共查询到20条相似文献,搜索用时 15 毫秒
1.
Cupriferous bogs of the Coed y Brenin area,north Wales and their significance in mineral exploration
《Applied Geochemistry》1986,1(4):519-525
A number of bog areas with richly cupriferous peats have been outlined during a geochemical soil survey investigating the distribution of Cu, Mo, Pb and Zn in the vicinity of the Coed y Brenin porphyry copper deposit. During the first half of the last century considerable amounts of peat were extracted from the bog known as “Turf Copper” and ash derived from burning this peat was smelted as a source of Cu. “Turf Copper” bog is situated immediately to the west of the main outcrop of porphyry-style mineralization in this area. In addition, three small Cu bogs were delineated in the area of Bryn Coch to the south of the main mineralized zone, where disseminated Cu mineralization outcrops.Waters draining into the bog areas are enriched in Cu up to 0.97 mg/l. Analysis of profile samples from the bogs has indicated extreme enrichment in Cu and variable enrichments in Mo, Pb, Zn, Mn, Co, Ag and Au. Mineralized intrusive rocks in this area are significantly enriched in Cu and Au. The enrichment of Cu, up to 5.72%, and Au, up to 0.13 ppm in ashed peat samples, reflects the mobilization of these elements from adjacent mineralization by ground and surface waters and their fixation by interaction with organic matter accumulated in the bogs.The recognition of cupriferous bogs and the sampling and analysis of peats, including analysis for Au, may provide useful indicators of Cu and Au mineralization, especially in glaciated areas where mineralization may be masked by transported overburden and geochemical anomalies displaced by hydromorphic agencies. 相似文献
2.
An ornamented, dome-shaped cavity, partially filled with mudstone, 4 m in diameter at its circular base and 1 m in height occurs in fluvial sandstone of the Carboniferous Boss Point Formation near Sackville, New Brunswick, Canada. The cavity formed by differential weathering and erosion of the mudstone. Its origin is enigmatic though its size, shape and relationship to the underlying mudstone bed on which it rests suggest a diapiric origin for the mudstone that filled it. On the other hand, the ornamentation on the cavity surface includes flute moulds, suggesting an erosional origin for the domal structure. Of the four principal hypotheses for its origin the one preferred by the authors involves formation by diapiric intrusion of semi-fluid mud into liquefied sand, soon after deposition. The ornamentation on the cavity surface would have formed as part of the intrusion process. Structures akin to flute moulds have been produced experimentally in support of this interpretation by differential flow across a cement-mix-mud interface in a flow box and also by diapiric intrusion of mud in a soft cement mix. By analogy the flute moulds on the cavity surface could have been formed in the same way. By this interpretation, primary sedimentary processes need not be invoked to explain their occurrence on either this cavity surface or on the numerous other mudstone cavity surfaces that are ubiquitous in the Permo-Carboniferous of eastern Canada. Results of this study have important implications with respect to the potential diversity of origins of flute moulds in general. 相似文献
3.
Stonehammer Geopark of New Brunswick, Canada is one of the newest destinations in the UNESCO‐assisted Global Geoparks Network, and the first in North America. Its rocks tell the amazing billion‐year story of the evolution of eastern North America. Highlights include some of the finest Precambrian stromatolites in the world, a Cambrian site that yielded one of the world's largest trilobites, and a Silurian section with a rich fauna of fish, crustaceans and sea scorpions. At the famous ‘Reversing Falls’ in Saint John, visitors can also see the boundary between the Late Precambrian Brookville Terrane and the western part of the Avalon Terrane, and learn about the late Silurian closure of the Iapetus Ocean during the final stages of the accretion of North America. In and around the city, Devonian pebbly sandstones represent the erosive remnants of the highlands formed as a result of that terrane accretion event, and slightly younger Carboniferous exposures further shed light on the evolution of life at a time when the region lay on the equator. These include early Carboniferous clubmoss forests preserved on the main highway east of Saint John, and late Carboniferous deposits rich in the remains of fossil plants, insects, giant arthropods, and some of the earliest reptiles—the latter recorded by spectacular trackways. Scattered Mesozoic outcrops and Quaternary moraines continue the story to the present day. Positioned at the gateway of Atlantic Canada, Stonehammer Geopark is a strategic part of an emerging geotouristic network that also includes UNESCO World Heritage Sites at nearby Misguasha, Quebec (Devonian coastal ecosystems) and Joggins, Nova Scotia (Pennsylvanian fossil forests). It presents a brilliant opportunity to teach visitors of the extraordinary story of Earth's evolution. 相似文献
4.
