WorldWideScience

Sample records for carnallite

  1. Development of microstructure during deformation of carnallite and bischofite in transmitted light

    NARCIS (Netherlands)

    Urai, J.L.

    1987-01-01

    During deformation of 5 × 5 × 0.1 mm samples of carnallite and bischofite in transmitted light, the development of the microstructure was followed by time-lapse photography. In dry samples, carnallite deforms by mechanical twinning, intracrystalline slip and by cataclastic processes. The addition of

  2. Preparation and characteristic research of anhydrous magnesium chloride with dehydrated ammonium carnallite

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ning-bo; CHEN Bai-zhen; HE Xin-kuai; LI Yi-bing

    2006-01-01

    Taking the saline lake bischofite and NH4Cl that was removed with the ammonia method and continuwas synthesized. And then the ammonium carnallite was dehydrated to some extent at 160℃ for 4 h. Ammonium carnallite reacted with ammonia at 240℃ for 150 min and the ammonation ammonium carnallite was produced. Finally, the ammonation ammonium carnallite was calcined at 750℃ into anhydrous magnesium chloride containing only 0.1% (mass fraction) of MgO. On the other hand, dehydrated ammonium carnallite was mixed with the solid ammonium chloride at mass ratio 1:4 at high temperature and with the differential pressure of HN3 above 30.5 kPa. The dehydrated ammonium carnallite of mixture was dehydrated at 410℃, and then calcined at 700℃ into anhydrous magnesium chloride with only 0. 087% (mass fraction) of MgO. X-ray diffraction and electron microscopy analysis results prove that anhydrous magnesium chloride obtained by both methods hasn't mixed phases, the particle is large and even has good dispersion, which is suitable for preparation of metal magnesium in the electrolysis.

  3. Preparation of anhydrous magnesium chloride in a gas-solid reaction with ammonium carnallite

    Institute of Scientific and Technical Information of China (English)

    Zhou Ningbo; Chen Baizhen; He Xinkuai; Li Yibing

    2006-01-01

    Dehydrated ammonium carnallite was synthesized with bischofite from salt lake and ammonium chloride solution in a 1:1 molar ratio of MgCl2:NH4Cl,dehydrated at 160℃ for about 4 h.The yield was above 85%.The product was then mixed with solid-state ammonium chloride with a 1:4 mass ratio for the further dehydration at 410℃.The decomposition of NH4Cl made a pressure of NH3 at 30.5 kPa to prevent the hydrolysis of ammonium carnallite.The anhydration of magnesium chloride was achieved at 700℃.The results showed that anhydrous magnesium chloride contains magnesium oxide in an amount that was less than 0.1% by weight.XRD pattern and SEM micrograph showed a good dispersion of ammonium carnallite and anhydrous magnesium chloride crystals with well-distributed big grains,just enough to meet the need for the production of magnesium metal in the electrolysis process.

  4. Preparation and Characterization of Anhydrous Magnesium Chloride in Organic Solvent%有机溶剂法无水氯化镁的制备与表征

    Institute of Scientific and Technical Information of China (English)

    周宁波; 陈白珍; 何新快; 李义兵

    2005-01-01

    Ammonium carnallite was synthesized by hydrated magnesium chloride in salt lake and ammonium chloride solution. Dehydrated ammonium carnallite was dissolved in methanol under low temperature by feeding ammonia, to prepare anhydrous magnesium chloride. The results show that anhydrous magnesium chloride contains magnesium oxide in an amount less than 0.1% by weight, the yield of magnesium chloride was above 99.5%. Ammonium carnallite, ammoniation magnesium chloride and anhydrous magnesium chloride were characterized by thermoanalysis, X-ray powder diffraction and scanning electron microscopy.

