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首页> 外文期刊>Journal of Asian earth sciences >Crust-mantle interaction during subduction zone processes: Insight from late Mesozoic Ⅰ-type granites in eastern Guangdong, SE China
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Crust-mantle interaction during subduction zone processes: Insight from late Mesozoic Ⅰ-type granites in eastern Guangdong, SE China

机译：俯冲带过程中的地幔相互作用：广东东部东部中生代Ⅰ型晚花岗岩的观察

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摘要

Zircon U-Pb dating and in-situ Hf-O isotopic compositions, combined with whole-rock geochemical and Sr-Nd isotope data, are systematically presented to constrain the timing and petrogenesis of the late Mesozoic granitoids in eastern Guangdong Province, SE China. Zircon U-Pb chronology shows that two intrusions were emplaced from the Middle Jurassic to Early Cretaceous (166-144 Ma). All the granitoids are classified as calcalkaline I-type granites with highly diverse elemental and isotopic compositions. The systematic variations in zircon Hf-O isotopes show that the granites can be categorized into three groups. The Donggang granitic porphyries (166 Ma) have the highest zircon delta O-18 values of 6.3-8.2%o (average of 7.7 parts per thousand) but the lowest epsilon(Hf)(t) values of - 8.0 to -1.4, with the oldest Hf model ages of 1.30-1.70 Ga. The Liuzhoushan monzogranites (144 Ma) have intermediate zircon delta O-18 values of 6.0-6.9%o (average of 6.4 parts per thousand) and epsilon(Hf)(t) values of - 5.0 to 0.3, with Hf model ages of 1.17-1.51 Ga. The late Early Cretaceous granitoids have the lowest delta O-18 values of 4.9-6.696o (average of 5.5 parts per thousand) but the highest epsilon(Hf)(t) values of - 3.2 to 3.3, with the youngest Hf model ages of 0.95-1.36 Ga. Zircon saturation temperatures of the Donggang, Liuzhoushan, and Xinwei (Sanrao) intrusions are calculated to be 642 degrees C, 722 degrees C, and 748 degrees C, respectively. Together with the variations in Sr-Nd isotopes, it appears that these granitoids were derived from the mixing of different proportions of mantle-derived components with Paleoproterozoic basement crust-derived magmas. The underplating of mantle-derived magmas into the continental crust, which supplied both heat and material contribution, was likely responsible for the generation of the most late Mesozoic I-type granites in eastern Guangdong. From Middle Jurassic to late Early Cretaceous, the increasing epsilon(Hf)(t) and epsilon(Nd)(t) values as well as the decreasing delta O-18 values and T(DM)2 ages indicate a progressive role of the crust-mantle interaction, corresponding to a gradually enhanced extensional tectonic environment. The northeast (NE)-ward younging trend and the enhanced crust-mantle interaction along coastal SE China were probably induced by the changing direction of the subducted plate from oblique to parallel to the continental margin.
机译：结合整个岩石地球化学和Sr-Nd同位素数据，系统地提出了锆石U-Pb测年和原位Hf-O同位素组成，以约束中国广东省东部东部晚中生代花岗岩的形成时间和成岩作用。锆石U-Pb年表显示，从侏罗纪中期到白垩纪早期（166-144 Ma）发生了两次侵入。所有的类花岗岩都被归为钙盐型I型花岗岩，其元素和同位素组成各不相同。锆石Hf-O同位素的系统变化表明，花岗岩可分为三类。东港花岗斑岩（166 Ma）的锆石三角洲O-18值最高，为6.3-8.2％o（平均7.7千分之一），但最低的epsilon（Hf）（t）值为-8.0至-1.4，其中最老的Hf模型年龄为1.30-1.70 Ga。柳州山辉长花岗岩（144 Ma）的锆石δO-18中间值为6.0-6.9％o（平均千分之6.4），ε（Hf）（t）值为-5.0到0.3，Hf模型年龄为1.17-1.51 Ga。早白垩纪花岗岩类的O-18值最低，为4.9-6.696o（平均值为千分之5.5），但ε（Hf）（t）最高）的值-3.2至3.3，最年轻的Hf模型年龄为0.95-1.36 Ga。计算得出的东岗，柳州山和新围（三饶）侵入体的锆石饱和温度分别为642摄氏度，722摄氏度和748摄氏度。 C分别。连同Sr-Nd同位素的变化一起，看来这些花岗石是由不同比例的地幔衍生成分与古元古代基底地壳衍生的岩浆混合而成的。来自地幔的岩浆向大陆地壳的下沉既提供热量又提供了物质贡献，这很可能是导致广东东部最晚的中生代I型花岗岩产生的原因。从中侏罗纪到白垩纪晚期，ε（Hf）（t）和ε（Nd）（t）值升高，δO-18值和T（DM）2年龄降低，表明地壳起着渐进作用。 -地幔相互作用，对应于逐渐增强的伸展构造环境。俯冲板块的方向从倾斜向平行于大陆边缘的变化可能是东北东南向年轻化的趋势以及沿中国东南沿海地壳-地幔相互作用的增强。

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  • 来源
    《Journal of Asian earth sciences》 |2020年第may1期|104284.1-104284.18|共18页
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  • 作者单位

    Chinese Acad Sci Inst Geol & Geophys State Key Lab Lithospher Evolut Beijing 100029 Peoples R China;

    Chinese Acad Geol Sci MLR Key Lab Metallogeny & Mineral Assessment Inst Mineral Resources Beijing 100037 Peoples R China;

    ChangAn Univ Sch Earth Sci & Resources Xian 710054 Peoples R China;

    Cent South Univ Sch Geosci & Infophys Changsha 410083 Peoples R China;

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  • 正文语种 eng
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  • 关键词

    Hf-O isotope; I-type-granite; Crust-mantle interaction; Eastern Guangdong; SE China;

    机译：Hf-O同位素;I型花岗岩地幔相互作用;粤东中国东南;

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