全文快速搜索:          
引用本文:孙磊,谢远云,康春国,迟云平,杜慧荣,王嘉新. 呼伦贝尔沙地重矿物、Sr-Nd同位素组成及其对亚洲风尘系统的指示[J]. 中国地质, 2021, 48(6): 1965-1974.
SUN Lei,XIE Yuanyun,KANG Chunguo,CHI Yunping,DU Huirong,WANG Jiaxin. Heavy minerals, Sr-Nd isotopic composition of sandy land in Hulun Buir, Inner Mongolia and their implications for Asian aeolian dust system[J]. Geology in China, 2021, 48(6): 1965-1974(in Chinese with English abstract).
【打印本页】   【HTML】   【下载PDF全文】   查看/发表评论  下载PDF阅读器  关闭
←前一篇|后一篇→ 过刊浏览    高级检索
本文已被:浏览 341次   下载 1272 本文二维码信息
码上扫一扫!
分享到: 微信 更多
呼伦贝尔沙地重矿物、Sr-Nd同位素组成及其对亚洲风尘系统的指示
孙磊1, 谢远云1,2, 康春国3, 迟云平1,2, 杜慧荣1, 王嘉新1
1.哈尔滨师范大学地理科学学院, 黑龙江 哈尔滨 150025;2.哈尔滨师范大学寒区地理环境监测与空间信息服务黑龙江省重点实验室, 黑龙江 哈尔滨 150025;3.哈尔滨学院地理系, 黑龙江 哈尔滨 150086
摘要:
呼伦贝尔沙地作为中国北方沙漠的重要组成部分,对其物质组成的深入探讨对于亚洲风尘系统的研究具有重要意义。重矿物特征和Sr-Nd同位素组成是解开沉积物演化过程和物源示踪的重要工具,但分选作用所造成的"粒度效应"一直是沙地重矿物和Sr-Nd同位素组成的制约因素。为分析呼伦贝尔沙地的物质组成及探讨分选作用对重矿物和Sr-Nd同位素组成的影响,采集了呼伦贝尔沙地19个风成沙和河流沙样品,并进行了分粒级处理。其中,对12个子样(<73 μm和73~125 μm两个粒级)进行了重矿物的鉴定分析,对23个子样(<63 μm、<30 μm和<11 μm三个粒级)进行了Sr-Nd同位素的测定。结果表明:不同粒度组分的重矿物含量、重矿物指数(ATi、GZi和ZTR)和重矿物组合存在明显差异;稳定和极其稳定矿物优先富集于细颗粒,使细颗粒沉积物的总体稳定程度加强。与以往Sr-Nd同位素粒度控制的研究结果不同,本文研究结果显示,87Sr/86Sr比值受粒度的影响很小,但Nd同位素组成明显受粒度效应的影响,并表现出粗颗粒组分有更高Nd同位素比值的趋势。Sr-Nd同位素组成存在时间效应,随时间发生变化,表明了风尘源区地球化学组成的不稳定性,这对于利用重矿物和Sr-Nd同位素进行亚洲风尘系统研究具有重要指示,在物源示踪时必须考虑宽/多粒度窗口以及充足的样品量以弥补粒度和时间效应带来的偏差。
关键词:  重矿物  Sr-Nd同位素  物源  气候变化  环境地质调查工程  呼伦贝尔沙地  内蒙古
DOI:10.12029/gc20210622
分类号:P736.2
基金项目:国家自然科学基金项目(41871013,42171006)和黑龙江省自然科学基金项目(LH2020D009)联合资助。
Heavy minerals, Sr-Nd isotopic composition of sandy land in Hulun Buir, Inner Mongolia and their implications for Asian aeolian dust system
SUN Lei1, XIE Yuanyun1,2, KANG Chunguo3, CHI Yunping1,2, DU Huirong1, WANG Jiaxin1
1.College of geographic science, Harbin Normal University, Harbin 150025, Heilongjiang, China;2.Heilongjiang province key laboratory of geographical environment monitoring and spatial information service in cold regions, Harbin Normal University, Harbin 150025, Heilongjiang, China;3.Geography Department, Harbin institute, Harbin 150086, Heilongjiang, China
Abstract:
As an important part of Northern China Desert, Hulun Buir sandy land is of great significance to the study of dust system in Asia. The characteristics of heavy minerals and the composition of Sr-Nd isotopes are the important tools to reveal the sediment evolution process and trace the provenance. But the "grain size effect" caused by sedimentary sorting has always been the limiting factor for the composition of heavy minerals and Sr-Nd isotopes in sandy land. Totally 19 aeolian sand and fluvial sand samples were collected from Hulun Buir sandy land and screened to analyze the material composition and discuss the effect of separation on the composition of heavy minerals and Sr-Nd isotopes. Among them, 12 sub-samples (<73 μm and 73-125 μm) were identified and analyzed for heavy minerals, and 23 sub-samples (<63 μm,<30 μm and <11 μm) were determined for Sr-Nd isotopes. The results show that there are significant differences in heavy mineral content, heavy mineral index (ATi, GZi and ZTR) and heavy mineral assemblage with different particle sizes. The stable and extremely stable minerals are concentrate preferentially onto the finer particles, which enhances the overall stability of the fine-grained sediments. Different from previous studies on Sr-Nd isotopic grain size control, our results show that the 87Sr/86Sr ratio is slightly affected by the grain size effect, but the Nd isotopic composition is significantly affected by it, and the coarse-grained components tend to have a higher Nd isotopic ratio. The Sr-Nd isotopic composition of Hulun Buir sandy land has "time effect". It shows that the geochemical composition of the dust source area is unstable. This study is of great significance for the understanding of Asian aeolian dust system study using heavy mineral and Sr-Nd isotopic composition. The wide or multiple grain size window as well as substantial amount of samples must be considered for source tracing.
Key words:  heavy mineral  Sr-Nd isotopic ratio  provenance  climatic change  environmental geological survey engineering  Hulun Buir sandy land  Inner Mongolia