  5. A new flow law for bischofite

    NARCIS (Netherlands)

    Muhammad, Nawaz; Spiers, Christopher; de Bresser, Hans; Peach, Colin

    2014-01-01

    Bischofite exits in the upper crust with its related minerals carnallite, sylvite and halite, and is known as the most ductile material within the halide family of minerals. It is normally extracted from the subsurface by solution mining in underground caverns. Abandonment of the caverns causes the

  6. Mineral resource of the month: magnesium

    Science.gov (United States)

    Kramer, Deborah A.

    2012-01-01

    Magnesium is the eighthmost abundant element in Earth’s crust, and the second-most abundant metal ion in seawater. Although magnesium is found in more than 60 minerals, only brucite, dolomite, magnesite and carnallite are commercially important for their magnesium content. Magnesium and its compounds also are recovered from seawater, brines found in lakes and wells, and bitterns (salts).

  7. Long term corrosion of glasses in salt brines

    OpenAIRE

    Roggendorf, Hans; Schmidt, Helmut K.

    1989-01-01

    Borosilicate glasses are supposed to be a suitable matrix for the fixation of calcined radioactive wastes. For the safety assessment of the disposal of these glasses in geological formations like carnallite or rock salt, their chemical durability in saturated salt brines has been investigated. Temperatures up to 200° C, pressures up to 130 bar, and corrosion times up to 5 years were applied. Special attention was given to the long term corrosion which is mainly characterized by the saturation...

  8. Model ideas of acoustic emission sources in elastoplastic and brittle salt rocks

    International Nuclear Information System (INIS)

    In laboratory experiments, under uninterrupted deformation conditions, the influence of surface pressure and deformation rate on the deformation and fracture behaviour of salt rocks with different in-situ behaviour, and the acoustic emission caused by it, were studied (sylvite, carnallite). The results obtained are the starting basis for simple model ideas on the reactions occurring in the material; reactions which determine the shape of the stress-deformation curve and are accompanied by acoustic emissions. (orig./MM)

  9. Characterization of compounds containing iodine

    International Nuclear Information System (INIS)

    In this paper, results and experience gained at the Karlsruhe reprocessing plant and experimental results determined at the prototype dissolver off-gass purification plant PASSAT are described. A milestone in the head-end off-gas purification concept has been set by optimizing an iodine filter using remotely exchangeable filter drums fitting into 400 litre waste casks. The dynamic leaching-out was measured in solutions of carnallite and NaCl. The iodine absorbing agent was AC6120-12 w/o Ag. (DG)

  10. New data on the Geochemistry of Gases in the Potash Deposits

    Directory of Open Access Journals (Sweden)

    I. I. Chaykovskiy

    2014-12-01

    Full Text Available The composition of the gas phase of salt rocks from a number of potash deposits located in Europe (Verkhnekamskoe, Starobinskoe and Asia (Tubegatanskoe, Zhylyanskoe Satimolinskoe was studied. It allowed dividing them into two groups. In Asian deposits, only authigenic dry gases were formed by diagenetic decomposition of organic matter. Structural exposure of these deposits led to the oxidation of methane and hydrogen and enrichment by carbon dioxide. European deposits were not structurally exposed to the oxidation process, but were exposed during salt rock formation. They experienced influx of heavy hydrocarbons from the underlying strata. The history of the formation of gas regime at the Verkhnekamskoe potash deposit could be divided into three stages. First stage may be characterized by a syngenetic capture of deep gases and authigenic organic matter converted during diagenesis to methane, which percentage gradually increases with an increase of the thickness of impermeable salt strata. Then the deep gases invaded the salt formation during sedimentation of the upper carnallite layers and top salt rock. Third stage was associated with folding processes accompanied by a mobilization of fluids scattered in the gas-fluid inclusions, and with probable influx of heavy hydrocarbons and carbon dioxide resulted in formation of the secondary salt zones. Replacement of carnallite layers leads to the release of isomorphous ammonium ion and formation of a hydrogen.

