本文選題：大埔?guī)r體 + 鋯石��； 參考：《地質(zhì)科技情報》2017年06期

【摘要】：大埔?guī)r體位于粵東北地區(qū),呈北東向的大巖基出露,出露面積約2 000km~2,主體巖性為中粒斑狀黑云母二長花崗巖。對大埔?guī)r體花崗巖巖石樣品進行了LA-ICP-MS鋯石U-Pb同位素測年,得到其結(jié)晶年齡為(143.8±1.5)~(139.2±1.1)Ma,屬于晚中生代早白堊世,為燕山期巖漿活動的產(chǎn)物。巖體w(Al2O3)在11.98%~14.18%之間,A/CNK為1.01~1.15,AKI在0.77~0.89之間,里特曼指數(shù)σ為1.72~2.7,Rb/Sr比值為1.32~8.05(平均為4.19),Nb/Ta比值為6.45~12.99。巖石具中等-強的δEu負異常,稀土元素配分模式為海鷗型。結(jié)合區(qū)域構(gòu)造背景及巖石地球化學(xué)分析認為,大埔?guī)r體侵位結(jié)晶與區(qū)域上太平洋板塊的俯沖后期巖石圈大面積伸展減薄、地幔物質(zhì)上涌、形成大規(guī)模巖漿活動有關(guān),形成于碰撞后的伸展構(gòu)造環(huán)境。
[Abstract]:The Tai Po rock body is located in the northeast of Guangdong Province. It is a large rock base with an area of about 2 000 km / m ~ 2, and the main lithology is a mesomorphic porphyry biotite monzogranite. The LA-ICP-MS zircon U-Pb isotopic dating of granite samples from the Tai Po rock mass has been carried out. The crystallization age is 139.2 鹵1.1 MaA, which belongs to the late Mesozoic early Cretaceous and is the product of Yanshanian magmatism. In the range of 11.98% to 14.18%, the ratio of A- / CNK is 1.01 / 1.15A = 0.77 / 0.89 and the Rtman index 蟽 is 1.72 / 2.7N / r / Sr = 1.32 / 8.05 (the average value is 4.19 / nb / Ta = 6.4512.99). The rocks have moderate to strong 未 EU negative anomalies and the REE distribution model is seagull type. Combined with regional tectonic setting and petrogeochemical analysis, it is concluded that the emplacement crystallization of the Tai Po rock mass is related to the large area extension and thinning of lithosphere in the late subduction of the upper Pacific plate, the upwelling of mantle material, and the formation of large-scale magmatic activity. Formed in the post-collision extensional tectonic environment.
【作者單位】： 廣東省地質(zhì)調(diào)查院;
【基金】：中國地質(zhì)調(diào)查局項目“廣東1∶5萬明山嶂煤礦、高陂圩、砂田圩、潭江圩四幅區(qū)域地質(zhì)礦產(chǎn)調(diào)查”(1212011220554);“廣東1∶5萬豐順縣、坪上、五經(jīng)富、揭陽縣幅區(qū)域地質(zhì)調(diào)查子項目”(DD20160032-18)
【分類號】：P588.1;P59

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