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We carried out an integrated study of zircon U-Pb geochronology, Hf isotopes and geochemistry on the paragneisses and amphibolites from the Chencai area, South China. The detrital zircon ages of four paragneisses range from 2974 to 501 Ma with the main peak at ca. 820 Ma. The detrital materials with Neoproterozoic age may derive from the Jiangnan Orogen and those of Palaeo-Mesoproterozoic age may come from the Wuyi terrane. The youngest age indicates that the protoliths of the

To investigate the tectonic framework of the basement of the Cathaysia Block, we selected the representative Cambrian strata in different parts of the South Wuyi area along the southern Nanping-Ninghua-Ganzhou Tectonic Belt (NNGTB). Integrated petrographic and geochronologic studies, as well as geochemical analysis, were carried out on the low-grade metasedimentary rocks of the Niujiaohe Formation in south Jiangxi Province and the Lintian Formation in southwest Fujian Province. The metasedimentary rocks of the Niujiaohe and Lintian formations are dominated by metasandstones and metasiltstones. They have low chemical index of alteration (52.6-77.4) and high index of compositional variability (0.84-1.42) values, suggesting weak chemical weathering and low clastic maturity. Their relatively low Th/U (4.12-6.81) and Rb/Sr (0.68-5.97) ratios reflect a simple recycling history. Detrital zircon geochronological studies indicate prominent source differences for the clastic rocks along the NNGTB. In the Ruijin area, the Niujiaohe Formation displays a Neoproterozoic peak at ca. 741 Ma, which is consistent with the widespread intermediate-acid igneous rocks in the NNGTB. By contrast, the Lintian Formation from the Changting and Mingxi areas contains more pre-Nanhuan detritus, which are predominantly in Grenvillian ages. Furthermore, the peak numbers of detrital zircon ages increase gradually from the Ruijin to Changting and Mingxi areas, indicating that their sources become more diverse. The geochemical features, in combination with detrital zircon age distributions, indicate that the Niujiaohe and Lintian formations are probably deposited in a back-arc basin. These evidences suggest that the Cathaysia Block was assembled by multiple terranes during the Neoproterozoic to the

The North Qinling Orogen underwent subduction and collision processes during the Palaeozoic, but the tectonic framework remains unclear. To investigate the tectonic evolution of the North Qinling Orogen, we selected the Devonian granites from the northeastern margin of the North Qinling Terrane. Integrated petrographic, geochemical, and geochronological studies, as well as Sr-Nd-Hf isotopic analyses, were carried out on the newly identified Devonian granites from the Hengjian area in the northeastern North Qinling Terrane, Qinling Orogenic Belt. Zircon laser ablation inductively coupled plasma mass spectrometry U-Pb dating reveals that these granites were crystallized at 396-387 Ma. The granite samples are metaluminous to weakly peraluminous (A/CNK = Al 2 O 3 /(CaO+Na 2 O+K 2 O) = 0.86 to 1.12), with high SiO 2 (60.6-76.5 wt%) and high total alkaline (Na 2 O + K 2 O = 8.45-11.0 wt%) contents. The granites are enriched in Th, rare-earth element, Zr, and Hf and depleted in Sr, Nb, Ta, P, Eu, and Ti. They are characterized by high Zr + Nb + Ce + Y contents (511-990 ppm) and 10,000*Ga/Al ratios (2.71-3.32), as well as high zircon-saturation temperatures (T Zr = 819-885 C, average = 845 C), which indicate that they are typical A-type granites. The granites have low Y/Nb (0.39-0.67) and Yb/Ta (0.56-0.83) ratios, resembling those of the A 1 -type granite, which indicates that they are formed in anorogenic settings. They also have low ( 87 Sr/ 86 Sr) i ratios (0.7055-0.7071) and negative ε Nd (t) values (À10.1 to À8.40) and variable zircon ε Hf (t) values (À8.46 to +14.7), with the two-stage model ages of 2.0-1.8 Ga and 1.9-0.4 Ga, respectively. These geological features suggest that the granites of the Hengjian area were most likely generated by partial melting of mafic lower crust induced by asthenospheric ascent. The A-type granites were generated in a continental rift environment during 396-387 Ma, corresponding to the closure of the Shangdan Ocean and the opening of the Palaeo-Tethyan Ocean during the Early Devonian.

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