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智利南部的蛇绿岩杂岩代表白垩纪弧后盆地盆底镁铁质部分的残余,此盆地自北而南显著变宽,其长度超过600公里。对呈楔状的原始弧后盆底的北端(萨莱托杂岩)和南端(托图加杂岩)蛇绿岩的详细的野外及地球化学方面的研究表明,在盆地形成期间玄武岩浆侵位到先存的大陆地壳的方式,南北间存在着重大的差异。在原始盆地狭窄的北端,镁铁熔浆侵入到大陆壳的扩散构造带内,造成硅锅质大陆壳的广泛再活化和改造。而在原始盆地的较宽的南部,在所确定的海洋扩张中心的位置上看来已有镁铁岩浆侵入。所观察到的这种北—南变化,造成了从具有洋陆中间型地壳到典型洋壳特征的弧后盆地的形成。这些变化被解释为代表弧后盆地的不同演化阶段。它是由导致弧后盆地地慢对流的俯冲作用与会聚板块边界一边的应力释放之间的微妙作用而形成的,可能与洋脊俯冲作用有关。在应力释放前,热从地幔底辟体传递到地壳底部,引起了南美普遍的硅质火山作用。随着应力的释放,从地幔衍生的熔浆顺着构造通道喷发到地表,导致了岛弧后面断裂带广泛地玄武岩质火山活动和硅质火山作用的终止。起初,玄武岩浆侵入陆壳的扩散带中,引起硅铝质地壳岩石的改造。后来不断形成自地幔来的镁铁岩浆的侵入带,最终导致发育了大洋型扩张中心。在南部智利和另一些地方的观察表明,会聚板块边界一边的水平应力的变化,可能是确定大陆壳区域性响应引起弧后对流的俯冲作用的主要因素,因此是镁铁质地幔熔浆侵位到地壳的机制。可推测,在南部智利观察的各种岩石也可在大洋盆的张开阶段形成,而目前已下伏于大西洋型大陆的边缘。
The ophiolite complex in southern Chile represents remnant of mafic part of the Cretaceous back-arc basin, which broadened significantly from north to south with a length of more than 600 km. Detailed field and geochemical studies of the wedge-shaped primitive northern arc basins (Saleto complex) and southern tip (Putugan complex) ophiolites show that basaltic magma emplacement There are major differences between North and South into the way of the pre-existing continental crust. At the narrow northern end of the pristine basin, mafic magma intrudes into the diffusion tectonic belt of continental crust, resulting in the extensive reactivation and remodeling of the silicon pot mass continental crust. In the wider southern part of the pristine basin, however, magma magma intrusions appear to have taken place at the site of the determined oceanic expansion. The observed North-South changes have resulted in the formation of back-arc basins from the mid-oceanic crust to the typical oceanic crust. These changes are interpreted as representing different stages of evolution in the backarc basin. It is formed by the subtle interaction between the subduction of the slow convection in the back-arc basin and the stress release on the edge of the convergence plate, possibly related to the subduction of the ocean ridge. Before stress was released, heat was transferred from the mantle diapir to the bottom of the crust, causing widespread silicic volcanism in South America. With the release of stress, the melt derived from the mantle erupted along the tectonic channels to the surface, resulting in the extensive basaltic volcanic activity and the termination of the siliceous volcanic activity in the back of the island arc. At first, the basalt magma invaded the diffusion zone of the continental crust, causing the alteration of the Si-Al crustal rocks. Later, the invaded zone of mafic magma originating from the mantle continued to form, eventually leading to the development of an oceanic expansion center. Observations in southern Chile and elsewhere indicate that changes in horizontal stress on one side of convergent plate boundaries may be the main determinant of regional subduction of continental crust convection causing convection after the arc and are therefore mantle magma emplacement The mechanism to the crust. Presumably, rocks of all kinds observed in southern Chile may also form during the open oceanic basin, but now sank on the margins of the Atlantic Ocean.