四川盆地古近纪沙漠沉积特征及古风向意义  

Depositional Features of the Desert in the Paleogene Sichuan Basin and the Significance for the Reconstruction of Palaeowind Direction

作　　者：刘立安[1] 姜在兴[1] 

机构地区：[1]中国地质大学能源学院,北京100083

出　　处：《地质科技情报》2011年第2期63-68,共6页Geological Science and Technology Information

基　　金：国家科技重大专项(2009ZX05009-002);教育部"长江学者"与创新团队发展计划(IRT0864)

摘　　要：基于前人研究成果,通过野外地质调查、室内分析测试对四川盆地古近系柳嘉组红层沉积物的性质、结构、原生沉积构造及石英颗粒表面结构进行了系统分析,分析结果进一步证明了本区古沙漠的存在。将其沙漠沉积分为沙丘和丘间两种沉积类型,对丘间又细分为干丘间和湿丘间,针对不同的沉积类型也明确了相应的识别标志。通过对沙丘前积层倾向的测量,重建得到当时的古风向为西-北西西风向,古新世时期该地区受盛行西风带控制,同时也受到古地理格局的影响,这一现象同时也可能表明了当时的副热带高压带要比现在更偏向低纬,古大气环流强度也要弱于现在。Based on the field geological investigations and laboratory tests,and the previous research achievements,this paper makes a systematic analysis of the red bed deposits in Liujia Formation of the Paleogene Sichuan Basin in terms of the properties,textures,primary structures and the surface textures of the quartz grains.The analysis is made on the basis of the analysis results further confirm the existence of ancient deserts in this area.Moreover,this paper classifies the depositional types into two types： the sand dune and the interdune,with the interdune further classified into dry interdune and wet interdune.Besides,the paper presents different identification markers for different depositional types.By the measurement of the foreset bed,the palaeowind direction is reconstructed as W-NWW.This indicates this area was controlled by the prevailing westlies in Early Paleogene and influenced by the palaeogeographic framework as well.This phenomenon can show that,compared with the present time,the subtropical high pressure belt of Early Paleogene was closer towards the low latitude and the ancient atmosphere circulation was weaker in strength.

关 键 词：四川盆地 柳嘉组 古近纪沙漠 沉积特征 古风向 

分 类 号：P534.61[天文地球—古生物学与地层学]