中文摘要：

庙垭碳酸岩位于东秦岭武当山隆起的西南缘，呈岩株状产出，主要由方解石组成，富含稀土矿物，是我国大型轻稀土矿床。该区全岩的C．O同位素数据δ18O=11％o～12．49％o，δ13c=-3．79％。～5．68％0，落在了初始火成碳酸岩的范围之外，表明可能受到高温分离作用的影响。流体包裹体相态较单一，主要由气液两相包裹体和气液三相包裹体组成，均一温度120～400℃，为中低温，盐度为3．89％o一10．48％o为中低盐度，这与典型的碳酸岩中流体包裹体具有相似的特征。通过与牦牛坪典型的岩浆热液脉型REE矿床在C—O同位素、包裹体及微量元素的对比研究，发现两者的成因机制并不相同，庙垭稀土矿床是典型的岩浆型，缺少萤石等热液矿脉，大量矿物的分离结晶，特别是方解石的堆积结晶作用，导致其方解石具有相对较低的均一温度和盐度，这也使碳酸岩岩浆更富集REE，有利于REE成矿。

英文摘要：

The Miaoya REE deposit associated with carbonatite-syenite complexes is located in the southwestern mar- gin of the Wudang Terrane at the east Qinling orogenic belt. The carbonatite occurs as stocks and principally consists of calcite. The carbonatite-syenite complexes contain abundant REE-rich minerals, and form a large LREE deposit in China. The carbonatite C-O isotopic data are δl8O = 11%o - 12.49%o, and δ13C = -3.79%o -5.68%o, which is de- viated from primary mantle-derived C-O isotopic compositions, indicating that they were affected by high temperature fractional crystallization. The phases of fluid inclusions are much uniform. There are two types of fluid inclusions having been observed, including two-phase and three-phase fluid inclusions. The fluid inclusions have homogeneous temperature from 120°C to 400°C and moderate-low salinity from 3.89%o to 10.48%o. There are similar features with typical carbonatites worldwide. Compared with REE deposit of hydrothermal ore-veins in Maoniuping in C-O isotope, fluid inclusions and trace elements, there are different genesis processes. Miaoya carbonatite is typical magmatic REE deposit, which is absent in hydrothermal gangue mineral veins, such as fluorite and so on. The fractional crystalliza- tion of abundant minerals, particularly calcite resuhed in that the fluid inclusions have comparatively low temperature and salinity and make the residual carbonatitic liquids much richer in REE to form REE deposit.