地理科学 ›› 2017, Vol. 37 ›› Issue (12): 1885-1893.doi: 10.13249/j.cnki.sgs.2017.12.012

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地球化学组成揭示的杜蒙沙地化学风化和沉积再循环特征及其对风尘物质贡献的指示

袁方1(), 谢远云1(), 詹涛2, 康春国3, 迟云平1, 马永法2   

  1. 1. 哈尔滨师范大学黑龙江省普通高等学校地理环境遥感监测重点实验室,黑龙江 哈尔滨 150025
    2. 黑龙江省第二水文地质工程地质勘察院,黑龙江 哈尔滨 150030
    3. 哈尔滨学院地理系,黑龙江 哈尔滨 150086
  • 收稿日期:2016-12-06 修回日期:2017-03-21 出版日期:2017-12-20 发布日期:2017-12-20
  • 作者简介:

    作者简介:袁方(1992-),女,硕士,主要研究方向为亚洲风尘系统物源示踪。E-mail:535038276@qq.com

  • 基金资助:
    国家自然科学基金项目(41471070)资助

Source-area Weathering and Recycled Sediment for Dumeng Sandy Land Inferred from Geochemistry Compositions: Implication for Contribution to Aeolian Dust

Fang Yuan1(), Yuanyun Xie1(), Tao Zhan2, Chunguo Kang3, Yunping Chi1, Yongfa Ma2   

  1. 1. Key Laboratory of Remote Sensing Monitoring of Geographic Environment for Heilongjiang Province, Harbin Normal University, Harbin 150025, Heilongjiang, China
    2. The Second Hydrogeology and Engineering Geology Prospecting Institute of Heilongjiang Province, Harbin 150030, Heilongjiang, China
    3. Geography Department, Harbin Institute, Harbin 150086, Heilongjiang, China
  • Received:2016-12-06 Revised:2017-03-21 Online:2017-12-20 Published:2017-12-20
  • Supported by:
    National Natural Science Foundation of China(41471070).

摘要:

对杜蒙沙地的河流冲积砂、河漫滩泥质粉砂、沙质古土壤和风成沙等不同类型沉积物进行了采样(27组),对这些样品的细颗粒组分(<63 μm)进行了常量元素、微量元素、稀土元素(REE)和Sr-Nd同位素比值等地球化学分析,就杜蒙沙地的化学风化、沉积再循环特征及其对风尘物质的贡献等展开了讨论。结果显示,杜蒙沙地的地球化学组成表现出空间的均一性,低的化学蚀变指数CIA(48~56,平均52)及A-CN-K和A-CNK-FM图解均表明了杜蒙沙地仅遭受了低级的化学风化程度。沙地的成分成熟度较低,大部分河流沉积物表现出初次循环沉积特征,系大兴安岭东侧中酸性岩浆母岩风化剥蚀的产物经嫩江搬运堆积形成;古土壤表现出与河流沉积物相同的初次循环特征,表明古土壤的成土母质是河流沉积物,这与野外地层出露情况一致;风成沙表现出再循环沉积特征,系河流沉积物就地起沙搬运堆积形成。不活动元素比值、REE和Sr-Nd同位素比值等物源判别图解,结合植被和地貌状况,一致表明杜蒙沙地与东北平原中东部的风尘物质没有地球化学亲缘关系,其对该地区(甚至下风向更远地区)的大气风尘的贡献很小。

关键词: 杜蒙沙地, 地球化学组成, 沉积再循环, 化学风化, 风尘物质

Abstract:

In this study, twenty seven sets of the <63 μm fine-grained subsamples from fluvial sand, floodplain muddy silt, sandy paleosoil and aeolian sand, respectively, in Dumeng Sandy Land, were collected and analyzed for major, trace elements and REE as well as Sr-Nd isotopic compositions to evaluate their source-area chemical weathering and sediment recycling, and to infer their contribution to aeolian dust. It can be concluded, based on low values of chemical index of alteration (CIA=48 to 56, mean value of 52), combined with A-CN-K and A-CNK-FM diagrams, that Dumeng Sandy Land was subjected to weak degree of chemical weathering. The relatively high values of index of compositional variability (ICV=0.95 to 1.2, mean value of 1.05) suggest an immature source. It follows from Zr/Sc vs. Th/Sc plot, integrated with CIA vs. WIP and MFW plots that the majority of fluvial sediments are characterized by first-cycle sediment, sourced from weathering-eroding products of intermediate to felsic rocks in eastern Great Xingan Mountains by transportation of NenJiang River and its tributaries. The paleosoils have the identical first-cycle fingerprints to fluvial sediments, suggestive of their soil parent material being fluvial sediments, consistent with field observation. The good sediment recycled signature, however, characterizes aeolian sands, suggesting that these aeolian sands were derived in situ from fluvial sediments. The integrated provenance tracing plots, involving the ratio of immobile elements, REE and Sr-Nd isotopic composition, in combination with vegetation and geomorphy feature, consistently suggest that Dumen Sandy Land bears a poor geochemical affinity with aeolian dust, indicative of its very little contribution to atmospheric dust to the eastern and central NE Plain.

Key words: Dumeng Sandy Land, geochemistry composition, sediment recycling, chemical weathering, aeolian dust

中图分类号: 

  • P512.2