Native Sulfur Deposits Research Articles

On the origin of native sulfur deposits in Gebel El Zeit, Gulf of Suez, Egypt

Elemental sulfur deposits occur in Gebel El Zeit in various locations, rock types and forms. They occur as fine disseminations, fracture fillings and cone-shaped sulfur aggregates in powdery anhydrite in Little Zeit, Ras Zeit and northeast of the Cairn Hill; as fine disseminations in coral reefs east of Little Zeit and as vug fillings in the dolostones and limestones of Little Zeit and Ras Dip respectively. These types are associated with oil seepage and impregnations and are of bioepigenetic origin. Sulfur is recorded also as stratiform dissected bands in laminated rosette calcite and brown gypsum northeast of the Cairn Hill, where sulfur is of syngenetic origin, formed by biological activity.

Sulphur eruptions at Volcán Poás, Costa Rica

Since the recent desiccation of the crater lake at Volcan Poas, Costa Rica, vigorous fumarolic activity on the exposed lake bed has been associated with the manifestation of miniature sulphur volcanoes, sulphur flows and sulphur pools. In this paper, observations of 2–3 m high, active sulphur volcanoes are reported, and mechanisms for their formation proposed and discussed. Their ejecta, composed of milled particles, crystals and accretionary lapilli of sulphur, are unlike previously described pyroclastic sulphur deposits, and probably form from a spray of crystallised sulphur forced to the surface by fumarolic gases passing upwards through shallow bodies of liquid sulphur. While much of the erupted material is recycled, the reservoir of molten sulphur can also be replenished by influxing magmatic-hydrothermal fluids. δ34S isotope ratios of several samples of native sulphur collected at Poas range between −9.4 and −12.3‰ (CDT). These are among the isotopically lightest volcanic deposits of elemental sulphur reported, although this pronounced depletion is readily explained by the likely formation of the sulphur under the acidic conditions of the aqueous lake and hydrothermal system. The total amount of native sulphur deposits contained within lake sediments at Poas, and perhaps at other active volcanoes with crater lakes, is potentially substantial. A large explosive eruption could, by volatilisation and oxidation of this sulphur, inject large volumes of sulphur dioxide into the atmosphere. The greenish colouration of the sulphur, reminiscent of other documented terrestrial sulphur eruptions, is probably due to impurities. This emphasises the point that interpretation of spectral reflectances of the jovian moon Io, regarding the possible contribution of sulphur, cannot rely on extrapolation of laboratory data for pure materials.

Regional geologic setting of epithermal gold deposits, Chile

Epithermal gold deposits in Chile are Cretaceous to Cenozoic in age. The ores and the volcanic rocks with which they are associated were generated at a noncollisional, ocean-continent convergent plate margin. They are related to long, slightly sinuous north-northeast-trending magmatic belts roughly parallel to the Pacific coast. Most of the deposits are associated with eroded volcanic centers and subvolcanic porphyries. North-south variations in the nature, extent, and timing of magmatism control the succession of mineralization events.In the Late Cretaceous, vein districts (e.g., El Bronce) and hydrothermal alteration zones were formed in central Chile. Paleocene-Eocene volcanic rocks constitute a large, diffuse volcanic field in the Antofagasta region (21 degrees -26 degrees S), which contains epithermal precious metal and porphyry copper deposits associated with coeval extrusive rocks (e.g., Faride, San Cristobal, Guanaco, and Cachinal de la Sierra). In the late Eocene-early Oligocene, volcanism diminished and finally ceased in northern Chile, probably as a consequence of highly oblique plate convergence. Oligocene magmatism was restricted to emplacement of porphyries carrying copper deposits along transtensional zones within a strike-slip fault system. One of these deposits (Potrerillos), hosted by sedimentary rocks, developed epithermal gold mineralization in its cupola (El Hueso).The late Oligocene to mid-Miocene magmatic province of north-central Chile (26 degrees -31 degrees S) coincides approximately with the modern, nonvolcanic, fiat slab segment of the Chilean Andes and hosts the largest number of known epithermal developments. Deposits such as El Indio-Tambo, Nevada, La Pepa, Lobo, Marte, and La Coipa are hosted by Oligocene-Miocene volcanics. The deposits are associated with large zones of argillic and advanced argillic alteration, in some places related to shallow-level stocks and flow domes. A younger event of alteration-mineralization is recognized in the eroded cores of middle Miocene composite volcanoes, which cap some of the older altered areas (e.g., Refugio, La Laguna). The main alteration event began at 23 Ma, continued after a major deformation event initiated at 18 to 16 Ma, and ended at 11 to 8 Ma. The precious metal deposits and mineralized zones of the Oligo-Miocene province were exposed by erosion after the cessation or eastward shift of volcanism in the late Miocene, which was probably due to shallowing of the subduction zone between 26 degrees 30 and 33 degrees S.Late Miocene to Holocene magmatism in Chile is present in two segments beneath which the dip of the Benioff zone remains steep: north of 27 degrees S (Central Volcanic zone, CVZ) and south of 33 degrees S (Southern Volcanic zone, SVZ). The Central is characterized by widespread Neogene hydrothermal alteration zones and native sulfur deposits associated with composite volcanoes, calderas, subvolcanic intrusions, and active geothermal fields which are superimposed on the Oligocene-Miocene volcanic belt. These features are believed to represent a very shallowly eroded epithermal environment. In this setting the late Miocene Choquelimpie deposit is located in the exposed core of a volcano.

