-derived melt, whereas the monzogranite was dominantly sourced by the crystalline basement rocks. It is thus suggested that the associated igneous suites formed in a rift-related setting, and under plating of mantle-derived melt and mantle input had played a significant role during the magmatism. This plutonism event is synchronous with the initial deposition of widespread rift-basins in South China, which was succeeded by huge volumes of mid-late Neoproterozoic to Paleozoic sedimentary successions. These findings hence attest that the magmatism took place in a within-plate environment and a consecutively rift-related event was likely initiated at 850 Ma. In the interior of the Yangtze block, which is also widely recorded along its northern, western and northeastern margins and in the Cathaysia block. (C) 2016 Elsevier B.V. All rights reserved.

This paper reports an integrated study of in situ U-Pb geochronology and elemental geochemistry of zircons from the Xianglushan iron-polymetallic deposit in western Guizhou Province, Southwest China. Genetic relationship between this new type of deposit and unroofing of the Emeishan large igneous province (ELIP) is focused. Along with the zoning pattern in spatial distribution of diverse weathering-related deposits along the southern and southeastern margins of the ELIP, it is suggested that the genesis of the iron-polymetallic deposit was specialized by factors of coastal paleogeography in hot-humid climate, where iron-enriched laterites formed, and repetitive marine transgression-regression occurred during the Late Permian.