A Study On Petrology And Geochrounolgy Of The Heilongjiang Complex In The Huanan, Heilongjiang Province

Metamorphic rocks of the Heilongjiang complex are argillaceous schist, mafic rocks, ultramafic rocks, metamorphic rocks and marble and other siliceous rocks formed by an epidote blueschist facies-amphibolite facies-metamorphism-a greenschist facies and by the strong influence of tectonic deformation belt. Similarity to ophiolitic melange zone is really considered as a true Jiamusi block and Songnen block the formation process of subduction collage rock sequences. Based on the Heilongjiang complex zone of the typical glaucophane, mudstone and metamorphic petrology, mineralogy, structural geology, geochronology, etc. investigated, results are shown as following:The Heilongjiang complex is consist of greenschist rocks and tectonic mylonites. The Heilongjian complex belt is really considered as a true Jiamusi block and Songnen block the formation process of subduction collage rock sequences. Huanan sticking out Heilongjian complex is obvious different with Mudanjiang,Yilan,Luobei complex, mainly displays in: At the present we didn't discovery high-pressured minerals in Heilongjiang complex,such as glaucophane, moreover the lineation direction is different. Huanan sticking out Heilongjiang complex is not normal ground, but it is a metamorphic rocks. There are two main parts,one part is felsic schist, about 70% of Heilongjiang complex. Another part remain in the felsic schist and have different kinds of rocks. Results show that zircons from analyzed sample present available Th/U ratio between 0.27～1.27, and show well defined two group ages, i.e. weighted average 206Pb/238U ages are 511±10 Ma (n= 13, MSWD= 1.6) and 274.7±3.6 Ma (n= 9, MSWD=0.91). The oldest ages from 969—747Ma is very similar with the zircon dating of biotite-granulitite apparent isochron age 922Ma, both of that imply the age of protolith diagenesisdiagenism, it mainly come from the origination of mesoproterozoic to neoproterozoic.These ages along with metamorphic age of～511 Ma display that the Heilongjiang complex, contains detrital zircons, which are possibly derived from the spatially intimately associated Mashan complex. The group age～275Ma obtained subsequently suggest another orogenic event, probably representing the closure of the Paleo-Asia oceanic plate during the late Paleozoic.