Oxygen and Sulphur Isotope Ratios of Sulphate Minerals in Native Sulphur Deposits

The isotope ratios 31S/32S and 18O/16O of secondary minerals, gypsum, celestite and barite, in the largest Polish deposits of sulphur-bearing limestones has been analysed. These paragenetic minerals are highly differentiated in δ34S and weakly in 18O: gypsum has the lowest delta values (+32‰ and +15‰, respectively) barite in contrast has δ34S between +60 and +70‰ and δ18O around +23‰, while celestite has the isotopic compositions between these two extremals. The distinct differentiation among these paragenetic minerals suggests a large isotope separation between sulphate ion and sulphates with Sr and Ba cations, which were formed at low temperatures. Some literature data may be simply interpret with the assumption of large isotope separation in this process.

The Alberta Sulphur Industry

Abstract Alberta is now the world's leading exporter of elemental sulphur, or ‘brimstone’. From a standing start in the early fifties this commodity now occupies an important place in Alberta's economy. Several organizations have emerged from this growth: Cansulex Limited in 1962 to handle offshore marketing for its member companies; Alberta Sulphur Research Ltd. (ASR) in 1964 to conduct research on separation and sulphur production problems; the Sulphur Development Institute of Canada (SUDIC) in 1973 to develop and expand uses for sulphur and to provide technical assistance on industry problems; and Sultran Ltd. in 1976 to manage the transportation of Alberta sulphur to the western ports. A Perspective on the World Sulphur Industry While sulphur has been recognized and used since man's early beginnings, the modern sulphur industry has its roots in the Industrial Revolution. New processes and industries were spawned which required large amounts of sulphuric acid, sulphur's main byproduct. This demand was met from native sulphur deposits, the most important of which were in Sicily, and pyrites from Scandanavia and Spain. Just before the turn of the twentieth century, the Frasch process was developed to exploit the vast native sulphur deposits (associated with salt domes) of the U.S. Gulf Coast. By the 1920s, the U.S. Frasch industry dominated the world sulphur market. Large-scale exploitation of sour gas fields in Canada and France in the 50's resulted in involuntary sulphur production and created a strong new factor in world supply. In 1970, byproduct sulphur production surpassed sulphur from voluntary operations for the first time and this trend is continuing. The U.S. Frasch industry, which produced 60% of Western World supply in 1950, now only accounts for 15%. In addition to sulphur recovered from sour gas and oil, and from native deposits using the Frasch process; the other primary sources of sulphur today are mined native deposits, roasting of pyrites (iron sulphides) and recapture of SO2 fumes from non-ferrous metals smelting. World production of sulphurin- all-forms in 1981 was about 54 million t and of elemental sulphur, about 35 million t. The world's major producers are listed in Table l. On the consumption side, about 80% of all sulphur is used in the form of sulphuric acid which is most often used only as a processing chemical. About one-half of world consumption is used in the manufacture of phosphatic fertilizers; the remainder is used in a wide variety of industries, the most significant of which are non-ferrous metal production, petroleum refining, iron and steel production, paints, chemicals, and pulp and paper. Geographically, the largest regions of sulphur usage in 1981 were North Amerlca (primarily the U.S.A.), 28%; East Europe (primarily the U.S.S.R.), 25%; West Europe, 19% and Asia at 15% (FERTECON data). About 15 million t of elemental sulphur are traded annually in the international market. Canada is the major supplier to this market, selling about 5 million tpa. Together with Poland, these two countries account for about two-thirds of world trade, with the remainder supplied in smaller quantities by a number of countries.

