The Neoarchean greenstone belts of the Canadian Superior Province host world-class Au and base metal (Cu-Zn-Pb) massive sulfide deposits with distinct geological features, including a wide range of different host rocks and crustal settings. The range of settings is reflected in the trace metal signatures of their ores. This study examines the trace element geochemistry of pyrite from 55 different Archean volcanogenic massive sulfide (VMS) deposits in Canada to test the relationship to their host rocks, the deposit sizes and their grades. The database includes 258 samples of pyrite from 47 deposits in the Abitibi Greenstone Belt (AGB), together with 30 samples from 8 deposits in the Western Superior (Sturgeon Lake, Uchi, Benny, and Manitouwadge belts) and 45 samples from 6 deposits in the Slave Province (Hackett River, Amooga Booga, and High Lake belts). We used statistical methods to characterize the trace element geochemistry of pyrite in grab samples from the deposits, as well as larger samples representing many thousand of tonnes of ore from monthly concentrates. The study focused on pyrite mineral separates comparing samples from different deposits and different ore types within individual deposits. The analysis shows the trace element geochemistry of pyrite is a useful fingerprint of the different mineralizing systems, with trace element enrichments and depletions reflecting different source rocks, inferred temperatures of ore formation, and the scales of the hydrothermal systems. A comparison of the Abitibi samples to other deposits in the Superior Province shows distinct trace element signatures between primitive and more evolved crustal settings of different age. Similar results are found among 102 samples of pyrite from 30 deposits in Proterozoic and Phanerozoic belts across Canada. District-scale variations in pyrite chemistry mainly reflect host rock and correlate different bulk Cu/(Cu+Zn) grade ratios of the deposits. Pyrite samples from Cu-rich deposits are enriched in Cu, Bi, Co, Ni, Se, Te and Mo; whereas pyrite samples from Zn-rich deposits are enriched in Pb, Ag, Cd, In, Ga, Sn, As, Sb, Hg and Tl. The same patterns are observed in Cu-rich versus Zn-rich zones of individual deposits. Statistical analyses reveal pyrite samples from VMS deposits in the AGB that are associated with primitive mafic-ultramafic tholeiitic rocks (e.g., Potter-Doal and Genex from Timmins, and East Sullivan and Dunraine from Val d'Or camps) are enriched in Cu (>5000 ppm), Co (>1500 ppm), Se (>4000 ppm), and Ni (>250 ppm), whereas pyrite from deposits associated with tholeiitic to calc-alkaline felsic rocks (e.g., Abcourt-Barvue from the Amos-Barraute camp) are commonly enriched in Pb, Ag, Au, Cd, In, Sn, As, Sb, Hg, Tl (10s to 100s of ppm). These variations closely match primary trace element abundances in unaltered volcanic rocks compiled from over 4000 high-quality analyses of samples from the Superior Province. Whole-rock data for rhyolite confirm high concentrations of Pb, Ag, Bi, Te, Cd, In, Ga, Sn, Hg, and Tl compared to basalt and komatiite, which have higher Cu, Co, Ni, and Se. The variation in trace element concentrations in pyrite is remarkably consistent for different deposits. We note that randomly sampled pyrite from almost any part of a deposit with a bulk enrichment in a particular element shows notable enrichment in that element compared to pyrite from other deposits. Pyrite from a deposit with a bulk enrichment in Te, for example (Quemont in the Noranda camp), will almost certainly contain more Te than pyrite from other Te-poor deposits. We test this observation among 47 deposits for 15 different elements. Pyrite samples from Au-rich VMS deposits (e.g., Horne, Quemont, Bousquet #2, and Dumagami) have anomalous Au (>6 ppm) and Te (>70 ppm). Co-enrichment in other elements such as Bi, Se, In and Sn may reflect a common felsic magmatic source. Other trace element enrichments appear to reflect the scale of the hydrothermal system (e.g., depth and extent of leaching). For example, pyrite samples from several large-tonnage deposits (Kidd Creek, Horne #5 Zone, and Geco) have high Sn concentrations (from 450 to 15000 ppm) possibly reflecting the large volumes of felsic rock from which the Sn was extracted. In other deposits, co-enrichment of Sn with Bi (>100 ppm) and In (>10 ppm) suggest a magmatic contribution to the ore fluids Principal Components Analysis (PCA) combined with hierarchal clustering confirms systematic trace element variability in pyrite from deposits with different host rocks and bulk Cu/(Cu+Zn) ratios. However, pyrite from deposits in different terranes seems to record major differences in the crustal compositions of those terranes. For example, pyrite samples from bimodal-felsic deposits show the same trace element signatures (i.e., enrichments in Ag, As, Sb, and Hg) in the AGB and in the Western Superior. In contrast, pyrite samples from deposits in the Slave craton tend to show a distinct enrichment in Pb, U and Th that may be related to the more mature and thicker crust in the Slave compared to the AGB. Other deposit types (magmatic Cu vein deposits, orogenic Au deposits) also show dramatically different pyrite compositions. Pyrite concentrates from magmatic Cu vein deposits in Chibougamau are enriched in Cu, Co, Ni, Te, As, Sb compared to VMS in the AGB, and samples from orogenic Au deposits in Timmins and Val d'Or are enriched in Au and Mo and depleted in Pb, Bi, As, and Sb compared to VMS. These differences highlight the potential application of the trace element signatures of pyrite during exploration for different deposit types in the same region. Trace element signatures of pyrite in grab samples compared favourably to much larger bulk samples from the same deposits (e.g., monthly concentrates and mine tailings) giving some confidence that the much smaller samples can provide a reliable first-order fingerprint of the deposits as a whole. LA-ICP-MS analyses of individual pyrite grains also agreed well with bulk analyses of pyrite over a wide range of trace element concentrations (10s to 100s of ppm).

