张伊琳^1,,
董艳¹,
吴超²,
钱鹏^1,,,
郑祥民²
1. 南通大学地理科学学院, 江苏 南通 226007
2. 华东师范大学地理科学学院, 上海 200241

基金项目: 国家自然科学基金项目（批准号：41601189和41671003）、江苏省大学生创新创业训练计划重点项目（批准号：201510304049Z）和南通市重点实验室项目（批准号：CP12016005）共同资助


详细信息

作者简介: 张伊琳, 女, 23岁, 本科大学生, 地理科学(师范)专业, E-mail:550996190@qq.com

通讯作者: 钱鹏, E-mail:tempo@ntu.edu.cn

中图分类号: S151;P595

收稿日期:2017-10-26
修回日期:2018-01-17
刊出日期:2018-03-30

Diffuse reflectance spectrum characteristics of the Huangnishan loess in Nantong, Jiangsu Province and their paleoenvironmental significances

Zhang Yilin^1,,
Dong Yan¹,
Wu Chao²,
Qian Peng^1,,,
Zheng Xiangmin²
1. School of Geography, Nantong University, Jiangsu Nantong 226007
2. Department of Geography, East China Normal University, Shanghai 200241


More Information

Corresponding author: Qian Peng,E-mail:tempo@ntu.edu.cn

MSC: S151;P595

--> Received Date: 26 October 2017
Revised Date: 17 January 2018
Publish Date: 30 March 2018


摘要
摘要:选取长江下游江苏南通黄泥山黄土堆积为研究对象，运用磁滞回线、热磁曲线与漫反射光谱特征分析其磁性矿物组成，结合色度参数、地球化学特征，探讨黄泥山黄土记录的古环境信息。研究发现，黄泥山黄土中亚铁磁性矿物主要为磁铁矿、磁赤铁矿，不完整反铁磁性矿物主要为赤铁矿（Hm）、针铁矿（Gt）。剖面中Hm/Gt值在U1（147~124 cm）和U3（39~0 cm）层中小于1，在U2（123~40 cm）层中大于1，这指示U1、U3层形成于相对干燥的气候环境，U2层形成于相对湿润的气候环境。色度参数亮度（L^*）、红度（a^*）值与磁化率（χ）及总铁的百分含量（TFeOx%）、化学风化指数（CIA）随深度变化趋势相关性明显，且指示U1和U3层经历了相对U2层较弱的成壤作用。因此，黄泥山黄土漫反射光谱特征及色度参数L^*和a^*值可作为黄土风化与夏季风强度的替代性指标。与其他典型黄土剖面特征对比，黄泥山黄土总体上经历了相对干冷的气候环境，其中U2阶段的沉积环境相对暖湿，U1和U3较为干冷。该研究对长江下游地区古气候干湿变化及古环境重建具有一定的参考价值。
关键词: 下蜀黄土/
漫反射光谱/
磁化率/
古环境/
南通

Abstract:The Huangnishan loess section(31°57'11.51″N, 120°52'28.18″E) is located at the lower reaches of the Changjiang River with the altitude of 29.3 meters, and the profile is ca.147 cm in thickness. In this study, samples of the Huangnishan loess were collected at 6 cm intervals and subjected to the analyses of diffuse reflectance spectrum environmental magnetism and geochemical compositions. The magnetic hysteresis loop and thermomagnetic curve illustrate that the main ferrimagnetic minerals in the Huangnishan loess are magnetite and maghemite. The diffuse reflectance spectrum data show that the imperfect antiferromagnetic minerals in the Huangnishan loess are mainly of hematite(Hm)and goethite(Gt). Based on lithology and magnetic susceptibility(χ), 3 units are identified in the Huangnishan section. Hm content is relative lower in layer U1 (147~124 cm)and U3 (39~0 cm)than that in layer U2 (123~40 cm). The Hm/Gt ratio values in layer U1 and U3 are less than 1, and more than 1 in layer U2, indicating that layer U1 and U3 were formed in the relatively dry environment, and layer U2 was formed in relatively humid environment. The trends of brightness(L^*)and redness(a^*)curves of chroma parameters have significant correlation with the proxies of magnetic susceptibility(χ)and TFeOx%, CIA, indicating that the pedogenesis of layer U1 and U3 were weaker than that of layer U2. Therefore, Hm/Gt, L^* and a^* values in the Huangnishan loess can be used as the proxy indexes of pedogenesis and paleoenvironment. In conclusion, the Huangnishan section has experienced relatively dry-cold condition. During this period, layers U1 and U3 have relatively weak pedogenic and dry-cold condition, and layer U2 have relatively strong pedogenic and wet-warm environment. This study could contribute to the scientific study of paleoclimate changes and paleoenvironment reconstructions in the lower reaches of the Changjiang River.
Key words:the Xiashu loess/
diffuse reflectance spectrum/
magnetic susceptibility/
paleoenvironment/
Nantong



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