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一种含钠和锌的尖晶石矿物产于中国大陆科学深钻主孔超镁铁岩中,以出溶的方式存在于钛铁矿和磁铁矿中,长5～60μm,宽2—3μm,化学组成(wB％)为MgO 17．143％-22．337％,Al2O3 63．646％-66．492％,FeO 9．784％-13．924％, ZnO 1．649％-6．386wt％,Na2O 0．029％-0．219wt％。Na2O与ZnO在尖晶石中的含量呈正相关关系。经同步辐射测得其为尖晶石单晶,空间群为Fm3m,晶胞参数为a=0．83781nm。根据尖晶石与钛铁矿、石榴石(pyr=56—58mol％)共生和石榴石退变为顽火辉石和镁绿泥石的特点,表明该尖晶石来自超镁铁岩,它们一起经历了至少为角闪岩相的变质作用。广泛的混溶间断现象及其所造成的出溶结构出现在氧化物中,表现为Mt-Usp、Mt-Spl及Mt—Ilm之间的交生。根据前人有关Mt-Usp和Ilm-Gk-Hem固溶体系的实验,表明主孔岩石的氧逸度相对较低,形成温度应在720℃以上。这些早期在岩浆分离结晶过程中形成的铁钛氧化物出溶体,在后来的超高压变质作用下可能发生再次固溶和因降温减压造成的出溶。
A spinel mineral containing sodium and zinc is produced in the main deep-hole macadam in the Chinese mainland and is present in ilmenite and magnetite in the form of a solution of 5 to 60 μm in length and 2- The chemical composition (wB%) is 17.143% -22.337% for MgO, 63.646% -66.492% for Al2O3, 9.784% -13.924% for FeO, and 1.649% for ZnO. 386 wt%, Na2O 0.029% -0.219 wt%. The content of Na2O and ZnO in spinel has a positive correlation. It was spinel single crystal measured by synchrotron radiation, the space group was Fm3m, and the unit cell parameter was a = 0.83781nm. According to the symbiosis of spinel with ilmenite, garnet (pyr = 56-58 mol%) and garnet degenerated into enstatite and magma, indicating that the spinel came from ultramafic rocks that together Experienced at least amphibolite facies metamorphism. Extensive miscibility and the resultant dissolution structures appear in the oxides and appear as intergrowths between Mt-Usp, Mt-Spl and Mt-Ilm. According to the previous experiments on the Mt-Usp and Ilm-Gk-Hem solid solution systems, it is shown that the main well rock has a relatively low oxygen fugacity and the formation temperature should be above 720 ° C. These early iron oxide precipitates formed in the process of magma separation and crystallization may undergo re-solution and dissolution due to cooling and decompression under the subsequent ultra-high pressure metamorphism.