Department of Earth Sciences (Fredericton)

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Orientation analysis and relationships between joints, faults and lamprophyres of the Monashee Complex, Southeastern Canadian Cordillera, British Columbia.
Orientation analysis and relationships between joints, faults and lamprophyres of the Monashee Complex, Southeastern Canadian Cordillera, British Columbia.
by Alice Gillam, The Monashee complex, southeast British Columbia is an area of high-grade metamorphic rock, within are two crystalline basement exposures: Thor-Odin and Frenchman's Cap. The complex has undergone a series of deformation periods, involving folding, refolding shearing and faulting. The last period of deformation occurred in the Eocene, and involved ductile and brittle extension, pegmatite and lamprophyre intrusion. It is believed that the brittle faulting occurred during the end of the Eocene as the region cooled, and that lamprophyre intrusion occurred during both ductile and brittle extension. The faults within northern Thor-Odin fall within four distinct orientation groups: of large, regional faults such as the Victor Creek fault; the major glacial valley lineaments; then more local smaller faults; and lastly splay faults with minimal displacement associated with the smaller faults. All except one of the lamprophyres are oriented similarly to the local smaller faults thus, it is probable that most lamprophyres post-date faulting, and intruded along these pre-existing planes of weakness. • The majority of lamprophyres found within northern Thor-Odin have only undergone low grade retrograde metamorphism however, one lamprophyre was found to be completely recrystallised and fractured within a pegmatite in a shear zone. It is probable that this lamprophyre intruded while ductile shearing was occurring, thus indicating that the lamprophyres in this region intruded over a period of time, during and after extensional shearing and faulting., University of New Brunswick. Department of Geology.
Origin of gold bearing hematitc breccias at the Lake George Antimony Mine, Western New Brunswick
Origin of gold bearing hematitc breccias at the Lake George Antimony Mine, Western New Brunswick
by Alexander Geoffrey Whaley, The Lake George Antimony deposit is located in southwestern New Brunswick. The main Au-Sb mineralization is hosted in stock-work veining emplaced into the Kingsclear Group metasedimentary rocks. These veins are believed to be spatially and temporally related to a granodiorite intrusion. To the east, northeast and southeast lies an hematite breccia and alteration zone. Previous studies indicate that this zone is coeval with but not related to, the Au-Sb mineralization event. This study proposes that this zone was formed from Carboniferous faulting, at epithermal to surface depths. The ---.. breccias are divided into three groups, hematite, carbonate-hematite and carbonate-quartz types. Hematite breccias are defined by a dominantly hematite matrix with angular to chemically corroded clasts. Carbonate-hematite type breccias consisting of a wide variety of textures from jigsaw patterns to rotated, rounded, clast supported and collapse. Carbonate-quartz type breccias have a varying abundances of carbonate and quartz, with highly chemically altered clasts. All three breccias are produced from localized faulting, indicating tectonic comminution, fluid assisted, and corrosive wear mechanisms. Carbonate-hematite breccias, also have wear abrasion, collapse, and impact mechanisms, which are produced by stronger and more continuous faulting. Gold, Sb, and other metals are enriched in carbonate-hematite and carbonate-quartz breccia types. This enrichment is likely related to mobilized Sb-Au from the Sb-Au-quartz carbonate veins at the Lake George deposit. Gold appears to be correlated with arsenopyrite or pyrite abundance and deposited on surfaces of iron oxides, iron hydoxides, and Mn oxides.These minerals may have been produced from near surface meteoric water circulation reacted with weathered product., University of New Brunswick. Department of Geology.
