半干旱区沼泽沉积剖面特征元素比值及其物源、氧化还原变化信息

Ratios of Specific Elements and Their Implications for Original Source of Sediments and Redox Condition within Sedimentation Profile of the Marsh in Semi-arid Areas

沼泽发育过程中堆积的各类沉积物真实地记录了区域环境演变与沼泽发育过程。以霍林河下游漫流区向海沼泽湿地为研究对象,由137Cs2、10Pb法定年实现沉积层深度坐标向年代坐标的转换,对其典型沉积剖面特征元素比值进行了综合剖析。结果表明:稳定元素对比值Ti/Al是判断不同沉积物来源是否一致的较好指标。剖面上下Ti/Al比值在一定层序的波动变化表明物源的波动性,洪水成因可能性较大。综合比较,V/(V+Ni)比值用于沼泽湿地缺氧沉积环境的判别标准可靠性较好。贫氧环境是向海沼泽湿地主要特征之一,其次是缺氧或含氧环境,各环境之间频繁振荡,体现了内流河下游半干旱区沼泽地表水周期和干湿环境转换频繁的特征。

Accumulative sediments during marsh development really recorded the region environment change and marsh processes. A case study on the Xianghai marsh wetlands at downstream of an interior river-Huolin River has been conducted and ratios of specific elements in the typical sedimentation profile has been revealed on the basis of ^137Cs,^210Pb dating result. The ratio of dual stable elements Ti/Al can be served as a good indicator to determine whether original source of sediments came from the same provenance and the fluctuation of Ti/Al ratio represented the change of the original source of sediments that might be caused by flooding events. Totally the ratio of V/（V＋Ni） is a good indicator to judge the oxygen-deficient facies sedimentation environment of marsh wetlands. The sediments in Xianghai marsh wetlands is typically characterized by dysaerobic environment and much or less anaerobic or aerobic environment. Frequent vibration among them indicates the character of frequently change between arid and humid environment in periods of surface water downstream of an interior river in semi-arid region.