Chemistry and isotope ratios of sulfur in basalts and volcanic gases at Kilauea volcano, Hawaii

Eighteen basalts and some volcanic gases from the submarine and subaerial parts of Kilauea volcano were analyzed for the concentration and isotope ratios of sulfur. By means of a newly developed technique, sulfide and sulfate sulfur in the basalts were separately but simultaneously determined. The submarine basalt has 700 ± 100 ppm total sulfur with δ 34 S Σs of 0.7 ± 0.1 ‰. The sulfate/sulfide molar ratio ranges from 0.15 to 0.56 and the fractionation factor between sulfate and sulfide is +7.5 ± 1.5‰. On the other hand, the concentration and δ 34 S Σs values of the total sulfur in the subaerial basalt are reduced to 150 ± 50 ppm and −0.8 ± 0.2‰, respectively. The sulfate to sulfide ratio and the fractionation factor between them are also smaller, 0.01 to 0.25 and +3.0‰, respectively. Chemical and isotopic evidence strongly suggests that sulfate and sulfide in the submarine basalt are in chemical and isotopic equilibria with each other at magmatic conditions. Their relative abundance and the isotope fractionation factors may be used to estimate the ƒo 2 and temperature of these basalts at the time of their extrusion onto the sea floor. The observed change in sulfur chemistry and isotopic ratios from the submarine to subaerial basalts can be interpreted as degassing of the SO 2 from basalt thereby depleting sulfate and 34S in basalt. The volcanic sulfur gases, predominantly SO 2, from the 1971 and 1974 fissures in Kilauea Crater have δ 34 S values of 0.8 to 0.9%., slightly heavier than the total sulfur in the submarine basalts and definitely heavier than the subaerial basalts, in accord with the above model. However, the δ 34 S value of sulfur gases (largely SO 2) from Sulfur Bank is 8.0%., implying a secondary origin of the sulfur. The δ 34 S values of native sulfur deposits at various sites of Kilauea and Mauna Loa volcanos, sulfate ions of four deep wells and hydrogen sulfide from a geothermal well along the east rift zone are also reported. The high δ 34 S values (+5 to +6%. o) found for the hydrogen sulfide might be an indication of hot basaltseawater reaction beneath the east rift zone.

New Observations on the Pleistocene Evaporites of Montallegro, Sicily and a Modern Analog

ABSTRACT The Montallegro Formation (Pleistocene) of the southern part of Sicily, contains several gypsum-bearing zones. The gypsum deposition appears to be the result of reprecipitation of dissolved adjacent, Messinian (Late Miocene) deposits. The Montallegro gypsum occurs as laminar, crystalline gypsum, disseminated acicular gypsum in marls and also as gypsum 'trees.' Associated with the gypsum-bearing marls are nodular and laminar native sulfur deposits. These sulfur deposits have formed probably syndepositionally with the emplacement of the gypsiferous marls, as the result of biological activity. Analogies are drawn between many of the features described from the Montallegro Formation and some solar salt pan evaporites from California.

