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A-type granites are a spectrum of especial felsic rocks that are produced commonly within an extensional environment. They are rare before middle Paleoproterozoic but present abundantly since the late Paleoproterozoic, probably indicating a causal change of tectonics and geodynamic mechanism in the continental evolution of the Earth. An early Mesoproterozoic A-type granite belt was recognized in the southern margin of the North China Craton (NCC) in recent decades. The occurrence of this type of rocks indicates a possible spatial–temporal link between the tectonic evolution of the NCC and the breakup of the Columbia supercontinent during the Mesoproterozoic. The Zhangjiaping granitic pluton is located in the southern margin of the NCC and one part of the A-type granite belt. It can be divided into three zones according to their textural and compositional differences of the rocks with a gradually increasing degree of evolution inwards: wall zone, intermediate zone and core zone. LA-ICP-MS zircon U–Pb dating shows that it was emplaced at ca. 1.53 Ga. Petrologically, the Zhangjiaping granites contain perthite and calcic amphibole but are lack of alkali mafic minerals. Geochemically, all the Zhangjiaping granitic rocks show an affinity to fractionated aluminous A-type granites, with enrichment in silicon and total alkali, and depletion in MgO, CaO and P 2 O 5 with negative Eu, Sr and Ti anomalies, as well as high FeOt/MgO, TiO 2 /MgO and Ga/Al ratios and high HFSEs (i.e., Zr, Nb, Ce, Y) concentrations. Such signatures, along with their low ε Hf ( t ) values (−12.5 to −4.0) of all the granites from the Zhangjiaping pluton, obviously indicate that the Zhangjiaping aluminous A-type granites were derived from partial melting of the crustal calc-alkaline granitoids (i.e., the granodiorites of the Taihua Complex in the study area) and experienced fractional crystallization during magmatic evolution. Their generation would be related to the underplating of mafic magmas in an extensional regime. Integrated with regional data, the Zhangjiaping aluminous A-type granites were the products of anorogenic magmatism likely corresponding to the breakup of the Columbia supercontinent. [ABSTRACT FROM AUTHOR]

The Xuebaoding W–Sn–Be mining area, located in the Songpan–Garze orogenic belt in western China, is known for producing large, colorful, euhedral crystals of scheelite, cassiterite, and tabular beryl. Zircon LA-ICP-MS U–Pb dating of the Wuzhutang granite yields a concordia age of 218.96 ± 2.1 Ma, and a weighted mean 206Pb/238U age of 218.98 ± 1.12 Ma. Cassiterite LA-MC-ICPMS dating of the quartz vein bearing beryl, cassiterite, and scheelite, yields a concordant age of 213.5 ± 1.7 Ma. These observations indicate that magmatic activities and mineralization on the western side of the Zibaishan dome occurred during the late Indosinian, prior to their occurrence on the eastern side of the dome, reflecting the fact that the granite may have undergone two epochs of magmatic evolution and metallogenic processes. Geochemical analysis revealed that the Wuzhutang granite has relatively high A/CNK (average: 1.05) and differentiation index (DI; 81.16~85.88) values, and that they are enriched in W, Sn, Be, Li, and Cs. Unlike the Pukouling and Pankou granites, the Wuzhutang granite contains a certain amount of plagioclase and relatively high contents of Ba (633~1007 ppm) and Sr (334~411 ppm). Sr–Nd–Pb isotope values (87Sr/86Sr(t) = 0.70747–0.70865, εNd(t) = −6.35 to –4.34, 206Pb/204Pb = 18.186–18.3, 207Pb/204Pb = 15.556–15.592, and 208Pb/204Pb = 38.268–38.432) indicate a Mesoproterozoic basement origin for the Wuzhutang granite. We suggest the three granites belong to a peraluminous magma system and were derived by partial melting of the upper crust, the magma of the Wuzhutang granite originated from a deeper source and exhibits a lower degree of differentiation than that of the Pankou and Pukouling granites. [ABSTRACT FROM AUTHOR]

The pre-Jurassic geotectonics in Northeast China and its adjacent regions are characterized by collision of microcontinental blocks. The Yanbian region lies between the North China block (NCB) and the Khanka block (KB). Along the Dashanzui–Antu–Kaishantun collision belt, the Yanbian pre-Jurassic fold belt can be divided into two parts. One part represents the western margin of the KB, which consists of Late Proterozoic metamorphic basement and a Permian active continental margin. The other one is located at the eastern margin of the NCB and is composed of Proterozoic passive margin deposits, where the Seluohe and Qinglongcun groups are developed, and rocks of the Permian passive margin. Collision of these two parts took place along the Dashanzui–Antu–Kaishantun collision zone during the Late Permian to Early Triassic, as evidenced by the emplacement of syncollision granites and A-type granites. In northeast China and adjacent regions, a series of microcontinental blocks collided with one other from the end of Early Paleozoic to the Early Triassic. The collision event that took place in the Yanbian region may represent the latest collision event in the Paleo-Asian oceanic domain. [Copyright &y& Elsevier]

Granite is an important soil-forming rock and is widely distributed in the cold-temperate forest area of northeast China, such as northern Greater Hinggan, where its biochemical weathering plays an important role in the formation of local soils. Due to the special latitude and elevation, lichen plays a crucial role in the biochemical weathering of granite here, of which the role of low molecular organic acids (short for organic acids) is of interest. We simulated the concentrations of oxalic acid (OA) and succinic acid (SA) in the local lichens of Northeast China, applied OA or SA (10, 20, 30, 40, and 50 mmol L–1) to granite powders for 1 (10 min), 10, 20, 30, 40, 50, or 60 days, and studied the effects of organic acids on the bio-weathering process of granite, such as the dissolution regularity of various ions and the morphological changes of rock surfaces. OA and SA both induced the weathering and dissolving of granite, significantly promoted the release of Na+, K+, Al3+, Fe3+, Mg2+, Mn2+, Ca2+, and from granite powders. For the ion dissolution, the effect of OA was stronger than that of SA. Infrared analysis showed that both organic acids did not change the structures of their own groups, and the weathering mechanism was mainly the complexation of organic acids. The results of electron microscopy also presented the dissolution of granite powders by organic acids, and the effects were enhanced as the treatment time increased. After organic acid applications, the concentrations of dissolved ions from the granite powder varied with the type and concentration of organic acids, and treatment time. The concentration of each ion usually reached its maximum at 50 or 40 mmol L–1 OA, and 50 mmol L–1 SA (except for Fe3+ of some treatments). At day 1, the concentrations of , Al3+, Fe3+, and Mn2+ treated with OA were higher than those of other times. Compared with SA, OA could dissolve more ions from granite powders, especially at day 1. However, the metal ions dissolved by OA were easy to complex with OA, so the concentrations of ions treated by SA were higher than those of OA, and the ions dissolved by OA would enter into the soils more frequently in OA–metal complexes. [ABSTRACT FROM AUTHOR]