Shuangjingzi middle Triassic syn-collisional crust-derived granite in the east Inner Mongolia and its constraint on the timing of collision between Siberian and Sino-Korean paleo-plates.
Shuangjingzi middle Triassic syn-collisional crust-derived granite in the east Inner Mongolia and its constraint on the timing of collision between Siberian and Sino-Korean paleo-plates.
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发表时间：
2007
影响因子：
1.8
通讯作者：
Li Jin;Sun Gui
中科院分区：
文献类型：
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作者：
Li Jin;Sun Gui
双井子花岗岩侵入于内蒙古东部西拉木伦河以北晚古生代增生-碰撞杂岩中，该岩体在中生代经历了强烈的韧性变形，矿物组合以白云母为主，SiO_2、Al_2O_3含量高，碱性高，Na_2O/K_2O比值低（1），高A/CNK（1.02~1.08）和A/NK（1.20~1.35）比值，轻稀土富集，Eu异常弱，亏损Ti、Sc，特别是亏损Nb、Ta，富集Th，高~（143）Nd/~（144）Nd（0.512229~0.512286）和（143 Nd/144 Nd）i（0.512068~0.512199）比率，低-（Nd）（t）（-2.71~-5.28）值与较年轻的Nd亏损地幔模式年龄有关（1000~ 1300 Ma），高~（87）Sr/~（86）Sr（0.713516~0.722096）和（87 Sr/86 Sr）i（0.705756~0.709187）比值，表明该岩体为壳源岩体可能主要来自古生代增生碰撞杂岩和古老大陆边缘的重熔。两个花岗岩样品的锆石SHRIMP U-Pb定年结果分别为229.2±4.1Ma和237.2± 2.7Ma，表明该岩体的形成时代为中三叠世，根据已有的地质资料，认为西伯利亚板块与中朝古板块沿着沙尔木龙缝合带的碰撞作用始于中二叠世（约270 Ma），结束于中三叠世，导致早、中三叠世从北山向东经内蒙古南部至吉林中部的东西向巨型造山运动，本区晚三叠世岩浆活动发生在造山构造演化晚期的拉张背景下，这意味着该地区地壳演化新阶段的开始。
The Shuangjingzi granite intruded the Late Paleozoic accretion-collisional complex,which is exposed in the north of Xar Moron River,eastern Inner Mongolia.This pluton underwent the intensively ductile deformation during the Mesozoic,and is characterized by occurrence of muscovite in mineral assemblage,high SiO_2,Al_2O_3 and alkaline content,low Na_2O/K_2O ratio (1), higher A/CNK (1.02～1.08) and A/NK (1.20～1.35) ratios,light REE enrichment with weak Eu anomalies,depleted Ti and Sc, especially depleted Nb and Ta but enriched Th,higher ~(143)Nd/~(144)Nd (0.512229～0.512286)and(~(143)Nd/~(144)Nd)_i(0.512068～0.512199)ratios,lowere-(Nd)(t) (-2.71～-5.28)values with younger Nd depleted mantle model ages (1000～1300Ma),higher ~(87)Sr/~(86)Sr (0.713516～0.722096) and (~(87)Sr/~(86)Sr)_i(0.705756～0.709187)ratios in petro-chemistry,indicating that this pluton is crust-derived,probably mainly come from the re-melting of Paleozoic accretion-collisional complexes and older continental margins. SHRIMP U-Pb dating of zircons from two samples of this granite yields apparent ages of 229.2±4.1Ma and 237.2±2.7Ma,indicating the occurrence of this pluton in the Middle Triassic.Available geological data make us get conclusions that the collision along the Xar Moron suture between Siberian and Sino-Korean paleo-plates began at middle Permian (about 270Ma),and ended in the middle Triassic,which led to uplifting of a huge EW-extended mountain from Beishan eastwards through southern Inner Mongolia to central Jilin during the early to middle Triassic,and that the Late Triassic magmatic activities in the area occurred in the extensional setting in the late stage of tectonic evolution of the mountain,implying the beginning of a new stage of the crustal evolution of the area.