The tops and bottoms of porphyry copper deposits

Although it is now widely accepted that porphyry copper deposits consist of zonally arranged shells of alteration and mineralization centered on high-level, calc-alkaline stocks, the nature of their uneconomic upward and downward extensions remains undocumented. This paper attempts to characterize these upward and downward extensions and to integrate the resulting concepts into a hypothetical model for complete porphyry copper systems. Examples from Chile, Argentina, and elsewhere are used to aid in the substantiation of the model. Programs of exploration for porphyry ore deposits can clearly benefit from the application of a model of this sort.A typical porphyry copper-bearing stock is inferred to grade downward into stock-work mineralization and potassium silicate alteration in a phaneritic intrusive, which in turn is transitional downward to an essentially unaltered pluton of considerably larger dimensions than the stock. Porphyry copper deposits are normally located in the basement beneath a comagmatic volcanic pile, which is transected by a column of hydrothermal alteration representing the upper parts of the porphyry copper system. This alteration consists of propylitic and argillic types with localized patches of silicification and advanced argillic alteration. The volcanic pile is thought to constitute a strato-volcano which possesses large native sulfur deposits and small quantities of base metals, particularly copper, in sublimates at high-temperature fumaroles in the vicinity of its central vent; these surficial deposits are considered as the effluent products of active porphyry copper systems.The available evidence favors the emplacement of the tops of typical porphyry copper deposits at depths of 1.5-3 km beneath the summits of stratovolcanoes and suggests that entire porphyry copper systems possess vertical extensions as great as 8 km.At Chuquicamata, Chile, a major high-angle fault may have cut the porphyry copper deposit, and subsequent erosion has removed the portion of the deposit that was situated in the upthrown block. The hydrothermal alteration pattern in the remaining part of the ore body is incomplete and terminates abruptly against the fault. The unaltered, phaneritic granodiorite, containing minor veins and pegmatitic bodies, in the upthrown block is interpreted as the root zone of the Chuquicamata porphyry copper system.The lower most, mineralized part of a porphyry system is believed to be exposed at Los Loros, Chile. There a zone of molybdenum-rich and copper-poor potassium silicate alteration carrying abundant K-feldspar occupies an area in the interior of a relatively large pluton of phaneritic granite.At Farallon Negro, northwest Argentina, several small porphyry copper deposits pierce the infrastructure of a temporally related, andesitic stratovolcano. This unusual locus of the deposits above the subvolcanic basement enables it to be determined that porphyry copper emplacement was a late event in the construction of the stratovolcano, succeeded only by the formation of minor rhyolite intrusives and epithermal veins.Extensive zones of pyritic alteration including widespread silicification, in which intrusive rocks are virtually absent, are visible in the centers of eroded stratovolcanoes, as at Cerro Marquez in northern Chile. Such zones are interpreted as the columns of alteration spanning the vertical interval between porphyry copper deposits and the vent areas of uneroded volcanoes. At Cerro Queva in northwest Argentina, lead-silver mineralization associated with advanced argillic alteration is located in an alteration zone beneath the summit regions of a stratovolcano.It may be concluded that during the final stages of construction of stratovolcanoes, fumarolic and hot-spring activity are the surficial manifestations of the efflux of metal-bearing magmatic fluids from magma chambers during retrograde boiling, the interaction of these fluids with the groundwater system and the consequent formation of alteration and mineralization. The proposed model implies that porphyry copper systems effectively span the boundary between the plutonic and volcanic environments.

Potential for discovery of native sulfur deposits in caldera volcanoes of the Kuril Islands

Potential for discovery of native sulfur deposits in caldera volcanoes of the Kuril Islands

Prognostication of native sulfur deposits in sedimentary formations

Structural, paleogeographical, karst and other criteria for appraisal of sulfur potential of certain territories are discussed, together with prospecting indications of sulfur and their mapping. --IGR Staff.

