吉林大阳岔地区小阳桥寒武-奥陶剖面中海绿石矿物学研究

本文总结了小阳桥剖面的寒武系-奥陶系界线附近海绿石矿物学特征,并对该地层剖面附近的沉积环境进行讨论。

MINERALOGICAL STUDY OF GLAUCONITE IN A CAMBRIAN-ORDOVICIAN PROFILE AT XIAOYANG-QIAO AREA, DAYANGCHA, JILIN PROVINCE

In this paper the mineralogical characters of glauconites occurred at the lower and upper parts of the boundary between Cambrian and Ordovician of Xiaoyangqiao profile are summarized. The sedimentary environment of the strata is also discussed.The samples of the glauconites have been determined by various methods such as X-ray diffraction, scaning-electromicroscopy, differential thermal analysis, infrared and mossbauer spectroscopy, exchange capacity of cations and X-ray fluorescence spectrum analysis, etc.The X-ray powder analysis revealed that the glauconites have the 1M-1Md mica type of structure and belong to the dioctahedral type of structure, but the modern sediments of glauconites of South and East China Sea have an intermediate structure between the dioctahedral and trictahedral types. The expanding layers in glauconites of the research area and of South and East China Sea are 10-15% and 20% respectively.The main compositions for studied glauconites are similar. In these glauconites, K2O is about 7 wt%, Fe2O3 about 13-16 wt%, FeO 3-4 wt% and Al2O3 11-13 wt%, but the glauconites in recent ocean are high in Fe2O3 and low in K2O and Al2O3.The mineralogical characters of glauconites ocurred at the upper and lower parts of the boundary between Cambrian and Ordovician are similar, suggesting that the formation environments of the glauconites are similar and belong to shallow sea sedimentary facies with inclined slope, but the glauconite in arenite may be formed in a slightly different environment. It may undergone transformation of diagenesis changes.