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Strain-mediated voltage-controlled switching of magnetic skyrmions in nanostructures

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npj Computational Materials 2018年第1期4卷 147-153页

作者： Jia-Mian Hu tiannan yang Long-Qing Chen Department of Materials Science and Engineering The Pennsylvania State UniversityUniversity ParkPA 16802USA Department of Materials Science and Engineering University of Wisconsin–MadisonMadisonWI 53706USA

Magnetic skyrmions are swirling spin structures stabilized typically by the Dyzaloshinskii-Moriya *** existing control of magnetic skyrmions has often relied on the use of an electric current,which may cause overheating in densely packed *** we demonstrate,using phase-field simulations,that an isolated Néel skyrmion in a magnetic nanodisk can be repeatedly created and deleted by voltage-induced strains from a juxtaposed *** a skyrmion switching is non-volatile,and consumes only~0.5 fJ per switching which is about five orders of magnitude smaller than that by current-induced *** is found that the strain-mediated skyrmion creation occurs through an intermediate vortex-like spin structure,and that the skyrmion deletion occurs though a homogenous shrinkage during which the Néel wall is temporarily transformed to a *** findings are expected to stimulate experimental research into strain-mediated voltage control of skyrmions,as well as other chiral spin structures for low-power spintronics.

关键词： vortex magnetic repeatedly

Coherent Chemical Variation Trends of the 55-25 Ma Magmatic Rocks in SE Tibet:N-S Direction Lithospheric Stretching of Eurasia during Early Stage of India-Eurasia Collision

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Acta Geologica Sinica(English Edition) 2023年第5期97卷 1283-1305页

作者： yang tiannan DONG Mengmeng XUE Chuandong XIN Di LIANG Mingjuan Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China Chinese MNR Laboratory of Deep Earth Sciences and Technology Beijing 100037China Department of Earth Sciences Kunming University of Science and TechnologyKunming 650093China Geological Museum of Guizhou Guiyang 550081China

The progressive indentation of India into Eurasia generated an E-W-trending orthogonal collision belt and a N-S-trending oblique collision *** available data reveals that~70%of the Cenozoic igneous rocks in eastern and southeastern Tibet are concentrated within an ENE-trending,~550-km long and~250-km wide magmatic zone(CMZ)that once separated the orthogonal and oblique collision *** Latitude 26°N Line is now its southern *** onset timing of magmatism of the CMZ varies gradually from~55 Ma in the westernmost part to~27 Ma in the *** the magmatism successively occurred and suddenly stopped at~25 *** segmented and coherent chemical variation trends found suggest that the CMZ magmatic rocks were formed due to partial melting of the heterogeneous upper mantle and crusts of *** of Paleo-and Neotethyan oceanic plates generated this compositional and mineralogical *** with available geophysical data,the CMZ was diachronously formed in response to asthenosphere upwelling induced by NNW-SSE-direction lithosphere *** difference in responses of the orthogonal and oblique collision belts to the indentation of the Indian continent has led to this lithosphere stretching.

关键词： tectonics geochemistry magmatic zone temporal/spatial distribution lithospheric stretch Eocene to Oligocene SE Tibet

Mesoproterozoic Continental Arc Type Granite in the Central Tianshan Mountains:Zircon SHRIMP U-Pb Dating and Geochemical Analyses

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Acta Geologica Sinica(English Edition) 2008年第1期82卷 117-125页

作者： yang tiannan LI Jinyi SUN Guihua WANG Yanbin Institute of Geology Chinese Academy of Geological Sciences Beijing 100037

The Central Tianshan belt in northwestern China is a small Precambrian block located in the southern part of the Central Asia Orogenic Belt （CAOB）, which is considered as ＂the most voluminous block of young continental crust in the world＂ that comprises numerous small continental blocks separated by Paleozoic magmatic arcs. The Precambrian basement of the central Tianshan Mountains is composed of volcanic rocks and associated volcano-sedimentary rocks that were intruded by granitic plutons. Geochemical analyses demonstrate that the granitic plutons and volcanic rocks were generated in the Andean-type active continental arc environment like today＇s Chile, and the zircon U-Pb SHRIMP dating indicates that they were developed at about 956 Ma, possibly corresponding to the subduction of the inferred Mozambique Ocean under the Baltic-African super-continent.

