S-isotope studies of shallow water, laminated gypsum and associated evaporites, Upper Permian, East Greenland

Three types of primary subaqueous gypsum occur in the Karstryggen Formation, Upper Permian of East Greenland: (1) planar laminated gypsum, having a narrow δ³⁴S range of 10.2 to 10.4א CDT, (2) algal laminated gypsum (9.2 to 12.0א), and (3) bottom nucleated gypsum crystals (11.6 to 11.7א). Type 3 was deposited from a residual brine in the basin while types 1 and 2 consist of seawater or mixed fresh water-seawater-derived sulphate with varying contribution of reoxidized sulphur originally deposited as sulphide or organic sulphur. Diagenetic nodular gypsum (7.3 to 10.8א) was formed by redistribution of marine or mixed fresh water-seawater-derived brines which precipitated the laminated gypsum with contribution of sulphate originally precipitated as sulphide or organic sulphur in the organic-rich sediments.