东秦岭丹凤群秦岭群宽坪群关系新探

NEW SPECULATION ON THE RELATIONSHIPS AMONG THE DANFENG GROUP, QINLING GROUP AND KUANPING GROUP IN THE EASTERN QINLING MOUNTAINS

东秦岭泥盆系分布区以北依次排列着丹凤群、秦岭群、宽坪群三套变质地层，之间被两条区域性大断裂所隔开。这三套地层沉积后均经历了三次强烈的褶皱、三次区域变质及三次韧性剪切，参考测年结果，提出了它们都是早元古代沉积的新认识。根据三套地层的沉积、岩性及地球化学特点，判定宽坪群为弧后大陆斜坡堆积，秦岭群与丹凤群为火山岛弧堆积。

North of the Devonian System in the eastern Qinling Mountains, are successively arrangedthree metamorphic suites,the Danfeng Group,Qinling Group and Kuanping Group,which are sep-arated by two regional major faults. After deposition,the three groups underwent three phases ofstrong folding,regional metamorphism and ductile shear. By referring to the results of age deter-mination,the authors propose a new idea that they were all deposited in the Early Proterozoic. Ac-cording to the sedimentary,lithological and geochemical characteristics of the three groups,it isconsidered that the Kuanping Group is backarc continenttal slope deposits,while the Qinling andDanfeng Groups are volcanic island arc deposits,all the three belonging to the front of the NorthChina plate.