Characteristics And Genesis Of Neoarchean Granitic Complex In Xing Cheng Area Of Western Liaoning

Neoarchean granitic complex composition is relatively complex in XingCheng TaiLiarea of western Liaoning, where mainly divides into biotite-feldspar gneiss and graniticgneiss in two categories.It is an important part of Neoarchean crust of the North ChinaCraton.This article selects two types of gneiss as research object,Combined with theresearch of mineralogy、petrology、geochemistry,It finally finds out the genesis of granticgneiss.On the basis of large scale measure of the field,It identifies temporal and spatialdistribution characteristics and relationships of the granitic complex，Its appearance of theoverall performance is extremely non-uniform, the two types of gneiss can be furtherdivided into different rock types.Granitic gneiss type can be divided fine/corese-grained/porphyritic/coarse-pegmatite granitic gneiss.They are all “fuzzy”gradual transition,Theshape is very irregular,no general characteristic of intrusive body;Biotite feldspar gneiss is divided biotite（hornblende） plagioclase/monzonite gneiss and felsic gneiss.Its occurrence relationship is for the gradient. Two types of gneiss is coordinated with deformation ortransitional relationships,a part of them displays “mutation”relationship,and biotite-feldspar gneissdistributes in the granitic gneiss with the irregular form of inclusions,it isdifficult to determine the shape and boundaries.Combination of microfabric study,It identifies that two categories of gneiss hasremarkable difference in the fabric.They all can be divided into two different types ofstructural phase:The native structure and new minerals structural phase.mineral particle size change of biotite feldspar gneiss is relatively small （0.2～1.5mm）,the content of Thenative structure is relatively based,the composition is quartz,plagioclase and biotite, thecontent of new minerals structural phase is relatively less;while minera,particle size change is relatively（0.2～5mm） in the granitic gneiss,,the content of new minerals structuralphase is relatively based,its composition is microcline,plagioclase and quartz, the contentof metasomatic relict texture phase is relatively less. From biotite-feldspar gneiss to granitic gneiss,It has the variation that the content ofnew minerals structural phase is graduallymore, the content of the native structure is gradually less.In the content elements,twotypes of gneiss in variation with SiO₂、MnO、CaO、TiO₂、Fe₂O₃T and CaO has lineardistribution trend.It has a complementary relationship in the content variation with SiO₂、MnO、MgO、TiO₂、Fe₂O₃T、CaO and P₂O₅.Both have similar characteristics in the contentvariation of trace and rare earth elements,which reveals two types of gneiss with closegenetic relation.In summary,with the comprehensive study of field geological work、mineralogy, petrology, geochemistry, It derives that granitic gneiss category belongs to anatectic granite.