摘要
商州蛇绿岩带具有完整的蛇绿岩套岩石组合；细碧岩与堆晶岩系具有过渡型洋中脊玄武岩地球化学特征。矿物学与岩石学研究证明，堆晶岩系是在总压与水压均较低条件下于封闭体系中分离结晶。用细碧岩主要元素估算的洋壳厚度为３．２ｋｍ，证明商州蛇绿岩带形成于慢速扩张脊。堆晶岩系Ｓｍ—Ｎｄ等时线年龄为８３２Ｍａ，结合北秦岭侵入岩带的同位素年龄，证明北秦岭在晋宁运动期间处于板块体制，并成为秦岭造山带演化历史中一个重要阶段。
The Shangzhou ophiolite belt has the perfect ohpiolite suite rock association and ocurs mainly in the form of ophiolite melange. The study of REE and trace element geochemistry shows that the spilite and cumulates display the features of basalts from a transitional mid-oceanic ridge. The mineralogical and petrologic studies indicate that most of the cumulates were formed by fractional crystallization from a closed system at low pressure. The thickness of oceanic crust calculated with the main elements of spilites is 3.2km, implying that the the Shangzhou ophiolite suite was derived from a slow-spreading ridge. The Sm-Nd isochron age of the cumulate is 832Ma, which indicates that the Shangzhou ophiolite was part of the North Qinling plate system during the Jinning movement.
出处
《地质与勘探》
CAS
CSCD
北大核心
1998年第4期7-12,共6页
Geology and Exploration
基金
北京中关村地区联合测试分析中心和地矿部秦巴攻关项目联合资助
关键词
蛇绿带
蛇绿岩
岩石组合
晋宁运动
构造运动
closed system, slow-spreading ridge, The Jinning movement,plate system
