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洋壳是位于大洋下面的地球最外层。洋壳与下伏地幔之间是一个地震渡带,称为莫霍面。一般认为,莫霍面代表以玄武岩型岩石向地幔(以橄榄石和辉石为主)的岩石变化。按照这一观点,洋壳是由玄武岩熔融物质的熔析形成的,这些熔融物质产生于地幔的部分分熔融并进入地壳岩浆囊,在岩浆囊中,熔融物质的冷却和结晶过程使不断扩张的板块稳定地增生。根据这个假说作出的各种预测,与海洋地球物理资料很不相符,这就不免令人对洋壳形成的这种假说是否正确产生怀疑。除此之外,至少还有两种对洋壳形成过程的解释与地球物理资料比较一致。一种是,洋壳是玄武岩脉由地幔储体分期注入而形成的。莫霍面是主要的岩石分界面。另一种是,洋壳为一力学分界层,在这一层中热收缩形成了裂隙,而地幔中的热收缩是受流体控制的。洋壳的上部是由玄武岩熔融物质分期喷出和侵入形成的,下部是通过地慢的迅速热液蚀变形成的,而地幔则是由粘性流在低于融点的温度下连续地或分期地注入的。
The oceanic crust is the outermost layer of the earth beneath the ocean. Between the oceanic crust and the underlying mantle is a seismic band, known as the Moho. It is generally believed that the Moho represents rocks that change from basaltic rocks to mantle (mainly olivine and pyroxene). According to this view, the oceanic crust is formed by the melting of basaltic melts that partially melt in the mantle and enter the crustal magma pockets, where the cooling and crystallization of the molten material expands Plate stable proliferation. The various predictions made on the basis of this hypothesis do not correspond well with the marine geophysical data, which cast doubt on the correctness of the hypothesis that the formation of the oceanic crust is correct. In addition, at least two explanations of the formation of the oceanic crust are consistent with geophysical data. One is that the oceanic crust is formed by the basalt veins being injected in stages by the mantle reservoirs. Moho is the main rock interface. The other is that the oceanic crust is a mechanical demarcation layer in which heat shrinks form fractures and the thermal contraction in the mantle is fluid-controlled. The upper part of the oceanic crust is formed by staging and intrusion of basaltic molten material, the lower part is formed by rapid slow hydrothermal alteration, and the mantle is formed by the viscous flow continuously or in phases below the melting point Injected