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By A. D. Davis, D. J. Dixon, J. L. Sorenson, C. J. Webb, S. Dawadi

Limestone-based material appears to be an effective arsenic removal process that has great potential for source reduction in drinking water. Limestone-based material offers several benefits to the drinking water community: 1) reasonable removal efficiency as compared to material cost, 2) broad geographic and water system applicability, 3) compatibility with other water treatment processes, 4) ease of technical use, and 5) low-cost disposal in ordinary landfills. Batch and column experiments have evaluated the removal efficiency of several limestone types. Additives and material alteration have increased the removal efficiency. Granulation of powdered limestone as a filter media currently is being investigated.

Jan 1, 2006

By Gordon B. French

The Occidental Oil Shale mining and retorting system for the production of shale oil has many advantages over the conventional underground mine and surface retort systems. For example only a portion of the oil shale is mined and transported to the outside, where it blends with the existing shale talus found on most of the slopes in the immediate area. The retorted spent shale is retained underground so that it does not become a surface disposal problem. The process consumes only minor amounts of water which is produced in adequate amounts in the retorting to fulfill all mining operations needs without outside supplies. Noise and dust levels are kept to a minimum with most of the facilities located underground. The exception being the generating stations and facilities as required to monitor air and water qualities, and last but not least, more than four times as much oil is pro¬duced from a given acre than from conventional surface processing. With the increased thicknesses as available on the government monopoly area this number could be increased by a substantial amount.

Jan 1, 1975

By D. R. Nagaraj, Napoleon Tercero, Raymond Farinato

Historically, as for most reagents used in flotation, the wide-spread use of dialkyl dithiophosphinates as collectors in practical applications has preceded a detailed scientific understanding of how they work. Dialkyl dithiophosphinates are a technologically and commercially important class of collectors used in the flotation processing of Cu-Au, complex polymetallic, and precious metal ores. Plant usage has demonstrated that dithiophosphinates exhibit higher selectivity and flotation rates for Cu sulfides, galena, and precious metal values in the presence of other gangue sulfides, than the traditionally used collectors such as dialkyl dithiophosphates and xanthates. They also have an attractive health, safety, and environmental (HSE) profile. Although dithiophosphinates received little attention in the past in the flotation research community, recently, there has been significant interest in this chemistry, and numerous studies have been conducted to understand the fundamental interactions of dithiophosphinates with several base metal sulfides and precious metals. A critical overview of fundamental studies, laboratory ore flotation, and plant practice of dithiophosphinates is given in this paper. The findings from these studies are rationalized and explained by drawing on concepts and insights from coordination chemistry. A comparison between the interactions with various minerals and metals of dithiophosphinate and dithiophosphate analogues brings out some of the subtleties that seemingly minor changes in collector chemistry can make. The critical overview and analysis given here is useful in identifying gaps in knowledge regarding this important class of compounds. This in turn can provide a basis for the design of studies to advance our understanding of dithiophosphinate flotation performance.

By E. Watkins, S. J. Schatzel, K. Ajayi, V. Gangrade

The National Institute for Occupational Safety and Health (NIOSH) has been conducting research related to unconventional gas wells positioned in abutment pillars associated with active longwall mining in Southwestern PA. The Ventilation and Explosion Prevention Team at NIOSH is working toward predicting and characterizing a hypothetical casing breach and its effect on the safety and health of mine workers, gas well workers, and the general public. An important aspect of this research is to distinguish coalbed gas from shale gas in the mine environment as an indicator of a casing breach. Another noncoal gas source exists in the region in the form of underground gas storage fields which also have the potential to migrate towards mine workings. During a potential gas breach, the addition of excess natural gas to coal mine environments will exceed the anticipated ventilation loading and can create a mine explosion hazard. A methodology has been developed to distinguish these gas sources. Gas samples from the three sources were analyzed by gas chromatography, and interpretive methods were applied to distinguish the populations graphically and statistically. Bivariate plots using the hydrocarbon index and the normalized molecular ratios showed that the sources occupy different regions of the graphs. All samples of non-coal gas contained under 2% CO2, and all coal samples included greater than this amount. A multivariate T-squared (T2) test analysis relating comparing data in pairs showed a low p-value (dimensionality parameter) and a high T2 test statistic for all comparisons, indicating that these sources are different and distinct gas populations. Ultimately, stakeholders from the mining and gas production industries can utilize this method to identify gas sources and a potential casing breach.

