雪峰山陆内造山带的构造特征与演化

在对雪峰山的地质构造及其演化作了研究，并和阿尔卑斯式、阿巴拉契亚式的造山带和远程推覆体作了对比研究以后，作者认为：雪峰山地区的地质构造以具有多期，多层次的层滑构造为主要特色。其主要特征表现为在垂向剖面上有着多个区域性滑脱层，发育株罗山式褐挣矣逆冲叠瓦推覆构造，但它不是阿巴拉契式远程异地推覆体而是准原地型的。逆掩推覆虽然使原来沉积相带变窄，但并未破坏原来扬子地块东南边缘自北西向南东的由台地相－－斜坡相－－深水盆地相的沉积古地理格局，它是陆内造山带常见的构造样式，是在陆内裂陷的背景上由于裂谷关闭时陆块拼贴碰撞(即所谓软碰撞)和陆内俯冲产生的。雪峰山地区也发育伸展剥离和滑覆构造，伴随每一次挤压造山、地壳加厚的过程，在后造山期，也有地壳的隆升、地壳的拉伸和厚度减薄，它是深部岩石圈拆沉作用在地壳中的表现。

TECTONICS AND GEOLOGICAL EVOLUTION OF XUEFENGINTRA CONTINENTAL OROGENE, SOUTH CHINA

The Xuefeng Mountains are located in the southeastern margin of the Yangtze Block, South China. The tectonics and geological evolution of this region have been studied and compared with the orogene and allochthonous nappes of Alpine and Appalachian types. The following features are recognized： 1. The development of inter-layer gliding is one of the major features of the Xuefeng Mountains. The glide structures have a regional scale and are of multi-layer and polycyclic characteristics. Discordant folds were well developed. in which the upper layers are usually more intensively deformed than the lower layers. Thrust or overthrust developed in the earlier stages, while gravity slide or extensional detachment in the later stages. The basement WSS thrusted rflore intensively in its front edge and detached from the cover, forming Jura-type folds, extended anticlines, imbricated thrusts, and foredeep depressions. A sequence of progressive deformations developed: inter-layer gliding-- inter-layer folding--imbricated thrusting--overthrusting(1ayer-cutting)gravity sliding or extensional detachment. Recoil structures formed on the hanging side of thethrusts. 2. Although imbrcated thrusts developed in the Xuefeng Mountains, klippes, structure windows, duplex and recoil structures, mega-recumbent folds or nappe sheets do not exist in this area. The displacement of thrust or glide does not exceed 50km. The hanging side of the thrusts is allochthonous in the relatively sense, as it resided in the same paleobiogeographic division with the downthrown side. The thrusting has narrowed the sedimentary facies, belts of original formations, but did not distort their sedimentary framework(platform facies’ continental facies’ abyssal facies). The Banxi, Xiajiang, and Danzhou groups are synchronous formations with different sedimentary facies and are not melanges. The outcrops of Early Paleozoic in southeast Guizhou Province are not in the structural windows but in synclines. The Proterozoic Banxi Group does not overlay on the Early Paleozoic strata. No Alpine-type allochthonous nappe has been found in the Xuefeng Mountains. 3. The tectonic evolution of the Xuefeng Mountains has been proceeded on the background of continental crust. Since the Late Caledonian orogene, intra-continental subduction had replaced the B-type subduction as the major geodynamic process in the area. Inter-layer gliding became the dominant form of deformation. When the rifts closed, the micro-continental blocks collided (soft collision), and inter-layer gliding occurred.