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通过对辉绿岩的高温高压交代实验及理论计算,研究了洋中脊的热液交代过程。这一交代过程的存在可以从洋中脊的热液化学组成、挖掘到的变质玄武岩样品的化学、矿物学以及陆地上的蛇绿岩露头得到证实。所获结果表明,Mg、Ca、Na的固定反应分别发生在不同的交代条件下。Mg的固定反应发生在海底热液对流圈的下降翼,Ca、Na的固定主要和上升翼有关,其中Ca反应发生于深部,Na反应则位于上升翼近于海底的部位。热液中Ca的迁出,伴随着H~+的产生。减压过程大大地增进了这一反应。和其他含钙交代相相比,绿帘石的稳定性也因此而提高。在热液体系中,绿帘石和斜长石这两个固溶体制约着热液的化学成分和pH值。东太平洋隆起21°N黑烟囱中喷出的热液来自于385—400℃、300—400bar的反应带。只要弄清了盐度的影响、由传导冷却而造成的退变质过程以及混合过程,就可确定所有热液的反应带的温压条件。
Through the experiment of high temperature and high pressure alternation experiment and theoretical calculation of diabase, the hydrothermal metasomatism of mid-ocean ridges was studied. This process of alteration can be confirmed by the chemical composition of the mid-oceanic ridges, the chemistry, mineralogy of the metamorphic basalts and the ophiolite outcrop on land. The obtained results show that the fixed reactions of Mg, Ca and Na occur under different conditions of replacement. The fixed reaction of Mg occurs at the descending wing of the convection circle of the hydrothermal fluid. The fixation of Ca and Na is mainly related to the ascending wing. The Ca reaction occurs in the deep part and the Na reaction is located in the part near the sea bottom of the ascending wing. The migration of Ca in hydrothermal fluids is accompanied by the generation of H ~ +. Decompression process greatly enhanced this response. Compared with other calcium-containing phases, the stability of the epidote is also improved. In hydrothermal systems, the two solid solutions of epidote and plagioclase constrain the chemical composition and pH of hydrothermal fluids. The hydrothermal fluid emanating from the 21 ° N black chimney in the eastern Pacific rises from the reaction zone at 385-400 ° C and 300-400 bar. The temperature and pressure conditions of the reaction zones of all hydrothermal fluids can be ascertained as long as the effect of salinity is clarified, the retrograde processes caused by conduction cooling, and the mixing process.