摘要
长江中下游中生代岩浆岩带称为扬子岩浆岩带。该带岩浆岩属高钾钙碱性岩系和橄榄安粗岩系，其基性端员玄武岩和辉长岩高钾富碱，硅弱不饱和，富集Rb、Ba、Th、K、LREE等强不相容元素，强烈亏损Cr、Ni等强相容元素；REE球粒陨石标准化曲线为右倾型，在La／Sm－La图上排列成一斜线，是地幔不同程度部分熔融为主的产物。基性岩εNd较高，Isr较低，在εNd-Isr图上沿地幔排列及其延长线分布，略向右漂移，显示AFC混合特征，这可能是幔源碱性玄武岩浆同化古老下地壳物质，同时发生分离结晶。铅同位素提供同样的信息。
The Mesozoic magmatic rock belt along the Middle and Lower Reaches of the 0Yangtze River, i.e.the Yangtze magmatic rock belt belongs to high-K calc-alkaline rock series and shoshonitic rock series. Their basic end-members are basalt and gabbro characterized by high alkaline(especially K) contents and weakly Si-unsaturation as well as enrichment of incompatible elements(such as Rb, Ba Th, K and LREE)and strong depletion of compatible elements (such as Cr, Ni,).The chondrite-normalized REE distribution patterns of these rocks show significant LREE enrichment. On the La/ Sm-La diagram, all basic samples plot on an oblique line, indicating that they were the products of partial melting of a mantle source in varying degrees. The basic rocks have higher Nd values and lower Isr ratios which plot roughly along the mantle array and its extension to the crustal side. Such Sr and Nd isotopic characters are interpreted by an AFC process, i.e. the parent mantle-derived alkaline-rich basaltic magma was assimilated by ancient lower crustal component during the fractional crystallization. Ph isotopic data support this interpretation for the genesis of these basic rocks.
出处
《地球化学》
CAS
CSCD
北大核心
1998年第3期258-268,共11页
Geochimica
关键词
基性岩
地球化学
长江中下游
岩浆岩
basic rock, geochemistry, the Middle and Lower Reaches of the Yangtze River