Two groups of granitoids associated with gold mineralization in the Appalachian orogen of southwestern New Brunswick are recognized: a Late Silurian to Early Devonian (423–396 Ma) granodioritic to monzogranitic series (GMS), and a Late Devonian (370–360 Ma) granitic series (GS). The GMS granitoids are relatively low in silica, calc-alkaline, metaluminous to weakly peraluminous, and show characteristics of normal (oxidized) to reduced I-type granites depending on the properties of country rocks. They may have been derived from partial melting of lower crustal rocks triggered by underplated basaltic magmas; and country rocks bearing reduced organic carbon and/or graphite may have played an important role in the reduction of normal I-type intrusions to reduced I-type, which is essential in the formation of intrusion-related gold systems. In contrast, the GS granites, although calc-alkaline and metaluminous to peraluminous, are relatively rich in silica, incompatible elements, and high field strength elements. They are fractionated I-type granites, and are probably related to the coeval Mount Douglas granite in the Saint George batholith through fractional crystallization. Their parental magmas may have been derived from partial melting of quartzofeldspathic sources at relatively low temperatures. Both GMS and GS intrusions are orogenic, although some of them display the affinity of those emplaced into a within-plate environment. The origin of intrusion-related gold systems in this region appears to be controlled by several factors, including magma sources, magmatic processes, redox conditions (country-rock nature), and local structural regimes. 相似文献
5.
The Ministers Island dike in southwest New Brunswick is a quartz tholeiitic member of the Late Triassic to Early Jurassic dike suite that outcrops along the east coast of North America. The dike's phenocryst assemblage is orthopyroxene + augite + plagioclase. The combination of petrographic, chemical (both phase and whole rock), isotopic and experimental work on representative samples from the dike places important constraints on the petrogenesis of the Ministers Island dike and by analogy on the other members of the dike suite. The petrographic, analytical and experimental results show that the Ministers Island dike magma underwent high pressure (0.8 to 1.0 GPa) fractionation of augite, followed by augite + orthopyroxene, and finally augite + plagioclase. The absence of olivine as either a phenocryst or an experimentally observed high pressure liquidus phase indicates that the magma evolved away from the Ol-Cpx-Opx-Plag pseudo-invariant point while still at high pressure and there was sufficient time for any olivine to settle out of the magma prior to emplacement of the dike. The Sr and Nd isotopic results support a metasomatised mantle source similar to EMI but with slightly more radiogenic Nd. 相似文献
6.
In the Bathurst District of New Brunswick there are more than 50 known occurrences of base metal sulphide mineralization within an area of Palaeozoic volcanic-sedimentary rocks approximately bounded by the Rocky Turn deposit in the north, the Key Anacon deposit in the east, the Heath Steele deposit in the south, and the Devil's Elbow deposit in the west. Only four of these occurrences are, or have been, producing mines; 19 are classed as “major occurrences”. The area is highly prospective for massive sulphide deposits of the Brunswick Mining and Smelting and Heath Steele type; it would obviously be of considerable importance to define the zones within the sequence where major occurrences should be sought.To determine whether exploration rock geochemistry could be used on a regional reconnaissance scale, 419 samples of rhyolite from an area of 2000 km2 (at an average density of one sample per 5 km2) were analyzed for total content of Cu, Pb, Zn, Ca, Mg, K, Na, Fe, and Mn. The data were processed by calculating the geometric mean of all samples in cells of approximately 10 km2. Contrary to the relations documented on a mine scale (within one kilometre of major deposits), where the clearest halos are given by major elements, it is the ore elements that give the best regional patterns.The producing mines and the most important of the known occurrences all lie in zones where rhyolite contains less than 10 ppm Cu. Element ratios considerably enhance anomalous relations. The Zn:Pb ratio of the sulphides in the main deposits is 2.4–2.8, regardless of grade. It is demonstrated that all present and past producing mines and the most important known major occurrences lie within well-defined zones of Zn:Pb ratios of 2.4–2.8. Similarly, zones where the Pb:Cu ratio is > 3.0 and the Zn:Cu ratio is > 7.0 also define the most important deposits. These ore-element relations derived from a low sample-density survey define priority zones for detailed exploration for significant major massive sulphide deposits. 相似文献
7.
