本文選題：鋯石U-Pb定年 + 形成時(shí)代　； 參考：《地質(zhì)論評(píng)》2017年04期

【摘要】：大紅山群位于揚(yáng)子地臺(tái)西南緣,是該區(qū)域上變質(zhì)級(jí)別相對(duì)較高、形成時(shí)代較老的地層單元。本文以侵位于大紅山群的侵入巖、紅山組頂部的變質(zhì)火山巖樣品為研究對(duì)象,運(yùn)用LA-ICP-MS方法對(duì)侵入巖、變質(zhì)火山巖進(jìn)行鋯石U-Pb定年。石榴黑云鈉長(zhǎng)片巖、變質(zhì)輝長(zhǎng)巖(DFe1406)和石英鈉長(zhǎng)石斑巖中鋯石為巖漿鋯石,3個(gè)樣品的鋯石數(shù)據(jù)點(diǎn)沿諧和線較集中分布,n(~207Pb)/n(~206Pb)年齡為約1.7 Ga到約1.5 Ga。變質(zhì)輝長(zhǎng)巖(DFe1454)中鋯石為變質(zhì)鋯石,n(~207Pb)/n(~206Pb)年齡從約0.8 Ga到約0.7 Ga。結(jié)合已有同位素定年資料,可得出如下結(jié)論:(1)限定了大紅山群中部紅山組的成巖年齡為1673～1643 Ma;(2)獲得了侵位于紅山組變質(zhì)輝長(zhǎng)巖中的變質(zhì)鋯石n(~207Pb)/n(~206Pb)加權(quán)平均年齡為748.9±5.7 Ma,表明大紅山群經(jīng)歷過(guò)約750 Ma前的變質(zhì),確定大紅山群經(jīng)歷850～750Ma的變質(zhì)作用,可能與Rodinia超大陸裂解期巖漿事件有關(guān)。
[Abstract]:The Dahongshan Group is located at the southwest margin of the Yangtze platform and is a relatively high metamorphic stratigraphic unit in this area. In this paper, the intrusive rocks located in the Dahongshan Group and the metamorphic volcanic rocks at the top of the Hongshan formation are studied. The zircon U-Pb dating of the intrusive rocks and metamorphic volcanic rocks is carried out by using LA-ICP-MS method. The zircons in the metamorphic gabbro (DFe1406) and quartz albite porphyry are magmatic zircons. The zircon data points of the three samples are distributed more closely along the harmonic line. The age ranges from 1.7 Ga to about 1.5 Ga in the metamorphic gabbro (DFe1406) and quartz albite porphyry. The zircon in the metamorphic gabbro (DFe1454) is a metamorphic zircon (207Pb / n ~ (?) 206Pb) ages ranging from about 0.8 Ga to about 0.7 Ga. Combined with available isotopic dating data, The following conclusions can be drawn as follows: (1) the diagenetic age of Hongshan formation in the central part of the Dahongshan Group is limited to 1673 ~ 1643 Ma ~ (2) the weighted mean age of zircon nongzhuo 207Pb / nnyn ~ (206) Pb transgression in the metamorphic gabbro of the Hongshan formation is 748.9 鹵5.7Ma. it indicates that the Dahongshan group experienced metamorphism about 750Ma ago. It is concluded that the 850~750Ma metamorphism of the Dahongshan Group may be related to the magmatic events during the Rodinia supercontinent pyrolysis.
【作者單位】： 成都理工大學(xué);
【基金】：中國(guó)地質(zhì)調(diào)查項(xiàng)目(編號(hào):12120113094900)“川滇黔成礦帶基底銅多金屬成礦帶成礦模式及其找礦模型研究”的成果~~
【分類號(hào)】：P597.3

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