论文部分内容阅读
本文根据作者近些年来对中国北方中生代富碱侵入岩钕、锶、铅同位素研究并结合前人工作得出 :在华北地台区富碱侵入岩的εNd(t)均为负值 ;而兴蒙地槽区的εNd(t)则全为正值εNd(t) εSr(t)图解上 ,前者投影点主要落在了富集地幔演化趋势线附近 ,而后者投影点主要落在了亏损地幔演化线附近。在地球不同区域铅模式图上 ,地台区钾长石铅投影点大部落在了地幔演化线附近 ,而地槽区的则落在了地幔与造山带演化线之间。以上事实说明华北地台区富碱侵入岩的物质来源与富集地幔关系密切 ,而地槽区的则与亏损地幔关系密切。同时也揭示出中生代华北地台区上地幔具有富集性 ,而兴蒙地槽区上地幔则具亏损性。
According to the authors ’recent studies on the neodymium, strontium and lead isotopes of Mesozoic alkali-rich intrusive rocks in northern China and their predecessors’ work, it is concluded that the εNd (t) of alkaline-rich intrusive rocks in the North Taiwan Platform are all negative. The εNd (t) of the monsoon region is all positive for εNd (t) εSr (t). The projection points of the former mainly fall near the evolution trend line of enriched mantle while the latter projection points mainly fall into the depleted mantle Near the evolution line. In the lead pattern maps of different regions of the earth, most of the potash feldspar projection points in the platform area are near the mantle evolution line, while the terrain area falls between the mantle and the orogenic belt evolution line. The above facts show that the source of the alkali-rich intrusive rocks in the North China platform area is closely related to the enrichment of the mantle while that in the terrain area is closely related to the depleted mantle. At the same time, it is also revealed that the upper mantle in the Mesozoic North China platform area is enriched, while the upper mantle in Xingmengdian area is deficient.