Mar 2, 2022

By Shani Engelbrecht, Belinda McFadzean, Avuyile Wali, Natalie Shackleton, Vratislav Malysiak

Frothers play a crucial role in sulphide and PGM ore flotation recovery, and AECI Mining Chemicals studies on PGM ores have shown significant flotation kinetic increases with the optimal frother-collector combinations. Using Senfroth 200 as the industry baseline, remarkable kinetic increases were observed with AECI Mining Chemicals developed frothers in the first concentrate. Even in the worst-case scenarios, 4E PGM recovery increased by 5% at a slightly higher concentrate grade. It is important not to limit frother dosage to a fixed value. Instead, enough frother should be added to maintain a stable bench float, measuring the dosages by frother volume before and after tests. Frothers can be specialized blends and their importance should not be underestimated. The results produced by formulating and innovating frothers to address specific industry challenges have been encouraging. Testing a frother on a plant scale does not have to be as daunting as with collectors, enabling the identification of the best frother-collector combinations at an industrial scale. AECI Mining Chemicals bench scale testwork has motivated plant-scale trials that have successfully transitioned to commercialization. This paper compares the results from metallurgical and froth stability tests and shows that occasionally frothers that have a less stable froth can have improved valuable mineral recoveries, while still exhibiting better drainage for reduced entrainment and mass pull. It was shown that caution should be used when relying only on simplified froth stability tests in the evaluation of new frothers.

Feb 1, 2025

By V. Claremboux

The transformation of raw iron ore into high quality steel can take place via several processes. A general consistent theme involves the upgrading of the iron ores via methods such as flotation and magnetic separation, the preparation of an agglomerate such as via pelletization or sintering, the smelting of the agglomerate into a high grade iron product, and the further refining of iron into specific steel alloys. Each of these steps admit potential for optimizations and alternatives, and the process overall is critical to meeting the world’s continuing iron demands.

Feb 1, 2025

By John Callahan

A stream sediment (minus 80-mesh and minus 60-mesh panned concentrates) and lithogeochdcal survey for gold did not locate any Triassic-age placer deposits in the northern Wadesboro and southern Sanford basins in North Carolina. A stream sediment geochemical program for uranium funded by the North Carolina Energy Institute did identify one and anomalous site (8.5 ppm U; 5 ppm Th) near Covenington, North Carolina and eighteen possibly anomalous sites (1-1.6 ppm U) . Five of the eighteen samples with uranium levels in the 1-1.6 ppm range have high thorium levels (112-853 ppm) and may indicate a monazite source for the uranium. Gold values as high as .83 ppm in the stream sediments and 9.3 ppm in the panned concentrates were obtained during the survey. Small (<.5mm) flattened grains of gold (1-4 grains) were observed along with coarse kyanite and/or monazite in some of the panned concentrates. A distinctive pattern of high gold values in the sediments was observed in the vicinity of Mangum, N. C. where Minard (13) reported values as high as 2.1 ppm £ram a Triassic lithology. Follow-up gold analyses on over 400 rock samples from twenty-eight exposures near Mangum failed to obtain any high values (<55 ppb). The presence of coarse kyanite, monazite and gold in panned concentrates may be from a source younger than the Triassic lithologies that the streams currently drain or adjacent Paleozoic rocks.

Jan 1, 1979

By A. Bruynesteyn

Many papers &apos;have been publihed on the role of the bacterium.Thiobacillus ferrooxidans in the oxidation of reduced sulfur compounds, and years of research have established the following environmental factors, which influence biological oxidation. 1. Oxygen is required for the oxidation of reduced sulfur compounds to the sulfate form. Sufficient oxygen. is available from the air, consequently, it is of importance to get the air to the bacteria. 2. The bacteria are active in the pH range 1.4 3.5. Maximum activity occurs at pH 2..0 - 2.8. 3. -In order to allow the bacterial populations to expand, certain essential nutrients must be available. Nitrogen has to be supplied for the production of body protein, and ammonia is the source most readily accepted by the bacteria. Carbon dioxide is the only utilizable source of carbon and the small amounts available in air are the primary source of this element. Small amounts of phosphate, manganese,, potassium,. calcium. and magnesium are also required. These trace minerals are available from the water and host rock in sufficient quantities. 4. Water is required as a carrier for the oxygen carbon dioxide and other nutrients, as-well as a solvent for the metallic sulfates produced. The bacteria are motile and the water allows the bacterial populations to spread:: bacterial activity ceases if the equilibrium relative humidity drops below 100%. 5.-optimum bacterial activity occurs at temperatures of 34 - 35°.C (93 -.95° F). All activity ceases above 45° C. At lower temperatures, activity its dramatically decreased, but there is still a significant amount at 10 - 11° C.- Thiobacillus ferruoxidans has been isolated from a mine with a year round temperature of 3° C. 6. Unpublished results from our laboratory show that biological leach ore oxidation takes place during the rest periods at the same rate as during the wet leaching periods providing there is a film of moisture remaining around the particles. Optimum conditions can be readily achieved in the laboratory, but application of our laboratory knowledge to commercial leaching dumps is riot as simple. Attempts to achieve improved environmental conditions for the bacteria in leaching dumps would require substantial capital investment and careful planning of leaching operations. This paper