关键词： Mesoproterozoic granite pluton magmatic arc Central Tianshan

Petrogenesis of the Late Eocene to Early Oligocene Yao'an Shoshonitic Complex,Southeastern Tibet:Partial Melting of an Ancient Continental Lithospheric Mantle beneath the yangtze Block

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Acta Geologica Sinica(English Edition) 2023年第6期97卷 1657-1670页

作者： DONG Mengmeng yang tiannan XUE Chuandong XIN Di LIANG Mingjuan YAN Qinggao Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China School of Earth and Space Sciences Peking UniversityBeijing 100871China Department of Earth Sciences Kunming University of Science and TechnologyKunming 650093China Geological Museum of Guizhou Guiyang 550081China Institute of Mineral Resources Chinese Academy of Geological SciencesBeijing 100037China

Cenozoic potassic-ultrapotassic igneous rocks are widespread in the southeastern Tibetan *** petrogenesis and magmatic processes remain subject to debate in spite of numerous *** all of the Cenozoic extrusive and intrusive rocks in the Yao’an area,western Yunnan Province,SW China,are geochemically shoshonitic,collectively termed here the Yao’an Shoshonitic Complex(YSC).The YSC is located in the(south)easternmost part of the ENE-WSW-trending,~550 km-long and~250 km-wide Cenozoic magmatic zone;the latter separates the orthogonal and oblique collision belts of the India-Eurasia collision *** published geochronological and thermochronological data revealed that the rocks of the YSC were emplaced over a short timespan of 34-32 *** and our new data suggest that the primary magma of the YSC likely was formed by partial melting of ancient continental lithospheric mantle beneath the yangtze *** part of the continental lithospheric mantle had likely not been modified by any oceanic *** crystallization of an Mg-and Ca-bearing mineral and TiFe oxides during the magmatic evolution probably account for the variable lithologies of the YSC.

关键词： Ancient continental lithospheric mantle Partial melting Yao’an Shoshonitic Complex Late Eocene to early Oligocene SE Tibetan Plateau

Late Cretaceous Adakitic Granites of the Southeastern Tibetan Plateau: Garnet Fractional Crystallization of Arc-Like Magmas at the Thickened Neo-Tethyan Continental Margin

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Acta Geologica Sinica(English Edition) 2019年第4期93卷 857-873页

作者： XIANG Kun XUE Chuandong yang tiannan XIE Zhipeng XIN Di JIANG Lili LAI Ruijuan Department of Earth Sciences Kunming University of Science and TechnologyKunming 650093China Institute of Geology Chinese Academy of Geological Sciences(CAGS)Beijing 100037China

The tectonic setting of Cretaceous granitoids in the southeastern Tibet Plateau,east of the Eastern Himalaya Syntax,is *** and mining of the Laba Mo–Cu porphyry-type deposit in the area has revealed Late Cretaceous *** and previously published zircon U–Pb dating indicate that the Laba granite crystallized at 89–85 ***-rock geochemistry,Sr–Nd isotopic data and in situ zircon Hf isotopic data indicate that the granite is adakitic and was formed by partial melting of thickened lower *** Ca,Fe,and Al contents decrease with increasing SiO2 *** and other geochemical characteristics indicate that fractional crystallization of garnet under high-pressure conditions resulted in the adakitic nature of the Laba *** granitoids are widespread throughout the Tibetan Plateau including its southeastern area,forming an intact curved belt along the southern margin of *** belt is curved due to indenting by the Indian continent during Cenozoic,but strikes parallel to both the Indus–Yarlung suture zone and the Main Frontal Thrust *** is therefore likely that Cretaceous granitoids in both the Gangdese and southeastern Tibetan Plateau areas resulted from subduction of Neo-Tethyan lithosphere.

关键词： adakitic granite geochemistry garnet fractional crystallization Cretaceous Neo-Tethyan subduction southeastern Tibetan Plateau

Petrogenesis of Early Carboniferous Ultramafic-Mafic Volcanic Rocks in the Southern Changning-Menglian Belt,Southeastern Tibetan Plateau:Implications for the Evolution of the Paleo-Tethyan Ocean

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Acta Geologica Sinica(English Edition) 2022年第3期96卷 858-874页

作者： XIE Zhipeng WU Xuelu WANG Tengfei XUE Chuandong yang tiannan WANG Wei SUI Binxi XIN Di Department of Earth Sciences Kunming University of Science and TechnologyKunming 650093China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China

