The Analysis Of Sedimentary Environment And Tectonic Setting Of Zhenzishan Formation In Upper Paleozoic Of Jiamusi Massif

In this paper，through the detailed research on the stratigraphic sequence、petrology、sedimentology and lithogeochemistry，where test by the baoqing-qitaihe highway side ofJiamusi，we reach the following conclusion：1.Using Dickinson method for the detrital composition statistics，the result showsthat the regularity of the conten of Zhenzishan formation sandstones between quartz andlithic fragmens is very obvious，which is a negative correlation.In the location of sectionfrom the top to the bottom，the content of quartz experienced two peaks and two troughs，while the lithic fragmens content changes in the opposite way.Illustrated by the tectonicenvironment of the Zhenzishan formation depositional stage experienced the changes theprocess from relative calm to relative activity，and then goes back to relative calm. Highcontent of feldspar in sandstones and main content of volcanic and metavolcanic lithicfragmens in lithic fragmens，suggest that the sandstones of Zhenzishan formation may bederived from the active continental margin.In the Dickinson diagram，the sediments ofZhenzishan formation originate fromrecycled orogen provenances.2.The geochemistry analysis of Zhenzishan formation sandstones shows that theprovenance of sandestones mainly has the characteristics of active continental marginand in some layers the tectonic environment of provenance is relatively stable.（1）The major elements on the whole profile reflects the sandstones of Zhenzishanformation is mainly from active continental margin，and the tectonic setting has a rule ofchanging from stable to activities，and back to stable.（2）In the trace elements discrimination diagrams，most of sandstone samples fallinto the continental island arc provenance area and active continental margin provenancearea，which shows the sandstones of Zhenzishan formaion mainnly derives from the islandarc and active continental margin，this is similar to major elements revealing the tectonicsetting of basic.（3）Rare earth elements found in Zhenzishan formation has the negative abnormalof Eu element，light rare-earth elements are rich，while the curve of heavy rare-earthelements is flat，which is the most similar with the graywacke rare earth distribution mode under the active continental margin tectonic setting.3.Based on the study of this paper and combining with the results of otherresearchers， discussing the tectonic setting evolution of the upper paleozoic of JiamusiMassif and the evolution rule of the tectonic background of Zhenzishan formationsedimentary period，it is indicated that the tectonic setting of upper paleozoic of Jiamusiformation experienced the passive continental margin to the active continental marginevolution process，which is the passive continental margin（Heitai formation）�'crustalextension（Laotudingzi formation）�'the conversion from extension setting to activecontinental margin（Qilikashan fomation、Beixing formation）�'Active continentalmargin （Guangqing formation、 Zhenzishan formation、 Erlongshan formation andYanggang formation）�'the stable environment transformation（Chengshan formation）.Such a change process withholds cyclic gradient characteristics； Sedimentaryenvironment of Zhenzishan formation experienced from stable to active，and back tostable.This cycle-type of gradual-changing process of sedimentary environment is similarto the upper paleozoic of Jiamusi massif tectonic environment evolutionprocess.Therefore，Zhenzishan formation experienced the sedimentary environmentevolution can be regarded as a min-version evolution process that reflexes the entireevolution process of the tectonic setting of the upper paleozoic of Jiamusi massif.