Cyclic formation and stabilization of Archean lithosphere by accretionary orogenesis : constraints from TTG and potassic granitoids, North China Craton

This study is financially supported by the National Natural Science Foundation of China (Grant Nos. 41502179, 41530207, 41472165) and Central University Basic Scientific Research Business Expenses of China University of Geosciences (Beijing) (Grant No. 2652015038). PAC acknowledges support from Australian Research Council grant FL160100168.Accretionary orogens are major sites of modern continental growth, yet their role in the development of Archean continental crust remains enigmatic. Diverse granitoid suites from tonalite-trondhjemite-granodiorite (TTG) to potassic granitoids appeared during late Archean, representing a period of major continental formation and stabilization. In this study, whole-rock geochemical and zircon U-Pb and Lu-Hf isotopic data are reported for Neoarchean granitoid gneisses from the Northern Liaoning Terrane, northeastern North China Craton (NCC). Older granitoid gneisses (~2592-2537 Ma) define three magmatic zones migrating from southeast to northwest, each showing a common magmatic evolution from high-pressure TTGs to medium-/low-pressure TTGs and potassic granitoids. They have depleted zircon ƐHf(t) of +0.5 to +8.7. Younger ~2529-2503 Ma potassic granitoids and TTGs occur throughout the terrane, which are marked by variable zircon ƐHf(t) of -4.7 to +8.1, and are coeval with regional high grade metamorphism. Petrogenetic modeling and changing Sr/Y and (La/Yb)N of the granitoids suggest that the crust experienced episodic thickening and thinning, and became progressively evolved through development of potassic granitoids and sedimentary successions. The metavolcanic basement to the granitoids display tholeiitic to calc-alkaline affinities, together with the top-to-the-northwest thrusting and associated VMS-type Cu-Zn deposits, suggesting cyclic crustal formation of Northern Liaoning within an accretionary orogen with a SE-dipping subduction polarity. Cyclic crustal thickening and thinning is related to tectonic switching from advancing to retreating relations between the downgoing and overriding plate. After ~2530 Ma, this accretionary system accreted to the ancient continental nucleus of NCC (Anshan-Benxi Terrane), signifying final lithosphere stabilization.Publisher PDFPeer reviewe

Late Neoarchean subduction-related crustal growth in the Northern Liaoning region of the North China Craton : evidence from ∼2.55-2.50 Ga granitoid gneisses

This study is financially supported by the National Natural Science Foundation of China (Grant Nos. 41272209, 41472165, 41502179, 41530207) and the Central University Basic Scientific Research Business Expenses of China University of Geosciences (Beijing) (Grant No. 2652015038).The North China Craton (NCC), dominated by ∼2.6-2.5 Ga tectonothermal events, provides a natural laboratory to study Neoarchean crustal growth and geodynamic evolution. Late Neoarchean granitoid gneisses are well exposed in the Northern Liaoning Province, located north of the ancient Anshan-Benxi terrane along the northeastern margin of the Eastern Block (EB) of the NCC. LA-ICPMS zircon U-Pb isotopic dating reveal that granitoid gneisses in the Qingyuan area can be grouped into two major episodes, i.e., ∼2559-2534 Ma strongly gneissic quartz dioritic and tonalitic to trondhjemitic gneisses; and ∼2529-2495 Ma weakly gneissic to massive quartz monzodioritic and monzogranitic gneisses, with subordinate tonalitic to trondhjemitic gneisses. The late magmatic episode was accompanied by regionally high-grade metamorphism (∼2510-2495 Ma). Most granitoid gneisses display highly depleted zircon εHf(t2) values (+4.2-+8.1), whereas one monzogranitic gneiss shows negative values of -4.7 to -1.0, indicating late Neoarchean crustal growth with minor involvement of ancient continental materials probably sourced from the Anshan-Benxi terrane. Geochemical and petrogenetic studies reveal that the quartz dioritic magmas were derived from partial melting of plagioclase-poor garnet amphibolites or eclogites metamorphosed from oceanic slab materials, with slab melts contaminated by mantle wedge peridotites during ascent. The tonalitic to trondhjemitic magmas stemmed from partial melting of mainly juvenile metabasaltic rocks with minor metagreywackes of lower arc crust. In comparison, the quartz monzodioritic and monzogranitic magmas were derived respectively from partial melting of depleted mantle sources metasomatized by slab-derived fluids and metagreywackes with different crustal resident ages at middle to lower crustal levels. Combined with previous studies of metavolcanic rocks, the Northern Liaoning Province records late Neoarchean crustal growth, evolving from mid-ocean ridge, through initiation and maturation of an intra-oceanic arc, to arc-continent collision. Arc-continent accretion and possibly slab rollback processes may have triggered reworking of both juvenile arc crust and minor ancient continental margin materials, generating the magmatic precursors for the monzogranitic gneisses. Overall, the intense late Neoarchean crustal growth of the EB was controlled mainly by arc-continent accretion, possibly linked to global assembly of cratonic fragments.PostprintPeer reviewe