  11. Application of nuclear physics methods to potassium-salts prospecting

    International Nuclear Information System (INIS)

    Radiation logging has proved to be a very useful method for identification of the main types of salt rocks in mines. Quantitative interpretation of gamma logs allows the potassium content to be estimated directly in the bore-hole. Comparison of the quantitative analysis for potassium, by a chemical method and a gamma-ray logging method, shows that the latter gives quite satisfactory results. It should be taken into account that chemical analysis of bore-core material concerns only the actual volume of the sample, while the radiation method gives information on the average potassium concentration of volumes about 10 times greater. Radiation logging proves to be useful not only for differentiation between sylvites and carnallites, but also enables some of the non-radioactive-salt minerals, such as kieserite or anhydrite, to be detected. It is possible by means of this method to estimate the content of the latter in potassium-salt rocks. Differentiation of clay salts from poor carnallites is also possible. Thus, a full geological profile of a given bore-hole may be obtained by applying the various radiation logging methods. Any doubts about the interpretation may be eliminated by the quantitative analysis of the neutron-gamma and gamma-gamma logs. The application, on an industrial scale, of radiation well-logging in potassium-salt mining is of great economic value. (author)

  12. The geological and material investigation programme

    International Nuclear Information System (INIS)

    The radioactive waste disposal problem is an interdisciplinary problem. The geological formation cannot be considered on its own, but must also be considered in connection with the engineering design of the disposal facility. Engineering design including the encapsulation of the glass in a 15 cm thick steel cylinder and a minimum 40 year cooling time ensures low temperatures in the salt-steel interface. Even if large quantities of carnallite were found 3.5 m away from the sides of the borehole, the temperature at 2500 m depth after taking into account temperature increase from radioactive waste will not release crystal water from the carnallite. Anhydrite layers, which may be found in the neighbourhood of Erslev 2 and at the depths contemplated for radioactive waste disposal, will not be continous, but only in the form of blocks of limited lengths. They cannot therefore form a passage to a water bearing aquifer. The volume of salt necessary for waste disposal - including a 200 m safety barrier - is less than 2 km3. The Mors dome with a salt volume of about 264 km3 provides a very substantial safety margin. The geological investigations have fulfilled the purpose of the present phase of investigations and show the Mors salt dome to be a suitable dome for disposal of high-level radioactive waste. (EG)

  13. Geotechnical investigations on backfill materials in the Asse salt mine

    International Nuclear Information System (INIS)

    The compression behaviour of rock salt grit is being investigated by compression tests at the Asse salt mine. The various test parameters are introduced and their results are discussed. The permeability of rock salt grit with saturated NaCl-brine in dependency upon the grain size and compactness, resp. the porosity, is being determined at the Asse salt mine. The test equipment and the results determined here are shown. In addition to laboratory tests, geotechnical investigations are taking place in a carnallitic chamber of the Asse salt mine which had been backfilled in earlier years. They chiefly concern measurements of the deformation rates in drifts - which were mined between the chambers in remaining pillars - as well as horizontal deformation measurements in the backfilling. (orig./DG)

  14. Green process to recover magnesium chloride from residue solution of potassium chloride production plant

    Institute of Scientific and Technical Information of China (English)

    Lin WANG; Yunliang HE; Yanfei WANG; Ying BAO; Jingkang WANG

    2008-01-01

    The green process to recover magnesium chlor-ide from the residue solution of a potassium chloride pro-duction plant, which comes from the leach solution of a potash mine in Laos, is designed and optimized. The res-idue solution contains magnesium chloride above 25 wt-%, potassium chloride and sodium chloride together below 5 wt-% and a few other ions such as Br-, SO2-4and Ca2+. The recovery process contains two steps: the previous impurity removal operation and the two-stage evapora-tion-cooling crystallization procedure to produce magnes-ium chloride. The crystallized impurity carnallite obtained from the first step is recycled to the potassium chloride plant to recover the potassium salt. The developed process is a zero discharge one and thus fulfills the requirements for green chemical industrial production. The produced magnesium chloride is up to industrial criteria.

