STUDY ON THE CONTROLLING STRUCTURE OF SALT DEPOSIT IN VIENTIANE PLAIN,LAOS
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The salt deposits in Vientiane Plain occurrence in Palaeocene Tagong Formation.The main Kalium-bearing minerals are carnallite and a little of sylvinite.During mineralization period,the Tagong Formation and salt deposits were controlled by NW-trending boundary faults and Tagong syncline.After mineralization period,the salt deposits were controlled by fold(salt syncline and salt anticline).The salt deposits formed broad and gentle fold under the horizontal stress.Inside syncline,deposition rate is relatively quickly and the thickness of clastic rocks upper salt seam is relatively large.On anticline,the thickness of clastic rocks upper salt seam is relatively thin.There are large density differences between salt deposits and clastic rocks,and the thickness of clastic rocks in the anticline is different from the one in syncline,so the salt deposits form differential loading.The salt deposits in syncline happened plastic flow towards anticline by larger loading.Thus the salt deposits in anticline become thicker,salt anticline form.The thickness of salt deposits in syncline becomes smaller.Thickness of the salt deposits in anticline is often great;its burial depth is shallow.The strata over anticline are often incomplete.With the salt anticline far development,the potash deposits pierce upper mudstone and expose oneself to relatively freshwater surroundings to suffer corrosion.Keywords:
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The salt-bearing series of Member 4 of Funing Formation in Zhaoji Sub-sag of the Hongze Sag consists of 5 parts:the gypsum bed submember over the upper salt bed,the upper salt bed submember,the midst fresh submember,the lower salt bed submember,the gypsum bed submember below the lower salt bed.In the period of salt sedimentation,the Zhaoji Subsag is adeep basin surrounded by mountains.With the weathering and erosion of the great depth of halite Stratum of Pukou Formation in the east,and the intrusion of ocean water of Jinhu Sag from the channels in the southwest now and then,many salt materials have been brought into the Zhaoji Sag.Because of hot and dry climate,the lake water evaporated,concentrated, deposited,and formed very deep Halite Stratum.The salt-bearing series is ring belt-like on the surface,with salt facies,sulfate facies,carbonate facies,and fragmental rock facies distributing from the center to outer.
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Thick salt deposits of Middle Pennsylvanian age are present in an area of 12,000 square miles in the Paradox basin of southeast Utah and southwest Colorado. The deposits are in the Paradox Member of the Hermosa Formation. The greatest thickness of this evaporite sequence is in a troughlike depression adjacent to the Uncompahgre uplift on the northeast side of the basin.The salt deposits consist of a cyclical sequence of thick halite units separated by thin units of black shale, dolomite, and anhydrite. Many halite units are several hundred feet thick and locally contain economically valuable potash deposits.Over much of the Paradox basin the salt deposits occur at depths of more than 5,000 feet. Only in a series of salt anticlines located along the northeastern side of the basin do the salt deposits rise to relatively shallow depths. The salt anticlines can be divided geographically and structurally into five major systems. Each system consists of a long undulating welt of thickened salt over which younger rocks are arched in anticlinal form. Locally there are areas along the axes of the anticlines where the Paradox Member was never covered by younger sediments. This allowed large-scale migration of Paradox strata toward and up through these holes in the sediment cover forming diapiric anticlines.The central or salt-bearing cores of the anticlines range in thickness from about 2,500 to 14,000 feet. Structure in the central core of the salt anticlines is the result of both regional-compression and flowage of the Paradox Member into the anticlines from adjacent synclines. Structure in the central cores of the salt anticlines ranges from relatively undeformed beds to complexly folded and faulted masses, in which stratigraphic continuity is undemonstrable.The presence of thick cap rock .over many of the salt anticlines is evidence of removal of large volumes of halite by groundwater. Available geologic and hydrologic information suggests that this is a relatively slow process and that any waste-storage or disposal sites in these structures should remain dry for hundreds of thousands of years.Trace to commercial quantities of oil and gas are found in all of the black shale-dolomite-anhydrite interbeds of the Paradox Member. These hydrocarbons constitute a definite hazard in the construction and operation of underground waste-storage or disposal facilities. However, many individual halite beds are of. sufficient thickness that a protective seal of halite can be left between the openings and the gassy beds.A total of 12 different localities were considered to be potential waste-storage or disposal sites in the Paradox basin. Two Sharer dome and Salt Valley anticline, were considered to have the most favorable characteristics.
