本文關(guān)鍵詞： 加里東期 桂東南 大村巖體 古龍巖體 LA-ICP-MS鋯石U-Pb定年 Hf同位素 地球化學(xué)　出處：《地質(zhì)通報(bào)》2017年Z1期 　論文類型：期刊論文

【摘要】：大村和古龍巖體產(chǎn)于揚(yáng)子地塊與華夏地塊拼合帶的西南段,對(duì)剖析華南區(qū)域構(gòu)造演化具有重要的地質(zhì)意義。對(duì)大村和古龍巖體的石英閃長(zhǎng)巖樣品進(jìn)行LA-ICP-MS鋯石U-Pb測(cè)年,獲得~(206)Pb/~(238)U年齡加權(quán)平均值分別為438±1Ma和435±2Ma,說(shuō)明2個(gè)巖體均形成于加里東期。大村和古龍巖體具有鈣堿性、準(zhǔn)鋁質(zhì)-過(guò)鋁質(zhì)特征的I型花崗巖。鋯石的ε_(tái)(Hf)(t)值主要集中在0~+4之間,二階段模式年齡(T_(DM2))主要集中在1.15~1.45Ga之間,指示物源主要來(lái)自中元古代新生的基性下地殼物質(zhì)。根據(jù)大村和古龍巖體的地球化學(xué)、Hf同位素組成、巖體發(fā)育暗色微粒包體等特征,結(jié)合區(qū)域地質(zhì)情況,認(rèn)為其是在陸內(nèi)碰撞造山期后伴隨巖石圈局部伸展-減薄,軟流圈高溫地幔物質(zhì)上涌,導(dǎo)致中元古代新生的基性下地殼部分熔融形成的酸性巖漿和幔源巖漿在源區(qū)不同程度的混合形成母巖漿,隨后又經(jīng)歷了一定程度的分異演化最終固結(jié)成巖。
[Abstract]:The Dacun and Gulong pluton occurred in the southwestern section of the Yangtze and Huaxia assemblage zones, which are of great geological significance for the analysis of the regional tectonic evolution in South China. LA-ICP-MS zircon U-Pb dating of quartz diorite samples from the Dacun and Gulong pluton is carried out. The weighted average values of Pb / P / T 238U were 438 鹵1Ma and 435 鹵2Marespectively, indicating that the two intrusions were formed in Caledonian. Dacun and Gulong granites have calc-alkaline and quasi-alumina-peraluminous characteristics. The 蔚 ~ (-1) of zircon is mainly between 0 ~ 4. The main source of indicator material is from the Mesoproterozoic basic lower crustal material. According to the geochemical HF isotopic composition of the Dacun and Gulong rock bodies and the development of dark particle inclusions in the rock mass, and so on, the two-stage model age is mainly between 1.15and 1.45Ga, and the source of the indicator material is mainly from the Mesoproterozoic material of the basic lower crust. Combined with the regional geological conditions, it is considered that it is associated with the local extension and thinning of lithosphere after the intracontinental collision orogenic period, and the high temperature mantle material upwelling in the asthenosphere. The acidic magma and mantle-derived magma formed by partial melting of the Mesoproterozoic basic lower crust formed the mother magma in different degrees in the source region and then underwent a certain degree of differentiation and evolution and finally consolidated diagenesis.
【作者單位】： 廣西壯族自治區(qū)地質(zhì)調(diào)查院;中化地質(zhì)礦山總局廣西地質(zhì)勘查院;廣西遙感中心;
【基金】：中國(guó)地質(zhì)調(diào)查局項(xiàng)目《桂東-粵西成礦帶地質(zhì)礦產(chǎn)調(diào)查》(編號(hào):D20160035)
【分類號(hào)】：P597;P581

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