基于SEM的辽南红色风化壳石英颗粒化学成因特征分析

CHARACTERIZATION OF THE CHEMICAL GENESIS OF RED WEATHERED CRUST QUARTZ GRAINS IN THE SOUTHERN LIAONING PROVINCE BASED ON SEM

石英颗粒表面形态特征广泛应用于古气候与古环境的重建。本研究选取辽南地区3个红色风化壳剖面,运用扫描电镜对其石英颗粒表面化学成因特征进行分析。然后根据化学成因特征构建化学作用度函数并建立量化指标,以揭示气候因子对石英颗粒表面改造的影响,在此基础上分析辽南地区红色风化壳发育特征的空间差异。结果表明:石英颗粒表面化学成因的特征以代表湿热气候的高能化学环境为主,指示风化壳在形成过程中经历了湿热的气候环境;将石英颗粒表面化学作用度与化学蚀变指数(CIA)进行比较,两者具备较强对应关系,且变化趋势呈现出很好的同步性,具有较强拟合性,进一步证明了石英颗粒表面化学作用度对气候环境的指示作用;对比各剖面化学作用度,剖面之间呈现出一定的差异性,从整体来看,辽南中部红色风化壳发育程度最高,东、西部红色风化壳发育程度次之。

The morphological characteristics of quartz particles are widely used in the reconstruction of paleoclimate and paleoenvironment. In this paper, three red weathering crust samples were selected from the southern Liaoning Province, namely, Lashufang sample collection site(LSF:39° 03′50″N, 121° 36′32″E), Chengshantou sample collection site(CST:39° 08′18″N, 122° 06′04″E), and Qidingshan profile(QDS:39° 15′07″N, 121° 41′02″E). The chemical genetic characteristics of quartz particles in red weathering crust were analyzed by scanning electron microscopy, on which the chemical interaction degree function was established and the quantitative indexes were established to reveal the influence of climatic factors on the surface modification of quartz particles, and on this basis, the paper analyzed the spatial differences in the developmental characteristics of red weathering crusts in southern Liaoning. The results show that the characteristics of the surface chemistry of quartz particles are mainly the high-energy chemical environment represented by the hot and humid climate, indicating that the weathering crusts experienced the hot and humid climate during the course of formation. After comparing chemical interaction degree of quartz particles and CIA value, they have a strong correspondence relationship, and the trends show good synchronization and a strong fit, further demonstrating the the chemical interaction degree play an indicative role in the climatic environment. Comparing the chemical interaction degree of each profile, the variability between profiles is large. In the process of weathering crust development, Qidingshan profile is the most strongly affected■, followed by Lashufang profile■and Chengshantou profile■, reflecting the highest degree of red weathering crust development in the central part of southern Liaoning and the degree of red weathering crust development in the east and west ranking in the second position.