摘要
系统研究了河北汉诺坝玄武岩中二辉麻粒岩和辉石岩捕虏体的Sr、Nd、Pb同位素特征。虽然未确定捕虏体的形成时代,但同位素特征显示它们可能为较近期(中生代以来)形成。低的Rb/Sr与高的87Sr/86Sr比值的解耦表明捕虏体的形成经历了较强的混合作用。在二元同位素相关图上,三类具不同矿物组成的辉石岩与二辉麻粒岩有密切关系,即二辉麻粒岩投点位置是三类辉石岩的共同端点。综合考虑捕虏体的空间分布及其在Sr、Nd、Pb同位素协变图上的关系,可以认为层离作用可较好地解释这些现象。
RbSr, SmNd and Pb isotopic systematics are reported for granulite and pyroxenite xenoliths in Hannuoba basalts, Hebei Province. The isotopic characteristics of xenoliths suggest that they might have formed recently, although there is no strict constraint on the precise age. The decoupling of low Rb/Sr and high 87Sr/86Sr ratios implies the multistage evolution history and strong mixing processes. There are close ties between granulite and pyroxenites with different mineral assemblages on the SrNd, PbSr and PbNd correlation figures. The granulite is the common endmember of the three kinds of pyroxenite. Combined with the distribution of the xenoliths in space and their isotopic relationships, It is proposed that delamination can be well used to explain the ties.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1998年第2期190-197,共8页
Acta Petrologica Sinica
基金
国家自然科学基金
关键词
玄武岩
麻粒岩类
辉石岩类
捕虏体
锶同位素
Delamination
Mixing
Sr
Nd and Pb isotopes
Granulite xenolith
Pyroxenite xenolith