Gold contents of sulfide minerals in granitoids from southwestern New Brunswick,Canada 总被引:4,自引:0,他引:4
The abundance of gold and selected trace elements in magmatic sulfide and rock-forming minerals from Silurian–Devonian granitoids in southwestern New Brunswick were quantitatively analyzed by laser-ablation inductively coupled plasma mass-spectrometry. Gold is mainly hosted in sulfide minerals (i.e., chalcopyrite, pyrrhotite, and pyrite), in some cases perhaps as submicron inclusions (nanonuggets). Gold is below detection (<0.02 ppm) in major rock-forming minerals (i.e., plagioclase, K-feldspar, biotite, hornblende, and muscovite) and oxides (i.e., magnetite, and ilmenite). Gold distribution coefficients between sulfide and granitoid melt are calculated empirically as: . This result suggests that gold behavior in the granitoid systems is controlled by the conditions of sulfur saturation during magmatic evolution; the threshold of physiochemical conditions for sulfur saturation in the melts is a key factor affecting gold activity. Gold behaves incompatibly prior to the formation of sulfide liquids or minerals, but it becomes compatible at their appearance. Gold would be enriched in sulfur-undersaturated granitoid magmas during fractionation, partitioning into evolved magmatic fluids and favoring the formation of intrusion-related gold deposits. However, gold becomes depleted in residual melts if these melts become sulfur-saturated during differentiation, leading to gold precipitation in the early sulfide phases of a granitoid suite. Late-stage Cl-bearing magmatic–hydrothermal fluids with low pH and relatively high oxidation state derived from either progressively cooling magmas at depth or convective circulation of meteoric water buffered by reduced carbon-bearing sediments, may scavenge gold from early sulfide minerals. If a significant amount of gold produced in this manner is concentrated in a suitable geological environment (e.g., shear zones or fracture systems), intrusion-related gold deposits may also be generated. Exploration for intrusion-related gold systems should focus on the areas around evolved phases of granitoid suites that remained sulfur-undersaturated. For sulfur-saturated granitoid suites, the less differentiated phase and associated structures are the most prospective targets.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
8.
C. E. White S. M. Barr R. A. Jamieson P. H. Reynolds 《Journal of Metamorphic Geology》2001,19(5):519-530
High‐P/low‐T metamorphic rocks of the Hammondvale metamorphic suite (HMS) are exposed in an area of 10 km2 on the NW margin of the Caledonian (Avalon) terrane in southern New Brunswick, Canada. The HMS is in faulted contact on the SE with c. 560–550 Ma volcanic and sedimentary rocks and co‐magmatic plutonic units of the Caledonian terrane. The HMS consists of albite‐ and garnet‐porphyroblastic mica schist, with minor marble, calc‐silicate rocks and quartzite. Pressure and temperature estimates from metamorphic assemblages in the mica schist and calc‐silicate rocks using TWQ indicate that peak pressure conditions were 12.4 kbar at 430 °C. Peak temperature conditions were 580 °C at 9.0 kbar. 40Ar/39Ar muscovite ages from three samples range up to 618–615 Ma, a minimum age for high‐P/low‐T metamorphism in this unit. These ages indicate that the HMS is related to the c. 625–600 Ma subduction‐generated volcanic and plutonic units exposed to the SE in the Caledonian terrane. The ages are also similar to those obtained from detrital muscovite in a Neoproterozoic‐Cambrian sedimentary sequence in the Caledonian terrane, suggesting that the HMS was exposed by latest Neoproterozoic time and supplied detritus to the sedimentary units. The HMS is interpreted to represent a fragment of an accretionary complex, similar to the Sanbagawa Belt in Japan. It confirms the presence of a major cryptic suture between the Avalon terrane sensu stricto and the now‐adjacent Brookville terrane. 相似文献
9.
