Geochemical Features and Petrogenesis of Miaoya Carbonatites,Hubei Province

The lens-shaped Miaoya carbonatite complex,located west of the Wudang massif,HubeiProvince,consists of several types of caxbonatites associated with syenites.According to theircomposition,the carbonatites can be classified into four types,i.e.,sovite,alvikite,carbon-bear-ing alvikite and ankeritic carbonatite.Their average composition is in agreement with theabundance values for carbonatites compiled by Gold(1966).There are three stages recogni-zable:the earliest sovite and alvikite followed by caxbon-bearing alvikite,with ankeritic car-bonatite being the latest.Some rules dominating the distribution of major and rare elementsare observed with respect to the evolution of these carbonatites,for example,Nb is essentiallyenriched in sovite.Except for niobite and ilmenorutile,there axe also pyrochlore,nioboeschy-nite and fersmite.RE are concentrated mainly in ankeritic carbonatite,within which bastna-site,parisite and monazite are found.In general,Ca,Nb,and Sr decrease,while Fe,Mg,Mn,and RE increase from earlier to later stages.It is suggested that the carbonatites aregenetically connected with syenitic magma.