  15. Chemical modeling of nuclear waste repositories in the salt repository project

    International Nuclear Information System (INIS)

    Salt deposits contain small amounts of water as brine in fluid inclusions in halite and in hydrous minerals, e.g., clays, kieserite (MgSO4 . H2O) and carnallite (KMgCl3 . 6H2O). For the candidate salt deposits, the total amounts of water as volume % brine are: Palo Duro Basin, Texas, approximately 1.8; Paradox Basin, Utah, approximately 5.0 for the carnallite-marker zone, and less than approximately 0.5 below this zone; Gulf Coast salt domes, less than 0.15. For the Palo Duro and Paradox salt, the brines are Mg-rich (approximately 20,000 mg/L to approximately 100,000 mg/L) and sometimes Ca-rich (up to about 20,000 mg/L) NaCl brines. Brine migration calculations have been made using calculations of the time-variant thermal gradient around the waste packages and conservatively high brine volumes in the salt (5.0 volume % for the Texas and Utah sites and 0.5 volume % for the Gulf Coast) as input data. The maximum amounts of brine that eventually migrate to each waste package are about 1.0m3 (for 5.0 volume % brine) and 0.2m3 (for 0.5 volume % brine). With current conceptual designs for waste package overpacks (10 to 15 cm thick low-carbon steel), the waste package is not breached by uniform corrosion within 10,000 years. In brines this material thus far shows only uniform corrosion. For the expected conditions, where the brine is provided solely by brine migration, the brine is consumed by reaction with the iron of the overpack nearly as fast as it migrates to the waste package. Therefore, for the expected conditions, data about corrosion rates, radiolysis, etc., are not important. However, it is essential that accurate volumes of in-migrating brine can be calculated

  16. Evolution of rheologically heterogeneous salt structures: a case study from the northeast of the Netherlands

    Science.gov (United States)

    Raith, A. F.; Strozyk, F.; Visser, J.; Urai, J. L.

    2015-07-01

    At the first order salt structures are controlled by the low flow strength of evaporites and by the tectonic boundary conditions. Rheological contrasts within an evaporite body have an important effect on the evolution of the internal structure of salt, but how this mechanical layering affects salt deformation at different scales is not well known. The potassium-magnesium salts (K-Mg salts) carnallite and bischofite are prime examples of layers with much lower effective viscosity than rock salt: their low viscosity presents serious drilling hazards but also allows squeeze solution mining. In contrast, anhydrite and carbonate layers (stringers) in salt are much stronger than halite. In this study, we used high-resolution 3-D seismic and well data to study the evolution of the Veendam and Slochteren salt pillows at the southern boundary of the Groningen High, northern Netherlands. Here the rock salt layers contain both the mechanically stronger Zechstein III Anhydrite-Carbonate stringer and the weaker K-Mg salts, providing an example of extreme rheological heterogeneities in salt structures. The internal structure of the two salt pillows shows areas in which the K-Mg salt-rich ZIII 1b layer is much thicker than elsewhere, in combination with a complexly ruptured and folded ZIII Anhydrite-Carbonate stringer. Thickness maps of supra-salt sediments and well data are used to infer the initial depositional architecture of the K-Mg salts and their deformation history. Results suggest that active faulting and the resulting depressions of the Zechstein surface above a Rotliegend graben caused the local accumulation of bittern brines and precipitation of the thick K-Mg salts. During the first phase of salt flow and withdrawal from the Veendam area, under differential loading by Buntsandstein sediments, the ZIII stringer was boudinaged while the lens of Mg salts remained relatively undeformed. This was followed by a convergence stage, when the K-Mg salt-rich layers were

  17. Modeling the interaction of mine brines with chloride minerals of potassium-magnesium deposits

    Science.gov (United States)

    Fetisov, V. V.

    2016-03-01

    The article is devoted to study of dynamics of saturation degree of suprasalt brines with respect to major chloride minerals of salt strata in the initial phase of an accident related to discontinuity of waterproof stratum in the mine of the Verkhnekamskoe salt deposit (Berezniki-3 mine, 1986). Physicochemical modeling has showed that the brines discharged into mine are in equilibrium with halite during all period of observation. At the same time, their degree of saturation with respect to sylvite and carnallite regularly decreases with the increase in inflow of the suprasalt Cl-Na brines. The initial stage of suprasalt brine penetration into mine is characterized by an increase in the saturation degree with respect to the considered chloride minerals, which is showed on the chart presented in the article. However, there are brines oversaturated with respect to halite, which occurs over a brief period. In contrast to the mine brines of different genesis being in equilibrium or close to equilibrium with sylvite, saturation index (SI) for this mineral decreases in the suprasalt brine. This allows one to recommend the use of this parameter in the study of the mine brines to timely detect suprasalt brines entering the mine.

  18. Simulation studies on metastable phase equilibria in the aqueous ternary systems (NaCI-MgCI2-H20) and (KCI-MgCI2-H20) at 308.15 K

    Institute of Scientific and Technical Information of China (English)

    Tianlong DENG; Baojun ZHANG; Dongchan LI; Yafei GUO

    2009-01-01

    The solubilities and densities of the aqueous metastable ternary systems (NaCl·MgCl2·H2O) and (KC1·MgCl2·H2O) at 308.15 K were determined by the isothermal evaporation method. On the basis of the experimental results, the phase diagrams for those systems were plotted. It was found that the former system belongs to the hydrate-I type with one invariant point of (NaCl + MgCl2·6H2O), two univariant curves, and two crystallization regions corresponding to halite (NaCl) and bischofite (MgCl2 · 6H2O); and the latter system belongs to the type of incongruent-double salts with two invariant points of (KC1+ KCl·MgCl2·6H2O) and (MgCl2·6H2O + KC1 ·MgCl2·6H2O), three univariant curves, and three crystallization regions corresponding to potassium chloride (KC1), carnallite (KC1·MgCl2 ·6H2O) and bischofite (MgCl2·6H2O). No solid solutions were found in both systems.

  19. Study on Salting Law during the Evaporation Process of the Mother Liquor of Phosphorylation Mother Liquor from Magnesium- hydroxide Production%磷酸处理后苦卤脱镁母液蒸发析盐规律研究

    Institute of Scientific and Technical Information of China (English)

    刘刚; 王学魁; 袁建军; 沙作良

    2011-01-01

    针对制盐苦卤利用氨法制取MS(OH)2的脱镁母液,加入磷酸并固液分离后的澄清液,实验研究了其蒸发析盐规律.研究证明,蒸发过程中NaCl和NH4Cl为主要析出盐类,其最终析出率分别为66.31%和33.41%,在研究的蒸发水量范围内,蒸发过程中有少量光卤石析出.%The salting law was studied during the evaporation process for the mother liquor which was obtained by treating the mother liquor of brine after making salt feom seawater with the methods of that the brine first reacted with ammonia and phosphate. The results showed that NaCl and NH4Cl are mainly crystallized during the evaporating process. In the range of the water evaporated, the recover ratio of the NaCl and NH4Cl were 66.31% and 33.41% respectively, and some of the carnallite was also formed.

  20. Geochemical evolution of groundwater in the Culebra dolomite near the Waste Isolation Pilot Plant, southeastern New Mexico, USA

    International Nuclear Information System (INIS)

    The Culebra Dolomite Member of the Rustler Formation, a thin (10 m) fractured dolomite aquifer, lies approximately 450 m above the repository horizon of the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico, USA. Salinities of water in the Culebra range roughly from 10,000 to 200,000 mg/L within the WIPP site. A proposed model for the post-Pleistocene hydrochemical evolution of the Culebra tentatively identifies the major sources and sinks for many of the groundwater solutes. Reaction-path simulations with the PHRQPITZ code suggest that the Culebra dolomite is a partial chemical equilibrium system whose composition is controlled by an irreversible process (dissolution of evaporites) and equilibrium with gypsum and calcite. Net geochemical reactions along postulated modern flow paths, calculated with the NETPATH code, include dissolution of halite, carbonate and evaporite salts, and ion exchange. R-mode principal component analysis revealed correlations among the concentrations of Si, Mg, pH, Li, and B that are consistent with several clay-water reactions. The results of the geochemical calculations and mineralogical data are consistent with the following hydrochemical model: (1) solutes are added to the Culebra by dissolution of evaporite minerals; (2) the solubilities of gypsum and calcite increase as the salinity increases; these minerals dissolve as chemical equilibrium is maintained between them and the groundwater; (3) equilibrium is not maintained between the waters and dolomite; sufficient Mg is added to the waters by dissolution of accessory carnallite or polyhalite such that the degree of dolomite supersaturation increases with ionic strength; and (4) clays within the fractures and rock matrix exert some control on the distribution of Li, B, Mg, and Si via sorption, ion exchange, and dissolution

  1. Trial storage of high-level waste cylinders in the Asse II salt mine

    International Nuclear Information System (INIS)

    This report covers the contract period 1976-77, as well as some of the tasks carried out during the extension in 1978, in the framework of the R and D programme for disposal of radioactive waste in salt formations. With regard to the in-situ tests for the liberation and migration of brine, the testing devices were examined successfully. Laboratory examinations carried out showed a stepwise liberation of the water contents in halite in dependence on the temperature. The amount of brine liberated stood in good agreement with the in situ results. A temperature test for borehole convergence resulted in definite convergence rates. Simultaneously no influence was registered in the stability of the surrounding rocks. For the realization of an integrated major experiment, temperature test field IV was mined on the 750 m level of the Asse Salt Mine and heater- as well as measurement drillings were carried out. Extensive rheological examinations are concentrated particularly on the halite and secondly on the Carnallite. They are chiefly based on uni- and multiaxial pressure tests. Computer programmes are developed to examine the heat generation in wastes as well as in salt. In comparison, the programme development of computer codes for the stability behaviour of rocks is still at a relatively early stage, because it has to build up on the results of heat generation. The works for the development of a transport container with a shielding combination are at a very advanced stage. An integrated disposal- and retrieval system was developed, tested and successfully demonstrated. A monitoring system in the mine has also been developed in its essential parts

  2. Study of polyhalite from the WIPP site, New Mexico

    International Nuclear Information System (INIS)

    Polyhalite (K2Ca2Mg(SO4).2H2O) is an important mineral present in the bedded evaporites of the WIPP site, southeastern New Mexico. Polyhalite contains two structurally bonded water molecules, and it is thus important to know if this mineral formed at or close to the time of sedimentation or, as proposed by others more or less continuously throughout the Mesozoic and Cenozoic. If formed much later than original evaporite formation, then this implies a new source of water in order for polyhalite to form in turn raising questions about water abundance and mobility in the bedded evaporites. Polyhalite is not well suited for Rb-Sr geochronologic study because of the large amounts of common Sr, but it has been shown to be suitable for study by the K-Ar geochronologic methods. Pure polyhalites and those mixed with very small amounts of impurities yield K-Ar dates in the range of 200 to 220 MYBP and indicate little if any, loss of 40Ar. Polyhalites mixed with sylvite, halite, and (Na,K)Cl yield lower ages due to loss of 40Ar from the halides. Apparent age lowering is proportional to halide content and an extrapolated age of formation of near 225 MYBP results. Collectively, the K-Ar data convincingly show that the polyhalites formed at the time of sedimentation (except for isolated occurrences near dike intrusions) in Late Permian time. Finally, thermodynamic calculations, supported by petrographic study, show that polyhalite is often stable with respect to carnallite, sylvite and other minerals formerly thought to be older than polyhalite. 1 figure, 1 table

  3. Geochemical evolution of groundwater in the Culebra dolomite near the Waste Isolation Pilot Plant, southeastern New Mexico, USA

    Science.gov (United States)

    Siegel, M.D.; Anderholm, S.

    1994-01-01

    The Culebra Dolomite Member of the Rustler Formation, a thin (10 m) fractured dolomite aquifer, lies approximately 450 m above the repository horizon of the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico, USA. Salinities of water in the Culebra range roughly from 10,000 to 200,000 mg/L within the WIPP site. A proposed model for the post-Pleistocene hydrochemical evolution of the Culebra tentatively identifies the major sources and sinks for many of the groundwater solutes. Reaction-path simulations with the PHRQPITZ code suggest that the Culebra dolomite is a partial chemical equilibrium system whose composition is controlled by an irreversible process (dissolution of evaporites) and equilibrium with gypsum and calcite. Net geochemical reactions along postulated modern flow paths, calculated with the NETPATH code, include dissolution of halite, carbonate and evaporite salts, and ion exchange. R-mode principal component analysis revealed correlations among the concentrations of Si, Mg, pH, Li, and B that are consistent with several clay-water reactions. The results of the geochemical calculations and mineralogical data are consistent with the following hydrochemical model: 1. (1) solutes are added to the Culebra by dissolution of evaporite minerals 2. (2) the solubilities of gypsum and calcite increase as the salinity increases; these minerals dissolve as chemical equilibrium is maintained between them and the groundwater 3. (3) equilibrium is not maintained between the waters and dolomite; sufficient Mg is added to the waters by dissolution of accessory carnallite or polyhalite such that the degree of dolomite supersaturation increases with ionic strength 4. (4) clays within the fractures and rock matrix exert some control on the distribution of Li, B, Mg, and Si via sorption, ion exchange, and dissolution. ?? 1994.

  4. Petrography, fine stratigraphy and petrofacies of the Stassfurt rock salt (Zechstein 2) in the development region of ASSE II salt mine near Brunswick

    International Nuclear Information System (INIS)

    The Stassfurt rock salt (Na2) in the Asse II salt mine constitutes a saline sequence of the sub-Hercynian basin. In the anticline of the Asse II the Na2 constitutes a core of the anticline with an interior special folding. The combination of underground mapping with the investigations of the salt petrography permits the recognition of stratigraphic unities and with it sedimentary and early diagenetic formation processes for the stratigraphic beds of the Hauptsalz (Na2β), the Speisesalz (Na2SP) and the Polyhalitbaenkchensalz (Na2P). An additional postdiagenetic new formation of minerals from the overlying Stassfurt potash layer (K2C) can be recognized in the kieseritic region of the ''Carnallitisch-Kieseritische Ueberganssalz (Na2K+C)'' and in the ''Tonliniensalz'' (Na2TL). The lower part of the Na2β belongs to a saline basin facies. In the upper part of the Na2β structural and textural characteristics refer to the swallowing of the saline sedimentation room. Simultaneously, more and more terrestrial influences of the saline sedimentation become conspicuous in the northwestern part of the Asse II. They have their clearest facies in the only locally formed Tonliniensalz (Na2TL). The petrographic review of the ''polyhalite region'', which encloses the upper part of the Na2β, the Na2SP and the Na2P, rendered obvious indications for a pseudomorphic origin of polyhalite from primarily sedimened gypsum. The replacement of anhydrite by polyhalite was compared to it as being of unimportant significance. The quantitative parts of the accessory minerals (polyhalite, anhydrite, kieserite, sylvite, carnallite) were determined by means of geochemical investigations in the stratigraphic horizons of Na2 in the mine Asse II. A regional comparison with the saline sedimentation of Zechstein 2 in the sub-Hercynian basin shows a progressive saline sedimentation cycle of the Stassfurt type for the fine stratigraphic division of the Na2 in Asse II. (orig./HP)

  5. Evolution of rheologically heterogeneous salt structures: a case study from the NE Netherlands

    Science.gov (United States)

    Raith, A. F.; Strozyk, F.; Visser, J.; Urai, J. L.

