Re-equilibration of zircon in aqueous fluids and melts
Re-equilibration of zircon in aqueous fluids and melts
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DOI：
10.2113/gselements.3.1.43
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发表时间：
2007-02-01
期刊：
影响因子：
4.5
通讯作者：
Tomaschek, Frank
中科院分区：
文献类型：
--
作者：
Geisler, Thorsten;Schaltegger, Urs;Tomaschek, Frank
天然锆石晶体通常表现出复杂的次级结构，穿过初级生长区。在锆石显示结构损伤所造成的自辐照，这种纹理是一个扩散反应过程中，一个含水物种向内扩散和“催化”结构恢复的结果。纳米孔隙发育，Ca、Al、Fe等溶剂元素富集，放射成因Pb损失。在含水流体和熔体中，通过溶解-再沉淀耦合过程替换具有未受损结构的锆石可以产生类似的织构。反应域通常具有较低的微量元素含量，并且可能含有孔隙和最初在固溶体中的铀、钍和/或钇相的包裹体。这两个过程对锆石年代学有相当大的影响。
Natural zircon crystals often show complex secondary textures that cut across primary growth zones. In zircon showing structural damage caused by self-irradiation, such textures are the result of a diffusion-reaction process in which a hydrous species diffuses inwards and "catalyzes" structural recovery. Nanoscale pores develop, solvent elements such as Ca, Al and Fe are gained, and radiogenic Pb is lost. In both aqueous fluids and melts, replacement of zircon with undamaged structure by a coupled dissolution-reprecipitation process can produce similar textures. The reacted domains,usually nave lower trace element contents and may contain pores and inclusions of uranium, thorium and/or yttrium phases, originally in solid solution. Both processes have considerable implications for zircon geochronology.