秦岭造山带主要构造岩石地层单元的构造性质及其大地构造意义

秦岭造山带由三大套构造岩石地层单位所构成，即１、二类不同的前寒武纪基底岩系；２、晚元古代－中三叠世主造山时期受板块构造和垂向增生构造控制的相关构造岩石地层单元；３、中新生代后造山期的陆内断陷与前陆和后陆盆地沉积及广泛的花岗岩浆活动。它们反映着秦岭带三个主要演化时期，在不同构造体制下的三种不同的基本地壳物质组成与结构。它们记录着秦岭造山带长期发展历史中的不同演化阶段的多种造山作用及其不同动力学机制的丰富信息。

Nature of Main Tectono-Lithostratigraphic Units of the Qinling Orogen: Implications for the Tectonic Evolution

The basic facts of the Qinling orogen are that it is composed of three distinct tectonostratigraphic units, which possess different crustal compositions and textures, and evolved in differing tectonic regimes in three stages. The lower unit presents two kinds of orogenic basements. The middle unit presents a Late Proterozoic--Middle Triassic succession, which consists of depositional sequences developed at both active and passive continental margins, subduction-related ophiolites and collisional granites. All these demonstrate a plate tectonic regime in this stage. In addition, widespread basement uplift also implies the subcrustal underplating and vertical accretion. The upper unit is made up of both intruded granites and sediments deposited in foreland, hinterland, and postorogenic rifted basins. Intensive magmatism and crustal deformation indicate strong postorogenic intracontinental orogenesis during the Mesozoic and Cenozoic eras.The fundamental composition and evolution of the Qinling were built up by different orogenensis under different mechanisms throughout its history.