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End_Page 689------------------------------Uranium deposits in the Salt Wash Member of the Morrison Formation in the Carrizo Mountains area appear to be closely related to depositional facies. In the vicinity of the Eastside mines, southeastern Carrizo Mountains, the Salt Wash consists of a lower part, 10 to 15 m thick, and an upper part, 55 to 60 m thick. The lower part contains mudstone and silty sandstone interpreted as overbank and partially abandoned channel-fill deposits. It also contains a few large lenticular channel sandstones deposited by meandering and possibly braided streams. Uranium deposits are uncommon in the lower part. The upper part of the Salt Wash contains a much greater percentage of braided-stream-deposited channel sandstones, many of which coalesce to form prominent continuous ledges. The finer grained low-energy deposits are very limited in extent, commonly being less than 200 m long, 20 m wide, and 2 m thick. They have a lenticular cross section and a scour base. They consist of interbedded mudstones, claystones, and sandstones and are interpreted as abandoned and partially abandoned channel fills. Subsequent scouring of these beds has resulted in clay-clast conglomerates which were incorporated as lag deposits in the bases of overlying channel sandstones. Detrital organic debris is uncommon but is present in some channel-lag deposits as well as in some of the bedded mudstones. Uranium depos ts in the Carrizo Mountains area are associated with abandoned and partially abandoned channel fill and with clay-clast lag conglomerates adjacent to major channel sandstone systems in the upper part of the Salt Wash. End_of_Article - Last_Page 690------------
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The Gas Hills uranium district is in central Wyoming along the southeastern margin of the Wind River basin. The initial discovery was made by Neil E. McNeice in the fall of 1953. Earliest development of the district's ore reserves was quite slow, but accelerated when the larger, more experienced mining firms became active in the area. Surface drilling proved to be the most effective tool for finding and developing the uranium ore reserves. New drilling techniques were needed to obtain samples of the below-water-table ores. Many methods were tried, but frozen core drilling and bucket augering proved to be the most reliable for obtaining accurate samples. Since the initial discovery, the Gas Hills uranium district has produced about 12% of the United States total production. The present land surface is characterized by barren, subdued, rolling hills. These are traversed locally by steeply dipping hogback ridges of older, more resistant rocks, which are the flanks of truncated, northward plunging folds formed by crustal disturbances prior to the deposition of the Wind River Formation. A steep erosional escarpment that rises abruptly above the north sloping basin floor bisects the region and divides the surface drainage between tributaries of the Wind River on the north and tributaries of the Sweetwater River on the south. Volcanism occurred during late Eocene time, as evidenced by relic vents at the southern end of the Rattlesnake Hills, and by local volcanic debris in the middle and upper Eocene rocks. Sedimentary rocks exposed in the Gas Hills uranium district include sandstone, limestone, dolomite, shale, and tuffaceous sandstone, mudstone, and shale. They range in age from Cambrian to Miocene and have a composite thickness of over 14,000 ft. The source beds for the uranium deposits are arkosic sandstones interstratified with lenticular mudstones and shales. Two distinct types of sandstone are present in the Wind River Formation. The youngest is yellowish-orange to yellowish-gray arkose, derived primarily from Precambrian gneissoid and granitoid rocks; it contains little clay, abundant calcium carbonate, and limonite cement, and is host for all uranium deposits of the district. The second type of sandstone is pale yellowish-gray to pale olive, derived from areas of schists of Precambrian age; it contains abundant clay matrix. There are four types of uranium deposits in the district, the most important being the solution-front deposits. They were formed along the margins of highly altered, tabular sand beds that are enclosed by overlying and underlying fine-grained siltstone, claystone, and carbonaceous mudstone beds. Solution fronts can be followed for long distances and individual ore bodies along them may reach thousands of feet in length. The solution fronts are ideally crescentic or C-shaped when viewed in cross section, with thin mineralization forming the tips of the crescents. The uranium minerals occur as earthy brown to black coating on, and interstitial fillings between, the quartz-sand grains. The primary uranium ore minerals are coffinite and uraninite. The three other types of deposits include transitional-bedded, oxidized, and residual-remnant deposits. Several quite large transitional bedded deposits have been mined, but the oxidized and residual-remnant deposits are commonly small and difficult to mine. Ground waters, trapped by the southward tilting of the Tertiary rocks during late Miocene time, became stagnant. These waters dissolved uranium and other elements from the enclosing rocks, and after erosion had exposed the highest beds of the Wind River Formation, the mineral-rich solutions gained egress from the enclosing sand aquifers on the north and the solution-front ore deposits began to form. End_of_Article - Last_Page 905------------
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ABSTRACT The European Zechstein is a Late Permian group of formations that consists of shale, limestone and dolomite, anhydrite, rock salt, and potash salts in cyclic alternation over 1,000 m thick. Some of the anhydrite formations contain (a) beds with a distinct fining-upward texture, sharp bases and gradational tops, here interpreted as turbidites; (b) other beds with tightly packed clasts of anhydrite up to one meter in size, here interpreted as mass-flow breccias, and (c) bedded anhydrite with folds and concave sliding planes which may represent slumps. The thickness variation of the sulphate body along with the facies pattern in the overlying and underlying carbonates suggests that the sulphates were piled up in a platform similar to a shallow-water carbonate platform along the basin margin. The sediments described in this paper were all found along the steep basinward slope of this platform. Depositional structures similar to those in the Zechstein have been described in the Messinian gypsum formation (Miocene, Italy) Here the evaporites were deposited on pre-existing topography and did not create the relief by their own accumulation as in the Zechstein. Both the Zechstein and the Messinian sulphate bodies, however, were shaped by a similar interplay of localized precipitation in shallow water (or adjacent sabkhas), reworking and downslope transport as clastic material, and not by in situ precipitation alone. During the evaporite stages sulphates accumulated in all parts of the basin from the marginal tidal flats to the basin interior.
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The Lisbon Valley fault follows a northwest strike along the crest of a salt anticline and cuts diagonally across the Big Indian Wash uranium area in San Juan County, Utah. Altered rocks collected along the fault zone have been studied microscopically and by X-ray diffraction, for significant mineralogical data with a bearing on mineralization. Abundant kaolin is found in altered Chinle strata near the fault and extending 50 to 300 feet away. In contrast, illite, chlorite, montmorillonite, and mixed-layer illite-montmorillonite are commonly found in unaltered Chinle Shale occurring elsewhere along the Lisbon Valley anticline. Veinlets of dickite occur in the zone of shear, accompanied by tiny veinlets of pyrite and globules of indurated asphalt. Both original copper sulphides and oxidized copper minerals occur in fractured rock along the Lisbon Valley fault over a wide stratigraphic range. Rocks along the fault zone have generally been bleached, and porous Burro Canyon Sandstone has been silicified for 50 or more feet away from the fault on the hanging-wall side. Solution activity in the fault zone is indicated by bleaching, silicification, and deposition of copper sulphides. Argillic mineral associations and indurated hydrocarbons indicate that the mineralizing solutions were heated. The western upthrown limb of the Lisbon Valley anticline contains uranium deposits which occur mostly in Triassic Chinle Shale, but also in Permian Cutler strata. The rising thermal mineralizing solutions active along the Lisbon Valley fault zone may have carried uranyl ions which were reduced and precipitated in Chinle strata. The passage of solutions to the Chinle most likely followed subsidiary fractures and certain porous beds found in the Permian Cutler Formation, known as sugar sands in the mining localities.
