粤北早古生代强过铝质花岗岩及其共生岩石的岩石成因及对广西运动的指示意义:来自元素和Sr-Nd-Hf同位素的制约
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中国地质调查局武汉地质调查中心

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National Natural Science Foundation of China (NSFC Project 41302046), China Geological Survey Project (No. 12120113063600 and DD20190047)


Petrogenesis and tectonic implications of the Kwangsian orogen: Constrains from geochemical and Sr–Nd–Hf isotopic compositions of the early Paleozoic peraluminous granites and coexisting rocks in Northern Guangdong, SE China
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1.China Geological Survey, Wuhan Center of Geological Survey;2.aChina Geological Survey, Wuhan Center of Geological Survey

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    摘要:

    本文系统报道了粤北地区早古生代强过铝质花岗岩及其共生岩石的锆石U-Pb年代学、主、微量元素及Sr-Nd-Hf同位素组成,探讨其源区特征、岩石成因及构造意义。青州花岗闪长岩为弱-强过铝质,A/CNK= 1.05–1.96。它们具有相对高的初始Sr同位素组成ISr= 0.7087– 0.7148和低的εNd(t)值(-11.2 – -10.1),以及变化的εHf(t)值-13.4– +4.81。与之不同,大帽山花岗闪长岩为准铝质(A/CNK= 0.79– 0.94),ISr= 0.7083– 0.7110, εNd(t)= -7.92– -5.28和εHf(t)= -8.69– -2.06。高寿石英闪长岩为准铝-强过铝质(0.87– 1.24),ISr值和εNd(t)值分别为0.7104– 0.7111和-9.64– -8.63。元素和Sr-Nd-Hf同位素组成结果显示,青州、大帽山和高寿花岗质侵入岩主要分别源自变杂砂岩、英安质岩和角闪石岩的部分熔融。结合前人的研究成果,这些强过铝质花岗岩形成于同造山环境。本文尝试提出一种关于华南早古生代花岗岩的岩石成因及区域地壳重组的新思路。而广西运动动力机制的揭示需要更加广阔的视野和更加丰富的地质证据。

    Abstract:

    This paper presents whole–rock major and trace elemental and Sr–Nd–Hf isotopic compositions, and zircon U–Pb geochronological data of the peraluminous granitic intrusion and coexisting granitiod rocks in the northern Guangdong province, South China, in order to investigate their source composition, petrogenesis and tectonic implications. The Qingzhou granodiorites are weakly to strongly peraluminous, with A/CNK values of 1.05–1.96. They have relatively high initial 87Sr/86Sr ratios (ISr= 0.7087– 0.7148), low εNd(t) values (-11.2 to -10.1), and varied zircon εHf(t) values of -13.4 to +4.81. By contrast, the Damaoshan granodiorites are metaluminous (A/CNK= 0.79– 0.94) in composition, with ISr values of 0.7083 to 0.7110, εNd(t) values of -7.92 to -5.28 and zircon εHf(t) values of -8.69 to -2.06. The Gaoshou quartz diorites are metaluminous–peraluminous with A/CNK of 0.87– 1.24. Their ISr values rang from 0.7104 to 0.7111 and εNd(t) values from -9.64 to -8.63. Geochemical data and Sr–Nd–Hf isotope compositions indicate that the Qingzhou, Damaoshan and Gaoshou intrusions are mainly derived from partial melting of metagreywackes, tonalitic rocks and amphibolites, respectively. Combined with the previous studies, these prealuminous granites formed in syn–orogen compression environment. In this paper, we test to provide a new way of thinking for the petrogenesis of the early Paleozoic granites in South China Block, and the regional crust restructure. A broader vision and more geological evidences are required to reveal the triggering factor of the Kwangsian orogen.

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  • 收稿日期:2021-01-15
  • 最后修改日期:2021-04-28
  • 录用日期:2021-05-04
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