We studied the geochemical characteristics of three types of Mesozoic igneous rocks from the Luzong volcanic basin: basaltic trachyandesite at Shuangmiao, pyroxene monzonite at Bajiatan, and quartz-syenite (A-type granite) at Huangmeijian. Based on analyses of whole-rock major elements, all investigated rocks are enriched in K, Na, Ti, Al, but depleted in Ca, representing a shoshonitic series. Trace element analyses show that these rocks are characterized by enrichments of large-ion lithophile elements and high field strength elements. Positive Nb and Ta anomalies in the chondrite-normalized spider diagram indicate that the shoshonitic volcanic rocks share similar features with Nb-enriched basalts, which are different from normal island-arc volcanical rocks (they are typically strongly depleted in Nb and Ta). Bulk-rock chemical compositions and Sr–Nd isotopes indicate that the three types of igneous rocks are geochemically comagmatic, suggesting that the melts were derived from an enriched mantle reservoir. We postulate an extensional tectonic setting for the formation of Luzong volcanic basin, possibly related to subduction of a palaeo-Pacific plate beneath the east Chinese continent during the Yanshanian period (Cretaceous). Therefore, the petrogenetic features of those volcanic rocks as well as A-type granites in the Luzong basin indicate that the regional large-scale Fe–Cu–Au mineralization was associated with oceanic slab melting, but not delamination or recycling of the ancient lower continental crust, as previously proposed.

Shapinggou porphyry Mo deposit is the largest Climax-type Mo deposit in China and probably also in the world, with total proven Mo reserves of over 2.2 million tonnes at an average grade of 0.17%. It is located in the western Dabie Mountains, along the eastern extension of the East Qinling Mo mineralization belt. Similar to the majority of Mo deposits in the Qinling Mo belt, it is located north of the Triassic suture between the north and south China blocks. The orebody is mainly hosted in Cretaceous high-K granitic porphyry and explosive breccia, with potassic, silicification, and sericite-pyrite alterations. Fluorite is common in Shapinggou, indicating high-F content. The porphyry is closely associated with a large quartz syenite intrusion. Re–Os dating of molybdenite yielded an isochron age of 111.1 ± 1.2 Ma for the mineralization. Zircon U–Pb ages are 111.7 ± 0.8 Ma and 111.9 ± 0.6 Ma for the granitic porphyry and quartz syenite, respectively. Shapinggou is similar to the well-known Climax and Henderson Mo deposits in terms of geochemical characteristics and alterations, etc. We propose that Mo-rich ore-forming materials accumulated underneath the Shapinggou region during the convergence of the North and South China blocks, whereas the final mineralization was triggered by asthenosphere upwelling induced by Pacific Plate subduction.

Late Cryogenian to Ediacaran magmatism of the East-Eastern Nigerian Terrane (E-ENT) in the Pan-African mobile belt provides a critical geological record that is important for unravelling regional tectonic and geodynamic setting. A detailed study that utilizes whole-rock elemental, in-situ zircon U-Pb and Lu-Hf isotopic geochemistry are conducted on the post-collisional granitoids from the Hawal Massif in the E-ENT. These granitoids are metaluminous to slightly peraluminous, alkali-calcic to calc-alkalic and ferroan in composition. U-Pb zircon ages suggest two granitic plutons were emplaced at 627 ± 4 Ma and ca. 580 Ma. Typically, these rocks are characterized by _ƐHf(t) values ranging from +3 to -9.03 and T^C_DM ages range from 1.3 to 2.1 Ga, suggesting mixing of juvenile mafic melts with the older continental crust at different stages of the Pan-African Orogeny. Slab break-off most likely induced upwelling of the asthenosphere which in turn cause partial melting of the sub-continental lithospheric mantle (SCLM) and the lower crust at the early stage of Late-orogenic to generate 627 ± 4 Ma granites. The magmatism at ca. 580 Ma may have resulted from vertical planar lithosphere delamination as a consequence of transpressive movement along lithospheric scale shear zones which triggered asthenosphere upwelling that facilitated significant crustal melting at the waning stage of the Pan-African orogeny. The presence of post-collisional granite at 627 Ma and distinct isotopic signatures of the E-ENT granitoids compared to those from the NW-Cameroon and Mayo Kebbi domain suggest that E-ENT may have undergone different Pan-African evolution.