摘要:
大巴山国家地质公园岩溶景观种类齐全、组成系统完整,其发育和分布受构造控制作用显著.文章探讨大巴山国家地质公园岩溶景观特征及其空间分层结构受构造控制的作用机制,发现岩溶空间形态总体呈现掀斜式强烈抬升、河流深切的亚热带中低山峡谷岩溶特点,新构造运动间歇性隆升对岩溶景观垂向发育影响较为显著.岩溶发育的空间层位划分为三个高程层级,从下至上连续分段为440~700 m,700~1 200 m,1 200~1 890 m.空间分层结构反映某一阶段地壳总体处于相对稳定的时期,发育水平岩溶系统(溶洞),后期地壳发生快速抬升,出现少量竖向岩溶系统(落水洞),溶洞的分布与相应的侵蚀基准面(现代河床、各级阶地)相适应.根据发育层级推测,研究区至少经历过四次规模较大的间歇性快速抬升构造活动,各级夷平面先后受喜马拉雅运动第Ⅱ幕和第Ⅲ幕影响.喜马拉雅运动多次间歇性快速抬升过程中,丰沛的地下水和地表水下切并快速溶蚀形成多层剥蚀台地.在新构造运动相对稳定期,有充分的条件循环交替溶蚀导致垂向、水平岩溶均出现较大规模发育.
Abstract:
The Dabashan National Geological Park hosts various types of karst landscapes and complete composition systems,of which the development and distribution are obviously controlled by the structure.This paper presents the features of karst landscapes of this park and studies the control of neotectonic movement on its spatial hierarchy.It is found that overall the karst space is characterized by intense tilting uplift,deep river incision,and canyons of low-medium mountains in subtropical zones.It can be divided into three elevation levels;the first is about 1 200 to 1 890 m,the second is 700 to 1 200 m,and the third 440 to 700 m.Such a spatial hierarchical structure reflects that overall the crust was in a relatively stable period when horizontal karst (caves)developed followed by fast crustal uplift with a small amount of vertical karst systems (sinkholes).The distribution of karst caves is adaptive with the corresponding base levels of erosion (modern riverbeds,terraces at all levels).It is inferred that the research area has experienced at least four large-scale intermittent rapid tectonic uplifts.The planation surfaces at all levels were affected the Ⅱ and Ⅱ episodes of the Himalayan Movement.Incision of abundant groundwater and surface water resulted in multilayer denudation platforms during these tectonic processes.During the relatively stable period of the neotectonic movement,there were adequate conditions of alternating cycle dissolution,leading to development of large-scale vertical and horizontal karst.
下载: