Principles of Oceanic Salt Deposition and Metamorphism

Abstract

Research Article| May 01, 1969 Principles of Oceanic Salt Deposition and Metamorphism HERMANN BORCHERT HERMANN BORCHERT Institut fiir Mineralogie, Petrographie, and Lagerstattenkunde, Technical University, Clausthal, 3392 Clausthal-Zellerfeld, West Germany Search for other works by this author on: GSW Google Scholar Author and Article Information HERMANN BORCHERT Institut fiir Mineralogie, Petrographie, and Lagerstattenkunde, Technical University, Clausthal, 3392 Clausthal-Zellerfeld, West Germany Publisher: Geological Society of America First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1969, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1969) 80 (5): 821–864. https://doi.org/10.1130/0016-7606(1969)80[821:POOSDA]2.0.CO;2 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation HERMANN BORCHERT; Principles of Oceanic Salt Deposition and Metamorphism. GSA Bulletin 1969;; 80 (5): 821–864. doi: https://doi.org/10.1130/0016-7606(1969)80[821:POOSDA]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Oceanic salt deposits result from evaporation processes in epicontinental sea basins which lack appreciable drainage either into or out of them. Optimal evaporation occurs in arid regions. Deposits are found generally after orogenic periods in the foreland or backland of strongly folded and faulted geosynclinal areas of germano-type tectonics.1 Most of the evaporites discussed in this paper are from the upper Zechstein rocks of Germany.Primary crystallization of these deposits proceeds under dynamic-polythermal conditions, with successive precipitates of dolomite, gypsum, halite, some epsomite, and carnallite, the most important primary minerals.Secondary variations in lateral mineral successions can be observed within distances of meters, and are connected with metasomatic replacement processes. Because of retrograde metamorphism, potassium-magnesium-sodium sulfates are formed in equilibrium with the high-sulfate content of the metamorphic solutions. This is in strong contrast to the sulfate deficiency in ordinary brines. The initially dilute solutions of retrograde metamorphism may be of foreign origin. However, the frequency of secondary replacement processes, especially in the potash beds, is essentially explained by the fact that most accompanying anhydrite beds have been deposited as gypsum. Thus, by geothermal heating, about 0.5 cubic meters of dilute CaSO4 solutions for each cubic meter of gypsum are set free.The salt deposits show a rhythm of true annual varves, even reflecting the 11-year solar period. The level of the ocean surface was the constant base level during deposition of the entire series of Zechstein 1 to 4. Communication channels of the English-German and Russian basins were restricted to, but not completely interrupted with the northern “Scandic” ocean, even during the stages of potassium salt formation.In anorogenic times and in regions with germano-type tectonics, sinking of the earth's crust is likely to occur at a rate of 0.1 to 1 mm per year. Thus, sinking of the sea bottom could not have been rapid enough to allow the contemporaneous deposition of several hundred meters of salts. “Descendent” processes and desert salt-pan conditions are not important for the successions of Zechstein deposits 1 to 4. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.