Macrofaunal Spatial Patterns in Relationship to Environmental Variables in the Richibucto Estuary,New Brunswick,Canada 总被引:1,自引:0,他引:1
Estuarine macrobenthos respond to a variety of environmental gradients such as sediment type and salinity, and organic enrichment.
A relatively new influence, organic loading from suspended bivalve culture, has the potential to alter this response. A study
on soft-bottom macrobenthic communities was carried out in the Richibucto estuary (46°40′N, 64°50′W), New Brunswick, Canada,
with samples collected from 18 stations in late September and early October 2006. The site consisted of a large tidal channel
originating upstream in a small river. The channel was punctuated by bag culture of oysters along its length. A total of 88
species were recorded. The mean values of abundance, species richness, and diversity (H′) of macrofauna were 11,199 ind. m−2 (ranged from 4,371 to 19,930 ind. m−2), 23.4 species grab−1 and 3.29 grab−1, respectively. In general species richness and H′ increased from the upper estuary to the estuarine mouth. Multivariate analyses clearly exhibited the spatial distribution
in community structure, which coincided with the locations along the estuary (the upper, the lower and the mouth), as well
as inside and outside the channel. Species richness and diversity H′ showed strong positive correlations with salinity (21.2–25.2 ppt), and abundance was positively correlated with water depth
(1.0–4.5 m). Abundance and species richness were negatively correlated with both of silt–clay fraction (3.3–24.8%) and sorting
(σI). Species richness was also negatively correlated with organic content (1.9–12.7%). The BIO-ENV analyses identified silt–clay
fraction, σI and salinity as the major environmental variable combination influencing the macrofaunal patterns, and silt–clay fraction
as the single best-correlated variable. 相似文献
10.
《Applied Geochemistry》2006,21(11):1986-1998
Elevated concentrations of Hg are present (averaging 36 μg/g), mainly as cinnabar, in the Murray Brook Au deposit, located in northern New Brunswick, Canada. After the mined ore was subjected to CN leaching, the tailings were deposited in an unsaturated pile, and 10 a after mine closure an estimated 4.7 × 103 kg of CN and 1.1 × 104 kg of Hg remain in the pile. Elevated Hg concentrations have been measured in the groundwater (up to 11,500 μg/L) and surface water (up to 32 μg/L) down-gradient of the tailings. To investigate the controls on Hg mobility and leaching persistence, laboratory experiments were conducted using unsaturated columns filled with tailings. Within the first 0.2 pore volumes (PV) eluted, the concentrations of Hg and CN increased to peak concentrations of 12,900 μg Hg/L and 16 mg CN/L, respectively. In the subsequent 0.9 PV, concentrations decreased to approximately 1300 μg Hg/L and 2.8 mg CN/L. Thermodynamic calculations demonstrate that >99.8% of the mobilized Hg in the tailings pore water is in the form of Hg–CN complexes, indicating that Hg mobility to the surrounding aquatic environment is directly dependent on the rate of CN leaching. One-dimensional transport simulations suggest that leached CN can be partitioned into conservative (24%) and non-conservative (76%) fractions. Extrapolation of simulation results to the field scale suggests that CN, and by extension Hg, will continue to elute from the tailings for at least an additional 130 a. 相似文献
11.
A lithogeochemical study was undertaken of the Millstream potash deposit, New Brunswick, Canada, a marine evaporite deposit with a complex depositional and tectonic history. The objective of the study was to determine if potash intersections in boreholes represent different geological horizons, or the same stratum repeated by folding or faulting. The deposit is found at a depth of 800–1000 m.Water-soluble and -insoluble fractions of drill core from five ore zones in four holes were analyzed using multielement ICP instrumentation following sequential hot water and aqua regia leaches. Meaningful variations in the data for the different ore zones were evident for eight elements in the water-soluble portion, and for seventeen elements in the water-insoluble residue. These results characterize a lowermost sylvinite unit which is relatively depleted in most elements, with the exception of Mg and Al in the residue. Regression analysis indicates a weak correlation between Fe and the common base metals, in contrast to the immediately overlying sylvinite unit which is relatively enriched in most elements, including Fe, but where Fe apparently exerts no control over the base metals. Cluster analysis confirms these two units are easily distinguished from each other. The upper two ore horizons are distinguishable from the lower units on the basis of different abundances of some elements, such as water-soluble B, and on the strong scavenging abilities of Fe on the common base metals.No single element is able to uniquely fingerprint a particular sylvinite horizon, but suites of elements are able to classify each horizon as geochemically distinctive. The results appear to confirm the validity of the geological correlations. 相似文献
12.
