扬子地块东段大陆岩石圈地幔的物质成分  

COMPOSITIONS OF CONTINENTAL LITHOSPHERIC MANTLE UNDER EASTERN YANGTZE BLOCK

作　　者：支霞臣[1] 陈道公[1] 周海涛[1] 李彬贤[1] 杨瑞瑛[1] 

机构地区：[1]中国科技大学地球和空间科学系,中国科学院高能物理研究所

出　　处：《大地构造与成矿学》1995年第1期17-34,共18页Geotectonica et Metallogenia

基　　金：国家自然科学基金

摘　　要：根据苏皖地区新生代碱性玄武岩中的尖晶石二辉橄榄岩包体的化学成分，讨论了扬子地块东段大陆岩石圈地幔的物质成分。以包体的平均成分代表该区岩石圈地幔的平均成分，依照地幔地球化学演化趋势，估计了该区岩石圈地幔的原始组成。采用最近提出的二辉石地质温度计，计算了包体的平衡温度，讨论了该区岩石圈地幔物质成分在垂向上的分布和变化，上地幔橄榄岩中的玄武质组分在垂向上由上而下亏损程度逐渐减小。包体中稀土元素丰度模式反映了该区岩石圈地幔演化的多阶段性。除了程度不同的部分熔融作用外，局部地段曾有隐性地幔交代作用发生，造成了地幔橄榄岩中主量成分和稀土元素的解耦现象。The compositions of continental lithospheric mantle(CLM) under Eastern Yangtze Block(EYB)are discussed here based on the compositions of spinel lherzolite xenoliths contained in Cenozoic alkalic basalts distributed over Jiangsu-Anhui area .The average and primary compositions of CLM under EYB are calculated and deduced by the compositions and geochemical evolution of peridotite xenoliths respectively. The equilibrium temperature for the noduels determined by new two-pyroxene geothermometer developed recently. The depletion degree of basaltic components in CLM under EYB are decreasing vertically from upper to lower.The decoupling between major compositions and REE abundances for the peridotite inclusions are interpreted by the multistage geochemical evolution of CLM under EYB.

关 键 词：扬子地块 岩石圈 大陆 地幔 化学成分 

分 类 号：P31[天文地球—固体地球物理学] P591[天文地球—地球物理学]