Oxidation of metal sulphides and their mobility within Brunswick mines tailings
Oxidation of metal sulphides and their mobility within Brunswick mines tailings
by Brian Corbett, The oxidation of tailings and its relation to grain size has been investigated at the Brunswick Number 12 Mine. The most recent tailings typically show higher metal contents than do 'stratigraphically' lower, older tailings, despite current extraction processes being more efficient. The tailings comprise sulphide grains, usually exceeding 90% volume at < 37 μm. These sulphide grains coagulate into "clumps" up to 1 mm diameter in polished sections during their preparation. Smaller sulphide grains liberated from these clumps show a greater tendency to oxidize than do the larger grains. This is attributed to an increased surface area of the smaller grains. When oxidized, sulphur-bearing minerals produce sulphuric acid. The acid may dissolve metals and transport them in solution to the perimeter seepage collection ditch as surface run- off (Welch, 1990). There is also evidence of material being transported to the underlying glacial till. This allows metals to enter the environment untreated. Acids are the primary cause of remobilization of metals. Other factors, such as density contrasts and grain size variations that affect porosity and water content, are also important. The oxidation reaction of metals produces sulphur dioxide which, if allowed to enter the environment, can contribute to acid rain and other pollutants. Control of grain size by an induced electrostatic charge, causing a net neutralizing effect, may coagulate particles, decrease surface area and depress overall acid generation from future tailings, University of New Brunswick. Department of Geology.
P-Total of an intrusive porphyritic dyke B. M. S. 12
P-Total of an intrusive porphyritic dyke B. M. S. 12
by S. Richmond, A quartz-feldspar porphyry dyke in the B.M.S. No. 12 deposit is late D1, which was the most intense deformation in the area (Luff, 1973). Ore textures in samples adjacent to the dyke show features typical of static recrystallization; this annealing event may be due to contact metamorphism associated with dyke emplacement or it may be related to the post-D1 regional metamorphic peak. Microprobe analysis of sphalerites, however are more compatible with the regional metamorphism, post-intrusion and post-D1. Total pressure during metamorphism was slightly greater than 5 kb. based on sphalerite geobarometry., University of New Brunswick. Department of Geology.
Paragenesis of the Humite group minerals In South-Eastern Quebec
Paragenesis of the Humite group minerals In South-Eastern Quebec
by Hurbert George, The Humite group minerals norbergite, chondrodite, humite and clinohumite, have been identified in crystalline marble and skarn type rocks in the Grenville gneisses of South Eastern Quebec, with the aid of X-ray diffraction data and Infra-red spectra. The geology of areas where these minerals occur is presented and the associated mineral assemblages described. An attempt has been made to correlate OH− content with relative transmittance of Infra-red energy, and to account for the paragenesis of the members of the series., University of New Brunswick. Department of Geology.
Passive water treatment at the Mount Pleasant Mine using sulphate-reducing bacteria.
Passive water treatment at the Mount Pleasant Mine using sulphate-reducing bacteria.
by Nicolette Stanley, The research was based at the Mount Pleasant Mine site in southern New Brunswick where Fe, Zn and As-contaminated water drains from the mine portal. The project involves the use of bacterial sulphate reduction to precipitate metals from the water as insoluble metal-sulphide minerals in anaerobic columns. The columns were filled with a permeable reactive mixture that would promote the growth of sulphate-reducing bacteria (SRB). Water samples were collected at six points along the 16 m column flow path, and analysed for the concentrations of major cations, anions, and trace metals, as well as, pH, Eh and alkalinity. The data suggest that sulphate-reducing conditions have been attained intermittently within the columns. During these time periods the S04 concentration decreased by between 30 and 70 %. With the onset of sulphate reduction, a decrease in Fe, Zn, and As was not immediately achieved as might be expected. Instead, during the first few intervals of sulphate-reduction, the concentration of Fe increased from approximately I 0 mg/L up to a maximum of 20 mg/L, and the As concentration increased also from 4 mg/L up to a maximum of 70 mg/L. The increases can be attributed to the coexistence of Fe(III)-reducing bacteria and SRB. Prior to the onset of sulphate-reducing conditions, Fe(ITI) oxy-hydroxides from the mine water accumulated in the. As sulphate-reducing conditions were attained in the columns, conditions were also favourable for the reductive dissolution of Fe(III) oxy-hydroxides. These reactions reduce iron to the soluble Fe(II) form, and also mobilize As which is associated with the Fe(III) oxyhydroxides through adsorption and