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长久以来认为:地壳的形成和地幔的地球化学演变大部分取决于俯冲带中洋壳的结局。最近的地球化学研究则致力于定量俯冲带中的地球化学通量(Plank等,1993;等)和致力于涉及Be的作为俯冲过程中,天然同位素示踪物的模式基础(Tera等,1986),很显然,在不同弧环境中,源自俯冲岩板的地球化学成分的影响是变化的。这里,我们得出一种在古增生杂岩体中的测量方法,目的在于判断在增生过程中俯冲岩板的作用,和确定在俯冲带中,进入地幔的地球化学通量。研究结果表明,从大洋板块鳞剥出玄武岩质洋壳最上部分,且其增生于增生杂岩的底部是俯冲带中一种普遍过程。1 增生杂岩 对确认古增生杂岩的一个重要依据是大洋物质(例如枕状玄武岩和深海沉积岩)与陆源沉积物共生。早期板块构造学说要求,在俯冲带,于上驮板块的前缘具有刮落作用过程和洋壳的增生;在现代或古代增生杂岩中,通常不能观察到这种过程的实例;相反,所有增生杂岩的共同特征是混杂岩内具大洋物质的块体,并在定义增生杂岩体时必需有的岩性组分部分。
It has long been assumed that the formation of the crust and the evolution of mantle geochemistry largely depend on the outcome of the oceanic crust in the subduction zone. Recent geochemical studies have focused on quantifying geochemical fluxes in the subduction zone (Plank et al., 1993; et al.) And on Be’s model basis for natural isotope tracers involved in subduction processes (Tera et al., 1986) , It is clear that the influence of geochemical components originating from the subducting slab varies in different arc environments. Here, we derive a measurement method in the Paleogene accretionary complex to determine the role played by the subducted rock during accretion and to determine the geochemical flux into the mantle in the subduction zone. The results show that the uppermost part of basaltic oceanic crust is peeled off from the oceanic plate scales, and its proliferation at the bottom of accretionary complexes is a common process in the subduction zone. An important basis for the identification of Paleogene in complex accretions is that oceanic materials such as pillow basalt and deep-sea sedimentary rocks coexist with terrigenous sediments. The theory of early plate tectonics requires that in the subduction zone there is a scraping process and the accretion of the oceanic crust on the leading edge of the pack; in modern or ancient accretionary complexes, an example of such a process can not generally be observed; instead, all accretions The common feature of the complex is that of the lithologic component that is necessary for the definition of the accretionary complex, as a mass of oceanic material within the melange.