本文選題：混合巖　切入點(diǎn)：巖石類型　出處：《礦物巖石》2017年02期

【摘要】：大別造山帶北大別超高壓變質(zhì)構(gòu)造單元中廣泛發(fā)育混合巖�；趯�(duì)羅田和岳西穹隆中混合巖的野外觀察、巖相學(xué)、礦物化學(xué)和鋯石LA-ICP-MS U-Pb定年系統(tǒng)工作,發(fā)現(xiàn)北大別混合巖主要分為中等深熔混合巖和高度深熔混合巖兩種類型。中等深熔混合巖為疊層狀混合巖和膨脹結(jié)構(gòu)混合巖;高度深熔混合巖為眼球狀混合巖和析離體狀混合巖。鋯石U-Pb同位素定年結(jié)果表明,混合巖中新生鋯石年齡范圍為125 Ma~138 Ma,加權(quán)平均年齡為130.7 Ma±1.8 Ma;兩個(gè)繼承鋯石的年齡分別為602.8 Ma±16.8 Ma和667.3 Ma±17.6 Ma;混合巖疊層狀暗色體中鋯石年齡連續(xù)且分布集中,加權(quán)平均年齡為703 Ma±10 Ma,代表原巖的形成年齡。北大別混合巖的原巖為新元古代的巖石,其混合巖化作用發(fā)生在140 Ma至125 Ma期間。不同淺色體中斜長(zhǎng)石的含量和牌號(hào)差異顯著,反映了淺色體形成于不同演化程度的熔體結(jié)晶。斜長(zhǎng)石-角閃石溫壓計(jì)估算結(jié)果顯示,混合巖形成的溫壓條件為723℃~768℃和370 MPa~520 MPa,對(duì)應(yīng)于中上地殼環(huán)境。混合巖的成因機(jī)制以長(zhǎng)英質(zhì)片麻巖水飽和條件下的富水熔融為主。其反應(yīng)為:黑云母+石英+斜長(zhǎng)石+水=角閃石+斜長(zhǎng)石(殘留)+花崗質(zhì)熔體。少數(shù)混合巖的成因機(jī)制為角閃片麻巖中角閃石的脫水熔融。其反應(yīng)為:角閃石+斜長(zhǎng)石+石英=單斜輝石+富水熔體。
[Abstract]:The migmatite is widely developed in the Dabie ultrahigh pressure metamorphic tectonic unit of the Dabie orogenic belt. Based on the field observation of the migmatite in the Luotian and Yuexi dome, lithofacies, mineralogical chemistry and zircon LA-ICP-MS U-Pb dating system, It is found that the Northern Dabie migmatite is mainly divided into two types: medium deep melt migmatite and high deep melt migmatite. The medium deep melt migmatite is composed of laminated migmatite and expansive structure migmatite. The highly submersible migmatite is an eyeball migmatite and an isolated migmatite. The zircon U-Pb isotopic dating results show that, The age range of new zircon in the migmatite is 125 Ma~138 Ma, the weighted mean age is 130.7 Ma 鹵1.8 Ma, the ages of two inherited zircons are 602.8 Ma 鹵16.8Ma and 667.3 Ma 鹵17.6Ma.The zircon ages in the laminated dark bodies of the migmatite are continuous and concentrated. The weighted mean age is 703 Ma 鹵10 Ma, which represents the age of formation of the original rocks. The protolith of the Beidabie migmatite is a Neoproterozoic rock, and its migmatization occurred between 140 Ma and 125 Ma. The contents and grades of plagioclase in different light-colored bodies vary significantly. The results of temperature and pressure estimation of plagioclase and hornblende indicate that, The temperature and pressure conditions of the migmatite formation are 723 鈩，

本文編號(hào)：1662931