Jan 1, 1972

By John E. Miller

Unit Rig & Equipment Co., manufacturer of Lectra Haul Trucks, is continually studying methods of reducing the operating costs of large haulage trucks. Reduction of haulage system operating costs is an important goal that equipment operators and equipment manufacturers constantly try to improve on. One of the most variable and important factors affecting operating costs is actual truck operating practices. An examination was centered on methods to optimize truck utilizaion. It was found that a very effective method of accomplishing this goal would be an Automatic Truck Control (ATC) system to automatically control a fleet of haulage trucks in a predetermined pattern. Economic studies were conducted which showed a very favorable reduction in mine operating costs by use of an ATC system. In 1970, Unit Rig & Equipment Company, in conjunction with SAAB-SCANIA began preliminary development of adapting for truck use a proven automated control system previously used for train systems, small trucks, and military target vehicles.

Jan 1, 1979

By Rock M. Poulin, Bruce G. Moulton, Daniel E. Nowak, David T. Cass

The Yacambu Irrigation Tunnel Project of 34 km, 5 meter diameter circular and horseshoe section, has been under construction since the early 1970&apos;s. Notable among the excavation challenges is high ground cover of 3,000m creating large lithostatic pressures in the tunnel alignment with subsequent plastic flow of the ground in the tunnel walls. The tunnel may converge from small amounts to 1 or more meters of diameter over long sections. Several excavation techniques have been attempted but all without desired results. The paper proposes a new machine concept that uses the history of ground experience as its basis for design.

Jan 1, 1995

By John J. Dwyer

As one begins to contemplate the organization of a talk with the title "Iron Ore - The Permanent State of Evolution," the main divisions appear to be the past, the present, and the future. But distaste for repetition of the present production achievements, which scarcely need additional description on this occasion, soon leads one to the conclusion that a more appropriate division of the subject is simply the past and the future . . . with emphasis on the future. We are working in the present, but it can only be understood by what has taken place in the years and decades gone by, and/or under what terms we will have to face the future. Evolution is more often thought of as a steady change - but steady change is really the product of revolutions, sometimes making headlines but often unnoticed at the time. With hindsight, we recognize the great importance of the emergence of the Bessemer converter and the open hearth and the vast influence that both have had on steel making and the changing ore demand. In this country we also see schooners opening the era for lake transportation of iron ore from Michigan to Take Erie. Later, steamships haul the ore from the Mesabi Range to the steel centers of the country. In order to take full advantage of the inland seaway, there had to be revolutions in ship design, loading and unloading facilities and channel and lock development. Full scale utilization of the resources of the Mesabi Range, itself, required parallel upheavals such as the development of new production equipment, and substitution of modern forms of energy for horsepower, and, yes, manpower, as well.

Jan 1, 1968

By J. P. Gliddon, G. C. Wade, J. W. Lill

Since 1980 a number of significant changes have been introduced at Palabora in an effort to offset the effects of reduced product price and increased unit costs of production. These changes and improvements include major equipment rationalization programs, the introduction of trolley-assisted truck haulage, adoption of a sophisticated computerized truck control system, pit design enhancements, improved drilling practices, use of emulsion explosives, and the installation of an in-pit crushing and conveying system. The various changes, their effect on the operation, and their contribution to cost reduction and improved productivity at Paihbora are considered.

