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硬柱石在基性岩石中通常稳定在低温-(超)高压的条件下.它是控制俯冲板片吸水/脱水、俯冲带流体演化和微量元素迁移的关键矿物.目前对大陆俯冲带榴辉岩中硬柱石分解过程和相关流体-元素活动的研究还很有限.大别山超高压变质带港河地区含硬柱石假象榴辉岩及内部发育的绿辉石-绿帘石脉体是进行该项研究的理想样品.通过矿物化学分析、相平衡模拟和质量平衡分析,证实港河榴辉岩中早期存在过超高压硬柱石.硬柱石在650-680℃/2.8-3.0GPa的条件下发生分解,释放大量超高压富水流体.脱水过程导致榴辉岩体积收缩和局部水压破裂,形成大量裂隙.富水流体汇聚进入裂隙,溶解裂隙(脉体)周围榴辉岩中绿帘石、蓝晶石、石英、金红石和磷灰石等矿物,同时导致靠近流体榴辉岩中主微量元素发生不同程度地迁移.逐渐靠近流体,水/岩比增大,溶解的强度和元素迁移的程度逐渐越大.富集硅酸盐组分和微量元素的超高压流体在榴辉岩折返过程中结晶成绿辉石-绿帘石脉体,残余的高压流体此后渗透进入榴辉岩,形成晚期的多硅白云母和冻蓝闪石等富集水溶性元素的变斑晶含水矿物.
In the basic rock, the hard rock is usually stabilized under the condition of low temperature - (super) high pressure, which is the key mineral that controls the water absorption / dehydration, fluid evolution and trace element migration in the subducting slab. The research on the dissolution process of lithic rocks and the related fluid-element activities are still limited.Duebaoshan ultrahigh-pressure metamorphic belt in Ganghe area contains the diorite eclogites and the internally developed omphacite- Of the ideal samples.Analysis of mineral composition, phase equilibrium simulation and mass balance analysis showed that the ultrahigh-pressured earthenic rocks existed in the early stage of the eclogite in the port of Heihe.Theodalite decomposed at 650-680 ℃ / 2.8-3.0GPa, Release a large number of ultra-high pressure water-rich fluid dehydration process leads to eclogite volume shrinkage and local water pressure fractures, the formation of a large number of fractures.Fluid-rich fluids converge into the fracture, dissolved fissures (eclogites) eclogite, Rock, quartz, rutile and apatite, at the same time lead to different degrees of migration of the major and minor elements in the fluid eclogite.With the fluid close to the fluid, the water / rock ratio increases, the strength of dissolution and elemental migration The degree of gradual increase.Ultrahydrofluid enrichment of silicate components and trace elements crystallized into omphacitific-epidote vein during the folding back of eclogite, and the residual high pressure fluid then infiltrated into eclogites to form Late Peridotrite and Cryolite amphibolite and other water-soluble elements of water-rich phenanthrene crystal mineral.