摘要:

The distributions of,,, titration alkalinity, Ca2+, and pH in interstitial waters collected from mine tailings and natural sediments in Rupert and Holberg inlets (Vancouver Island, British Columbia) are discussed. In natural sediments, dissolved ammonia, phosphate, and titration alkalinity increase with depth, and sulphate decreases, following established patterns for coastal sediments. In rapidly accumulating tailings, however, no dissolved phosphate enrichment is observed despite significant sulphate reduction. This phosphate depletion is accompanied by a calcium enrichment and a relatively high pH, which is probably due to the addition of lime to the tailings during milling. Solubility considerations suggest that the phosphate distributions in both tailings and natural deposits are controlled by equilibrium with respect to carbonate fluorapatite. Lime addition appears to increase the supersaturation of the pore water with respect to carbonate fluorapatite, resulting in phosphate consumption by the tailings. The tailings thus inhibit benthic phosphate regeneration, which is now known to be an important factor in the phosphorus budget of some coastal waters. It is demonstrated that such inhibition is not important in Rupert Inlet due to a short water residence time; however, it could be of significance in poorly mixed or stratified water bodies including lakes and some fjords.

ISSN:0008-4077    

DOI:10.1139/e84-001

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Detailed reconnaissance gravity surveys in the Deer Lake Carboniferous basin have been conducted using a station spacing of 2.5 km. The digitized aeromagnetic data for the basin were reduced to a 1:253 440 scale composite map. These two data bases were used to determine the configuration of major features and the total sediment thickness at various locations in the basin. Preliminary seismic results from reflection and refraction seismic surveys planned on the basis of these results are discussed. Modelling of gravity and magnetic data indicates that the Humber syncline contains approximately 1.2 km of sediments underlain on the west by rocks similar to the Long Range Complex. The eastern limb of the syncline is underlain by rocks similar to the Gull Pond Igneous Suite. The Howley Formation is deduced to be approximately 1.5 km thick and floored by rocks similar to the Topsails Igneous Suite.

ISSN:0008-4077    

DOI:10.1139/e84-002

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Seismic-wave velocities have been measured on 37 unconsolidated permafrost samples as a function of temperature in the range -16 to +5 °C. The samples, taken from a number of locations in the Canadian Arctic islands, the Beaufort Sea, and the Mackenzie River valley, were tighty sealed immediately upon recovery in several layers of polyethylene film and maintained in their frozen state during storage, specimen preparation, and until they were tested under controlled environmental conditions. During testing, the specimens were subjected to a constant hydrostatic confining stress of 0.35 MPa (50 psi) under drained conditions. At no stage was a deviatoric stress applied to the permafrost specimens. The fraction of clay-sized particles in the test specimens varied from almost zero to approximately 65%. At temperatures below -2 °C the compressional-wave velocity was observed to be a strong function of the fraction of clay-sized particles, but only a weak function of porosity. At temperatures above 0 °C the compressional-wave velocity was observed to be a function only of porosity, with virtually no dependence upon the fraction of clay-sized particles. Calculation of the fractional ice content of the permafrost pore space from the Kuster and Toksöz theory showed that for a given fraction of clay-sized particles the ice content increases with an increase in porosity. It is concluded that the compressional-wave velocity for unconsolidated permafrost from the Canadian Arctic is a function of the water-filled porosity, irrespective of the original porosity, clay content, or temperat

ISSN:0008-4077    

DOI:10.1139/e84-003

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The sedimentological evolution of the Rivière aux Outardes estuary was modified considerably during and after the construction of the hydroelectric dams on the river. Prior to 1965, the dominant river discharge was 1350 m3/s and the flood peak reached 2700 m3/s. Between 1965 and 1975, during the building activities, it fell to 430 m3/s and since 1955 it remained steady at 555 m3/s. Now, the variations range from 1300 m3/s during discharge periods to 0 m3/s during some filling periods. The most significant variations in the river discharge related to the creation of the reservoirs have modified the sedimentary equilibria and it is the aim of the present study to improve our understanding of the flow of the non-cohesive materials in the estuary.Before regulation, the sedimentary processes were dominated by seasonal variations of the river regime: the floods flushed out the fine material from the estuary. Between 1965 and 1975, the river discharge decreased, and the tidal wedge moved upstream. The erosion rate of the cliff edges decreased during working periods of regulation and the entry of marine material was increased particularly at the mouth of the river. The influence of the swell and the tide is more important than the effect of the river discharge.In the present estuarine system, the sedimentary budget is positive and the source of non-cohesive materials has been changed since the regulation of the river. The principal hydrodynamic processes in the estuarine environment of the Rivière aux Outardes are compared with those of non-regulated rivers in a subboreal climate, such as the Rivière St-Jean and the Rivière La Grande rivers. [Journal Translation]

