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The Wildcat Brook Mo-W deposit is located approximately 9 km east of the former Mt. Pleasant Sn-W-Mo mine in Charlotte County, New Brunswick. It is hosted by a leucocratic, quartz-feldspar [...]

The upper Triassic Nicola Group is an economically important succession of volcano-sedimentary rocks that host the Copper Mountain alkalic Cu-Au porphyry deposit. All known mineralization at Copper Mountain appears to [...]

The Wildcat Brook Mo-W deposit is located approximately 9 km east of the former Mt. Pleasant Sn-W-Mo mine in Charlotte County, New Brunswick. It is hosted by a leucocratic, quartz-feldspar porphyritic-to-aplitic, peraluminous, EW-striking, moderately north-dipping dyke intruding turbiditic metasedimentary wackes/argillites of the Fredericton Trough north of the Saint George batholith. High-grade Mo mineralization to 4 % (per metre) occurs in two niches: (i) molybdenite blebs to 4 mm disseminated in miarolitic cavities within albite- and muscovite-altered dyke, and (ii) medium-grade Mo mineralization at the margins/cores of 2-5 cm wide quartz veins cutting altered/ unaltered dyke and adjacent metasedimentary rocks. The mineralized dyke has been intersected by 17 diamond drill cores spanning approximately 250 m along both strike and dip. Dyke thickness ranges from 17 to 42 metres (27 m average), with a length-weighted average grade of 0.27 % Mo. Two styles of hydrothermal alteration occur in the dyke: albite and muscovite-quartz. Molar element ratio (MER) analysis of 110 drill core samples, constrained by petrography, reveal the addition of Na and loss of K and Ca during albite alteration: Microcline + Na+ = >Albite + K+, Anorthite + 4 Quartz + 2 Na+ = >2 Albite + 3 Ca+2, and the addition of K and loss of Na during muscovite plus quartz alteration: 3 Albite + K+ + 2 H+ = >Muscovite + 6 Quartz + 3 Na+. Because hydrothermal alteration recognized in the dyke can be described by balanced chemical reactions, these processes are mathematically linear. Furthermore, when plotted on MER diagrams the data continue to form linear trends. Unfortunately, when plotted in logarithmic space, as log ratios, patterns become decidedly non-linear, significantly complicating data interpretation. Additionally, the use of linear statistical procedures, such as principal components or regression analysis, on such log-transformed data is numerically invalid, and so is not an appropriate way to understand the causes of compositional variations in rocks. [ABSTRACT FROM AUTHOR]

Soils develop at chemical and physical gradients at the geosphere/atmosphere/biosphere/ hydrosphere interface. Their horizons are commonly poorly understood because they tend to be thin, poorly crystalline, and fine-grained, making their geochemistry and mineralogy difficult to characterize. Historic pedogeochemical investigations have employed small sample numbers, restricted element suites, and limited digestion methods, largely ignoring heterogeneity in the parent material. Thus, historical attempts to characterize horizon development have provided marginal geochemical and mineralogical insight. Fifty 360 cm³ soil samples within a 2 m thick vertical profile through a dystric (<5.5 pH) elluviated (w/Ae horizon) brunisolic soil developed in a homogeneous, ~5 m thick, fine-grained glaciofluvial sand in Nova Scotia's Annapolis Valley were collected to investigate soil profile development. This site is accessible via an excavator, lacks historical disturbance, hosts old-growth species consistent with a mature Acadian forest, and displays a simple mineralogy (quartz, feldspar, biotite, and muscovite derived from the peraluminous South Mountain Batholith). Variables measured include soil density, moisture, texture, Munsell color, pH, conductivity, magnetic susceptibility, ICP-ES/MS geochemical analyses of LiBO3 fusions (10 major/33 trace elements), aqua-regia (36 trace elements) and deionized water (30 major/trace elements) digestions, LECO total carbon and sulphur analyses, Penfield H2O+ analysis, and smear-mount XRD analysis on the -63 um sample fractions. Results indicate that parent material heterogeneity persists despite all efforts, as different textures and modal mineralogy were encountered at various depths. However, molar element ratio analysis could model/circumvent this variability, providing an understanding of chemical reactions involving quartz, alkali feldspar (Or90), apatite, Na-phengite, and ferroan kaolinite within the soil profile. THe depths where Na-phengite breakdown took place (via Fe oxidation), apatite dissolved, and kaolinite replaced albite in a sub-soil aquifer could be identified. Surprisingly, only small amounts of feldspar hydrolysis occurred, likely due to limited weathering since the glacial retreat from Nova Scotia. [ABSTRACT FROM AUTHOR]

