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One new species of the genus Sinopoda Jäger, 1999, S. muyuensis sp. nov. (♂, ♀), is described and figured from the Shennongjia Forestry District, Hubei Province, China. In addition, the male of Sinopoda wuyiensis Liu, 2021 is described for the first time from the Wuyishan National Nature Reserve, Fujian Province, China. [ABSTRACT FROM AUTHOR]

In this work, we report the geochemical, whole-rock Sr-, Nd-, and Hf-isotopes, and zircon U–Pb age and Hf–O isotopic compositions for six granitic intrusions in northeastern Fujian, coastal region of southeastern China, to elucidate the petrogenesis of aluminous and peralkaline A-type granites in this region. Zircon U–Pb dating of these rocks (including porphyritic syenites, porphyritic granites, alkali-feldspar granites, and arfvedsonite granites) yielded Late Cretaceous ages of 94–98 Ma. Mineral assemblage and geochemical features suggested that the arfvedsonite granites were peralkaline A-type but the porphyritic syenites, porphyritic granites, and alkali-feldspar granites were aluminous A-type. Geochemical data, whole-rock Nd–Hf isotopes (ε Nd (t) = −5.5 to −4.0, ε Hf (t) = −3.6 to 0), and the zircon Hf–O isotopes (ε Hf (t) = −3.0 to +1.4, δ18O = 5.4‰–6.0‰) indicated that the porphyritic syenites were produced by partial melting of crustal rocks in the lower crust. The porphyritic granites and alkali-feldspar granites had similar geochemical features and zircon Hf–O isotopic composition with the porphyritic syenites, suggesting that they were formed by feldspar-dominant crystal fractionation of deep crust derived syenitic magma under shallow crustal level. Compared with the aluminous A-type granites, the peralkaline A-type granites had lower abundance of Al 2 O 3 , MgO, CaO, Ba, and Sr, higher abundance of SiO 2 and HFSE, as well as higher ratio of total FeO/MgO, Ga/Al, and Rb/Sr. However, the whole-rock Nd-, Hf- and zircon Hf–O isotopic compositions of the peralkaline and aluminous A-type granites were similar. It could be inferred that the peralkaline A-type granites were formed by crystal fractionation of aluminous A-type granitic magmas. Since the studied A-type granitic intrusions were coeval with the bimodal volcanic rocks and the extensional basins in the coastal region of southeastern China, they were likely produced in an extensional setting, possibly during lithospheric thinning that resulted from the subduction of the paleo-Pacific plate beneath southeastern China. • Aluminous and peralkaline A-type granites were crystallized at 94–98 Ma. • Aluminous and peralkaline A-type granites were derived from a common source. • Aluminous A-type granite was produced by partial melting of lower crustal rocks. • Peralkaline A-type granite was formed via crystal fractionation. [ABSTRACT FROM AUTHOR]

A-type granites are a distinctive group of igneous rocks classified based on chemical and mineralogical criteria. Although numerous theories for the origin of A-type granite have previously been proposed, their genesis remains highly controversial. In the current study, we present bulk-rock geochemistry and zircon U Pb isotopes, Hf isotopes, and trace elemental data for a suite of quartz monzonite, porphyritic granite, and miarolitic alkali feldspar granite from the coastal area of Fujian, southeastern China, to evaluate the genetic link between these rocks. Zircon U Pb dating indicates that these rocks were crystallized at ∼94–102 Ma. Our data strongly suggests that lithological differences in these rocks are the result of crystal-melt segregation in the shallow crust. The quartz monzonites are enriched in Sr and Ba, with high Zr/Hf and low silica content and a weak negative Eu anomaly, representing the cumulate residue from the crystal-melt segregation of a magma reservoir. A limited fraction of zircon from the quartz monzonite has evolved trace element signatures (high Hf, Nb, Y, U; low Eu/Eu⁎), indicating that the quartz monzonite represents a mixture of accumulated crystals and high silicic melt trapped in cumulate mush. The miarolitic alkali feldspar granites and porphyritic granites are enriched in silica and Rb, and depleted in Sr and Eu. They also display low whole-rock Zr/Hf and Eu/Eu⁎ ratios, and high Rb/Sr ratios, representing highly evolved silicic melts that were segregated from a magma reservoir. The majority of the zircon grains from the miarolitic alkali feldspar granites exhibit the most evolved trace element signatures (high Hf, Nb, Y, U; low Zr/Hf and Eu/Eu⁎) of the entire suite. This reveals that these zircons crystallized from the high silicic melts extracted from a magma reservoir. Magma recharge and the exsolution of volatiles from the interstitial melt have promoted the segregation and upward extraction of high silica magmas from a compacting magma reservoir in the upper crust. Our work demonstrates that the miarolitic alkali feldspar granites with A-type granite features from the coastal area of southeastern China were generated by the crystal-melt segregation process in a shallow crustal magma reservoir. [ABSTRACT FROM AUTHOR]

• Multiple sources were involved in the origin of Cretaceous granitoids in Fujian. • A separate low δ18O crustal source existed in the origination of these granitoids. • Changing subduction direction induced the change in the compositions of these rocks. The major elemental and oxygen isotopic features of Cretaceous granitoids in the coastal area of southeastern China cannot be adequately explained by existing Sr-Nd isotopic models of two-component crust-mantle mixing. In this paper, we report the whole-rock elemental, and Sr-, Nd-, and Hf-isotopes, and the zircon U-Pb age and Hf-O isotopic compositions for the Puqian, Danyang, Qingliangshan, Nanyu, and Qishan plutons in northeastern Fujian of this area to further investigate their petrogenesis. The examined rocks included pyroxene diorite, monzodiorite, granodioritic enclave, monzogranite and alkali-feldspar granite. Zircon U-Pb dating gave crystallization ages of 115 Ma for the Puqian monzogranite and granodioritic enclave, 97–109 Ma for the Danyang monzogranite, 99 Ma for the Nanyu pyroxene diorite, 97 Ma for the Qishan alkali-feldspar granite, and 97–103 Ma for the Qingliangshan alkali-feldspar granite. Our new Sr-Nd-Hf-O isotopic and petrogenetic studies of these granitoids showed that, aside from the ancient crustal component (δ18O = 7.5‰, ε Hf (t) = −10) and the mantle-derived magma (δ18O = 5.3‰, ε Hf (t) = 2), a separate juvenile low δ18O crustal source (δ18O = 4.2‰, ε Hf (t) = 2) must be involved. Since the emplacement of the diorite-monzodiorite-granodiorite-monzogranite suite and the A-type granite was coeval with pull-apart basins and bimodal volcanic rocks, the Cretaceous granitoids in northeastern Fujian, coastal area of southeastern China, were emplaced in an extensional setting, possibly due to the backarc extension and the changing drifting direction of the paleo-Pacific plate. [ABSTRACT FROM AUTHOR]