Stable carbon isotopic composition of biogenic carbonates

The geology and sulfur isotopic composition of epigenetic pyrite of the Gas Hills district, Wyoming, indicate a bacterial origin for these sandstone-type uranium deposits. The δC 13 value of epigenetic calcite associated with organic materials, however, is heavier than the isotopic composition of calcite of biogenic native sulfur deposits. Stratigraphic and carbon isotopic evidence suggest that contamination by sedimentary carbonate is minimal in the Gas Hills samples. Field and laboratory data show that anaerobes produce isotopically heavier CO 2 and lighter methane than the associated organic material which they consume as an energy source. The δC 13 values of the salt-dome calcites overlap the methane field, the Gas Hills values overlap the CO 2 field, and analyses of Sicilian Sulfur limestones are intermediate. Deposits Gas Hills (calcites with organic material) Gulf Coast Cap rock Sicilian Sulfur limestone (gyngenetic calcites) Number of samples 20 35 27 Mean δC 13 −22.5 −37.9 −28.7 Sample standard deviation 4.0 6.7 8.9 Presumably a spectrum of values could be obtained by the oxidation of methane and contamination by the original bacterial CO 2 and sedimentary carbonate. The quantized values of the three deposits are, therefore, evidence of strong geologic control. Methane was stable under the reducing conditions (shown by the presence of uraninite and sulfides) of the Gas Hill, while methane was concentrated and oxidized in the cap rock of salt-domes (mineralogy includes native sulfur), and neither methane nor CO 2 was preferentially lost during the syngenetic precipitation of the Sicilian Sulfur limestone.

The Reservoir Mechanism of Sulfur Recovery

Published in Petroleum Transactions, AIME, Volume 207, 1956, pages 246–251. Abstract A reservoir mechanism of sulfur recovery by the Frasch process is presented. Improving the economics of recovery appears to be largely a well, rather than a reservoir problem. A most important factor is the limitation of the lateral extraction of sulfur about the wells due to the almost vertical flow of the injected hot water. Model studies are described which confirm the mechanism of sulfur recovery by presently used methods. Studies on a five-spot system indicate improved economics regarding recovery, recovery rate, thermal efficiency, and well spacing. Introduction Sulfur mining by the Frasch process is one of the most important methods of sulfur production. Developed by Herman Frasch in 1894, it enjoyed a rapid growth and presently supplies 40 per cent of the world's sulfur and about 80 per cent of the U. S. sulfur. The Frasch process of mining the underground native sulfur deposits involves melting the sulfur in place by introducing super-heated water into the sulfur bearing formations, and producing the sulfur as a liquid. Many problems are encountered in mining these native sulfur deposits, and sulfur production depends chiefly upon the nature of the sulfur deposit and the underground thermal efficiency of the heat transfer system. The Recovery Mechanism Sulfur is typically found in salt dome cap rock as crystal aggregates occurring within the cavities, seams, and pores of limestone and gypsum formations. Sulfur-bearing limestone is typically cavernous, vugular, and fractured. Porosity averages about 20 per cent and sulfur saturation averages approximately 25 per cent by weight. The sulfur bearing formations are very heterogeneous in nature and physical characteristics vary widely within small distances. Total cap rock thickness may vary from 50 to more than 1,000 ft, and net productive thicknesses from a few feet to a few hundred feet. In most cases the upper portion of the limestone formation is barren of sulfur, varying from 5 to 2,000 ft in thickness. The immediately overlying sediments and the underlying dense anhydrite formation provide permeability barriers to the flow of water from the cap rock section.

The origin of native sulphur deposits from isotope fractionation studies

Sulphur and carbon isotope abundance studies have been made on the sulphur well cores and adjacent formations of the Texas and Louisiana salt domes. The free sulphur was found to be depleted in S 34 with respect to associated sulphate by 3.9 per cent on the average. This compares to a 3.2 per cent fractionation of the sulphur isotopes in the formation of free sulphur from sulphate by bacterial action in North African lakes. Also, the associated sulphate was found to be enriched in S 34 as compared to adjacent anhydrite formations to various extents depending on the sulphur well investigated. Carbon isotope ratios obtained for the calcite matrix of the sulphur well cores showed that the carbon of the calcite was depleted by from 3.3 to 5.5 per cent in C 13 as compared to standard limestone. These results indicate that the calcite was formed simultaneously with the free sulphur from carbon of organic origin by a process resulting in some further fractionation of the carbon isotopes. All the isotope abundance data can be reconciled with the conclusion that the large sulphur deposits of the southwestern United States have been formed by living organisms.