The Waihi area of New Zealand, part of the Hauraki Goldfield, is located at the southern end of the Coromandel Peninsula, on the North Island, and is host to a number of actively mined and currently sub-economic, low-sulphidation epithermal gold- and silver-bearing quartz veins. The Waihi epithermal vein system is the largest of 50 known deposits on the Coromandel Peninsula. Veins in the Waihi area are hosted by Miocene to Pliocene volcanic rocks of andesitic to dacitic composition of the Coromandel Group. Two main units have been defined by previous studies and consist of a subjacent quartz-plagioclase-porphyritic andesite and superjacent plagioclase- porphyritic andesite; the former generally hosts wider and higher grade veins. Much of the area is overlain by younger ignimbrite, tuff, alluvium, and volcanic ash from the currently active Taupo Volcanic Zone to the southwest. This thesis study focuses on the Amaranth Vein, one of several large, currently sub-economic veins in the Gladstone Hill area. The Amaranth Vein is located within the town of Waihi, several hundred metres to the east of the active Martha open pit mine and a few hundred metres west of the Favona Vein, which is also currently being mined by underground means. Rocks in the Gladstone Hill area are characterised by strong to intense hydrothermal alteration that is manifested in the presence of abundant clay minerals (illite, interlayered illite-smectite, smectite, and chlorite) that have thoroughly replaced phenocrysts and groundmass. Typical alteration zonation consists of an illite-smectite-dominant argillic assemblage of variable intensity nearest to mineralised veins, grading outward into a less-intense propylitic chlorite-calcite-dominated assemblage. Pyrite and quartz are ubiquitous throughout the area and vein calcite, though prevalent in the nearby Martha deposit, is restricted to relatively isolated zones in the Gladstone Hill area. This thesis aims to quantify alteration intensities, identify alteration zonation, and develop associated geochemical vectors to gold mineralisation that may be used in the Coromandel Group to identify new deposits. Results available to date (visual drill core logs) allow assessment of the precision of visual estimates of alteration intensity. Once lithogeochemical data become available, a more comprehensive assessment of alteration intensity can be undertaken. [ABSTRACT FROM AUTHOR]

An oval structure in southwestern Nova Scotia measuring 350 x 420 m has been identified as a possible Late-Glacial age impact crater. Evidence for an impact origin is based on integrated analysis of geomorphic, magnetic, petrographic, ground penetrating radar and stratigraphic data. A magnetic survey of the site indicates that the regional linear magnetic pattern in granitic rock is interrupted and distorted within the raised crystalline crater rim, due either to shock remagnetization or reorientation of broken blocks. Probable shock-metamorphic features in rim rocks, not present in unaltered rocks outside the structure, include common single and multiple sets of closely spaced (~4-15 µm) planar microstructures in quartz and feldspar, kink-banded feldspar and biotite, reduced mineral birefringence, rare diaplectic feldspar and rare melt veinlets with flow textures. Fresh grain comminution, grain mosaicism and other lattice distortion features are pervasive. Ground penetrating radar shows that the crater has a depressed inner floor that is sharply ringed by a 10-m-high buried scarp. Heterogeneous material under the floor, interpreted as ejecta fallback or slumpback deposits, is overlain by stratified and faulted lacustrine sediment. A Late-Glacial age is inferred through similarities in sedimentation rates to nearby bogs with well-constrained ages and the lack of any evidence of ice-sheet reworking and associated glacial deposits. Strata within the structure appear to be wedge-shaped, indicating post-glacial differential subsidence and compaction. In addition to the main crater, a cluster of arcuate, rimmed scarps 1 km north of the structure may record additional smaller impact sites, suggesting the impactor fragmented upon entry into the atmosphere producing a crater field. The oval shape of the main crater may also indicate an oblique impact or impact doublet. Continuing research focuses on identifying ejecta material in lake sediments from southwestern Nova Scotia in order to elucidate any potential link to Late-Glacial environmental change. [ABSTRACT FROM AUTHOR]