河南鹤壁地幔捕掳体内磷灰石的发现及地幔交代作用OACSTPCD

Objective Mantle metasomatism is one of the important ways of lithosphere evolution.Explicit metasomatism is characterized by the occurrence of mantle minerals with metasomatism,which can provide direct evidence for mantle metasomatism.Apatite is a typical mineral of metasomatism in the mantle.Since the Mesozoic era,North China Craton(NCC)lithospheric has significantly thinned occurred at the easten margin of Taihang mountain tectonic belt,while the western part of Taihang mountain remained thicker con-tinental lithosphere.Taihang mountain tectonic belt is the transition zone between the eastern destructed NCC and the western stable NCC.Therefore,it is of great significance to study the mantle xenoliths in the Taihang Mountains tectonic zone for the destructionof the NCC.Hebi Area of Henan Province is located on the Taihang Mountain structural belt,where deep-seated magmatic rocks such as kimberlite are developed.Methods This article takes the mantle xenoliths carried by kimberlite as the object to research the proper-ties of the lithospheric mantle in the Hebi Area.Some apatite particles and a single apatite enclosed in py-roxene particle were found in the man-made heavy minerals from mantle xenoliths.Results Observation through stereoscopic microscope shows that the apatite is colourless,transparent,glassy luster and short colum in shape.Scanning electron microscope energy dispersion spectra shows that the encapsulated miner-als are consisted of Ca,P,O,F elements,and the host mineral is consisted of Si,Fe,Mg,Al,O elements.The electron probe results indicate that apatite chemical composition ranges from 53.525%to 56.514%,and w(P2O5)ranges from 37.372%to 40.851%.Experimental petrology research suggests that enstatite + calcite→olivine + diopside+CO2,and apatite and other minerals are produced as accessories.Therefore,the mineral combina-tion of pyroxene encapsulated apatite belongs to mantle metasomatism,indicating dominant metasomatism.Conclusion The discovery of apatites mantle metasomatism origin provides the direct evidence of dominant metasomatism of lithospheric mantle in the North China Craton.