Jan 1, 1987

By Heinrich H. Becker, Vladimir L. Konyukh, Sergey P. Koltsov, Valery A. Davidenkol

Ramifide conveyor transport of the biggest russian coal mine "Raspadskaya" is simulated by Petri nets. There are 6 longwalls with accidental output. 12 belts, and 5 transfer bunkers at this mine. It is necessary to coordinate transport links for recon- structed conveyor system. Many tasks were solved by dynamic simulation, such as estimation of transport lateness, influence of transfer bunkers on an unevenness of total coal flow, maximum filling of each bunker, maximum time of main conveyor refusal, co-ordination of unloading for dependent bunkers, choice of main conveyor. The problem of mine-wide conveyor transport animation for dispatcher is formulated in reference to mine "Komsomolets". OBJECT OF SIMULATION The biggest russian coal mine "Raspadskaya" is situated on a south part of Kusnetski coal basin (West Siberia). One mines about 20.000 tons of coal out of flat seams by 2.2-4.5 m thickness in a day. There are 6 fully- mechanized longwalls by output 720- 3600 tons in a shift in mine. Coal haulage to surface is carried out by 12 belts having 1.6 - 4.3 km length. For a smoothing over un- evenness of coal flows 5 transfer bunkers to 300 tons were intro- duced. The designed conveyor system is divided into two parts (Figure 1). In the upper part some coal from Face 1 comes through belt road C, into transfer bunker 8,. From the opposite side that bun-

Jan 1, 1996

By Tania Schmid, Marco Portal Valdivia, Sandra Nowosad

Today’s mining industry faces rapid transformation driven by automation, climate responsibility, and ESG demands, requiring more than technical expertise. Future mining engineers must blend engineering excellence with key human skills such as communication, leadership, resilience, empathy, adaptation to change, curiosity and lifelong learning. Based on two recent surveys, one to senior leaders with over ten years of experience in the mining industry and a second, focused on understanding the perceptions of young professionals, this paper explores which skills become core competencies by 2030 for navigating complexity, leading responsibly, and enabling sustainable transformation. Furthermore, it also examines how educational institutions can adopt strategies to foster the development of these critical skills, preparing future mining talent for evolving challenges.

Feb 22, 2026

By Tristan Joubert, Fabio Panella, LiLing Chen, Yung Loo, Michael Devriendt, Nasir Qureshi, Ahmad Ali

Tunnel inspections have traditionally been carried out manually by inspectors writing up observations and taking photos of defects. The results from the inspection and the defects observed are dependent upon the rigor of the inspectors and may be subject to repeatability and consistency issues and is often time consuming with elevated health and safety risks. This paper will discuss work that is being carried out in developing and implementing an innovative hardware and software solution integrating machine learning to automate the process of capturing objective tunnel condition information, offering cost and programme savings as well as health and safety improvements

Jun 13, 2023

By F. N. Siddiquie, Mohd Shaif, Rajiullah Khan, Juned Alam

Manganese ore bodies of Banswara Mn belt were classified into stratiform and stratabound types, based on their mode of occurrence, distribution, and their chemical characters. These ore bodies generally composed of braunite, pyrolusite, cryptomelane/ psilomelane, wad, etc. The stratiform-type Mn ore bodies are conformable with the associated host rocks (Mn phyllite, etc.) and occurred in the form of layers, bands, etc., which are variable in their shape and size. These ore bodies are also strongly folded with the enclosing host rocks. The others, which are stratabound-type Mn ore bodies, also showed an intimate association with the associated host rocks. These types of ore bodies occurred in thin layers, pockets, lenses, stringers, etc. The classified ore bodies are confined with Kalinjara formation of Aravalli Supergroup of Paleoproterozoic age. The ore bodies are structurally controlled and well associated with phyllite, schist, limestone, quartzite, etc. The stratiform-type ore bodies constitute a marginal to low Mn grade and are also characterized by lower Mn content (26.19–39.24%) along with the Mn/Fe ratio of 7.16–12.23, while the stratabound-type Mn ore bodies are rich in Mn (35.92–49.64%) along with the higher Mn/Fe ratio of 14.15–23.97. However, the poor Mn grade along with high siliceous impurities of Banswara Mn deposits is subjected to them for intermittent mining activities in the past and, consequently, did not attract the scientific and industrial community for the evaluation of these resources. Therefore, the authors attempted this study in a scientific and systematic manner (mode of occurrence/distribution and possible methods for evaluation/exploration) to evaluate the potential of existed and newer Mn deposit resources in the Banswara Mn belt. The whole findings would be very much helpful for exploration/ mining geologist along with other concerned, to completely evaluate these Mn deposits in the future.

