河北下营坊杂岩体地球化学特征、成因及构造环境指示意义  

Geochemistry of the Xiayingfang complex in Hebei Province:Petrogenetic and tectonic implication

作　　者：马金虎[1] 马晓辉[2] MA Jin-hu;MA Xiao-hui(Baoding Geological Engineering Survey Institute,Baoding 071051;Geophysical Exploration Institute of China Metallurgical Geology Bureau,Baoding 071051)

机构地区：[1]河北省保定地质工程勘查院,保定071051 [2]中国冶金地质总局地球物理勘查院,保定071051

出　　处：《矿产勘查》2019年第8期1751-1763,共13页Mineral Exploration

摘　　要：下营坊杂岩体相对亏损镁、铁、钙等组分,具富钾、准铝质-弱过铝质特征,可归类为富钾弱过铝质钙碱性系列的岩石。杂岩体中闪长玢岩和花岗斑岩地球化学特征对比,表明它们为同源岩浆连续演化的产物。闪长玢岩和花岗斑岩都是由壳幔混源的富钾钙碱性岩浆演化而来。闪长玢岩中Ba、K较为富集,Nb、Ta、Th、U均现较明显亏损,其岩浆源应为麻粒岩相下地壳与上地幔热物质的混合,具体过程可能是由于上地幔热软流圈上涌引起麻粒岩相下地壳的部分熔融,并且源区残留相为富Nb、Ta、Ti的金红石。其形成于一个正处于构造体制重大转折的大地构造背景下。Xiayingfang complex is relative loss of magnesium,iron,calcium and other components,With potassium-rich,quasi-aluminum-weaker than aluminum characteristics,it can be classified as rich in potassium weaker than aluminum calcium alkaline rock series.Through the comparison of the geochemical characteristics of diploid and porphyry in mixed rock,it is shown that they are the product of the continuous evolution of homologous magma.Both the diploids and the granulomatous porphyry evolved from the potassium rich calcium alkaline magma of the shell mantle mixed source.Ba and K are more abundant,Nb,Ta,Th,and U are all showing significant losses in the diploids.Its magmatic source should be a mixture of hot matter of upper mantle and lower the crust of the gneiss phase.The specific process may be due to the partial melting of the crust under the gneiss phase caused by the upwelling of the upper mantle thermal asthenosphere,and the residual phase of the source area is the rutile enriched by Nb,Ta,and Ti.It is formed in a geotectonic background that is in a major turning point in the tectonic system.

关 键 词：地球化学 岩石成因 构造意义 下营坊杂岩体 河北 

分 类 号：P588.12[天文地球—岩石学]