摘要
在汇聚板块边缘,滑脱面的滑动和沉积岩系的逆冲堆叠,导致孔隙水被压实排出。流体润滑了滑脱面,从而引起增生楔的生长。流体对流体制是地壳深熔的先驱事件。碱性花岗岩在次固相下有丰富的岩浆水出溶,并且促进了碱性长石的微组构重组织。上部地壳浅表流体的循环主要受岩浆侵位驱动。韧性剪切带Ti、Fe、Mg残留富集,Si、Ca、Sr带出,流体不混溶和相分离是Au沉淀的重要机制。断层带尤其深部断层带具有高的流体/岩石比率,岩石的体积损失量和可溶性元素的亏损量可以高达65％。造山带低级变质地体流体—岩石相互作用通常发生于岩石缓冲条件下,水/岩比值远低于1,流体循环与质量传输机制为渗透—扩散复合机制。变形岩石的质量传输机制包括:扩散;弥漫性渗透;渠道式渗透或流动。
Hydrous fluids play an important role in the development of an decollement below the convergent margins. Pore-fluids compacted below the decollement flow along it and are expelled a-long the frontal thrust zone or are injected into the trench. Large amounts of aqueous fluids de-pent upon the magnitude of sediment accretion. Significant mass losses of elements Si, Ca and Sr and gains in elements Ti, Fe and Mg are a common feature in the ductile shear zone. Volume loss in the deep ductile deformational zone is the main source for the silica in the upper ductile-brittle and brittle deformational zones. Fluid immiscibility and phase separation are important mechanisms for gold deposition. Fault zones and. especially, the deep fault zones are characterized by a high fluid / rock ratio, and herein the volume loss of deformed rocks and depletion of soluble elements can be as high as 65%. Fluid-rock interaction within the low-grade metamorphic terrain of an orogen generally occurred under the rock-buffered conditions, with the water / rock ratio far less than 1, and the mass transport mechanism is infiltration-diffusion composite control. Mineral-fluid reaction during metamorphism is close to equilibrium. Regional patterns of high fluid / rock ratios concentrically centered on deep-seated synmetamorphic plutonic intrusions further argue for a consideration of metamorphic hydrothermal cells at midlevels of the crust. Fluid flow through rocks therefore causes metamorphic mineral reactions to occur and acts as a fundamental driving force behind metamorphism. Mass transport mechanisms during deformation and metamorphism include; (1) diffusion; (2) pervasive infiltration; and (3) channellized infiltration or flow.
出处
《地质论评》
CAS
CSCD
北大核心
2000年第4期371-383,共13页
Geological Review
基金
国家攀登预选项目 (95-预-25
95-预-39)
国家重点基础研究发展规划项目 (G1999043204)
中国科学院资源与生态环境重大项目 (KZ951-B1-404)
关键词
流体-岩石相互作用
造山过程
质量传输
fluid-rock interaction
decollement
deformation
orogeny
mass-transfer