Homogenization temperatures and salinity data are presented for fluid inclusions from hydrothermal gangue minerals (quartz and fluorite) associated with porphyry wolframite-molybdenite-arsenopyrite-sphaleritebismuth-chalcopyrite-cassiterite mineralization within the Fire Tower ore zone, Mt Pleasant, New Brunswick. The data indicate that ore mineral precipitation occurred within a temperature range of 260° to 490°C from moderate to high salinity (10–42 wt% NaCl equivalent) aqueous fluids. Two stages of hydrothermal activity characterized by high (>30 wt% NaCl equivalent) salinity fluids are recognized; one which occurred at relatively high temperature (350°–490°C); and one which took place at lower temperature (180°–250°C). The high salinity, high temperature stage is interpreted to be the result of resurgent boiling. Dilution of these early fluids by convecting meteoric water resulted in low to moderate salinity fluids, which dominate the inclusion population. The low temperature, high salinity fluid inclusions are interpreted to represent late residual fluids derived from boiling which occurred as a result of a change in the pressure regime from dominantly lithostatic to hydrostatic conditions. 相似文献
13.
《Geoforum》2016
Hydroelectricity is an old yet reliable form of renewable energy, with acknowledged social and ecological impacts. A tension currently exists between such concerns and energy needs, with dam construction and removal ongoing around the world. It is critical to better understand the implications of both on local citizens. We performed map elicitation interviews with 20 locals around the prematurely-aging Mactaquac Dam and headpond, in New Brunswick, Canada, to understand if and how they came to accept the dam landscape, and what they want for its future. A Baselines of Acceptability conceptual framework was developed to guide the interpretation. Respondents demonstrated attachment to the dam-in-place landscape, even those initially disadvantaged by its construction, and a preference for keeping the headpond intact. Despite this demonstrated adaptability, the paper calls for improved transparency, scope and justice in energy landscape decision-making, as well as further testing of the framework with different demographics, infrastructure case studies and over time. 相似文献
14.
Five stations on the lower Saint John River, a complex multibasin estuary, were sampled semiquantitatively for zooplankton at biweekly intervals for one year, and qualitatively over a 4-year period. Planktonic Crustacea were dominated by the true estuarine copepods,Acartia tonsa andEurytemora affinis and the euryhaline marine copepodsOithona similis andPseudocalanus minutus. Atypical estuarine forms, confined to a lower fiord-like basin with salinity of 20‰, were the amphipod,Parathemisto abyssorum and the mysidErythrops erythrophthalma. River flows were highly variable from year to year. Certain basins function as lakes in some years and estuaries in other years, causing extreme zooplankton community fluctuations, and succession patterns dependent on salinity rather than season. On occasion freshwater zooplankters maintained viable populations at unusually high salinities (ca. 5‰). Vertical and horizontal distributions of zooplankters indicate that the estuary in fact comprises two systems: a true estuary in the upper reaches and the surface waters at the lower end, and a fiord in a subsidiary basin in the lower end. 相似文献
15.