Late Neoarchean crust-mantle geodynamics : evidence from Pingquan Complex of the Northern Hebei Province, North China Craton

This study is financially supported by the National Natural Science Foundation of China (Grant Nos. 41530207, 41502179, 41472165, 41602198) and Central University Basic Scientific Research Business Expenses (Grant No. 2652015038). PAC acknowledges support from Australian Research Council grant FL160100168.A late Neoarchean intra-oceanic arc along the northwestern margin of Eastern Block (EB), North China Craton, provides important insights into the nature of Archean mantle sources and crust-mantle geodynamics. The Pingquan Complex and the entire Northern Hebei Province (NHB) are located in the middle part of the arc, and overlap the northern extent of the Trans-North China Orogen. Zircon U-Pb isotopic age data reveal that the Pingquan Complex consists of ∼2537-2515 Ma dioritic gneisses, ∼2506-2503 Ma amphibolites, and ∼2491 Ma quartz monzodioritic to monzogranitic gneisses, and they show dominantly positive zircon εHf(t) (-0.6-+5.4) that are lower than coeval model depleted mantle values. Geochemical data for the Pingquan rocks and synchronous metabasalts and granitoid gneisses of Huai’an-Xuanhua and Dantazi complexes in the NHB are integrated. Except for the monzogranitic gneisses that were derived from partial melting of juvenile metagreywackes, the other rocks of the Pingquan Complex were derived from a metasomatized lithospheric mantle, and subjected to variable fractionation of clinopyroxene, hornblende and plagioclase, without significant crustal contamination. Moderately depleted zircon εHf(t), and high Sm/Hf and Nb/Ta (mostly of 1.34-3.96 and 15.50-32.58) suggest that the lithospheric mantle was enriched by subducted pelagic sediments metamorphosed to rutile-bearing eclogites before melting. Late Neoarchean crust-mantle geodynamic processes in the NHB are reconstructed. Intra-oceanic subduction initiated offshore of the northwestern margin of the EB at ∼2.55 Ga or earlier. Partial melting of slab basalts occurred at ∼2542-2499 Ma, with the melts contaminated by mantle wedge materials forming TTGs. Meanwhile, the sub-arc lithospheric mantle was enriched by fluids and melts released from slab basalts and pelagic sediments, and partial melting of this moderately depleted mantle generated ∼2537-2503 Ma diorites and basalts. Following final accretion of the arc onto the continental margin of the EB, the slab rollback/breakoff and asthenospheric mantle upwelling triggered partial melting of the metasomatized lithospheric mantle and crustal anatexis, generating ∼2491 Ma quartz monzodioritic and monzogranitic rocks. Accordingly, the NHB records Neoarchean crustal growth linked to oceanic subduction and arc-continent accretion, and highlights the importance of resolving the nature of mantle sources and crust-mantle interactions in understanding Archean crustal growth and evolution.PostprintPeer reviewe

Insulin-like growth factor 1 regulates excitatory synaptic transmission in pyramidal neurons from adult prefrontal cortex

