Search

The formation and distribution of late Mesozoic volcanic rocks in northeast (NE) China remain unclear due to the superimposed influence of the tectonic regimes of the Mongol–Okhotsk Ocean (MOO) and Palaeo-Pacific Ocean (PPO) in Northeast Asia. This study reports the petrogenesis and tectonic settings of Early Cretaceous volcanic rocks from the Erlian Basin (EB) using petrology, geochronology, whole-rock geochemistry, and Sr–Nd–Hf isotopes. The U–Pb data for the magmatic zircons indicate that the volcanic rocks, including the trachytic rocks and rhyolites, erupted approximately at ~141–135 Ma. Trachytic rocks and rhyolites exhibit comparatively high SiO2 (58.74–65.77 wt. % and 71.35–72.99 wt. %, respectively) and alkali content, low Mg values (mean 25 and 24, respectively), and Cr, Co, and Ni contents, which differ from the geochemical characteristics of mantle-derived magmas. Furthermore, the positive εHf(t) (1.7–10.5) and εNd(t) (2.4–2.9) values of trachytic rocks and the positive εHf(t) values (4.3–6.6) of rhyolites indicate that these rocks were derived from the partial melting of the juvenile crustal materials. The relatively homogeneous zircon Hf isotopes and systematic variation of major and trace elements in these coeval volcanic rocks suggest that they have a common magma source and resulted from the development of the parent magma in the crustal magma chamber. Our results, combined with previous studies, demonstrate that Early Cretaceous volcanism in the EB records an extensional tectonic regime caused by lithospheric delamination after the closure of the MOO. During the Late Cretaceous, NE China was predominantly controlled by the PPO tectonic regime, accompanied by overall uplift and denudation of large-scale faulted basin groups. [ABSTRACT FROM AUTHOR]

Permo-Carboniferous felsic magmatic rocks are widely exposed on the northern half of the south-eastern Central Asian Orogenic Belt. However, their origin and spatiotemporal distribution are unknown. Herein, zircon U-Pb-Hf isotopic data, major and trace element compositions of the whole-rock, and Sr-Nd isotopic data derived for felsic volcanic rocks and granites of the Chaganaobao and Baiyinaobao areas in central Inner Mongolia are combined with the data from previous studies. The integration of these results reveals that the Uliastai Continental Margin, Erenhot-Hegenshan Ophiolite Belt, and Northern Orogenic Belt have coeval magmatic lull or trough at c. 307 Ma, which overlap with the closure timing of the Hegenshan Ocean. The Latest Carboniferous−Early Permian (c. 303−295 Ma) felsic volcanic rocks in the Chaganaobao area of the Uliastai Continental Margin comprise dacite, trachydacite, and rhyolite, while demonstrating positive whole-rock εNd(t) (+2.9 to +4.7) and zircon εHf(t) values (+7.65 to +13.78). Early Permian granites of the Baiyinaobao area located within the Northern Orogenic Belt show positive εHf(t) values (+ 2.70 to +11.33) and low TFe2O3 + MgO + TiO2 contents. The geochemical composition reveals that those felsic magmatic rocks mainly originate from the partial melting of juvenile crustal components with subordinate input of mantle-derived melts. Those c. 305−275 Ma felsic magmatic rocks from the north of the south-eastern Central Asian Orogenic Belt exhibit affinities of post-collision type granites in geochemical nature. Therefore, the flare-up of the Early Permian magmatism surrounding the Erenhot-Hegenshan Ophiolite Belt could be related to the extension after the final closure of the Hegenshan Ocean. [ABSTRACT FROM AUTHOR]

The mineral composition, whole-rock geochemistry, Sr–Nd isotopes, and in situ zircon U–Pb and Lu–Hf isotopes for mafic and intermediate-felsic volcanic rocks in the Sonid Youqi area were determined to unravel their petrogenesis and the Early Permian tectonic setting of the Solonker Zone, Central Asian Orogenic Belt. Zircon U–Pb ages suggested that these rocks formed in the Early Permian. The mafic volcanic rocks were depleted in Ba, Th, and Nb, enriched in Rb, U, and Sr, and had variable zircon εHf(t) values, with constant Th/Yb and variable Ba/La ratios, indicating that the mafic magma originated from the fluid-metasomatized mantle. The intermediate-felsic volcanic rocks were depleted in Ba, Th, Nb, Ta, and Ti and enriched in Sr, Zr, and Hf. Geochemical modelling and mineralogical observations suggested that magma mixing dominated the magmatic process. These features, along with variable SiO2 and MgO contents and zircon εHf(t) values of +9.40 to +13.47, suggested that these rocks originated from the mixing of melts from the mantle and juvenile crust. Early Permian volcanic rocks from the Solonker Zone had depleted Sr–Nd isotopic compositions, similar to those from the Japan Sea back-arc basin basalts. Their geochemical characteristics differed from those rocks formed during the initial subduction. In combination with previous studies, we suggest that the generation of these Early Permian rocks from the Solonker Zone occurred in an extensional tectonic setting that induced by the slab break-off of Hegenshan Ocean. [ABSTRACT FROM AUTHOR]

Sodium butyrate is one of the most popular feed additives in animal husbandry. In recent years, sodium butyrate has been increasingly used as supplement in aquaculture. The present study is to investigate the intestinal mRNA and microRNA response to diet with sodium butyrate in grass carp (Ctenopharyngodon idella), an important aquaculture species in China. mRNA and microRNA profiles of intestine of grass carp fed with diet contained 0, 1.0, 2.5, 5.0, 7.5 and 10.0 g/kg sodium butyrate were obtained by RNA‐seq using Illumina Hiseq 2,500 platform. The feeding trial was performed using 18 individuals of 1‐year‐old grass carp (n = 3 for each group) and lasted for 40 days in tanks in laboratory. A total of 349,860,852 sequence reads were generated from six intestinal libraries. Functional analysis of differentially expressed genes showed that genes participated in immune pathways tend to be activated by sodium butyrate supplementation. A total of 700 microRNAs were obtained, including 275 conserved microRNAs and 425 novel microRNAs which are potentially involved in regulating 14,300 genes. Spearman's correlation analysis identified 18 pairs of microRNA‐mRNA associated with immune pathways (p <.01 and R<−0.5). The potential genes targeted by microRNAs include CXCL12, AKT1S1, Cab39 and MHCII which are important genes associated with intestinal immune pathways. To our knowledge, this is the first integrated profiling of both mRNA and microRNA in intestine with supplementation of sodium butyrate in grass carp. The present results suggest that sodium butyrate affects intestinal immune system by regulating microRNA‐mRNA interaction in fish. [ABSTRACT FROM AUTHOR]