Geochronology and geochemistry of leucogranites from the southeast margin of the North China Block: Origin and migration
Geochronology and geochemistry of leucogranites from the southeast margin of the North China Block: Origin and migration
复制标题
华北地块东南缘淡色花岗岩年代学和地球化学：成因与运移
DOI：
10.1016/j.gr.2013.08.019
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发表时间：
2014-11
影响因子：
6.1
通讯作者：
Li S.G., Wang S.J., Guo S.S., Xiao Y.L., Liu Y.C.
中科院分区：
文献类型：
--
作者：
Li S.G., Wang S.J., Guo S.S., Xiao Y.L., Liu Y.C.
本文对华北陆块东南缘蚌埠地区晚侏罗世花岗质侵入体进行了系统的年代学、地球化学和地质研究。岩石的FeO + MgO + TiO 2含量和铁镁矿物丰度很低，Al饱和度指数（ASI = 0.92-1.09）也很低，表明这些花岗质侵入体为偏辉浅色花岗岩。蚌埠浅色花岗岩中含有丰富的继承性新元古代火成和三叠纪变质锆石，与邻近大别-苏鲁造山带的超高压（UHP）变质岩的年龄高度一致，但与围岩存在明显差异。岩浆增生锆石环的年龄为167-148 Ma，与苏鲁造山带侏罗纪混合岩化作用的时间一致。矿物包裹体，如石英，长石，磷灰石，钛，黑云母，白云母和多硅白云母（Si = 3.58）没有柯石英发生在三叠纪变质锆石表明，源岩的浅色花岗岩可能只经历了高压（HP），而不是超高压变质。此外，继承变质锆石陡峭的HREE配分模式，以及极低的体稀土含量和Sr-Nd-Pb同位素特征表明，大别-苏鲁造山带中的浅色花岗岩很可能是俯冲长英质片麻岩部分熔融的产物，而不是玄武质榴辉岩，其源区为残余褐帘石。低Rb、高Sr含量和低Rb/Sr比值表明，变质浅色花岗岩是由贫云母正片麻岩形成的。浅色花岗岩的熔融温度约为700-710 °C，这是使用锆石中的钛和锆饱和温度测定法估计的。继承变质锆石的变质锆石中钛的温度为681 ± 60 °C，代表了原岩形成的温度，与熔融温度没有显着差异。因此，需要存在H2O的熔融来产生低温熔体。通过对合肥盆地侏罗系地层的沉积相分析，认为晚侏罗世苏鲁造山带受郯庐断裂的影响向北迁移至蚌埠隆起以东，造成了合肥盆地地形的差异和中下地壳侧向压力梯度。这种侧向压力梯度可能驱使苏鲁造山带部分熔融的地壳（混合岩）向西流入华北板块蚌埠隆起的中下地壳。重力驱使熔体上升进入蚌埠隆起的中上地壳，形成浅色花岗岩侵入体。蚌埠隆起区晚侏罗世浅色花岗岩的北西西向-东南向分布特征可能指示古河道水流的方向。
Systematic geochronological, geochemical and geological data for the Late Jurassic granitic intrusions from the Bengbu area in the southeastern margin of North China Block (NCB) are presented in this paper. The very low FeO + MgO + TiO2contents and ferromagnesian mineral abundance as well as low Al-saturation indexes (ASI = 0.92–1.09) of the rocks document that these granitic intrusions are metaluminous leucogranites. The Bengbu leucogranites contain abundant both inherited Neoproterozoic igneous and Triassic metamorphic zircons, showing a high agreement in ages with the ultrahigh-pressure (UHP) metamorphic rocks from the adjacent Dabie–Sulu orogen, but significant different from the country rocks. The magmatic overgrown zircon rims give the ages of 167–148 Ma, consistent with the time of Jurassic migmatization in the Sulu orogenic belt. Mineral inclusions such as quartz, feldspar, apatite, titanite, biotite, muscovite and phengite (Si = 3.58) without coesite occurring within the Triassic metamorphic zircons suggest that the source rocks of the leucogranites might have experienced only high-pressure (HP) rather than UHP metamorphism. Furthermore, steep HREE patterns of the inherited metamorphic zircons, plus very low bulk REE contents and Sr–Nd–Pb isotopic characteristics, suggest that the leucogranites were most likely derived from partial melting of subducted felsic gneiss rather than basaltic eclogite in Dabie–Sulu orogen, with residual allanite in the source. Their low Rb, high Sr contents and low Rb/Sr ratios suggest that the metaluminous leucogranites are derived from mica-poor orthogneiss. Melting temperature for the leucogranites is about 700–710 °C as estimated using combined Ti-in-zircon and zirconium saturation thermometries. Inherited metamorphic zircons yielded metamorphic Ti-in-zircon temperature of 681 ± 60 °C, representing that for protolith-forming, which shows no significant difference from the melting temperature. H2O-present melting is thus required to generate the low-temperature melt. Sedimentary facies analysis of the Jurassic strata in the Hefei basin suggests that the Sulu orogen had been northward moved to the east of the Bengbu uplift by the Tan–Lu Fault in the Late Jurassic, resulting into a contrasting topography in this area and lateral pressure gradient in the local middle-lower crust. This lateral pressure gradient may drive the partially molten crust (migmatite) in Sulu orogen westward flow into the middle-lower crust of the Bengbu uplift in NCB. Gravity then drove melt to ascent into the middle-upper crust of the Bengbu uplift to form the leucogranitic intrusions. The NWW–SEE distribution of the later Jurassic leucogranites in Bengbu uplift may indicate the direction of ancient channel flow.
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DOI：
10.1360/03yd0045
发表时间：
2005
期刊：
Science in China Series D: Earth Sciences
影响因子：
--
作者：
Wenliang Xu;Qing-hai Wang;De‐Bin Yang;Xiaochun Liu;Jing-hui Guo
通讯作者：
Wenliang Xu;Qing-hai Wang;De‐Bin Yang;Xiaochun Liu;Jing-hui Guo
DOI：
10.1007/bf02875393
发表时间：
2001-11
期刊：
Science in China Series D: Earth Sciences
影响因子：
--
作者：
Guang Zhu;Chuanzhong Song;Daoxuan Wang;Guosheng Liu;Jiawei Xu
通讯作者：
Guang Zhu;Chuanzhong Song;Daoxuan Wang;Guosheng Liu;Jiawei Xu
影响因子：
64.8
作者：
Jin-lu Lin;Michael D Fuller;Wen-you Zhang
通讯作者：
Jin-lu Lin;Michael D Fuller;Wen-you Zhang
影响因子：
3.9
作者：
V. Chavagnac;B. Jahn
通讯作者：
V. Chavagnac;B. Jahn
影响因子：
3.5
作者：
D. Rubatto;J. Hermann;A. Berger;M. Engi
通讯作者：
D. Rubatto;J. Hermann;A. Berger;M. Engi