浙江方岩丹霞地貌发育的年代、成因与特色研究

Age Genesis and Characteristics of Danxia Landform of Fangyan in Zhejiang Province,China

方岩丹霞地貌在大地构造上隶属于华南褶皱系构造单元,该单元在燕山运动时期,由于太平洋板块俯冲入欧亚板块之下,促使大陆边缘地壳重新活动。晚侏罗世末至早白垩世,本区构造应力场由晚侏罗世的北西-南东向挤压,转为早白垩世的北东-南西向挤压和北西-南东向的拉张,发育了永康早白垩世断坳盆地,在盆地中沉积了下白垩统永康群馆头组(K1g)、朝川组(K1c)和方岩组(K1f)地层。中生代晚期永康盆地逐渐隆升,结束了红层沉积,遭受侵蚀,方岩地区丹霞地貌密集围谷、密集方山和廊穴等青年期的地貌特点表明该区大规模的抬升发生在较近的地质年代。

Danxia Landform of Fangyan which located in Yongkang Basin belongs to South China fold geotectonic framework, which made fringes of continent become activities again while the Pacific Plate system in dived under the Eurasian Plate in the period of Yanshan Tectonic-Movement. The ruptured Yongkang Basin was formed as tectonic stress field changing extrusion of NW-SE to extension of NW-SE from later Jurassic to earlier Cretaceous, so strata of Guantou Formation （ K1 g）, Chaochuan Formation （ K1 c）, and Fangyan Formation （ K1 f） of Yongkang Group in lower Cretaceous were accumulated in the Basin. In late of Mesozoic, the Yongkang Basin uplift gradually, the red-layer sediments ended accumulating and suffer from erosion. The characteristics of the earlier developed stage in Fangyan such as dense encircled valleys, mesas and aisle-liked caves prove that the large-scale uplift tectonic movement in this area should occur in recent geological epoch.