Abstract：The Langshan tectonic belt is an important part of the giant orogenic belt in the north margin of North China Platform, with ductile shear zone as one of the major structural styles, reflecting deep structure of the crust. The geochemical characteristics of the mylonitized siliceous banded limestone in the southwest of Langshan Ⅱ ductile shear zone are discussed to study the composition changes of the mylonitized rock from protolith in different deformation strength. The analysis results show that, compared with the content of the protolith, there are differences of major and trace elements in the siliceous banded limestone by deformation strength. Among the major elements of deformed rocks, only CaO is the exported component, all the others are imported ones. The trace elements such as Rr, Sr, Ba, Pb, Ti, Cr, Cu, Nb, Ta, Zr and Hf are enriched and Ni relatively deficient. The REE distribution patterns of deformed siliceous banded limestone and protolith are basically consistent, which are characterized by right-dipping curves with enrichment of LREEs and depletion of HREEs, and obvious negative Eu anomaly, indicating the REEs have relative stability and homology during ductile shearing.
刘绍昌, 周洋, 李昊, 代博洋, 明小娜, 杨建强. 内蒙古狼山中部糜棱岩化硅质条带状灰岩地球化学特征研究[J]. 地质与资源, 2020, 29(4): 319-326,318.
LIU Shao-chang, ZHOU Yang, LI Hao, DAI Bo-yang, MING Xiao-na, YANG Jian-qiang. GEOCHEMISRY OF THE MYLONITIZED SILICEOUS BANDED LIMESTONE IN CENTRAL LANGSHAN AREA, INNER MONGOLIA. GEOLOGY AND RESOURCES, 2020, 29(4): 319-326,318.
Chen Y P, Wei C J, Zhang J R, et al. Metamorphism and zircon U-Pb dating of garnet amphibolite in the Baoyintu Group, Inner Mongolia[J]. Science Bulletin, 2015,60(19):1698-1707.
Wang Z Z, Han B F, Feng L X, et al. Geochronology, geochemistry and origins of the Paleozoic-Triassic plutons in the Langshan area, western Inner Mongolia, China[J]. Journal of Asian Earth Sciences, 2015,97:337-351.
Zhai M G, Santosh M. The early Precambrian odyssey of the North China Craton:A synoptic overview[J]. Gondwana Research, 2011,20(1):6-25.
Zhao G C, Cawood P A, Li S Z, et al. Amalgamation of the North China Craton:Key issues and discussion[J]. Precambrian Research, 2012,222-223:55-76.
Wang Z Z, Han B F, Feng L X, et al. Tectonic attribution of the Langshan area in western Inner Mongolia and implications for the Neoarchean-Paleoproterozoic evolution of the western North China Craton:evidence from LA-ICP-MS zircon U-Pb dating of the Langshan basement[J]. Lithos, 2016,261:278-295.
Peng R M, Zhai Y S, Wang Z G, et al. Discovery of double-peaking potassic volcanic rocks in Langshan Group of the Tanyaokou hydrothermal-sedimentary deposit, Inner Mongolia, and its indicating significance[J]. Science China Series D:Earth Sciences, 2005,48(6):822-833.
Darby B J, Ritts B D. Mesozoic structural architecture of the Lang Shan, North-Central China:Intraplate contraction, extension, and synorogenic sedimentation[J]. Journal of Structural Geology, 2007,29(12):2006-2016.
Dan W, Li X H, Wang Q, et al. An Early Permian (ca. 280 Ma) silicic igneous province in the Alxa Block, NW China:A magmatic flare-up triggered by a mantle-plume?[J]. Lithos, 2014,204:144-158.