本文選題：鋯石U-Pb年齡　切入點：古特提斯洋　出處：《地球化學(xué)》2017年01期

【摘要】：大紅柳灘花崗巖體位于康西瓦構(gòu)造帶南側(cè),甜水海地體的北部,是三十里營房-奇臺達(dá)坂花崗巖帶的主要巖體之一。該巖體具有明顯的巖相分帶,其東部-東北部為二長花崗巖,而西南部則為二云母花崗巖。本文對西南部二云母花崗巖進(jìn)行了巖石學(xué)、元素和同位素地球化學(xué)及同位素年代學(xué)綜合研究,同時對二長花崗巖進(jìn)行了元素地球化學(xué)研究。二云母花崗巖明顯富SiO_2、Al_2O_3和K_2O,貧MgO、CaO和TiO_2,屬于高鉀鈣堿性系列巖石;二云母花崗巖的鋯石LA-ICPMS U-Pb年齡為(209.6±1.5)Ma,與東部二長花崗巖年齡一致,表明兩者是同一構(gòu)造事件的產(chǎn)物。二云母花崗巖稀土總量低(∑REE 56.0~66.1μg/g),強(qiáng)烈虧損重稀土元素,Eu負(fù)異常不明顯(δEu為0.81~0.98),低Y(~7μg/g)和Yb(~0.5μg/g),Sr/Y比值較高(~20),Nb、Ta和Ti含量低,Nb/Ta比值高(21~23),表明其源區(qū)有石榴子石和金紅石殘留,說明二云母花崗巖形成壓力可能為1~1.5 GPa,是殼源物質(zhì)部分熔融形成。研究顯示,大紅柳灘花崗巖形成于古特提斯洋閉合之后的同碰撞過程,是甜水海地體和西昆侖地體碰撞造山作用的產(chǎn)物,西昆侖造山帶東部的古特提斯洋閉合以及碰撞造山時代可能晚于該造山帶的中部和西部。
[Abstract]:The Dahongliutan granite body is located in the southern side of the Kangxiwa tectonic belt and the northern part of the sweet water Haitian body. It is one of the main rock masses in the 30-li barracks-Qidaidaban granite belt.The rock body has obvious lithofacies zonation, its east-northeast is monzonitic, and southwestern is dimica granite.In this paper, the petrology, element and isotope geochemistry and isotopic chronology of the monomorphite granites in the southwest of China are studied. At the same time, the elemental geochemistry of the monzogranites is also studied.The dimica granite is obviously rich in SiO-Sh _ 2Al _ 2O _ 3 and K _ 2O, MgO _ 2O _ (Cao) and Tio _ (2), belonging to the high-potassium calc-alkaline series rocks, and the zircon LA-ICPMS U-Pb age of the dimica granite is 209.6 鹵1.5 Ma, which is consistent with that of the eastern monzogranite, indicating that the two rocks are the product of the same tectonic event.The amount of rare earth elements is low (鈭，

本文編號：1724363