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大别-苏鲁造山带橄榄岩原岩属性可分为壳源和幔源橄榄岩,它们在矿物结构、变质演化以及全岩和单矿物化学成分上存在一系列差别.幔源橄榄岩来自于俯冲板块之上的古老华北克拉通岩石圈地幔,记录了俯冲板块与地幔楔之间相互作用的信息.石榴橄榄岩峰期条件下都显示石榴石和尖晶石共存,石榴石和尖晶石的稳定性和成分都受全岩富化程度控制,尖晶石成分不能用来判别部分熔融程度.难熔幔源纯橄岩中普遍发育低Mg高Ca橄榄石取代早期斜方辉石结构,指示硅不饱和熔体-橄榄岩反应过程,它可能是导致纯橄岩Re-Os同位素年龄偏年轻的原因之一.幔源橄榄岩/辉石岩中的金红石、钛斜粒硅镁石和锆石是俯冲地壳熔/流体迁移高场强元素进入地幔楔的直接矿物学证据,只有通过精细的原位元素和同位素工作,才能准确限定交代介质来源、时间和交代过程.大陆俯冲带地幔楔氧逸度变化范围宽泛(FMQ=5.50~1.75),并随深度增加而减小,但其氧逸度计算结果受矿物组合、温压条件以及折返过程中的脱氢-氧化作用等因素影响.本文对橄榄岩-辉石岩复杂体系相关系、大陆俯冲之前的地幔过程、地壳交代对地幔楔元素-同位素-氧逸度以及物理性质的改造等重要研究方向提出了建议.
The original rock properties of the Dabie-Sulu orogenic peridotite can be divided into crustal and mantle-derived peridotites, which have a series of differences in mineral structure, metamorphic evolution, and whole rock and single mineral chemical composition. The mantle-derived peridotites come from subduction The ancient North China craton lithospheric mantle above the plate records the interaction between the subducted slab and the mantle wedge.The garnet and spinel coexist under the peak of garnet peridotite and the stability of garnet and spinel And composition are controlled by the degree of full rock enrichment, spinel composition can not be used to determine the degree of partial melting .Malsed mantle source dunite widespread development of low Mg high Ca olivine replace the early orthopyroxene structure, indicating that silicon is not saturated Melt-peridotite reaction, which may be one of the reasons for the young age of Re-Os isotopes of dunite.The rutile, titanic steatite and zircon in the mantle source peridotites are subducted crust Direct mineralogical evidence of melt / fluid migration of high field strength elements into mantle wedges can accurately define the source, timing and process of metasomatism only through fine in-situ elemental and isotopic work. The mantle wedge has a wide range of oxygen fugacity (FMQ = 5.50 ~ 1.75), and decreases with increasing depth. However, the calculation results of oxygen fugacity are affected by factors such as mineral assemblage, temperature and pressure conditions and dehydrogenation-oxidation in the reentry process This paper puts forward some suggestions on the research fields of the complex systems, the mantle processes before the continental subduction, the crustal alteration, the wedge-element isotope-oxygen fugacity, and the modification of the physical properties of the mantle.