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前言洋壳演化的模型传统上是将原地剖面研究与蛇绿岩研究结合起来。大洋盆地中的钻探证实了据蛇绿岩推测的构造,但表明,根据许多蛇绿岩提出的区域变质带并不与原地地壳相适应。主要差别如下:(1)原地地壳的上部数十米的蚀变大多数是弥漫型的;下伏岩石的蚀变是变化的。相反,前人认为变质程度、蚀变的弥漫度随蛇绿岩深度的增加而增加。(2)在深海钻探计划504B 孔处取样的原地地壳中的低温和高温环境之间的界限清晰,而已有报道蛇绿
Introduction The model of oceanic crustal evolution has traditionally combined in situ profile studies with ophiolitic studies. Drilling in the oceanic basin confirms the supposed structure of ophiolite, but shows that the regional metamorphic zones proposed by many ophiolites do not conform to the in situ crust. The main differences are as follows: (1) Most of the tens of meters of alteration in the upper crust of the in situ are diffuse, and the alteration of the underlying rock changes. On the contrary, the degree of metamorphism and alteration of the ancients thought that the depth of ophiolites increased with the depth of ophiolites. (2) There is a clear boundary between the low-temperature and high-temperature environments in situ crust sampled at Deep Hole B 504B, whereas ophiolite