欢迎访问《高校地质学报》官方网站,今天是
分享到:

高校地质学报

• 构造地质学与沉积学 • 上一篇    下一篇

中国典型河流沉积物石英释光性质初探及其物源指示意义

刘健辉,姜锋, 陈杰,孙千里,陈静*, 陈中原   

  • 出版日期:2018-02-20 发布日期:2018-02-26

Luminescence Properties of Quartz in the Sediments from Typical Chinese Rivers and Their Implications for Provenance

LIU Jianhui,JIANG Feng,CHENJie,SUN Qianli,CHENJing*,CHENZhongyuan   

  • Online:2018-02-20 Published:2018-02-26

摘要: 石英是地球表面分布最广的矿物之一,抗风化能力较强且性质稳定,是母岩信号的最佳载体。前人研究结果表明石
英的释光(包括光释光OSL 和热释光TL) 灵敏度和母岩以及沉积过程存在一定关系,已初步被应用于沙漠沉积物的判源研
究中。河流与海域沉积物相关研究在国内研究较少,文章拟尝试对中国东部沿海三条重要河流(黄河、长江和浊水溪) 沉
积物中的石英释光性质进行分析,探讨其应用于物源判别的可能性。通过7 个粒级(<4 μm 、4~16 μm 、16~32 μm 、32~
45 μm 、45~63 μm 、63~90 μm 、90~125 μm) 的石英释光灵敏度的对比分析发现,同一河流下游河口沉积物中不同粒级的
石英释光灵敏度差异明显,<4 μm 和>45 μm 粒级的石英110℃TL 峰和OSL 灵敏度较小,4~45 μm 粒级较强;黄河、长江
和浊水溪同粒级沉积物中石英110℃TL 峰和OSL 灵敏度均有明显差异,尤其是63 μm 以下粒级,均表现为长江最大,黄河
次之,浊水溪最小。母岩差异和流域搬运—沉积过程是影响河流沉积物石英释光灵敏度的主要因素。沉积物在长江流域内
的滞留时间长,石英在流域内的辐照—晒退循环次数增多从而使其释光灵敏度增大,同时流域内广泛分布的富含微量元素
的火成岩产出的石英晶体晶格缺陷较多,这两者导致其石英释光灵敏度较大。黄河河口沉积物中石英释光灵敏度继承了其
源区黄土高原的特征。浊水溪是山溪性短途河流,水面坡降大,沉积物可迅速被从源区搬运至河口区,石英接受辐照—晒
退循环次数少,且其源区母岩多以变质岩为主,这可能是其石英释光灵敏度偏小的原因。石英释光灵敏度随粒级的变化,
推测与石英自身发光性质以及河流中沉积物搬运方式的不同有关。泥沙入海后,石英释光灵敏度虽然存在随海域搬运—沉
积过程增大的可能性,但据上述研究来看,其增加幅度可能远小于长江、黄河和浊水溪河流间石英释光灵敏度的差值,因
此可尝试利用细粒级(4~45 μm) 石英释光灵敏度为指标进行黄、东海陆架物源追踪探索。

关键词: 石英, 物源, 黄河, 长江, 浊水溪, 释光灵敏度

Abstract: Quartz, one of the most widely distributed minerals on the earth surface, is believed to be the best carrier inheriting parent
rock information due to its strong resistance to weathering. The luminescence (thermoluminescence and optically stimulated
luminescence) sensitivity of quartz has been preliminarily tried to trace eolian sediment provenances since it is closely related to its
parent rock and transport-deposit processes. However, little is known about luminescence properties of quartz in the fluvial sediments.
The present study compares the luminescence properties of quartz derived from three important rivers of the eastern China (Huanghe,
Yangtze and Zhuoshui) and further discuss its possibility of tracing marine sediments. Through analysis of luminescence sensitivity of
quartz among 7 sediment size fractions (<4 μm, 4~16 μm, 16~32 μm, 32~45 μm, 45~63 μm, 63~90 μm, 90~125 μm) from Huanghe,Yangtze and Zhuoshui rivers, the results show that the luminescence sensitivities of 110℃ TL peak and OSL of quartz changed with
quartz grain size and the sensitivities of fine and coarse quartz grains are much lower than those of medium quartz (4~45 μm). It is also
found a significant difference of luminescence sensitivities in all quartz particle fractions among Huanghe, Yangtze and Zhuoshui
rivers, with the highest in Yangtze and the lowest in Zhuoshui River. The irradiation and bleaching experiments indicate that
transport-deposit processes might have increased the luminescence sensitivities of quartz to some degree. The quartz experienced more
irradiation and bleaching cycles in the Yangtze drainage basin because the transport time of sediments from source to sink was much
longer, which might lead to high luminescence sensitivities of quartz. Besides, the quartz generated from mafic igneous rocks in the
upper Yangtze also had high luminescence sensitivities. The luminescence sensitivities of quartz from Huanghe sediments inherit
quartz properties from Loess Plateau. As a short mountainous river, Zhuoshui River transported sediments quickly from source to the
sink, which resulted in low luminescence sensitivities of quartz due to less irradiation and bleaching cycles. In addition, metamorphic
rocks distributed widely in the drainage basin produced quartz with low luminescence sensitivities. Meanwhile, high luminescence
sensitivities of quartz with medium grain size were believed to the related to fluvial transport pathway and quartz properties. Although
increases in quartz luminescence sensitivities are predictable when fluvial sediments are transported in the sea, the increment might be
much less than the differences among the three rivers based on the above results. Therefore, quartz luminescence properties of 4~45
μm fraction are suggested to use for tracing marine sediments in the shelf of Yellow Sea and the East China Sea.

Key words: quartz, provenance, Huanghe, Yangtze, Zhuoshui, luminescence sensitivity