ISSN:0008-4077    

DOI:10.1139/e84-004

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The area of the East South "C" (ESC) orebody of the Dickenson mine, Red Lake, consists of variably altered and mineralized basalt, basaltic volcaniclastic rocks, minor sulphidic iron formation, and a series of mainly postdeformation dykes. Except for the dykes, the rocks are in general well foliated. The macroscopic structural geometry of the stratiform rocks has been determined to a large extent by movement on schistosity-parallel faults.Three broad types of mineralization or alteration are recognized: an Na–Ca–Mg depletion with associated Fe–Mn enrichment controlled by primary permeable structures in basalt; a series of carbonate and quartz or "chert" veins emplaced into fissures; and auriferous silicified and sulphidized zones controlled by vein-filled fractures. The last is the main mineralization type in the ESC orebody on the 24th level of the mine, which was the focus of this study. Although all mineralization types occur within the mine, they are not directly associated either temporally or spatially on a mesoscopic scale. All, however, appear to have been overprinted by or formed synchronously with the amphibolite-facies metamorphism.A rich variety of metamorphic mineral assemblages occurs in the volcanic rocks because of the chemical effect of pre- or synmetamorphic hydrothermal alteration. These assemblages and the composition and mineral associations of arsenopyrite in the ESC orebody closely constrain the conditions of metamorphism to 520–540 °C and 3.8–4.2 kbar (380–420 MPa) fluid pressure.

ISSN:0008-4077    

DOI:10.1139/e84-005

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Detailed clay mineralogical characterization was completed on four major glaciogenic surficial deposits in northeastern Alberta. The mineral species identified and quantified were mica, montmorillonite, beidellite, kaolinite, chlorite, and vermiculite. Although there were quantitative differences in the amounts of mica, kaolinite, and chlorite in the Legend unit, the similarity of the mineral species in all deposits precluded their use for a definitive assessment of sediment provenance.Oxygen isotopic data for the clay separates served as a useful criterion for differentiation of deposits. Differences in isotopic signature were related to the inclusion of materials from the underlying Cretaceous marine sediments and to the admixture of materials from preweathered Shield sediments. The difference in isotopic signature of the clay separates was specifically related to the formation conditions of the micaceous component.

ISSN:0008-4077    

DOI:10.1139/e84-006

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

A large group of discrete peaks occurs on the northeastern surface of Orphan Knoll at water depths between 1800 and 2800 m. Long-range side-scan sonographs are used in conjunction with seismic reflection profiles to establish their flattened conical form. They commonly rise to 300 m above the sea floor and occupy basal areas up to 2 km in diameter at that level. Inclusion of the buried lower parts of these mounds may double estimates of both the height and diameter. The sonographs indicate that the mounds have a random distribution within an elongate northwesterly trending belt. Previous suggestions of their possible origin, such as remnants of dykes or ridges of resistant sedimentary strata, are rejected and an alternative explanation of a zone of partially buried Devonian reef knolls is proposed.

ISSN:0008-4077    

DOI:10.1139/e84-007

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Detailed analyses of oxygen isotope–water relations in <3, 13, and 109 Ma old mid-ocean ridge basalts reveal that, to a first approximation, the low-temperature alteration of deep-sea basalts in the upper few hundred metres of the igneous crust can be modelled as the partial conversion of basalt to smectite formed in isotopic equilibrium with seawater. Second-order variations in δ18O versus H2O+plots are used to show that this approximation breaks down in detail because secondary mineral assemblages and mass transfer vary widely in response to subtle variations in temperature and (or) fluid flow. Strongly oxidized open systems can evolve relatively low δI8O hydrous oxide-rich assemblages if leaching is efficient (DSDP (Deep Sea Drilling Project) site 396), or relatively anhydrous high δ18O K-feldspar-rich assemblages if plagioclase breaks down (site 417), compared with the clay-mineral-dominated assemblages common in somewhat more restricted flow environments. Zonal distribution and common superposition of various alteration mineral assemblages within rock fragments cause significant small-scale isotopic heterogeneity. A simplified low-temperature alteration scheme involving (a) early-stage Fe–K–Mg clay minerals, (b) middle-stage K-feldspars, oxides, or smectites, depending on the duration, rate, and temperature (?) of fluid flow, and (c) late-stage zeolites and (or) carbonates, is recorded in rather complex time variations in δ18O versus H2O+for individual rock parcels.