Aug 16, 2021

By Doug Williams, Kent J. McGrew, Dr. Jack Murphy

For some time, selenate has eluded water treatment by conven­tional means such as precipitation and clarification. This has been due to the nearly universal solubility of all oxidized sele­nium species, the low levels required for surface discharge, and almost identical chemical behavior to all forms of oxidized sul­fur. The last characteristic makes selenate particularly difficult to deal with in acid mine waters where sulfate can easily be on the order of one gram per liter. Approaches such as ion exchange or reverse osmosis often tum into total demineraliza­tion schemes for the sake of removing a "trace" selenium species that may be present on the order of 108 sulfate/selenate. Reduction of selenate to selenite or elemental selenium by chemical means has been relatively unresearched. Some limit­ed success has been reported (Murphy, 1988) using ferrous hydroxide as a reducing agent; however, the reaction time as reported is too slow to be useful in a practical plant design. One significant difference between selenate and sulfate is that selenate has been discovered to be reducible in acid solution by elemental iron when catalyzed by soluble copper. Since the +4 or zero valence states of selenium are rather easy to deal with by coprecipitation with iron salts or alum, the elemental iron dis­solved in the process contributes to the overall process by pro­viding sludge upon raising the pH that can be separated by con­ventional clarification. Commercial production of selenium using copper catalyzed reduction of selenite to selenium metal via sulfur dioxide is well established, however, at the < 5 ppb requirements for surface discharge this reduction process equili­brates at levels far too high to be useful to low level selenate removal criteria. The reaction reported herein uses elemental iron for reduction of selenate with copper acting either as a cata­lyst or as a coprecipitation agent. This method, employed with conventional sludging, clarification and filtration can provide an economic method to achieve non detectable selenium (< 0.005 mg/I). Iron consumptions for the conditions tested have been on the order of 3 lbs/1,000 gallons treated. This represents as little as $0.06 or $2.00 per 1,000 gallons based on using a scrap source of iron or the purchase of electrolytic iron for the process.

Jan 1, 1996

By Kerry J. Stanaway, Thomas E. Garnar

Titanium was discovered in 1791 and, four years later, was named after the Titans of Greek mythology. Titanium metal was first made in 1910, but was not used commercially until the 1950s when it was nick-named The Wonder Metal of the Age. The first titanium dioxide (TiO2) white pigments were produced commercially in 1915; more than 90% of the titanium minerals produced in the world today are used in the manufacture of white pigments. The remaining 10% are used to manufacture titanium metal and other uses such as welding rod fluxes. Titanium mineral mining began in the United States between 1880 and 1900 in Chester County, Pennyslvania. Rutile from a deposit near Roseland, VA, was mined in 1901. The use for the rutile was limited to production of a few titanium chemicals and for coloring ceramics. Larger scale mining for ilmenite, rutile, and zircon began in Florida to provide chemical materials for use in World War I in 1918. This mining ended in 1928. Large scale mining of titanium minerals in Australia began when Benick, Anderson, and Porter (later called Tamco) started mining the beach sands at Yamba in New South Wales in 1935. Ilmenite production from beach sands in the State of Kerala in southwestern India also began in the 1930s. The 1940s saw many changes in titanium mineral mining. Extensive deposits of ilmenite and ilmenite-bearing iron ores were discovered in eastern Quebec. The Pigments Department of E.I. Du Pont de Nemours & Co. lost their high grade Indian ilmenite supply after World War II began, and they were forced to use lower grade ilmenite from National Lead&apos;s (now NL Industries) Sanford Lake Deposit, near Tahawus, NY, in the Adirondack Mountains. At the end of the war, Du Pont undertook an intense search for a domestic ilmenite source. With the cooperation of the US Bureau of Mines, Du Pont geologists found a very large deposit east of Starke, FL, in 1946. In 1948 Du Pont entered into a contract with Humphreys Gold Corp., who operated a heavy minerals mine near Jacksonville, FL, to construct a plant and operate it for a period of ten years. The plant started up in 1949 and operated under Humphreys&apos; management until the contract expired in 1958. Du Pont has operated the plant since that time. In 1956, a second plant was designed and built by Du Pont a few kilometers northeast of the town of Lawtey. The 1960s saw titanium mineral production expand in the southeastern US with Humphreys&apos; contract mining Du Pont&apos;s ore body at Folkston, GA. In the early 1970s. American Cyanamid and Union Camp Paper Co. formed a joint venture company, Titanium Enterprises (TE), to mine and separate titanium minerals from Union Camp&apos;s ore deposit southwest of Green Cove Springs, FL. In 1975 the TE plant was shutdown and later sold to Associated Minerals (USA), Inc. (AMC), a subsidiary of Renison Goldfields Consolidated Ltd., an Australian company. It now operates under the name RGC (USA). Mineral production grew in the 1970s with the development of extensive heavy mineral deposits at Eneabba in Western Australia and Richards Bay in the Republic of South Africa. The 1980s saw the construction of a very large ilmenite mine and synthetic rutile processing plant in the state of Orissa southwest of Calcutta, India. At the same time, concern for titanium mineral shortages expected by the end of this century, gave rise to a flurry of exploration activity during the mid 1980s. As a result, large deposits were found in Virginia and North Carolina. New deposits were also discovered in Australia. Fig. 1 shows the distribution of world titanium deposits and mines. The world TiO, production capacities are given in Table 1.

