發(fā)布時間：2018-09-14 16:14

【摘要】：華夏地塊西段的云開地區(qū)出露少量早古生代基性侵入巖,多以小巖株狀侵入前寒武紀(jì)變質(zhì)地層或與同期片麻狀花崗巖共生,巖石類型主要為輝長巖和蘇長輝長巖。LA-ICP-MS鋯石U-Pb測年顯示,信宜竹雅和高州石板輝長巖結(jié)晶年齡約為445Ma。輝長巖巖石地球化學(xué)以富MgO、CaO,相對貧TiO_2為特征,具有極低的稀土元素總量(∑REE=20.8×10~(-6)~26.6×10~(-6)),輕稀土元素略微富集,虧損Nb、Zr、Ti、P等高場強(qiáng)元素。鋯石ε_(Hf)(t)均為弱的負(fù)值,Hf同位素一階段模式年齡介于1.1~1.4Ga之間,顯示富集地幔源區(qū)特征。構(gòu)造環(huán)境分析表明,輝長巖與火山弧玄武巖相似。綜合前人研究認(rèn)為,華夏地塊早古生代存在一系列具典型弧火山巖特征的基性巖類,這對早古生代構(gòu)造運(yùn)動的認(rèn)識具有重要的限定作用。
[Abstract]:A small amount of early Paleozoic basic intrusive rocks appeared in Yunkai area of the western part of the Huaxia massif, and most of them intruded into the Precambrian metamorphic strata or symbiotic with the corresponding schneismatic granites. The main rock types are gabbro and sulcanite. LA-ICP-MS zircon U-Pb dating shows that the crystallization age of Xinyi Zhuya and Gaozhou slate gabbro is about 445 Ma. The rock geochemistry of gabbro is characterized by rich MgO,CaO, and relatively poor TiO_2, with extremely low REE contents (鈭，

本文編號：2243214