ISSN:0008-4077    

DOI:10.1139/e84-008

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Laminated and massive sulfide (pyrite, sphalerite, galena) mineralization and massive barite – fluorite–galena lenses occur in Upper Silurian – Lower Devonian Road River Formation shales of the Vulcan property along the eastern flank of the Selwyn Basin, Northwest Territories, Canada. The 5 km thick stratigraphic section, ranging in age from Hadrynian through Mississippian, offers insight into the nature of the Mackenzie Platform – Selwyn Basin transition. Abrupt facies changes, synsedimentary faults, debris flows, local unconformities, and the presence of high-potassium mafic flows indicate extensional tectonics during deposition of the Road River Formation. Mineralization resulted from heated, metal-rich basinal brines that vented on the sea floor up normal faults.Sulfur-isotope studies indicate that both sulfate and sulfide were derived from the exhaling metalliferous brine. Sulfur-isotope data also suggest that reduction of sulfate in the brine occurred as a result of organic decomposition, possibly during thermal maturation of hydrocarbons at temperatures greater than 80 °C. Fluid inclusion observations indicate that the brine salinity reached 26 wt.% NaCl for at least a portion of the evolution of the hydrothermal system.Cooling of the brine during venting into bottom waters caused initial rapid precipitation of fine-grained barite, resulting in a baritic buildup above vent areas. Continued percolation of the brine through the baritic mound caused recrystallization of the barite and then the deposition of interstitial fluorite and galena. In other areas the dense ore fluid collected in topographic depressions, or brine pools, in which sulfide minerals accumulated under anoxic conditions. Location of hydrothermal vents, paleotopography, and intensity of hydrothermal activity were the main controls on the thickness, distribution, and grade of Vulcan mineralization.

ISSN:0008-4077    

DOI:10.1139/e84-009

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The Eocene Chuckanut Formation of Washington's North Cascades comprises as much as 6000 m of alluvial strata and is one of the thickest nonmarine sequences in North America. It is exposed in several disconnected outcrop belts that are remnants of what was probably an extensive fluvial system in western Washington. In this study, seven stratigraphic members are defined in the main outcrop belt of the Chuckanut Formation near the town of Bellingham. Their ages, based on fission-track zircon dates, palynologic studies, and correlation by mapping, extend from the Early to the Late Eocene.Three types of fluvial systems contributed to the Chuckanut Formation and are distinguished on the basis of their lithology, sedimentology, and petrology. The first comprises fine-load meandering-river deposits of the Lower Eocene Bellingham Bay Member and the Middle Eocene Slide Member. Sandstones are arkosic and had their main source in rapidly uplifted, high-grade metamorphic terranes in eastern Washington. The second type comprises braided- and coarse-load meandering-river deposits of the Middle to Upper Eocene Padden Member. The Padden Member occurs only in the western part of the outcrop belt and was derived form the Coast Plutonic Complex of southern British Columbia to the north. Sandstones are arkosic but are richer in lithic fragments than sandstones of the underlying Bellingham Bay Member and interfingering Slide Member. The third fluvial-system type comprises conglomerate-rich braided-river and alluvial-fan deposits of the lower Middle Eocene Governors Point Member and the Middle to Upper (?) Eocene Maple Falls, Warnick, and Bald Mountain members. Sandstones from these units are both lithic and arkosic. These strata were locally derived from uplifts on the northern basin margin.The petrology of down-basin correlatives of the Chuckanut Formation on the northeast Olympic Peninsula is incompatible with derivation through the Chuckanut fluvial system. This petrologic contrast supports a model for large-scale Eocene dextral offsets in the continental margin of Washington.

ISSN:0008-4077    

DOI:10.1139/e84-010

出版商:NRC Research Press    

年代:1984

数据来源: NRC