Generation of leucogranites via fractional crystallization: A case study of the Jurassic Bengbu granite in the southeastern North China Craton
Generation of leucogranites via fractional crystallization: A case study of the Jurassic Bengbu granite in the southeastern North China Craton
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分异结晶生成淡色花岗岩——以华北克拉通东南部侏罗系蚌埠花岗岩为例
DOI：
10.1016/j.lithos.2019.105271
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发表时间：
2020
期刊：
影响因子：
3.5
通讯作者：
Zhang Ding-Yuan
中科院分区：
文献类型：
--
作者：
Li Chao;Yan Jun;Yang Chao;Song Chuan-Zhong;Wang Ai-Guo;Zhang Ding-Yuan
形成浅色花岗岩的岩浆作用与板块碰撞密切相关。淡色花岗岩作为地壳深熔作用的产物，为壳内分异和区域构造演化提供了线索。蚌埠地区位于北中国克拉通东南缘，大别造山带以北150 公里处，东界为潭城-庐江断裂带。蚌埠地区广泛分布晚侏罗世浅色花岗岩。采集了蚌埠浅色花岗岩(BLG)的岩石样品，分析了全岩地球化学、锆石U-Pb年代学、锆石Lu-Hf同位素、石英石Sito同位素和总的锶-钕-铅同位素数据。锆石U-Pb定年获得了这些浅色花岗岩的形成年龄为∼160 Ma。样品具有较高的SiO_2(72.4 wt.%−76.9 wt.%)、碱(7.3 wt.%−9.4 wt.%)和Al_2O_3(13.4 wt.%−15.5 wt.%)含量。除了两个具有稀土元素四元组效应的样品外，所有岩石都具有高的分异指数(95-99)，极低的铁-镁-钛氧化物含量(总铁镁钛含量为1.4wt%， 为0.3 wt.%， 为0.2wt.%， 为0.2wt.%)，低的Zr/Hf(20-50)和Nb/Ta(5-25)比值。这些数据表明，BLG是一种高分馏的花岗岩。此外，样品还含有新元古代和三叠纪的锆石，具有低的钛锆石温度(682697 °C)，低的Rb含量(<；高丰度，高锶(48-791ppm)，低Rb/Sr比值，低放射性成因铅同位素组成(206Pb/204Pb(T) = 17.169-17.297)，高丰度的锶-钕-氢同位素组成(87Sr/86Sr(T) = 0.7082-0.7104，εND(T) = −16.6~−12.3，锆石εHf(T) = −14.5~−21.7)。综合年代学和地球化学研究结果，认为北大别花岗片麻岩是由三叠纪大陆俯冲俯冲到蚌埠地区之下的北大别花岗片麻岩经水合部分熔融后发生高度分离结晶形成的。南中国地块与北海陆块碰撞后，东海陆块中的晚侏罗世花岗岩类，包括北海陆块在内，形成于造山后的伸展环境，并受到印支板块持续俯冲和退缩的影响。
The magmatic processes that form leucogranites are closely related to plate collision. As the products of crustal anatexis, leucogranites provide clues to intracrustal differentiation and the regional tectonic evolution. The Bengbu area is located along the southeastern margin of the North China Craton (NCC), 150 km north of the Dabie Orogen, and is bounded by the Tancheng–Lujiang Fault Zone to the east. Late Jurassic leucogranites are widely distributed in the Bengbu area. We collected samples of the Bengbu leucogranite (BLG) and analyzed data on whole-rock geochemistry, zircon U–Pb geochronology, zirconin situLu–Hf isotopes, quartzin situO isotopes, and total bulk Sr–Nd–Pb isotopes. Zircon U–Pb dating yielded formation ages for these leucogranites of ∼160 Ma. The samples are characterized by high SiO2(72.4 wt.%−76.9 wt.%), alkali (7.3 wt.%−9.4 wt.%), and Al2O3(13.4 wt.%−15.5 wt.%) contents. In addition to two samples exhibiting the rare-earth element tetrad effect, all rocks have high differentiation index values (95–99), extremely low iron–magnesium–titanium oxide contents (total Fe2O3< 1.4 wt.%, MgO < 0.3 wt.%, TiO2< 0.2 wt.%), and low Zr/Hf (20–50) and Nb/Ta (5–25) ratios. These data suggest that the BLG is a highly fractionated granite. Furthermore, the samples contain Neoproterozoic and Triassic zircons, have low Ti-in-zircon temperatures (682–697 °C), low Rb contents (<192 ppm), high Sr contents (48–791 ppm), low Rb/Sr ratios, low radiogenic Pb isotopic compositions (206Pb/204Pb(t) = 17.169–17.297), and highly enriched Sr–Nd–Hf isotopic compositions (87Sr/86Sr(t) = 0.7082–0.7104,εNd(t) = −16.6 to −12.3, and zirconεHf(t) = −14.5 to −21.7). Taken together, the geochronological and geochemical results suggest that the BLG was formed by high-degree fractional crystallization after hydrous partial melting of the North Dabie granitic gneisses, which have been subducted beneath the Bengbu area by Triassic continental subduction. Following collision between the South China Block and the NCC, Late Jurassic granitoids in the eastern NCC, including the BLG, were generated in the resulting post-orogenic extensional environment and were also influenced by ongoing subduction and rollback of the Izanagi Plate.
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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
影响因子：
6.1
作者：
Li S.G., Wang S.J., Guo S.S., Xiao Y.L., Liu Y.C.
通讯作者：
Li S.G., Wang S.J., Guo S.S., Xiao Y.L., Liu Y.C.
影响因子：
3.9
作者：
Jin-Hui Yang;Sun‐Lin Chung;S. Wilde;Fu-Yuan Wu;M. Chu;C. Lo;H. Fan
通讯作者：
Jin-Hui Yang;Sun‐Lin Chung;S. Wilde;Fu-Yuan Wu;M. Chu;C. Lo;H. Fan
影响因子：
56.9
作者：
E. Scherer;C. Münker;K. Mezger
通讯作者：
E. Scherer;C. Münker;K. Mezger
影响因子：
3.5
作者：
Chaohui Liu;Guochun Zhao;Fulai Liu;Jia Cai
通讯作者：
Chaohui Liu;Guochun Zhao;Fulai Liu;Jia Cai
DOI：
--
发表时间：
1986
期刊：
--
影响因子：
--
作者：
J. D. Cr-nlrnNs
通讯作者：
J. D. Cr-nlrnNs