摘要
通过野外露头及相关室内研究,分析了龙虎山世界地质公园及邻区白垩系辫状河相沉积特征及其与丹霞地貌发育规律关系。研究认为:龙虎山世界地质公园丹霞地貌发育除了与冲积扇相沉积有关外,还与辫状河相沉积有关,表现为辫状河道巨厚砂体为丹霞丘陵地貌发育提供物质基础;发育于辫状河道中呈小型透镜体或扁平状、脉状体的河床滞留沉积和洪泛沉积,易风化剥蚀形成溶蚀风化崩塌型丹霞地貌。此外,多期河道的多旋回沉积交错叠置形成楔状交错层理,其层系上下界面平直,层系厚度在小范围内变化很快,层系内细层的倾向相反,为后期风化剥蚀提供了条件,易形成溶蚀风化崩塌型丹霞地貌。进一步研究发现丹霞丘陵地貌、溶蚀风化崩塌型丹霞地貌分布与辫状河相沉积平面展布具有较好的一致性,吻合度较高。本文首次研究了辫状河沉积体系与丹霞地貌发育特征的关系。
Through field outcrop survey and indoor studies, the authors analyzed the relationship between Danxia landform development regularity and Cretaceous sedimentary characteristics of braided river facies in the Longhushan world geopark and adjacent areas. The results show that the development of Danxia landform was connected with not only alluvial fan facies sediments but also braided river facies sediments, characterized by the huge thick sand bodies of braided river facies which provided material basis for Danxia hilly landform. The mini-type lenticles and platykurtic or veinlike sediments of retention river and flood developed in braided river facies were weathered and denuded easily to form corrosion-weathering-collapse Danxia landform. Furthermore, the crossing superimposition of multi-cyclic sediments on multi-period river channels would form a wedge-shaped cross bedding that lineds up and down, the group thickness would change rapidly in a small area, and the dip directions of laminae were opposite to each other, which offered conditions to later stage weathering and denudation, thus easily forming corrosion-weathering-collapse Danxia landform. Further investigation has revealed that the distribution of Danxia hilly country and corrosion-weathering-collapse Danxia landform is well in accord with horizontal distribution of braided river sedimentary facies. This is the first study of the relationship between the braided river depositional systems and landform development characteristics.
出处
《地球学报》
EI
CAS
CSCD
北大核心
2012年第3期379-387,共9页
Acta Geoscientica Sinica
基金
江西省自然科学基金项目(编号:2010GZC0001)
龙虎山世界地质公园地质遗迹保护项目联合资助
关键词
龙虎山世界地质公园
丹霞地貌
白垩系
辫状河相沉积
Longhushan world geopark
Danxia landform
Cretaceous
braided river facies sediments
