本文選題：帕米爾 + 穆爾尕布巖體��； 參考：《中國(guó)地質(zhì)》2017年04期

【摘要】：穆爾尕布巖體位于塔吉克斯坦帕米爾地區(qū)中部,中帕米爾和南帕米爾之間的Rushan-Pshart縫合帶中,巖石類型主要由輝長(zhǎng)巖和少量閃長(zhǎng)巖組成,呈巖株?duì)钋秩胗谛略糯??)薩雷吉爾加組淺變質(zhì)碎屑巖中。根據(jù)LA-ICPMS鋯石U-Pb定年結(jié)果,穆爾尕布巖體中輝長(zhǎng)巖的年齡為(232.0±1.5)Ma,閃長(zhǎng)巖的年齡為(231.5±1.9)Ma,兩者在誤差范圍內(nèi)一致,代表了該巖體的形成時(shí)代。輝長(zhǎng)巖和閃長(zhǎng)巖中鋯石的εHf(t)值變化范圍分別為4.8~12.1、6.4~10,加權(quán)平均值為8.1±1.5(MSWD=6.5)和7.9±0.8(MSWD=2.4),顯示其原巖來源于地幔物質(zhì),其單階段Hf模式年齡TDM1分別為477~621 Ma,391~672 Ma,指示其原巖為寒武紀(jì)—前寒武紀(jì)基底。巖石地球化學(xué)研究表明,輝長(zhǎng)巖類具有貧堿、低Al、富Mg特征,屬于低鉀(拉斑)系列,閃長(zhǎng)巖類則顯示富Si、Al,貧Mg、低Ti的特征,屬于鈣堿性-高鉀鈣堿性系列;兩者的稀土和微量元素特征相似,稀土總量高,呈輕稀土富集的右傾型配分型式,無Eu異常或輕微正Eu異常,微量元素富集大離子親石元素,虧損高場(chǎng)強(qiáng)元素,指示穆爾尕布巖體可能形成于島弧環(huán)境。綜合區(qū)域地質(zhì)資料,認(rèn)為在晚三疊世Rushan洋陸俯沖尚未結(jié)束,表明洋盆閉合時(shí)限晚于232 Ma。
[Abstract]:The Murgarab body is located in the Rushan-Pshart suture zone between the Middle Pamir and the South Pamir in Tajikistan. The rock type is mainly composed of gabbro and a small amount of diorite, which intruded into the Neoproterozoic in the form of a rock plant. In the shallow metamorphic clastic rocks of the Sarejilga formation. According to the LA-ICPMS zircon U-Pb dating results, the ages of gabbro and diorite are 232.0 鹵1.5Maand 231.5 鹵1.9Ma. both of them are consistent within the error range and represent the age of formation of the body. The variation range of zircon 蔚 Hfft in gabbro and diorite is 4.812.1 / 6.4kW (weighted average 8.1 鹵1.5 MSWDU 6.5) and 7.9 鹵0.8MSWDU (2.4g), respectively, indicating that the source rocks originated from mantle material, and their single-stage HF model age TDM1 is 4777221 Ma391M 672 Ma, indicating that the protects are Cambrian-Precambrian basement. The results show that the zircon is derived from mantle material and its age of one-stage HF model is 4770.21 Ma-391mg / 672 Ma., indicating that the source rocks are Cambrian-Precambrian basement. The petrogeochemical study shows that gabbro is characterized by alkali-poor, low-Al-rich and Mg-rich, and belongs to low-K series, while diorite is characterized by rich Si-Al, poor Mgand low Ti, and belongs to calc-alkaline-high-potassium calc-alkaline series. Their rare earth elements and trace elements are similar, the total amount of rare earths is high, and they are in the right dip pattern of light rare earth enrichment. There is no EU anomaly or slight positive EU anomaly, and trace elements are enriched in large ion lithophile elements and depleted in high field strength elements. It indicates that the Murgarab rock may be formed in the island arc environment. Based on the regional geological data, it is considered that the Rushan oceanic subduction was not over in the late Triassic, indicating that the closure time of the oceanic basin was later than 232 Ma.
【作者單位】： 中國(guó)地質(zhì)科學(xué)院;中國(guó)地質(zhì)調(diào)查局西安地質(zhì)調(diào)查中心;
【基金】：中國(guó)地質(zhì)調(diào)查局項(xiàng)目(121201112036、12120114018601)資助~~
【分類號(hào)】：P588.12

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