Insulin-like growth factor 1 (IGF1) influences synaptic function in addition to its role in brain development and aging. Although the expression levels of IGF1 and IGF1 receptor (IGF1R) peak during development and decline with age, the adult brain has abundant IGF1 or IGF1R expression. Studies reveal that IGF1 regulates the synaptic transmission in neurons from young animals. However, the action of IGF1 on neurons in the adult brain is still unclear. Here, we used prefrontal cortical (PFC) slices from adult mice (∼8 weeks old) to characterize the role of IGF1 on excitatory synaptic transmission in pyramidal neurons and the underlying molecular mechanisms. We first validated IGF1R expression in pyramidal neurons using translating ribosomal affinity purification assay. Then, using whole-cell patch-clamp recording, we found that IGF1 attenuated the amplitude of evoked excitatory postsynaptic current (EPSC) without affecting the frequency and amplitude of miniature EPSC. Furthermore, this decrease in excitatory neurotransmission was blocked by pharmacological inhibition of IGF1R or conditional knockdown of IGF1R in PFC pyramidal neurons. In addition, we determined that IGF1-induced decrease of EPSC amplitude was due to postsynaptic effect (internalization of a-amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid receptors [AMPAR]) rather than presynaptic glutamate release. Finally, we found that inhibition of metabotropic glutamate receptor subtype-1 (mGluR1) abolished IGF1-induced attenuation of evoked EPSC amplitude and decrease of AMPAR expression at synaptic membrane, suggesting mGluR1-mediated endocytosis of AMPAR was involved. Taken together, these data provide the first evidence that IGF1 regulates excitatory synaptic transmission in adult PFC via the interaction between IGF1R-dependent signaling pathway and mGluR1-mediated AMPAR endocytosis

Comparative pore structure analysis of highly porous graphene monoliths treated at different temperatures with adsorption of N-2 at 77.4 K and of Ar at 87.3 K and 77.4 K

We prepared nanoporous graphene monolith of different porosity by high temperature treatment up to 2073 K in Ar. The porosity is comparatively evaluated with N-2 adsorption isotherms at 77.4 K and Ar adsorption isotherms at 87.3 K and 77.4 K. N-2 adsorption at 77.4 K shows an excess adsorption amount below 3 x 10(-3) of the relative pressure which is caused by the quadrupole moment of an N-2 molecule. This effect doesn't give significant influence on the determination of the total surface area from subtracting pore effect (SPE) method, the micropore volume from Dubinin-Radushkevich (DR) method and the total pore volumes from the Gurvitch rule. However, the peak of the micropore size distribution determined by Horvath-Kawazoe (HK) method from N-2 adsorption at 77.4 K shifts to a smaller size than that from Ar adsorption at 87.3 K by 0.05-0.09 nm. (C) 2015 Elsevier Inc. All rights reserved.ArticleMICROPOROUS AND MESOPOROUS MATERIALS. 209:72-78 (2015)journal articl

A Case Report of Tragaxofusp Causing Severe Tumor Lysis Syndrome In A Patient With Blastic Plasmacytoid Dendritic Cell Neoplasm

The patient was an 83-year-old male without significant past medical hsitory who presented to his primary care physician with several days of generalized malais

Control Strategy and Simulation of the Regenerative Braking of an Electric Vehicle Based on an Electromechanical Brake

The electromechanical brake (EMB) has very broad prospects for application in the automotive industry, especially in small- and medium-sized vehicles. To extend the endurance range of pure electric vehicles, a regenerative braking control strategy combined with an electromechanical brake model is designed that divides the braking modes according to the braking intensity and controls the regenerative braking force based on fuzzy theory. Considering a front-wheel-drive pure electric vehicle equipped with a floating clamp disc electromechanical brake as the research object, a structural form of electromechanical brake is proposed and a mathematical model of the electromechanical brake is built. Combined with the relevant influencing factors, the regenerative braking force is limited to a certain extent, and the simulation models of the electromechanical brake and the regenerative braking force distribution control strategy are built in MATLAB/Simulink. Co-simulation in MATLAB and AVL CRUISE software is conducted. The simulation results demonstrate that the braking energy recovery rate of the whole vehicle with the fuzzy control strategy put forward in this paper is 28.9% under mild braking and 34.11% under moderate braking. The control method substantially increases the energy utilization rate