【摘要】 前人基于北秦岭带广泛分布的与加里东期俯冲-碰撞相关的火山-岩浆-变质事件,认为秦岭加里东期造山运动仅仅局限于北秦岭带,中-南秦岭带由于"软碰撞"表现为泥盆系与下伏地层为连续或平行不整合接触关系,不存在加里东造山作用响应.通过对东秦岭地区中-南秦岭带出露的22条泥盆系与下伏地层接触关系剖面进行变形差异和间断缺失特征研究,且对不整合面之间"志留系红层"进行SHRIMP U-Pb年代学和沉积环境研究,结果显示东秦岭地区泥盆系与下伏褶皱基底地层(Pt3-S1)整体上呈区域性角度不整合接触(局部微角度不整合),不整合面之间缺失地层南北存在明显差异,上下地层存在明显不同构造变形特征.而旬阳县关防-公馆一线不整合面之间"志留系红层"时代为中-晚志留世(S2-3,<435Ma),其为东秦岭加里东期造山运动形成的前陆盆地在南秦岭地区前缘沉积的响应.基于上述事实,证实不仅北秦岭受加里东期造山运动影响且中-南秦岭带也发生强烈褶皱造山作用,从而为更深入地探讨东秦岭加里东期造山及沉积响应演化过程提供依据.更多还原

【Abstract】 As the volcanic-magmatic-metamorphic events related to the Caledonian subduction-collision are widely distributed in northern Qinling orogenic belt,Caledonian orogeny was believed to be limited there,and there is no response to Caledonian orogeny in southern-central Qinling orogenic belt,owing to the continuous/parallel unconformable"soft collision"between the Devonian and underlying strata.In this paper,deformation differences and discontinuous loss features of contact relationship between the Devonian and underlying strata of 22 outcrop sections in southern-central Qinling orogenic belt are investegated.In addition,the SHRIMP U-Pb geochronology and sedimentary environment on the"Silurian red strata"in unconformities are analyzed.It is indicated that the contact relationship between the Devonian and underlying folded basement strata(Pt3-S1)is a regional angular unconformity(regional micro-angular unconformity)in general,and the stratigraphic hiatus shows pronounced differences from north to south in eastern Qinling orogenic belt.What’s more,different tectonic deformation features are presented in upper and lower strata.It is believed that the age of"Silurian red strata"in unconformities is the Middle-Later Silurian(S2-3,<435Ma)along Guanfang-Gongguan in Xunyang County.It should be front sedimentary response with the foreland ba-sin formed by eastern Qinling Caledonian orogeny.It is confirmed that Caledonian orogeny induced strong folding orogeny in all Qinling orogenic belt,which will help us to get a better understanding for Caledonian orogenic-sedimentary evolution process in eastern Qinling mountains.更多还原