本文選題：A型花崗巖 + 高溫低壓環(huán)境��； 參考：《中國地質(zhì)》2017年01期

【摘要】：文章對(duì)內(nèi)蒙古邊家大院鉛鋅銀多金屬礦床深部正長花崗巖進(jìn)行了LA-ICP-MS鋯石U-Pb同位素測(cè)年,并對(duì)花崗巖的主量元素、微量元素和Sr-Nd同位素組成做了分析研究。結(jié)果顯示,邊家大院正長花崗巖加權(quán)平均年齡為(140.31±0.34)Ma,為大興安嶺南段早白堊世巖漿活動(dòng)集中期產(chǎn)物;研究區(qū)至少有兩期巖漿活動(dòng),早期酸性巖漿侵位,約10 Ma后中基性巖漿侵位,成巖與成礦同期進(jìn)行�；◢弾r地球化學(xué)特征具有高Si O2、K2O,低Mg O、Ca O、Ti O2的主量元素特征,A/CNK在0.98~1.19,屬于準(zhǔn)鋁-弱過鋁系列;富集Rb、Th、U、K等大離子親石元素(LILE),虧損Sr、P、Ti等高場(chǎng)強(qiáng)元素(HFSE);稀土總量ΣREE較大,δEu為0.12~0.14,強(qiáng)烈Eu負(fù)異常;(87Sr/86Sr)i和(143Nd/144Nd)i初始比值,分別介于0.7066~0.7077和0.5121~0.5122(t=140 Ma),εNd(t)為-5.0‰~-6.6‰,成巖物質(zhì)來自于中元古界下地殼鐵鎂質(zhì)源巖的部分熔融。研究表明邊家大院正長花崗巖是在早白堊世受到了蒙古—鄂霍次克海"剪刀式"閉合造山后的伸展條件和巖石圈減薄作用的影響,形成于高溫低壓環(huán)境的A型花崗巖。高溫低壓環(huán)境還可能與該區(qū)域巖石圈發(fā)生拆沉作用有關(guān)。
[Abstract]:In this paper, the LA-ICP-MS zircon U-Pb isotopic dating of the deep syenite in the Banjiayuan lead-zinc-silver polymetallic deposit, Inner Mongolia, has been carried out, and the main elements, trace elements and Sr-Nd isotopic compositions of the granite have been analyzed and studied. The results show that the weighted mean age of syenite is 140.31 鹵0.34 Ma, which is the product of early Cretaceous magmatic activity in the southern part of Daxinganling, and there are at least two periods of magmatic activity in the study area, the early acidic magma emplacement, and the middle basic magma emplacement after about 10 Ma. Diagenesis and mineralization take place at the same time. The geochemical characteristics of granites are characterized by high Sio _ 2 K _ 2O and low mg _ 2O _ (Ca) O _ (2) O _ (2) O _ (2). It is rich in large ion lithophile elements, such as RbBX, Th, U, K, and depleted in high field strength elements, such as SRP Pu Ti, the total amount of rare earth 危 REE is larger, 未 EU is 0.12U 0.14, and the initial ratios of strong negative EU anomalies, such as 87Srrr / 86Srti and 143NdP / 144NdI, are between -5.0 鈥，

本文編號(hào)：1817601