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Research Article| April 01, 1958 URANIUM DEPOSITS UNDER CONGLOMERATIC SANDSTONE OF THE MORRISON FORMATION, COLORADO AND UTAH DAVID A PHOENIX DAVID A PHOENIX U. S. GEOLOGICAL SURVEY, GRAND JUNCTION, COLO. Search for other works by this author on: GSW Google Scholar Author and Article Information DAVID A PHOENIX U. S. GEOLOGICAL SURVEY, GRAND JUNCTION, COLO. Publisher: Geological Society of America First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1958, 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 (1958) 69 (4): 403–418. https://doi.org/10.1130/0016-7606(1958)69[403:UDUCSO]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 DAVID A PHOENIX; URANIUM DEPOSITS UNDER CONGLOMERATIC SANDSTONE OF THE MORRISON FORMATION, COLORADO AND UTAH. GSA Bulletin 1958;; 69 (4): 403–418. doi: https://doi.org/10.1130/0016-7606(1958)69[403:UDUCSO]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 In southwestern Colorado and southeastern Utah, strata of conglomeratic sandstone are localized at the base of the Brushy Basin Member of the Morrison Formation of Jurassic age. These discrete lithologic units contain sedimentary structures oriented in a prevailing easterly direction. They are believed to cover about one-third of the underlying Salt Wash Member in southwestern Colorado and southeastern Utah, and they locally rest on ore-bearing sandstone in the Salt Wash Member. Eastward-trending planar cross-stratification and trough cross-stratification and a general westward coarsening of sediments in the conglomeratic sandstone strata suggest that they are the products of stream aggradation from westerly source areas.Uranium-vanadium deposits in the uppermost, almost continuous, layer of sandstone of the Salt Wash Member are classified according to their association with the conglomerate strata. Of the 363 deposits studied in the uppermost sandstone layer of the Salt Wash Member, 101 are known to be directly beneath conglomeratic sandstone strata, 211 are below the projected extension of conglomeratic sandstone strata, 33 are beyond the safe limits of such projection, and 18 are lateral to the margins of conglomeratic sandstone strata. At places, near clusters of deposits in the uppermost sandstone of the underlying Salt Wash Member, conglomeratic sandstone strata of the Brushy Basin Member are also mineralized.It is postulated that ground-water movement during deposition of the Morrison Formation in Late Jurassic time localized the uranium and vanadium. The direction of this ground-water movement is believed to have been related to streams that deposited the conglomeratic strata, so that in the ore-bearing sandstone metal ions contained in the ground water were localized in places of high transmissibility and in the vicinity of decaying organic debris. According to the age of the ores, precipitation of the metals was much later than their localization, probably during Late Cretaceous or early Tertiary time. 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.