The Changning-Menglian Belt represents the main Paleo-Tethyan Suture in the southeastern Tibetan Plateau,which divides Gondwana-and Eurasia-derived continental fragments from each *** belt contains ultramafic-mafic volcanic rocks that provide evidence of the tectonic processes which operated during the evolution of the Paleo-Tethyan *** geochemical data for Early Carboniferous volcanics in the southern Changning-Menglian Belt show that wehrlites have cumulate and poikilitic textures,and contain low-Fo(84.2-87.2)olivine,clinopyroxene with low Mg#values(79.4-85.6),and spinel with high Cr#values(67.8-72.4).Estimated equilibrium temperatures obtained using olivine-spinel Fe-Mg exchange geothermometry range from 978℃ to 1373℃(mean=1205℃;n=3).These observations combined with a lack of reaction or melt impregnation textures indicate that these units represent magmatic cumulates rather than having formed as a result of mantle-melt *** wehrlites and basalts in the belt have subparallel rare earth element(REE)-and primitive-mantle-normalized multi-element patterns with slightly positive Nb-Ta anomalies,but negligible Eu and Zr-Hf *** volcanics have similar Sr-Nd-Pb isotopic compositions withεNd(t)values of 4.2-4.5(mean=4.3;n=3)and 4.0-4.4(mean 4.2;n=4),respectively,and also have similar immobile element ratios,such as Nb/La,Nb/U,Th/La,Zr/Nb,Th/Ta,La/Yb,Nb/Th,Nb/Y,and Zr/*** characteristics indicate both units have ocean island basalt(OIB)-like geochemical affinities,consistent with the fact that the clinopyroxene in the wehrlites is compositionally similar to OIB-related cumulus *** suggests that both the wehrlites and basalts were derived from similar parental magmas that underwent generally closed-system magmatic differentiation dominated by fractionation of the olivine and *** parental magma was likely generated in an oceanic seamount setting from an OIB-type mantle source(i.e.,asthenospheric mantle)contain

关键词： geochemistry petrogenesis wehrlite OIB Changning-Menglian Belt Paleo-Tethys Tournaisian Manxin Tibetan plateau

Geochemistry and Detrital Zircon U-Pb Geochronology of Lower Carboniferous Clastic Sedimentary Rocks in the Changning-Menglian Belt: Implications for the Evolution of the Palaeo-Tethys Ocean

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Journal of Earth Science 2022年

作者： Zhipeng Xie Chuandong Xue tiannan yang Wei Wang Di Xin Department of Earth Sciences， Kunming University of Science and Technology Institute of Geology， Chinese Academy of Geological Sciences

Lower Carboniferous clastic sedimentary rocks （i.e.， the Nanduan Formation） in the Changning-Menglian Belt of the southeastern Tibetan Plateau may provide new insights into the tectonic evolution of the Palaeo-Tethys Ocean. This paper presents new petrographic， geochemical， and detrital zircon U-Pb age data to constrain the provenance and depositional setting of these rocks. Sandstone samples of the Nanduan Formation are all quartz arenites (Q;F;L;) and have high SiO;contents （85.1 wt.%–95.2 wt.%; average = 90.9 wt.%）， indicating high compositional maturity. They exhibit fractionated rare earth element （REE） patterns， with light REE enrichment [（La/Yb）;= 6.48–12.1] and negative Eu anomalies （Eu/Eu* = 0.53–0.74）， and marked negative Sr–Cs-V-Cr-Ni anomalies in upper continental crust-normalised multi-element diagrams. The geochemical features and heavy mineral assemblages suggest that sediments were mainly derived from ancient sedimentary rocks in cratonic interiors or stable continental areas， and were probably deposited in a passive continental margin setting. Detrital zircon U-Pb dating （n = 256） of the Nanduan Formation sandstones defined three distinct age peaks in the Pan-African （600–500 Ma）， younger Grenvillian （950–850 Ma）， and older Grenvillian （1250–1000 Ma）. Their zircon age spectra are similar to those of lower Palaeozoic sedimentary rocks （i.e.， the Mengtong and Mengdingjie groups） in the Baoshan-Sibumasu Block， but significantly different to those of older rocks in the Simao-Indochina and other surrounding blocks （i.e.， the western yangtze， western Cathaysia， western Qiangtang， Tethyan Himalaya， and Lhasa blocks）. This suggests that the Nanduan Formation was deposited at the margin of the Baoshan-Sibumasu Block. Combining the new data presented in this study with published data， we suggest that the Nanduan Formation and underlying Lancang Group were deposited in the same setting during the early and late Palaeozoic， respectively.

