花岗岩暗色微粒包体特征及其研究方向

Characteristics of mafic microgranule enclaves(MMEs) in granitoids and and future study prospects

通过调研近年来国内外学者对于花岗岩类中暗色微粒包体的研究成果,总结了其野外地质、岩相学、地球化学和同位素等特征以及成因研究中的主要问题。暗色微粒包体(MME)广泛分布于I型花岗岩中,一般呈随机分布,形态多样,但以塑性特征为主;一般认为是岩浆混合成因,其原始物源是玄武质岩浆,具典型的火成岩结构,发育针状磷灰石、环带结构和筛状结构的斜长石;相对于寄主岩石,暗色微粒包体富Fe,Mg,贫Si,Na,其锆石U-Pb年龄在误差范围内与寄主岩石年龄一致等,反映了壳幔源岩浆的混合事件。暗色微粒包体与岩浆动力学行为、矿化关系及区域地质演化等方面值得进一步研究、探索。

This study summarized the main features of mafic magmatic enclaves,or mafic micro-granular enclaves（MMEs）,such as their geological characteristics in field,petrological characteristics,geochemical and isotopic characteristics and reviewed the genetic problems.Basically,MMEs are randomly scattered in I-type granite and occur in multi-forms but plastic form dominates.Genetically it is widely accepted that MMEs are formed by magma mingling.The original material is basaltic magma with typical igneous texture and development of acicular apatite,rapakivi and sieve textured plagioclase.Compared to the host granitic pluton,MMEs are much enriched in Fe,Mg and depleted in Si and Na.U-Pb age of MMEs in range of the host rock.All these features may reflect an event of crust-mantle magma mingling/or mixing.It is evident that future researching hot spots in MMEs will be on the link between MMEs and mineralization,magma dynamics,regional tectonics and genesis of granitoid,etc.