No description available.

No description available.

The Lower Cbazyan (Middle Ordovician) Blackford Formation of the area studied consists of dominantly carbonate rocks deposited in a shallow sea which transgressed on a subaerially eroded carbonate terrane having up to 110 feet of relief locally. The lower two-thirds was deposited in a generally supratidal environment and grades up into rocks deposited in the gradually deepening waters of the intertidal and shallow subtidal environments. The Blackford is divisible into three parts. The lowermost part, which laterally is limited in extent, is a red to purple or yellow green breccia-conglomerate of chert and dolomite clasts in a silty to sandy argillaceous dolomite matrix. The middle part is brownish red to purplish red locally green and mottled, dolomite to dolomitic sandy siltstone. It is locally conglomeratic. It contains algal and faunal debris locally, and varying quantities of terrigenous detritus, including chert and dolomite clasts, rounded quartz grains) quartz crystals, an illite-mica-chlorite clay mineral suite, and a heavy mineral suite characterized by hematite, magnetite and kyanite. This terrigenous detritus dominantly was derived locally, from the unconformably subjacent Canadian (Lower Ordovician) Knox dolomites. The upper part of the Blackford is a sequence of gray to yellowish and greenish gray argillaceous calcilutites to calcareous claystones which grade into the overlying Elway Limestone. This part contains algae algal stromatolites, ostracodes, bryozoa and rare trilobites. Nodular black chert is locally present in the uppermost part. The proportion of coarse clastics and dolomite decreases upward whereas the clay content increases abruptly in the upper beds. The new assemblage is definitely volcanic. Abundant we11 preserved conodonts found with the biotite and apatite are potentially useful for precise paleontologic dating of this volcanism. The volcanic zone in the upper Blackford may be one previously recognized by Laurence in Lower Chazyan rockS at Douglas Dam, Tennessee. The Blackford volcanic zone is homotaxial with a bentonite recognized by Fox and Grant near Chattanooga and in Rhea County, Tennessee, and with one found by Miller and Fuller in the Rose Hill district, Lee County, Virginia, but it is somewhat older than either. The fairly widespread extent of the argillaceous limestones-calcareous claystones of the upper Blackford, and implicitly their contained conodont population, indicates that these synchronous units may be traceable over large areas of southwest Virginia. They are therefore potentially useful as a Olazyan reference time plane in this part of the Appalachians. / Ph. D.

Elevated manganese (Mn) concentrations have been measured in groundwater within the Roanoke River watershed, Virginia. Concentrations of Mn often exceed the secondary drinking water standard. A historic belt of Mn ores, the James River-Roanoke River Manganese District (JRRRMD), occurs in the eastern part of the watershed. The project objectives were to 1) evaluate the formation of the JRRRMD ore deposits and 2) analyze existing groundwater chemistry data to evaluate sources and processes that control groundwater Mn. Analysis of ore minerals, morphologies, and chemistry provides support that the ore deposits are supergene in origin, consistent with previous work. Spatial correlations between Mn ore locations and stream terrace deposits support a model of ore formation in which Mn-oxides were precipitated near discharge zones as anoxic groundwater mixed with oxic groundwater. Terrace deposits present at elevations higher than modern streams suggests that topography has been inverted, allowing ores to be found at higher elevations than what is typically associated with ores formed in discharge zones. Analysis of groundwater chemistry data shows positive correlations between Mn, calcium and bicarbonate concentrations in groundwater, suggesting that carbonate-bearing lithologies are probable sources of Mn to groundwater. Regionally, groundwater flows toward the Roanoke River where the flowpath terminus is marked by elevated Mn. The inverse correlation of Mn with dissolved oxygen suggests that reducing conditions that develop along flowpaths allow for Mn to persist in groundwater. Overall, results suggest that the same processes that allowed for formation of the JRRRM ore deposits continue to occur today. / Master of Science

No description available.

Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Science, 1987

The Bowen Basin is one of the most intensely explored sedimentary basins in Australia and hosts one of the world’s largest coking coal deposits. This study focuses on the Lenton deposit in the north-central part of the Bowen Basin and targets the Rangal Coal Measures, which are the youngest (245 Ma), most areally extensive and least structurally deformed coal measures in the study area. Six lithofacies were identified from detailed bed-by-bed logging of two cores and stratigraphically-upward comprise peatmire deposits of the Permian Blackwater Group overlain unconformably by braided fluvial strata of the Triassic Rewan Group. Coal-bearing strata of the Blackwater Group form a large-scale drying up sequence showing a change from permanent to seasonal waterlogged conditions related to the onset of regional uplift. Sedimentation was then terminated and a regional erosion surface formed by uplift related to the Hunter Bowen Orogeny. This, then, was overlain by braided fluvial strata of the Triassic Rewan Group.

ABSTRACT PRODUCTION OF HEAVY-MEDIA-QUALITY MAGNETITE CONCENTRATE FROM KESiKK&Ouml / PR&Uuml / IRON ORE TAILINGS G&uuml / ng&ouml / r, Kazim M. Sc. Department of Mining Engineering Supervisor: Prof. Dr. M. &Uuml / mit Atalay May 2010, 91 pages The aim of this research was to investigate the possibility of the production of a magnetite concentrate which is suitable for preparation of heavy media from iron ore tailings of G&uuml / ncem Mining Company magnetic separation facility. During the study, three different tailings named as low grade, medium grade and high grade with 5.91 % Fe3O4, 19.06 % Fe3O4 and 37.06 % Fe3O4, respectively, were used. Mineralogical analyses of test samples showed that magnetite and hematite were the major ore minerals while pyrite and chalcopyrite were found in trace amounts. Actimolite, tremolite, epidote, chlorite, quartz, calcite, and dolomite were the gangue minerals. The effects of feed particle size and applied magnetic field intensity on the Fe3O4 grade and recovery of concentrate were examined throughout magnetic concentration tests. The highest grade magnetite concentrate with 79.98% Fe3O4 content was obtained with 65.42% recovery from 100% -75 micron size feed at 1000 Gauss magnetic field intensity from high grade tailing.

The Sierra Mojada district consists of multiple types of mineral concentrations ranging from polymetallic sulfide deposits, "non-sulfide Zn" (NSZ) deposits, and a Pb carbonate deposit hosted by Upper Jurassic to Lower Cretaceous carbonates. This study focuses on the two non-sulfide Zn deposits, the Smithsonite Manto and the Iron Oxide Manto, that occur south of the San Marcos fault. The Smithsonite Manto shows karst features, including internal sediments interbanded with smithsonite (ZnCO₃). The Iron Oxide Manto consists of strata-bound zones dominantly of hemimorphite (Zn₄Si₂O₇ (OH)₂·H₂O) that fills pores in Fe-oxides. The mineralogy of the NSZ mineralization consists of smithsonite, hemimorphite and Zn clays (sauconite) associated mainly with calcite and Mn-Fe-oxides. Zn clays are abundant in the Smithsonite Manto, but no Zn clays have been found in the Iron Oxide Manto. This project attempts to constrain the origin of the NSZ concentrations through petrographic and mineralogical study of major Zn-bearing minerals, and their carbon and oxygen stable isotopes and Pb isotope geochemistry. Smithsonite in the Smithsonite Manto occurs as botryoidal aggregates consisting of scalenohedral or rhombohedral microcrystals and banded colloform or massive smithsonite in open spaces, whereas smithsonite in the Iron Oxide Manto occurs as rhombic microcrystals grown in pore spaces or finely intergrown with Fe-oxides. Both Fe-poor and Fe-rich smithsonite are found in the Iron Oxide Manto. Under optical-CL, smithsonite displays complex growth zoning that can be related to variable trace element content. Trace elements semiquantitatively analyzed using LA-ICP-MS show that most blue luminescent smithsonite has lower Mn contents than pink to bright red luminescent zones in smithsonite. Preliminary fluid inclusion petrography in hemimorphite and calcite suggests that fluid composition can be related to precipitation of NSZ minerals from freshwater to slightly saline waters. Calculated salinities for two phase (liquid +vapor) and single phase (liquid) inclusions in hemimorphite range between 0.0 and 1.6 wt. % NaCl equivalent, and salinities of inclusions in calcite were between 0.0 and 1.1 wt. % NaCl equivalent. The oxygen isotope values for smithsonite are relatively constant (avg. [delta]¹⁸O[subscriptVSMOW] = 21.9 ± 0.5[per mille]), whereas [delta]¹³C[subscriptVPDB] values range from -8.4 to -1.1 [per mille]. The oxygen isotope values in late calcite are within the same range of smithsonite, whereas the average values of the carbon isotope are lower by 5 [per mille]. Formational temperature of smithsonite is calculated to be between 26 ~ 40 °C using the modern groundwater composition at Cuatro Ciénegas. Similar Pb isotopic compositions of smithsonite and cerussite to galena suggest the source of metals in the NSZ deposits presumably originate from the sulfide deposits. / text