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西宁盆地保存了一套晚始新世(大约42～34 Ma)沉积的以红色泥岩和石膏为主交互产出的地层,其中石膏是该地重要的非金属矿产。石膏和红色泥岩具有明显的旋回特征,剖面下部和上部旋回厚度分别为约1m和2～5m,在盆地内具有良好的空间可对比性。这些旋回所跨越的时间与黄赤交角周期(4.1万年)和/或地球轨道周期(10万年)一致。在西宁盆地存在三种不同形态特征的石膏:微晶厚层状石膏、紧密堆积薄片状石膏和粗晶薄层状石膏。晚始新世西宁盆地气候干旱,水的补给量是西宁盆地石膏沉积的控制性因素。晚始新世地球黄赤交角和/或轨道周期性变化驱动了盆地内相对干旱和相对湿润环境的交互出现,相对湿润的气候为石膏沉积提供了有利条件,由水的补给量控制的潜水面高低导致了三种形态石膏层的形成。
The Xining basin has preserved a series of sedimentary facies of late Paleocene (~ 42-34 Ma) sedimentary dominated by red mudstone and gypsum, of which gypsum is an important non-metallic mineral. Gypsum and red mudstone have obvious gyration characteristics. The thickness of the lower part and the upper part of the profile are about 1m and 2 ~ 5m, respectively. There is good spatial contrast in the basin. The times spanned by these cycles are consistent with the Yellow-Ridge Crossing Period (41,000 years) and / or the Earth orbital period (100,000 years). There are three different types of gypsum in the Xining basin: thin-bedded gypsum, closely packed flaky gypsum, and coarse-grained thin-layer gypsum. Late Eocene Xining basin climate arid water recharge is the controlling factor of gypsum deposition in Xining basin. Late Pleistocene Earth’s yellow-reddish angle and / or periodic orbital changes drove the interaction of relatively dry and relatively humid environments in the basin. Relatively humid climate provided favorable conditions for gypsum deposition. Submersible surfaces controlled by water recharge Level led to the formation of three types of gypsum layer.