摘要
东秦岭商丹断裂带中松树沟超镁铁质岩体由两类橄榄岩组成。其中,第Ⅱ类橄榄岩的化学成分非常局限,高度富集Co,Cr,Ni,贫乏Ti,V,Cu,Y;亏损不相容元素(K+Na,Al.Sr.Ba.Nd,Ga和REE);稀土元素和同位素特征揭示它代表本区早期地幔分离部分熔融的残余部分,并作为本区元古代洋壳蛇绿岩底部的变质橄榄岩。而第Ⅰ类橄榄岩的岩石化学成分,微量元素和同位素表明,它不与第Ⅱ类橄榄岩同源,属橄榄石堆积晶渣和原生岩浆的混合物,具有洋壳蛇绿岩中堆晶杂岩的性质,两类橄榄岩的成因和演化历史相互独立,通过构造侵位伴生,并共同代表本区元古代洋壳残片。
The paper sums up geochemical characteristics of Songshugou ultramafite which can be divided into two series. The first type of pure peridotite has widely variation range of composition,the evolution of elements suggests that it seems to be a kind of mixture of typical cumulate and primary magma of oceanic ophiolite. On the contrary,the second type of peridotite,which contains metamorphic tectonic fabric,highly depleted incompatible elements(e. g. K+Na,Al.Sr, Ba,Nd,Ga and REE etc. )and strongly enriched relative compatible elements(e. g. Co,Ni,Cr). The characteristics of REE and isotopic information reveal that the second type represents remainder of partial fusion of early mantle. The two kinds of peridotite were associated by tectonic emplacement and implicates that there had been oceanic plate motion in Neoproterozoic Subera.
出处
《矿物岩石》
CAS
CSCD
1993年第2期14-20,共7页
Mineralogy and Petrology
关键词
橄榄岩
蛇绿岩
镁铁质岩
地球化学
peridotite
ophiolite
metamorphic fabric
incompatible elements
compatible elements
remainder mantle
Songshugou
