为了明确鄂尔多斯盆地东部马家沟组岩盐的地球化学特征和成因,本文通过对碳酸盐岩C、O、Sr同位素及微量元素进行分析和研究,发现研究区内δ13C介于-0.346%~0.108%之间,Sr同位素比值明显较低,Sr/Ba比值均大于1。稀土元素总体上呈现轻稀土元素相对富集,重稀土元素相对亏损的特征。单元素Ce具有微弱的正异常,Eu具有明显的负异常,Sr/Cu比值均大于10,V/(V+Ni)值总体介于0.7~0.8之间。认为该区在马四、马五段沉积期气候干旱炎热,水体较深,处于还原环境,为典型的海相沉积环境,且岩盐在沉积的过程中有可能受到了幔源物质的影响。

In order to define the geochemical characteristics and cause of formation for the rock salt in the Majiagou Formation, east part of Ordos Basin, C, O, and Sr isotopes and trace elements of carbonate rocks are analyzed and studied. The results show that δ13C concentration is between -3.46‰ and 1.08‰, isotope ratios of Sr are significantly low, the ratio between Sr and Ba is generally bigger than one, LREE is enriched more than HREE, Ce has a weak positive anomaly, Eu has an obvious negative anomaly, and the ratio between V and (V+Ni) is between 0.7 and 0.8. Experimental results indicate that since the climate is dry and hot, the water is deep, and the depositional environment is reductive and marine, the depositional process of rock salt is affected by mantle derived materials.