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本文根据对苏联托勒巴契克火山(1975—1976年喷发)拉长石巨晶火山砾中岩浆包裹体的研究结果,重溯该类拉长石巨晶结晶生长的热历史及其形成过程。从拉长石巨晶的中心到边缘,随着结晶温度降低(1220→1160℃)化学成分逐渐贫钙(An_(62.7)→An_(57.2))。岩浆包裹体的化学成分表明,该类拉长石巨晶于一种碱性玄武质熔浆中结晶,尔后由火山爆发作用抛出地表。作者直接利用岩浆包裹体中所捕获的天然熔浆进行实验岩石学研究,重现了天然岩浆的结晶、演化过程。实验研究还查明了该类火山砾所经受的最后热事件,从晶体边缘到中心的最大热梯度为110℃。拉长石巨晶的边缘部分在1160℃遭受淬冷,从而使得该带中的岩浆包裹体为非演化型单相玻璃包裹体;中心部分在1220至1050℃间缓慢冷却,所含包裹体属演化型。托勒巴契克火山拉长石巨晶火山砾形成过程中,温度和冷却速率乃是控制其结晶生长的主导因素。
Based on the study of magmatic inclusions in the Jurassic volcanic conglomerates of the Tolbachcha volcano (erupting in 1975-1976), this paper reviews the thermal history and the formation process of the crystalline growth of such exponential giant beryl. From the center of the elongated macrocrystal to the edge, the chemical composition is gradually depleted in calcium (An 62.7 -> An 57.2) as the crystallization temperature decreases (1220 → 1160 ° C). The chemical composition of the magma inclusions indicates that the macrocephalitic crystals crystallize in a basic basaltic magma and later erupt from the surface by volcanic eruptions. The author directly uses the natural magma trapped in magmatic inclusions to carry out experimental petrology and reproduces the crystallization and evolution of natural magmas. The experimental study also identified the last thermal event experienced by this volcanic conglomerate, with a maximum thermal gradient from the edge of the crystal to the center of 110 ° C. The edge part of the elongated macrostructure is quenched at 1160 ℃, so that the magmatic inclusions in the zone are non-evolving single-phase glass inclusions. The central part is slowly cooled from 1220 ℃ to 1050 ℃, and the inclusions are of evolved . During the formation of Volcanic Epikulite volcanic conglomerate in Tollebach, temperature and cooling rate are the dominant factors that control the crystal growth.