co-precipitation. After 200 days of running the experiment, the iron concentration started to decrease across the columns from 12 mg/L to 8 mg/L. This is an indication that the SRB are becoming the predominant microbial colony in the columns and that the excess iron hydroxides have been depleted. During time periods when sulphate reduction was occurring, the concentration of Zn decreased significantly versus distance along the flow path, with initial concentrations of 4.5 mg/L declining to less than I mg/L. Sulphate reduction generally results in an increase in pH from 6 to 6.5 across the columns, however, during the last period of sulphate reduction the pH increased to 8. Currently the columns are not achieving sulphate reduction continuously. The SRB require an optimal anaerobic environment with a continuous source of organic substrate and sulphate to remain active. The temperature and flow rate are also variables that can change the activity of the SRB. The minimum temperature and maximum flow rate for the survival of the bacteria have not been determined. If sulphate reduction is to be used for passive treatment of the mine water then changes in these conditions would have to be studied systematically to determine the minimum residence time in the reactive material required to treat the water and whether the organic substrate used will be a limiting ingredient., 3 unnumbered pages after last number page, University of New Brunswick. Department of Geology.
Petrochemical and petrographic analyses of lamprophyric dykes of the Ards Peninsula, Ireland
Petrochemical and petrographic analyses of lamprophyric dykes of the Ards Peninsula, Ireland
by Garth Adrian Norman, A petrochemical and petrographical comparative study of the lamprophyric dykes of the Ards Peninsula was undertaken to investigate geochemical variation in the series. The lamprophyres are divided into two compositional groups on the basis of the dominant femic minerals and further partitioned on the grounds of their phenocrystic phase assemblages, groundmass constituents and degrees of alteration. Most are clinopyroxene- and/or phlogopite-bearing minettes, a few are hornblende porphyrites and spessartites. Fifteen major-, minor- and trace-element analyses and petrographic studies were performed. The dykes are characterized by unusually low K20, P205 and compatibles and enrichments in A1203, FeO*, Na20 and volatiles. Petrogenetic modelIing indicates a possible crystal olivine + or - clinopyroxene + or - phlogopite fractionation accompanied by low degrees of partial melting with an influx of an external, volatile-rich, aqueous fluid depleted in K and P prior to intrusion. High, but variable, volatile components are partly primary and partially a reflection of post-magmatic chloritization and carbonatization., University of New Brunswick. Department of Geology.
Petrogeochemical assessment of the various felsic volcanic and subvolcanic igneous rocks associated with Sn- Cu-Zn and W-Mo-Bi mineralization in the north zone, Mount Pleasant, New Brunswick
Petrogeochemical assessment of the various felsic volcanic and subvolcanic igneous rocks associated with Sn- Cu-Zn and W-Mo-Bi mineralization in the north zone, Mount Pleasant, New Brunswick
by Brittany Charnley, Mount Pleasant is located in southern New Brunswick along the northern segment of the Appalachian Mountains and sits 370 m above sea level. It is a late Devonian sub- volcanic-eruptive complex and consists of a 13 by 35 km caldera containing sedimentary and volcanic rocks dating to the upper Devonian and is intruded by sub volcanic-plutonic rocks, while the Saint George Batholith, forms the southern boundary of the caldera. Granitic intrusions in the Mount Pleasant caldera are the McDougall Brook and Mount Pleasant Granitic suites. Mount Pleasant is divided into two main mineralized zones: the North Zone and the Fire Tower Zone. It has numerous Sn-Cu-Zn-In (North Zone) and several W-Mo-Bi (Fire Tower Zone & North Zone) deposits. This study was focused in the North Zone where 35 samples were collected and used for geochemical analyses to characterize the highly altered rocks associated in the area and to try to date the Mount Pleasant Granitic intrusions (GRI, GRII, GRIII). Work with the pXRF, XRD and SEM has been done to discriminate and characterize the rocks sampled from the North Zone. The Th/Ti ratio derived from the pXRF data was used as a discriminating factor to determine the protoliths of the rocks sampled. Based on geochemical attributes, three grouping were distinguished that represent the Little Mount Pleasant Formation, McDougall Brook tuff and Granite II. Further geochemical work was done with respect to alteration and mineralization, and this study found that sericitization, chloritization, sulfidation and fluorite alteration are major alteration assemblages in the area. With respect to mineralization, W, Sn, Bi and Mo correlate the strongest to this alteration index (Fe/K). The age of GRII was established to be 371 ± 2 Ma based on U-Pb dating of a hydrothermal monazite found in a quartz vein related to Sn+Zn-In mineralization.