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^(40)Ar/^(39)Ar Dating of Deformation Events and Reconstruction of Exhumation of Ultrahigh-Pressure Metamorphic Rocks in Donghai, East China

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Acta Geologica Sinica(English Edition) 2003年第2期77卷 155-168页

作者： LI Jinyi, yang tiannan, CHEN Wen and ZHANG Sihong Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037E-mail: jyli@*** Chinese Acad Geol Sci Inst Geol Beijing 100037 Peoples R China

Recent investigations reveal that the ultrahigh-pressure metamorphic (UHPM) rocks in the Donghai region of East China underwent ductile and transitional ductile-brittle structural events during their exhumation. The earlier ductile deformation took place under the condition of amphibolite facies and the later transitional ductile-brittle deformation under the condition of greenschist facies. The hanging walls moved southeastward during both of these two events. The 40Ar/39Ar dating of muscovites from muscovite-plagioclase schists in the Haizhou phosphorous mine, which are structurally overlain by UHPM rocks, yields a plateau age of 218.0±2.9 Ma and isochron age of 219.8Ma, indicating that the earlier event of the ampibolite-facies deformation probably took place about 220 Ma ago. The 40Ar/39Ar dating of oriented amphiboles parallel to the movement direction of the hanging wall on a decollement plane yields a plateau age of 213.1±0.3 Ma and isochron age of 213.4±4.1 Ma, probably representing the age of the later event. The dating of pegmatitic biotites and K-feldspars near the decollement plane from the eastern Fangshan area yield plateau ages of 203.4±0.3 Ma, 203.6±0.4 Ma and 204.8±2.2 Ma, and isochron ages of 204.0±2.0 Ma, 200.6±3.1 Ma and 204.0±5.0 Ma, respectively, implying that the rocks in the studied area had not been cooled down to closing temperature of the dated biotites and K-feldspars until the beginning of the Jurassic (about 204 Ma). The integration of these data with previous chronological ages on the ultrahigh-pressure metamorphism lead to a new inference on the exhumation of the UHPM rocks. The UHPM rocks in the area were exhumed at the rate of 3-4 km/Ma from the mantle (about 80-100 km below the earth's surface at about 240 Ma) to the lower crust (at the depth of about 20-30km at 220 Ma), and at the rate of 1-2 km/Ma to the middle crust (at the depth of about 15 km at 213 Ma), and then at the rate of less than 1 km/Ma to the upper crust about 10 km

关键词： ultrahigh-pressure metamorphic rocks structural deformation 40Ar/39Ar dating exhumation Donghai East China

Eocene Basins on the SE Tibetan Plateau: Markers of Minor Offset along the Xuelongshan–Diancangshan–Ailaoshan Structural System

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Acta Geologica Sinica(English Edition) 2020年第4期94卷 1020-1041页

作者： LIAO Cheng yang tiannan XUE Chuandong LIANG Mingjuan XIN Di XIANG Kun JIANG Lili SHI Pengliang ZHU Wenbin WAN Liangchun TANG Jing YU Jing WU Pinglei Key Laboratory of Deep–Earth Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China School of Earth and Space Sciences Peking UniversityBeijing 100871China Faculty of Land Resource Engineering Kunming University of Science and TechnologyKunming 650093China China University of Geosciences Beijing 100083China

The offset of geological bodies provides robust evidence of displacement along a fault or ductile shear zone. The amount of displacement along the Xuelongshan–Diancangshan–Ailaoshan structural system, southeastern Tibetan Plateau, is uncertain because of the lack of offset geological markers. This NNW–SSE-trending system is developed in three isolated metamorphic complexes and interjacent nonmetamorphosed rocks. They are expected to record similar post-Eocene strain, although their structural patterns should be distinct. Geological mapping in the area between the Xuelongshan and Diancangshan metamorphic complexes has revealed a small Eocene basin, the Madeng Basin, located to the west of the structural system. The sedimentary and volcanic successions of the Madeng Basin are comparable to those of the Jianchuan Basin, which is located to the east of the structural system. Zircon U–Pb geochronological and bulk geochemical data demonstrate that the volcanic rocks of both basins formed during 37–34 Ma and share the same geochemical features. These data suggest that the Madeng and Jianchuan basins previously constituted a single basin, with the distribution of high-K volcanic rocks in the basins defining an ENE–WSW-trending volcanic belt that shows a limited dextral offset of ≤20 km across the Xuelongshan–Diancangshan–Ailaoshan structural system. Therefore, the northern segment of the structural system records no evidence of large-scale lateral movement/displacement. The results suggest that the Indochina block, which is bounded by the Xuelongshan–Diancangshan–Ailaoshan structural system to the east and the Sagaing Fault to the west, has not extruded southward as a whole but rather has been deformed by pervasive crustal shortening.

关键词： offset marker Eocene basin Xuelongshan–Diancangshan–Ailaoshan structural system southeastern Tibetan Plateau India–Eurasia collision