| 造山带橄榄岩中锆石的成因及其地质意义 |
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| 引用本文： | 郑建平,赵伊,熊庆.造山带橄榄岩中锆石的成因及其地质意义[J].地球科学,2019,44(4):1067-1082. |
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| 作者姓名： | 郑建平 赵伊 熊庆 |
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| 作者单位： | 1.中国地质大学地球科学学院, 湖北武汉 430074 |
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| 基金项目： | 国家自然科学基金41873032国家重点研发计划"深地资源勘查开采"重点专项《燕山期重大地质事件的深部过程与资源效应》项目《鄂霍茨克洋与太平洋构造域叠合的岩浆作用与成矿响应》2016YFC0600403 |
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| 摘 要： | 造山带橄榄岩记录了板块俯冲、碰撞、折返等复杂过程信息，可分为壳源和幔源两种类型.造山带橄榄岩（特别是幔源类型）中锆石极为罕见，锆石内部具有橄榄岩的特征矿物或组合包裹体说明这些锆石可以生长于地幔中.造山带橄榄岩在经历板块汇聚（例如超高压变质等）复杂作用过程中，经历了不同时期的熔/流体的交代作用，对橄榄岩的矿物组合和元素组成都能产生重要影响.橄榄岩中锆石作为典型的交代作用产物，它的形成受控于熔/流体的化学组成、来源属性以及形成物理化学环境等.幔源型造山带橄榄岩中锆石的形成过程可能包括:（1）锆石结晶能力强，在地幔环境变化中Zr优先与其他地幔硅酸盐矿物中的Si结合，形成锆石；（2）原始锆石的溶解和含Zr矿物相（如石榴石等）的破坏或晶间熔体析出，在亚固相线条件下形成锆石；（3）再循环地壳物质来源的熔/流体，交代地幔楔并结晶形成锆石.因此利用锆石可以揭示特定岩石圈域的演化历史，有助于深刻理解大陆克拉通及其边缘过程.
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| 关 键 词： | 造山带橄榄岩 锆石成因 结晶能力 Zr元素饱和 地幔交代作用 岩石学 |
| 收稿时间： | 2018-09-19 |
Genesis and Geological Significance of Zircons in Orogenic Peridotite |
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| Abstract: | Orogenic peridotites record the complex geological processes of continental subduction, collision and exhumation, and they can be divided into two types: crustal origin and mantle origin. Zircons are rarely found in orogenic peridotites. The in-situ zircons and zircon inclusions with mantle-rock mineral assemblages indicate that the zircons can grow within the peridotites. During the complex processes of plate aggregation (such as UHP metamorphism), the orogenic peridotites experienced the melt/fluid interaction in different periods, which have an important impact on the mineral and elemental compositions of peridotites. Zircon is one of the typical metasomatic minerals of orogenic peridotites. The zircon formation is controlled by the composition of the melt/fluid, source properties, and the formation of a physical and chemical environment. The mantle-derived zircons from orogenic peridotites have three origins:(1) Zircon has strong crystallization ability, and Zr prefers to combine with Si from silicate minerals in mantle rocks to form zircons. (2) Metamorphic destruction of Zr-bearing mineral phases and precipitation from intergranular melts generated can nucleate zircons under sub-solidus conditions. (3) The melt/fluid from the recycled crust can metasomatize the mantle wedge and form zircons. Thus, zircons can be used to unravel the history of specific lithospheric domains and thus contribute to our understanding of the evolution of continental cratons and their margins. |
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