贺兰山汝箕沟三叠纪钙质结核特征及环境意义

Characteristics and environmental significance of the calcareous coneretions in Rujigou of Hela mountain

研究贺兰山汝箕沟三叠统延长组地层发育钙质结核的形态,通过宏观、微观观察,分析钙质结核层特征,通过野外数据采集分析地球化学特征和环境特征.结果表明:钙质结核中微量元素Ba含量相对富集,而其他微量元素,如V、Sr、Co、Zr、Cr、Rb、Ni、B等含量相对较少;钙质结核中CaO质量分数为32.28%,CaO与MgO的质量分数比为27.31,表明其生成在温度较高、气候炎热、蒸发量大而且较为干旱的时期.因此,分析钙质结核的特征,对研究区当时的沉积环境研究有一定意义.

Many different sizes of spherical calcareous coneretions was found in the group of Upper Triassic strata in Rujigou of Helan Mountain.They are embedded in the purple-red siltstone strata.Researches into their geochemical characteristics have shown that the Ba content is relatively high,but the contents of V,Sr,Co,Zr,Cr,Rb,Ni and B are relatively low.The contents of Cao and CaO/MgO are 32.28% and 27.31%,which show that they were formed during the an extreme climate with high temperature,rapid evaporation and dry weather.In short,the emergence of calcareous coneretions can be seen as a more reliable weather signs.