Abstract:

Reencoding of the geological and geochemical data concerning the Guidong Composite Granite Body(CGB) with the hypothesis of insitu melting and crustal convection suggests that the Guidong CGB was formed by repeated crustal melting of this area in the Mesozoic. On that basis, this paper rebuilds the melting interface(MI) formed in different Yanshanian periods: the MI formed in the Early Jurassic totally tilts from south to north, which resulted in the early Yanshanian granite cropping out from inner facies to transitional facies and to margin facies from south to north on the presentday denudation plane; the MI formed in the melting event of the Late Jurassic totally tilts from north to south, and the distribution of granite bodies formed in this period was basically limited within the old member of the Guidong CGB thus usually more acid than the old one; the melting event of the Early Cretaceous produced a southward tilting MI and formed two kinds of rocks, quartz syenite and subdaciteporphyry. Difference of the rocks is likely concerning with the source rocks involved into the melting event. Metallogenic prediction on the above model in the Xiazhuang orefield, eastern Guidong CGB, has been approved by drillings to a certain extent.

Key words:  Guidong composite granite body, Xiazhuang orefield, insitu melting, MI shape