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ABSTRACT Development of oil, salt, and sulphur deposits at Gulf Coast salt domes has continued to add to knowledge about these structures. Additional data of particular significance have resulted from deeper drilling near the margins of the basins in east Texas and southwestern Alabama, and production of salt from a number of additional domes both for the purposes of chemical manufacture and to provide storage for propane and butane. Data relating to the cap rock continue to be developed at the older sulphur mines and at recently opened new ones, as well as in exploratory drilling for oil and sulphur. It is the purpose of this paper to review the mineralogy of the salt and cap rock of Gulf Coast salt domes in the light of the new data. The presence of salt has been proved at 234 domes which occur in the series of closely related basins extending from southwestern Alabama across Mississippi, Louisiana, and Texas to the Rio Grande River. Data from some 35 domes representing all of the basin areas show that the salt all has the same general mineralogical characteristics. Typically it is a bluish-gray, compact aggregate of large rounded to elongate grains of halite that contain varying amounts of small anhydrite grains. The anhydrite is concentrated in narrow dark bands that were complexly folded when the End_Page 147------------------------ salt was intruded from depth to form the salt domes. Recent studies by Robert Balk at Grand Saline (Texas) and Jefferson Island (Louisiana) mines have brought out details of structure in the salt that are related to intrusion. The water insoluble residues of the salt, although composed predominantly of sand-size crystals and cleavage fragments of anhydrite also include some 20 other minerals in the form of small crystals. The minerals of these residues are composed of the more abundant elements found in sea water, and are believed to have been precipatated when the salt crystallized from solution. The chemical and mineral composition of the salt in domes together with the banding or bedding, the inclusions of gas and liquid, and of deformed beds of anhydrite, sand, and shale prove that the salt originally was deposited as a normal bedded deposit. Salt from deep wells in southwestern Alabama has horizontal bands or bedding planes that apparently are undeformed and has different insoluble residue than salt from domes. Argillaceous insoluble residue from this bedded salt contained Jurassic pollen. The striking difference between the bedded salt and the salt of the nearby McIntosh dome, which is typical of Gulf Coast salt domes, indicates that the two types of salt are not correlative and that the dome salt probably is the older. Similar undeformed bedded salt, that is unlike the salt in domes and that apparently also is of Jurassic age, has been encountered in east Texas and north Louisiana wells. Typically the cap rock of salt domes consists of coarsely crystalline, horizontally banded anhydrite overlain by a zone of secondary, coarsely crystalline calcite. Gypsum, sulphur, pyrite, and other secondary minerals occur in varying abundance, particularly at the contact of the two zones and in the calcite zone. Detailed petrographic studies have shown that the anhydrite zone contains the same mineral suite as the water insoluble residue of the salt and that the calcite zone has formed as a result of alteration of the anhydrite zone. Further evidence that even very thick salt dome cap rocks can be formed by the accumulation of insoluble residue is being provided by the literally thousands of cubic yards of anhydrite sand that are being removed from brine wells at several domes including McIntosh (Alabama), Choctaw and West Hackberry (Louisiana), and Bryan Mound, Stratton Ridge and Palangana (Texas). More direct evidence of the manner of origin of cap rock has been obtained at the Lake Washington and Pelican Island domes in Louisiana where coring recently has revealed that fragments of bedded anhydrite included in the cap rock are of the same character as fragments occurring in the salt. End_of_Record - Last_Page 148-------
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Striking mineralogic and chemical changes occur in outcrops of a Permian redbed sequence overlying oil-productive parts of the prolific multireservoir oil accumulation at the Cement anticline, Oklahoma. Gypsum beds along the flanks are altered abruptly to erosion-resistant carbonate rocks at the crest of the fold in the Keechi Hills. Associated sandstones, typically red and friable in the surrounding region, are altered to pink, yellow, and white on the flanks of the anticline and to hard carbonate-cemented gray sandstone at the crest. The zone of cementation, confined to sandstone intervals, extends to a depth of at least 2,500 ft. Calcitized gypsum exceptionally deficient in C13 and light-carbon/heavy-oxygen cements directly overlie petroleum-productive zones near regions where fluids have superior vertical avenues of communication (faults and an unconformity at shallow depths and of limited extent along the crest). Away from these avenues of leakage, the influence of hydrocarbons on the isotopic composition of the carbonate cements decreases systematically. Color changes in the sandstones are related to reduction and dissolution of iron in the presence of hydrocarbons. Much of the hydrocarbons leaked from Missourian reservoirs beneath the crestal unconformity. Dense crude oil from stratigraphically discontinuous reservoirs along the basinward flank of the structure are associated with low-salinity pore water. Paraffinicity and salinity of waters decrease systematically with increasing depth of burial; these salinity variations, initially effected by ingress of water squeezed from expandable clays in the bordering basin, may have played a role in the selective solution of low-molecular-weight fractions. Water, vertically expelled along the crest, was desalted in passing from sandstone to shales. Large volumes of sandstone thereby were cemented off in shallow Permian rocks in places over the crest; the uncemented sandstones are petroleum-productive do n the flanks.
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