Origin of Nodular and Bedded Anhydrite in Permian Shelf Ssdiments, Texas and New Mexico

摘要: Studies of anhydrite in Permian shelf sediments Texas and New Mexico indicate similarities to Recent gypsum deposits Laguna Madre, coastal south Texas. occurs with greatest frequency within cyclical clastic carbonate sediments. The most common form (other than pore-filling or replacement origin) is the nodule. Nodules are packed varying degrees, ranging from widely spaced individuals dense zones which have been misinterpreted as "beds." Two types truly bedded occur: thin discrete layers, laminated beds. In rosettes, bladed crystals, beds occur below sediment surface. Thin sheets lagoon water periodically blown over mud flat areas where evaporation markedly increases salinity. concentrated brines percolate downward, supplying hypersaline ground precipitated (Fisk, 1959). discovery nodules that pseudomorphous after euhedral gypsum, closely resemble crystals crystal aggregates, suggests a similar mode origin.