【摘要】：華夏地塊西段的云開(kāi)地區(qū)出露少量早古生代基性侵入巖,多以小巖株?duì)钋秩肭昂浼o(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(zhǎng)巖和蘇長(zhǎng)輝長(zhǎng)巖。LA-ICP-MS鋯石U-Pb測(cè)年顯示,信宜竹雅和高州石板輝長(zhǎng)巖結(jié)晶年齡約為445Ma。輝長(zhǎng)巖巖石地球化學(xué)以富MgO、CaO,相對(duì)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(chǎng)強(qiáng)元素。鋯石ε_(tái)(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(zhǎng)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(duì)早古生代構(gòu)造運(yùn)動(dòng)的認(rèn)識(shí)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，

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