Petrographic analysis of undeformed and deformed pseudotachylite from the Seaforth Head Region of the Outer Hebrides Thrust zone, Isle of Lewis, Scotland
Petrographic analysis of undeformed and deformed pseudotachylite from the Seaforth Head Region of the Outer Hebrides Thrust zone, Isle of Lewis, Scotland
by Christine A. Brown, Undeformed and deformed pseudotachylite of the Seaforth Head region in the Outer Hebrides Thrust zone was analyzed by both light and SEM microscopy, and by x-ray analysis. An examination of the pseudotachylite and its microstructures was performed. Undeformed pseudotachylite which appears to be optically isotropic, consists of a fine, equant-grained matrix and porphyroclasts of plagioclase, quartz, and amphibole when examined using SEM microscopy. The deformed pseudotachylite's compositionis similar to that of the undeformed but contains a fabric defined by compositional layering and other deformational evidence. The deformed pseudotachylite has two distinct types of pseudotachylite bands-- Area A and Area B. Area A contains more porphyroclasts than Area B and Area B contains more K-feldspar. Compositional analysis was performed on the pseudotachylite indicated that the plagioclase ranged in composition from An40 to An65 with clustering of plagioclase composition for the deformed at An26 and An36 whereas the undeformed was found at An34 and An64. Calcic amphibole was found in both the deformed and undeformed pseudotachylite. The evidence found within the pseudotachylite supports the friction melt theory of formation caused by cyclic seismic activity., University of New Brunswick. Department of Geology.
Petrography, alteration and deformation of the Toussaint Shear Zone, Verneuil, Quebec.
Petrography, alteration and deformation of the Toussaint Shear Zone, Verneuil, Quebec.
by Ian C. Bliss, The principal gold mineralization on the GOG-CGK property in Verneuil, Quebec is completely hosted within the Toussaint Shear Zone (TZS). The shear zone is parallel to sub-parallel to lithologic units and has a sharp footwall contact with diorite and a more gradational contact with gabbro hanging wall. The majority of the shear zone is hosted within an intermediate volcanogenic/crystal tuff unit but also extends into the gabbro. The maximum width of the shear zone is 27 metres. Four mineralized horizons occur in the TZS of which two are sub-economic having values between 0.4 and 3 ppm Au. All of these horizons are parallel/sub-parallel to the lithological contacts. The two 'low gold horizons' outline the hanging- and footwall limits of the shear zone., University of New Brunswick. Department of Geology
Petrology of metasomatic rocks of the Manitouwadge greenstone belt, Northern Ontario
Petrology of metasomatic rocks of the Manitouwadge greenstone belt, Northern Ontario
by David A. Copeland, The Manitouwadge greenstone belt is a remnant of Archean supracrustal rocks that have been metamorphosed to upper amphibolite facies (625°C and 3-6Kbar). This belt is composed of metasedimentary and metavolcanic rocks that outline a regional synform. The synform is a host to Cu-Zn mineralization and associated syn-volcanic hydrothermal alteration. The petrological aspects of the Oam-Crd-Grt gneisses and associated lithologies of this belt are described. A complex deformational and metamorphic history has been revealed. These rocks are found to have high concentrations of Fe, Mg, and Al, while being depleted in alkali elements. Trace and rare earth element data suggest that these rocks have felsic to mafic volcanic protoliths. The application of Grt-Bt thermometry has yielded temperatures between 475 and 520°C, which are well below those at peak metamorphic conditions, 4 unnumbered pages after last numbered page, University of New Brunswick. Department of Geology.
