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Abstract: In this paper, we report on zircon U–Pb dating, Hf isotopes, major and trace elements, and Sr–Nd isotope data, with the aim of constraining the petrogenesis and regional tectonic evolution of late Paleozoic volcanic rocks in the Zhangguangcai Range of eastern Heilongjiang Province, NE China. Located in the eastern segment of the Central Asian Orogenic Belt (CAOB), between the Siberian and North China cratons, the late Paleozoic volcanic rocks in the Zhangguangcai Range are composed mainly of basalt, basaltic andesite, rhyolite, and minor dacite. The results of LA–ICP–MS zircon U–Pb dating for two basaltic rocks, three rhyolites, and one dacite indicate that they formed in the early Permian (ca. 292Ma). The mafic rocks have SiO2 =50.13–53.80wt.%, K2O=0.98–2.28wt.%, Mg#=0.51–0.71, Cr=144–541ppm, Ni=74–260ppm, (87Sr/86Sr)i =0.7044, and ε Nd (t)=+4.28, whereas the felsic rocks have SiO2 =69.12–77.98wt.%, K2O=3.09–5.33wt.%, Mg#=0.17–0.36, (87Sr/86Sr)i =0.7032, and ε Nd (t)=+4.32. These data are typical of bimodal volcanism. The mafic volcanic rocks are characterized by a strong enrichment in large ion lithophile elements (LILEs) such as Rb, Ba, Sr, and Pb, depletion in high field-strength elements (HFSEs) such as Nb, Ta, and Ti, depletion in heavy rare-earth elements (HREEs), and weak negative Eu anomalies (Eu/Eu* =0.88–0.94). On the other hand, the felsic rocks show a strong depletion in Nb, Ta, Sr, P, and Ti, enrichment in Th, U, and K, and relatively large negative Eu anomalies (Eu/Eu* =0.28–0.95). Taken together, these data suggest that the mafic magma was derived from the partial melting of a depleted lithospheric mantle, modified by subducted slab-derived fluids, and that the felsic magma originated by partial melting of newly accreted crust. The early Permian bimodal volcanic rocks, together with the coeval A-type granites, indicate an extensional environment, similar to a back-arc basin. Such a setting was possibly related to subduction of the Paleo-Asian oceanic plate beneath the Jiamusi and Songnen–Zhangguangcai Range massifs. [Copyright &y& Elsevier]

Abstract: We undertook LA-ICP-MS U–Pb dating of detrital zircons from Late Paleozoic sedimentary rocks in eastern Heilongjiang Province, NE China, with the aim of constraining the tectonic evolution of the eastern segment of the Central Asian Orogenic Belt (CAOB). Detrital zircons from quartz sandstone of the Devonian Heilonggong Formation in the Zhangguangcai Range yield age populations of ∼2503, ∼1833, ∼903, ∼802, and 551–403Ma. Zircons from quartz sandstone of the Devonian Baoquan Formation in the Lesser Xing''an Range yield age clusters at ∼2500, ∼800, and 489–425Ma. These ages reveal that: (1) rocks from the Heilonggong and Baoquan formations were deposited after 391 and 413Ma, respectively; (2) these rocks were sourced from regions with rocks as old as ∼2500Ma, with dominant age populations of ∼2500, ∼1833, 903–800, and 551–403Ma; and (3) in addition to new lower crust accreted during the Phanerozoic (as revealed by voluminous Phanerozoic granitoids with positive εNd values within the CAOB), it appears that several remnants of an ancient Precambrian basement occur adjacent to these Late Paleozoic basins (e.g., the Shangzhi, Tangyuan, and Baoqing basins) that occur within microcontinental massifs including the Songnen–Zhangguangcai Range, Xing''an, and Erguna massifs. Detrital zircons from quartz sandstone of the Devonian Heitai Formation on the eastern margin of the Jiamusi Massif yield peak age populations of 569, 542, 509, and 484Ma, similar to those obtained from zircons within the Mashan Group of the Jiamusi Massif. These age data indicate that: (1) deposition of the Heitai Formation on the eastern margin of the Jiamusi Massif had started by 484Ma, and (2) these sediments were sourced entirely from the Jiamusi Massif. The widespread occurrence of detrital zircons with ages of 480–550Ma within Late Paleozoic basins in the Lesser Xing''an–Zhangguangcai Ranges and the Jiamusi Massif, combined with the presence of a Caledonian (445–499Ma) I-type granitoid belt in the Lesser Xing''an–Zhangguangcai Ranges, indicates that amalgamation of the Songnen–Zhangguangcai Range and Jiamusi massifs took place before the Early Devonian, probably during the late stage of the Early Paleozoic (after ∼445Ma). [Copyright &y& Elsevier]