Zoned sodic amphibole: Petrologic indicator of changing pressure and temperature during tectonism in the Bathurst Area,New Brunswick,Canada 总被引:1,自引:0,他引:1
W. E. Trzcienski Jr. Dugald M. Carmichael Herwart Helmstaedt 《Contributions to Mineralogy and Petrology》1984,85(4):311-320
Amphibole, zoned from an actinolite core through a barroisite layer to a crossite or ferroglaucophane rim, coexists with epidote, chlorite, albite, quartz, phengite, sphene, magnetite, and calcite in metabasites of the Tetagouche Group near Bathurst, New Brunswick. Stratigraphic, structural and regional-metamorphic evidence suggests that these rocks were situated in the hangingwall of a SE-dipping subduction zone during the Taconian Orogeny. Using microprobe analyses of the coexisting minerals, a dehydration reaction and a subsequent hydration reaction have been balanced in the system SiO2-Al2O3-TiO2-Fe2O3-(Fe, Mg, Mn)O-CaO-Na2O-K2O-H2O, so as to describe the development of the zoned amphiboles. Relatively large coefficients for magnetite in these reactions accord with the absence of sodic amphibole in associated magnetite-free metabasites, indicating that ferric iron has a significant effect on the transition from greenschist to epidote-blueschist fades. Relatively small residuals of FeO, MgO and MnO show that these components are only weakly partitioned between the reactant and product assemblages. The procedure of Holland and Richardson (1979) has been used to calculate apparentP-T paths that trace the growth histories of the zoned amphiboles from a low-P environment to a high-P environment. Although the apparent pressure-change is implausibly large and the final temperature implausibly low, it is clear that the Bathurst metabasites followed a very differentP-T path than those of the Austrian Alps, despite their identical mineral assemblage. 相似文献
16.
17.
18.
About 25 economically significant, Kuroko-type massive sulfide bodies lie in a metamorphosed volcano-sedimentary complex (probable Middle Ordovician) known as Tetagouche Group, in Bathurst area, New Brunswick. Despite unresolved structural complexities, it does appear that they were deposited during a particular phase of volcanic activity and are, therefore, contemporaneous. Most of the sulfide bodies are closely associated with iron-rich rocks representing various facies of iron formation, and together with sulfides it constitutes the “ore horizon‘ which, therefore, is highly magnetic. Aero-magnetic and ground-magnetic techniques are useful to locate the ore horizon but problems are created because of the occurrence of iron-rich rocks with no sulfide, along another horizon in the Tetagouche Group.Petrographic and geochemical characteristics of various types of iron-rich rocks have been studied to see if the iron-rich rocks of the ore horizon can be distinguished from the iron-rich rocks of the other horizon. The iron-rich rocks found in the Tetagouche Group can be classified into five types: (1) cherty magnetitic rocks; (2) iron-rich chloritic rocks; (3) sideritic rocks; (4) basic iron formation; and (5) maroon shale. The basic iron formation, which is quite magnetic, gives a false indication of the ore horizon wherein the presence of any of the first three types of rocks is expected. Moreover, the basic iron formation is generally similar in appearance and mineralogy to some of the cherty magnetitic and chloritic rocks.Regarding major element composition, TiO2, Na2O, Al2O3 and CaO are higher whereas Fe2O3, FeO and MnO are lower in the basic iron formation than in the other iron-rich rocks. These geochemical characteristics can help distinguish the barren rocks of the basic iron formation from those of the ore horizon during the exploration programs. 相似文献
19.
A hydrogeological study was conducted in northwestern New Brunswick, Canada, to improve the predictability of fracture-dominated groundwater flow within folded bedrock composed of fine-grained turbidites. Borehole televiewer logging and outcrop mapping, integrated with hydraulic packer tests revealed enhanced hydraulic conductivity associated with northeasterly striking bedding-plane fractures formed during folding and flexural slip. These fractures impart azimuthal anisotropy to the aquifer because of moderately dipping fold limbs. High-angle fractures form a well-developed non-stratabound network, comprising two open fracture sets striking NNE parallel to the current direction of principal stress, and WNW parallel to the direction of principal stress that dominated during the Acadian orogeny. The subset of fractures showing significant oxidation, deemed most important to the groundwater flow system, is dominated by bedding-plane and high-angle fractures striking near-parallel to the maximum principal stress direction, resulting in extensional opening and enhanced hydraulic conductivities. An equivalent porous media model, incorporating anisotropy and varying hydraulic conductivity with depth, indicates that horizontal flow dominates the aquifer with relatively minor exchange between different model layers. These findings have implications for understanding flow directions in the Black Brook Watershed and elsewhere in the Matapédia Basin where fractures formed under similar stress conditions. 相似文献
20.
Please?refer?to?the?attachment(s)?for?more?details. 相似文献