Isotope ratios in Zechstein carbonates

Ten exploration wells penetrating the Zechstein from the Weser-Ems-Region (North- Western Gerrnany) were investigated in respect to the facies, the petrographic features and isotopic composition of the Ca2-carbonates. The carbonate deposits of the ten wells are located at the southern marginal platform of the Gennan Zechstein Basin. The thickness of the Ca2- carbonates varies between 40 and 220 m.
Sedimentation of the Ca2 started with the transgression of the Zechstein sea over the sulfates of the Al. The inundation of the Al-platform is characterised by the growth of thick ooid- layers. These layers are divided into two cycles, witch can be characterised as two shallowing upward-cycles with inter- to subtidal sediments at the end of the cycles. The sediment structures and the particle composition (ooids, grapestones, peloidal grains and bioclasts) of the Ca2-carbonates allows the differentiation in high energy or protected ooidsands and less agitated tidal-flat sediments.
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本研究针对德国西北部威悉-埃姆斯地区（Weser-Ems-Region）的10口穿透蔡希斯坦（Zechstein）地层的勘探井展开调研，重点分析其Ca₂碳酸盐岩（Ca2-carbonates）的岩相特征、岩石学特征与同位素组成。该10口井中的碳酸盐岩沉积均分布于德国蔡希斯坦盆地（Zechstein Basin）的南部边缘台地，其Ca₂碳酸盐岩的厚度介于40米至220米之间。

Ca₂碳酸盐岩的沉积作用始于蔡希斯坦海（Zechstein Sea）侵漫Al层硫酸盐地层的海进过程。Al台地的被侵漫过程以厚层鲕粒（ooid）层的发育为典型特征。这些鲕粒层可划分为两个沉积旋回，二者均表现为向上变浅旋回，旋回末期发育潮间至潮下带沉积物。通过分析Ca₂碳酸盐岩的沉积构造与颗粒组成（包括鲕粒、葡萄石粒、球粒颗粒与生物碎屑），可将其划分为高能或受保护的鲕粒砂坪，以及水动力条件较弱的潮坪沉积物。
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