Jan 1, 1994

By B. Pina

The conversion of maf coal to pyridine solubles and gas was investigated in a microautoclave batch reactor for two Kentucky washed coal samples (Ky. #9 and Ky. #11). Solvent hydrogen donor strength was controlled by the tetralin content of a mixed 1-methyl naphthalene-tetralin solvent. Primary liquefaction conversions greater than 90% in 10 minutes of reaction time at 427°C were achieved in liquefaction solvents with moderate hydrogen-donor strength (circa 40% tetralin). A modified irreversible first order rate expression, containing a parameter (a) to account for the intrinsic reactives of the maf coal, described the experimental kinetic data rather well. The integrated form of this rate expression is -k1e x = a (a- ß)e (eq. 1) Parameter ß in equation (I) is the pyridine solubility of the starting maf feed coal, x is the primary liquefaction fractional number of conversion, k1 is the specific reaction velocity constant and ? is reaction time. Primary liquefaction rate was found to be quite temperature sensitive and independent of coal when a liquefaction solvent containing 40% or more tetralin was employed. Primary liquefaction rate appears to depend on liquefaction solvent hydrogen donor strength for solvents containing = 40 wt.% tetralin. The intrinsic reactives in the maf feed coal or a appear to depend mainly on the inertinite group maceral content of the coal for the two coals studied in liquefaction solvents containing 3 40wt.% tetralin. In contrast, a appears to decrease in liquefaction solvents of low donor strength., i.e; solvents with less than 40wt.% tetralin.

Jan 1, 1984

By Marshall D. Himes, Erich U. Petersen

The Sheep Creek deposit near White Sulfur Springs, Montana, is a middle Proterozoic stratabound and strataform sediment- hosted massive sulfide containing 4.5 million tonnes (5.0 million tons) averaging 2.5% copper, and 0.1% cobalt in the upper sulfide zone (USZ) and 1.8 million tonnes (2.0 million tons) averaging 6% copper in the lower sulfide zone (LSZ). Mineralization is hosted in lower Newland shales and debris flow conglomerates in the graben controlled Helena Embayment of the Belt Basin. USZ mineralization is characteristically high in Cu, Co, Ni, Ba, As, Pb, and Ag. Mineralogically it consists of barite, pyrite, chalcopyrite, and tennantite with minor amounts of marcasite and various cobalt minerals. By contrast, the LSZ is higher in Cu, Ni, and Au and lower in Co, As, Pb, and Ag. Mineralogy of the LSZ consists of dolomite, pyrite, and chalcopyrite. In both zones significant amounts of cobalt, nickel, arsenic and copper are incorporated in pyrite rims. Tennantite controls the abundance of numerous trace elements in the ores. Fluid incluison data from hydrothermal USZ barite suggests that mineralization took place at temperatures in excess of 250°C, under relatively oxidizing conditions (f02 = 10-32+1) from moderately saline (1.1-3.5m), metal rich brines. The absence of barite in the LSZ suggests mineralization under more reduced conditions (f02 = 10.38+2). Mineralization was initiated following basin subsidence in excess of 400m. Contemporaneous with movement along a growth fault(s) was upward migration of hot metal-bearing fluids which permeated the loosely consolidated sediments and may have vented on the sea floor. The differences in the two zones may be explained by the effects of variations in local basin morphology and solution chemistry.

Jan 1, 1990