牛改红^1,2,,
李孝泽^1,,,
王兆云^1,2,
金培红³,
柳本立^1,4
1. 中国科学院西北生态环境资源研究院, 中国科学院沙漠与沙漠化重点实验室, 甘肃 兰州 730000
2. 中国科学院大学, 北京 100049
3. 中国科学院西北生态环境资源研究院油气资源研究中心, 甘肃 兰州 730000
4. 甘肃省戈壁荒漠生态与环境野外科 学观测研究站(敦煌), 甘肃 敦煌 736200

基金项目: 中国科学院沙漠与沙漠化重点实验室基金项目（批准号：KLDD-2020-013）、新疆生产建设兵团地质勘查基金项目（批准号：DD2018001和2016006）和中国科学院青年创新促进会优秀会员项目（批准号：Y202085）共同资助


详细信息

作者简介: 牛改红, 女, 25岁, 硕士研究生, 自然地理学专业, E-mail: niugaihong@lzb.ac.cn

通讯作者: 李孝泽, E-mail: lixiaoze@nieer.ac.cn

中图分类号: P534.62;P512.21/P931.1

收稿日期:2021-03-29
修回日期:2021-06-10
刊出日期:2021-11-30

Depositional environment evolution of ZK1 drilling section since 8 Ma in the Baiyanghe alluvial fan on the western margin of Junggar Basin, NW China

NIU Gaihong^1,2,,
LI Xiaoze^1,,,
WANG Zhaoyun^1,2,
JIN Peihong³,
LIU Benli^1,4
1. Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, Gansu
2. University of Chinese Academy of Sciences, Beijing 100049
3. Oil and Gas Research Center, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, Gansu
4. Research Station of Gobi Desert Ecology and Environment in Dunhuang of Gansu Province(Dunhuang), Dunhuang 736200, Gansu


More Information

Corresponding author: LI Xiaoze,E-mail:lixiaoze@nieer.ac.cn

MSC: P534.62;P512.21/P931.1

--> Received Date: 29 March 2021
Revised Date: 10 June 2021
Publish Date: 30 November 2021


摘要
摘要:准噶尔盆地西缘白杨河冲洪积扇发育典型，但其环境过程问题亟待解决。在该扇西缘ZK1剖面（137 m深）古地磁定年基础上，提取粒度、磁化率、有机质、碳酸钙、孢粉、砂粒微形态、矿物成分等样品信息，综合分析表明：8 Ma以来研究区环境主要在中纬度内陆干旱荒漠至荒漠草原范围演变，包括2个阶段6个亚阶段：阶段Ⅰ（8.1~5.3 Ma）主要为湖泊期，包括亚阶段1（8.1~7.2 Ma）浅湖、亚阶段2（7.2~6.9 Ma）戈壁和亚阶段3（6.9~5.3 Ma）滨湖；阶段Ⅱ（5.3 Ma至今）为冲洪积扇期，由亚阶段4（5.3~3.6 Ma）扇体开始发育形成的干冷扇缘、亚阶段5（3.6~1.1 Ma）为较干冷环境下的第二次快速成扇期和亚阶段6（1.1 Ma至今）最干冷环境下的第三次极快成扇期组成。该扇主要形成于5.3 Ma以来，主要经历了5.3 Ma、3.6 Ma、1.1 Ma等3次成扇期。其发育阶段和环境演化与晚新生代古地中海Messinian期干化事件、半球乃至全球阶段性降温、青藏高原隆升及其远程效应等关系密切。
关键词: 晚新生代/
准噶尔盆地/
冲洪积扇/
环境演变

Abstract:The alluvial fans and their stratigraphies, widely developed in the inland basin-mountain transition zone of Northwest China, are good records of regional environmental evolution and the major geological and palaeo-environmental events of the Late Cenozoic, such as, the inland aridification of Central Asia, the uplift of the Qinghai-Tibet Plateau and its effects etc. Among the numerous alluvial fans distributed across the foothills of the western margin of the Junggar Basin, the Baiyanghe alluvial fan is typical and relatively large, provides a favorable geomorphological and stratigraphic setting for investigating the environmental evolution and strongtium-rich water and soil of this region. At present, the environmental evolution of the fan demand deeperly studies. Here by field investigation the paper is mainly on the paleomagnetic chronology and palaeo-environmental reconstruction of ZK1 (137 m depth) profile(46°18'59.04″N, 84°43'45.11″E) drilled in the western margin of the Baiyanghe alluvial fan.
About the paleomagnetic chronology study, a total of 200 paleomagnetic samples of ZK1 section were selected for thermal or alternating demagnetization. According to 171 effective magnetic dip data obtained, the magnetostratigraphic polarity sequence of ZK1 section was constructed. Correlation with GPTS of Cande and Kent showed, the section has deposited since 8 Ma, in which the age of 134.4 m, 94.0 m, 67.4 m and 28.3 m layers were 8.07 Ma, 5.30 Ma, 3.58 Ma and 2.58 Ma, respectively.
Based on the above timescale, the palaeo-environment reconstruction of the fan was carried out, in which the environmental proxy indexes include particle size, magnetic susceptibility, organic matter, calcium carbonate, sporo-pollen, surface microstructure characteristics of quartz sand, mineral composition, deposition rate, etc. The comprehensive analysis showed that, since 8 Ma, the environments of the study area has basically evolved from inland arid desert to desert steppe in the middle latitude, including two stages and their six sub-stages. Stage Ⅰ(8.1~5.3 Ma) comprised a shallow lake environment in temperate inland arid desert steppe during substage 1 (8.1~7.2 Ma), an arid desert Gobi environment during substage 2 (7.2~6.9 Ma), and a lakeside environment in arid desert steppe during substage 3 (6.9~5.3 Ma). Stage Ⅱ(< 5.3 Ma) is alluvial fan formed by a dry and cold temperate interior arid desert or desert steppe environment during substage 4 (5.3~3.6 Ma), followed by the second period of extremely rapid fan formation under further drying and cooling of the inland arid desert or desert steppe environment during substage 5 (3.6~1.1 Ma), and finally the third period of extremely rapid fan formation under a shift in from inland arid desert environment during substage 6(< 1.1 Ma). The Baiyanghe alluvial fan was mainly formed since 5.3 Ma, dominantly during three fan-building periods starting at 5.3 Ma, 3.6 Ma and 1.1 Ma, respectively. These development stages and their corresponding environmental drivers are basically related to Mediterranean drying event happened in 5.5~5.3 Ma, periodic cooling of hemispheric or global temperatures, uplift of the Qinghai-Tibet Plateau and its far-field effects.
Key words:Late Cenozoic/
Junggar Basin/
alluvial fan/
environmental evolution



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