【作者】 沙茜；

【导师】 刘志宏； 马瑞；

【作者基本信息】 吉林大学 ， 构造地质学， 2012， 博士

【摘要】 差应力一直是地学的一个研究热点，那么差应力对岩石的部分熔融有什么影响，并且这些影响又表现在哪些方面呢？为了探讨和解决这些科学问题，本文通过高温高压的实验手段对差应力对岩石部分熔融的影响及其作用机制进行讨论与分析。实验主要分为静态熔融实验和动态熔融实验两种类型。实验后首先对熔体含量进行统计以及对实验重要参数进行确定，然后分别描述了动、静态熔融实验后样品的显微特征，研究主要包括三部分内容：差应力对岩石熔融程度的影响；熔体的静、动态实验分布特征；熔体成分的迁移与分异。第一部分内容包括的实验有黑云母斜长片麻岩的静、动态实验，角闪变粒岩的静、动态实验，辉长岩的静、动态实验，然后通过找出同样的熔融程度所对应的差应力和温度之间的关系，最后得出差应力对岩石熔融程度的影响。第二部分，通过对比描述了细粒闪长岩静、动态实验中熔体的分布特征，试图找出差应力在熔体的迁移过程中所扮演的角色。第三部分中，进行了细粒闪长岩静、动态实验，辉长岩的动态实验，浅粒岩的静态实验，细粒花岗岩的静、动态实验，对实验后样品进行电子探针测试，对主量元素进行分析，并主要通过对SiO₂含量的变化进行对比，讨论熔体成分的迁移及其分异特征。通过对比研究笔者得出结论：（1）.在酸性岩、中性岩和基性岩中，岩石的熔融程度均会随着温度和差应力的升高而增大；（2）.差应力的参与作用可以使岩石熔点降低；（3）.在黑云母斜长片麻岩中：以800℃为基准,差应力每增加5MPa其带来的影响与温度升高20℃的效果相当，在角闪变粒岩中以700℃为基准差应力每增加5MPa其带来的影响与温度升高40℃的效果相当，辉长岩中以700℃为基准差应力每增加5MPa其带来的影响与温度升高50℃的效果相当。可见，基性岩石的熔融对差应力的敏感程度最高，中性岩次之，酸性岩石最不敏感。（4）.通过对细粒闪长岩静、动态结果中熔体的分布对比可知，细粒闪长岩在动、静态实验中熔体的分布规律与相关研究成果（如辉长岩动态实验及黑云斜长片麻岩静态实验）的熔体分布规律比较一致,说明在中性岩石中，构造差应力仍然作为熔体的迁移和形成连通的三维网络结构的主要驱动力。（5）.差应力大大提高了熔体迁移的速率，并且在以含水矿物为主的岩石中的速率要远大于在其他岩石中的速率。（6）.在细粒闪长岩的部分熔融实验中，在差应力的作用影响下，角闪石作为含水矿物首先发生脱水熔融，而斜长石等矿物后熔，所以，差应力间接的控制了熔体成分由基性向酸性转化。（7）.在辉长岩的动态熔融实验中，由于熔体成分在差应力的作用下不断分异与富集，可形成成分较辉石更为基性的橄榄石；并且Fe的富集形成了磁铁矿雏晶，说明差应力促使岩石发生成分的分异，为岩石成分的分异提供了有利条件。更多还原

【Abstract】 Differential stresses is always a research hotspot on geology,and what’s theinfluences about the differential stresses for rocks’ partial melting and which aspects itmanifest?In order to discuss and resolve these scientific problems this paperinvestigate and analysis the effects and mechnisms of differential stresses on rocks’partial melting by the method of HTHP.It mainly contains two kinds of types which are static and dynamic meltingexperiments. After the experiments we firstly count the melt content and make sureimportant experimental parameters, secondly we respectively depict the micrographiccharacteristics of static and dynamic experiments. Researches mainly contain threeparts:the effects of differential stresses on rocks melting;distribution characteristics ofmelt in static and dynamic experiments;melt component’s migration anddifferentiation.The first part static and dynamic experiments are made up of samples ofbiotite-plagioclase gneiss,hornblende granulite and gabbro.We can gain the effects ofdifferential stresses on rocks melting by contrasting the same melting degreecorresponding to differential stresses and tem-perature.In part two,we try to find whatrole the differential stresses will play in the process of melt migration throughdescribing and contrasting melt characteristics of fine-grain diorite in static anddynamic experiments.In part three,we have finished static and dynamic experimentsof fine-grain diorite and granite and dynamic experiments of gabbro and static experiments of leptite,I do some electron probe tests and mainly analyze majorelements and contrast the variation of SiO₂contents to explore migration anddifferentiation of melt components.Finally, we obtain some conclusions:（1）.In acid and neutral rocks their meltingdegrees both show positive correlation with differential stresses andtemperatures.（2）.Different stresses can decline the melting points.（3）.The effect of20℃is equal to5MPa to biotite plagioclase gneiss and the effect of40℃is equal to5MPa to hornblende granulite and the effect of50℃is equal to5MPa togabbro.Basic rock is the most sensitive to different stresses,mesite is less and acidrock is the least.（4）.The distribution characteristics of fine-grain diorites’ static anddynamic experiments suggest it is accordance with other results such ascharacteristics of gabbro dynamic and biotite plagioclase gneiss static meltingexperiments which show that in medium rock differential stresses also are regarded asthe main driven-stress for migration of melt and forming joined3D networktexture.（5）.The differential stresses greatly increase the rate of melt migration and therates in rocks mainly composed by hydrous minerals are much faster thanothers.（6）.In the fine-grain diorite partial melting experiments hornblende as hydrousminerals firstly begin to melt under the effect of differential stresses but plagioclasesmelt later,so differential stresses control the melt components changing from basalticrock to andesite.（7）.In the gabbro’s dynamic melting experiments because of meltcomponents continuously assembling it will form olivine whose component is morebasaltic,also magnetite crystalline nucleus can be formed which suggest thatdifferential stresses promote rocks’ composition differentiation and provide favorableconditions for separation of rocks’ composition.更多还原