    2016-01-01

    The growth of salt structures is controlled by the low flow strength of evaporites and by the tectonic boundary conditions. The potassium-magnesium salts (K-Mg salts) carnallite and bischofite are prime examples of layers with much lower effective viscosity than halite: their low viscosity presents serious drilling hazards but also allows squeeze solution mining. In contrast, intrasalt anhydrite and carbonate layers (stringers) are much stronger than halite. These rheological contrasts within an evaporite body have an important control on the evolution of the internal structure of salt, but how this mechanical layering affects salt deformation at different scales is not well known. In this study, we use high-resolution 3-D seismic and well data to study the evolution of the Veendam and Slochteren salt pillows at the southern boundary of the Groningen High, northern Netherlands. Here the rock salt layers contain both the mechanically stronger Zechstein III Anhydrite-Carbonate stringer and the weaker K-Mg salts, thus we are able to assess the role of extreme rheological heterogeneities on salt structure growth. The internal structure of the two salt pillows shows areas in which the K-Mg salt-rich ZIII 1b layer is much thicker than elsewhere, in combination with a complexly ruptured and folded ZIII Anhydrite-Carbonate stringer. Thickness maps of supra-salt sediments and well data are used to infer the initial depositional architecture of the K-Mg salts and their deformation history. Results suggest that faulting and the generation of depressions on the top Zechstein surface above a Rotliegend graben caused the local accumulation of bittern brines and precipitation of thick K-Mg salts. During the first phase of salt flow and withdrawal from the Veendam area, under the influence of differential loading by Buntsandstein sediments, the ZIII stringer was boudinaged while the lens of Mg salts remained relatively undeformed. This was followed by a convergence stage, when the

  6. Evolution of rheologically heterogeneous salt structures: a case study from the northeast of the Netherlands

    Directory of Open Access Journals (Sweden)

    A F. Raith

    2015-07-01

    Full Text Available At the first order salt structures are controlled by the low flow strength of evaporites and by the tectonic boundary conditions. Rheological contrasts within an evaporite body have an important effect on the evolution of the internal structure of salt, but how this mechanical layering affects salt deformation at different scales is not well known. The potassium–magnesium salts (K-Mg salts carnallite and bischofite are prime examples of layers with much lower effective viscosity than rock salt: their low viscosity presents serious drilling hazards but also allows squeeze solution mining. In contrast, anhydrite and carbonate layers (stringers in salt are much stronger than halite. In this study, we used high-resolution 3-D seismic and well data to study the evolution of the Veendam and Slochteren salt pillows at the southern boundary of the Groningen High, northern Netherlands. Here the rock salt layers contain both the mechanically stronger Zechstein III Anhydrite–Carbonate stringer and the weaker K-Mg salts, providing an example of extreme rheological heterogeneities in salt structures. The internal structure of the two salt pillows shows areas in which the K-Mg salt-rich ZIII 1b layer is much thicker than elsewhere, in combination with a complexly ruptured and folded ZIII Anhydrite–Carbonate stringer. Thickness maps of supra-salt sediments and well data are used to infer the initial depositional architecture of the K-Mg salts and their deformation history. Results suggest that active faulting and the resulting depressions of the Zechstein surface above a Rotliegend graben caused the local accumulation of bittern brines and precipitation of the thick K-Mg salts. During the first phase of salt flow and withdrawal from the Veendam area, under differential loading by Buntsandstein sediments, the ZIII stringer was boudinaged while the lens of Mg salts remained relatively undeformed. This was followed by a convergence stage, when the K-Mg salt