Petrology, geochemistry, and distribution of the copper zones at the Brunswick No. 12 volcanogenlc massive sulfide deposit, Bathurst Mining Camp, New Brunswick
Petrology, geochemistry, and distribution of the copper zones at the Brunswick No. 12 volcanogenlc massive sulfide deposit, Bathurst Mining Camp, New Brunswick
bv Erin M. Powe, The Brunswick No. 12 volcanogenic massive sulfide deposit of the Bathurst Mining Camp is a vent-proximal, exhalative deposit formed above a well-developed feeder pipe (stockwork zone). The deposit is divided into three mineralogically and texturally distinct lenses: 1) massive pyrite-pyrrhotite-chalcopyrite (basal Cu zone); 2) lead-zinc ore; and 3) massive pyrite. There are five overprinting folding events recognized at the Brunswick No. 12 mine. The basal Cu zone is found in the nose of an F1-F2 asymmetrical recumbent fold; the region experienced upper-greenschist grade metamorphism with temperatures up to 425°C and pressures in excess of 700 MPa. Samples totaling 78 were collected from 9 drill cores on the 1125m level of the mine; all the drill holes intersect pyrite-pyrrhotite-chalcopyrite intervals along the entire strike of the deposit. Re-assaying of these drill hole samples yielded an average of 1.28% Cu, 1.05% Zn, 0.28% Pb, 48.2 g/t Ag, 0.52 ppm Au, 0.03% Bi, 0.013% Sb, 0.077% Co, 0.4% As, low Sn values ( < 30 ppm), and low Se values ( <50 ppm). A significant Spearman Rank correlation exists (> 95% Cl) between Cu and Ag, Bi, and Co, whereas a weak to moderate positive correlation exists between Pb and Zn with Cu. This deposit is petrochemically similar to the Brunswick No. 6 deposit located approximately 10 km southeast of Brunswick No. 12. Although the Brunswick No. 12 deposit is being mined primarily for Zn and Pb, respectively, significant amounts of Cu can be found in three sections of the deposit: the hanging wall zone, footwall zone, and the "425 level" zone. The combined Cu zones are estimated to contain 64.5 Mt grading 0.98% Cu, of which 5.4 Mt grades 1.53% Cu. The principle opaque minerals identified in the Cu zone are pyrite, pyrrhotite, chalcopyrite, sphalerite, arsenopyrite, and galena. Minor minerals include quartz, magnetite, native bismuth, bismuthinite, chalcocite, bomite, cassiterite, ilmenite, and rutile. Pyrite occurs as euhedral grains (0.02mrn to 0.84mrn), porphyroblasts and porphyroclasts, which have overgrown chalcopyrite, pyrrhotite, and sphalerite, and are hosted within a matrix of recrystallized chalcopyrite and pyrrhotite. Pyrrhotite within the Cu zone is abundant (up to 60%) and dominantly monoclinic, although hexagonal and triclinic pyrrhotite are also present. Chalcopyrite-diseased sphalerite grains are present in the Cu zone, and they account for less than 10% of the total sphalerite grains within the zone. The average composition of the diseased sphalerites is X (FeS)sp = 0.14, whereas the X(FeS)sp = 0.17 for non-diseased sphalerite grains within the Cu zone. The relatively high Cu and low base metal contents within the basal Cu zone of the deposit is consistent with its occurrence above the stockwork feeder zone; the proximity of the basal Cu zone to the vent is distribution of metals within the deposit is interpreted to reflect a high-temperature zone refining system. This is consistent with the high abundance of chalcopyrite, arsenopyrite, and native bismuth all of which have higher temperature sensitive solubilities than sphalerite and galena, resulting in high Cu/Zn and Cu/Pb within the Cu zone., University of New Brunswick. Department of Geology.

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