Rhythms of saline lake sediments of the Palaeogene and their palaeoclimatic significance in the Qianjiang Sag, Jianghan Basin
Zhang Yongsheng Yang Yuqing Wang Guoli Qi Zhixian
1 Institute of Mineral Resources, Chinese Academy of Geological Sciences(CAGS);
2 Open Laboratory of Saline Lake Resources and Environments, CAGS, Beijing 100037
3 Logging, Welltech-China Oilfield Services Limited, Beijing 101149
4 Department of Science and Technology Development, SINOPEC, Beijing 100029
5 Institute of Exploration and Development, Jianghan Oilfield Branch, SINOPEC, Qianjiang 433124, Hubei
Saline lake sediments are characterized by multi-stage and long peroid of salt formation, continuous sedimentation and cyclicity of salinization-desalinization, so they are an important research object with respect to the reconstruction of palaeoclimate and the study of global change. Take for example the salt rhythms of the Qianjiang Formation in the Qianjiang Sag of the Jianghan Basin (which is a typical Paleogene saline lacustrine basin in eastern China, through a detailed study on cores, the authors have determined for the first time the Ⅳ-order salt rhythm based on Ⅰ-,Ⅱ-and Ⅲ-order salt rhythms which were determined previously and got to know that the sedimentary process followed the primary balanced sequence of desalinizing →salinizing and crystallization of salt minerals from halite rock → (mud-bearing) glauberite rock → dolomite-bearing mudstone (mud-bearing dolomite)→ mudstone → dolomite → glauberite rock → halite rock. The authors also analyzed the grade Ⅳ-order salt rhythm and the correspondence its sedimentary records and the fluctuation of the palaeosalinity of waters and the short-scale (0.05 – 1.0 ka duration) change of dry-moist palaeoclimate. According to the wide developmentof the typical warm-phase salt minerals such as primary glauberite and its thin bed in the Qianjiang Formation, it may be inferred that the dry palaeoclimate in the drainage area of the Jianghan Basin during the Late Eocene to Early Oligocene was of warm-dry type, rather than of cold-dry type.
出版日期: 2005-08-01
作者简介: 张永生,男,1963年生,1995年获博士学位,现为中国地质科学院矿产资源研究所研究员,主要从事盐湖学和沉积学研究。E-mail: zys_601@126. com
. Rhythms of saline lake sediments of the Palaeogene and their palaeoclimatic significance in the Qianjiang Sag, Jianghan Basin[J]. JOPC, 2005, 7(4): 461-470.