摘要:

Metazoan trace fossils of Early Cambrian and older age have been found in parts of the Gog, Cariboo, and Miette Groups of eastern British Columbia and western Alberta. Most of them occur in beds immediately below the zones containing the earliest Cambrian trilobites and archaeocyathids. These beds represent a variety of sedimentary environments, including the beach and littoral (Skolithos– facies), and shallow marine (Cruziana– facies) environments in the upper McNaughton Formation of the Gog Group: and a moderately deep marine environment in the Midas Formation of the Cariboo Group. Below these zones evidence of organic life is mainly restricted to stromatolites in carbonate rocks, and simple feeding-burrows in argillaceous silt-stones. A rare, but important trace fossil in this zone is a doubly furrowed trail, which is herein namedDidymaulichnus miettensis(gen. et sp. nov.). This fossil indicates that metazoans existed before the Cambrian Period by a span of time represented by the net deposition of up to 2000 m of detrital sediments.

ISSN:0008-4077    

DOI:10.1139/e72-001

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The Precambrian Apsley gneiss forms part of the Grenville Series, outcropping mainly in Chandos Township in southeastern Ontario. The principal member is a biotite-microcline-oligoclase-quartz rock. Its original premetamorphic nature cannot be determined by geological criteria: the most likely protoliths are silicic volcanics or sandstones.Analyses of 49 specimens are compared in various ways with large numbers of igneous and sedimentary rocks of similar ranges in bulk composition. Two-variate scatter diagrams proposed by Köhler and Raaz, by Weisbrod, and by Moine and de la Roche permit identification of sedimentary parentage in favorable cases. Discriminatory analysis is better, and the following function (wt. % values) is recommended for rocks of this kind:Positive values of DF indicate probable igneous parentage; negative values are sedimentary. Discriminant functions including trace elements cannot be adequately appraised until more data are available for ordinary sedimentary rocks.The Apsley biotite gneiss is probably a series of interstratified silicic volcanics (about 60%) and sandstones.

ISSN:0008-4077    

DOI:10.1139/e72-002

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

X-ray powder diffraction methods, successful in quantitative determination of silicate minerals in fine-grained rocks, have been applied to the determination of calcite, dolomite, and magnesite in greenschist facies meta-volcanic rocks. Internal standard graphs employing two standards (NaCl and Mo) have been determined.Carbonate mineral modes (calcite and dolomite) for 6 greenschist facies meta-volcanic rocks obtained by the X-ray powder method have been compared to normative carbonate mineral contents calculated for the same rocks. This comparison showed a maximum variation of 7.7 wt.% between the X-ray modes and the normative carbonate mineral contents of the rocks. Maximum standard deviation for the X-ray modes of these rocks was equivalent to 4.4 wt.%.

ISSN:0008-4077    

DOI:10.1139/e72-003

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The strain geometry of southern New Brunswick can be analyzed in terms of four major structural sub-divisions, which mark a variation in style from tilting and translation of rigid strata, single-phase cylindrical folding by flexural slip, polyphase folding by flexural flow, to extreme cataclastic flow with attendant transposition of early planar fabrics. Shallow dips of planar elements and shallow plunges of hinge lines occur in distinct zones, Maximum strain occurred along the northeast-trending Lubec-Belleisle zone, where vertical attitudes of planar and linear elements prevail. Cataclastic fabrics are regionally developed together with narrow mylonitic zones.Rock heterogeneity in part influences structural style, with early granitic plutons tending to act as rigid buttresses, but the major sub-divisions are not controlled by lithologic boundaries. The structural sub-divisions transgress the present position of fault boundaries.Southern New Brunswick is probably a relict continental margin. If regional folding, cataclasis, and later faulting can be attributed to the closing of the Proto-Atlantic seaway in Middle Devonian to Carboniferous times, the localization of intense strain in southern New Brunswick and particularly along the Lubec-Belleisle zone may be accounted for by assuming that stress concentrations would occur in the region of the shelf slope margin.

ISSN:0008-4077    

DOI:10.1139/e72-004

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Cenozoic–Mesozoic stratigraphy of the Nova Scotia shelf has been subdivided into three groups, twelve formations, and four members on the basis of subsurface information from approximately twenty offshore wells. The oldest stratigraphic unit recognized is salt, possibly of Early Jurassic age. The salt occurs in several sub-basins, where it is generally overlain by a conformable sequence of dolomite, anhydrite, limestone, and shale. Poorly sorted, feldspathic, clastic sediments disconformably overlie the evaporite sediments and adjacent basement rocks composed of metasediments and granite.The Western Bank Group consists of limestones and associated shales, which were deposited during widespread marine transgression. Marine sediments are in turn overlain by, and in part equivalent to, several thousand feet of Jurassic and Cretaceous sandstones and shales of the Nova Scotia Group. Sand deposition gradually waned in late Cretaceous time and the shelf was completely submerged. The overlying Gully Group of shales, thin limestones, chalk, and argillaceous sands was deposited in water depths ranging from bathyal to neritic. The Cenozoic section was finally truncated during a pre-glacial period of erosion.

ISSN:0008-4077    

DOI:10.1139/e72-005

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The Bamaji–Blackstone granite has 'invaded' volcanic rocks of the Lake St. Joseph area, northwestern Ontario. The resulting deformation, close to the granite, is substantially pure shear in three dimensions. This is indicated by flattened but not noticeably unidirectionally extended pillows, and by chocolate-tablet boudinage. Both features imply extensionin all directionsparallel to the granite margin and marked compression on horizontal axesnormalto the granite margin. The flattening (compression) is also suggested by buckled granitic dikes enclosed in the flattened pillows. The discrepancy between the strains in pillows and dikes is explained as due to the late arrival of the dikes. Flattening persists away from the granite, but is increasingly accompanied by marked extension on sub-vertical axes, a deformation pattern akin to die drawing.The flattening mode is ascribed largely to the diapiric uprise of the granite, much modified by inflation of the granite due to the arrival of granitic magma late in the 'invasion' process. The granitic dikes presumably represent some magma that escaped.

ISSN:0008-4077    

DOI:10.1139/e72-006

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Single-point resistance and spontaneous potential logs in fresh-water filled rotary-drilled test-holes provide data useful in geohydrologic studies in Saskatchewan. These geophysical logs are made by many of the water well drilling contractors in Saskatchewan on a routine basis. The logs provide good resolution of various lithologic units and provide data required to estimate the salinity of water in sand beds prior to constructing a well.Caliper logging offers a potentially useful method for evaluating hole conditions and the effect of drilling techniques on the formation in completion zones. The casing collar locator log run in a previously constructed well near Estevan demonstrates that this device can provide an accurate and objective measurement of the position and length of each joint of casing, the position of the screen assembly, and the location of screened and blanked intervals within the screen assembly. This tool should find general application in water well construction and maintenance practice.The neutron-epithermal neutron log provides a method of measuring the porosity of sand and gravel beds. The response of the gamma log is similar to that of the spontaneous potential log and the neutron-epithermal neutron log deflects in a fashion similar to the resistance and resistivity logs. Nuclear logs offer the advantage that they can be run in cased or uncased boreholes which may be filled with any type of fluid. They require more complicated and expensive instrumentation and slow-speed logging to obtain the required resolution. The normal resistivity logs offer the possibility of determining the concentration of dissolved solids in the formation water. The gamma-gamma log is a poor alternative to the natural gamma and neutron log for stratigraphic correlations.

ISSN:0008-4077    

DOI:10.1139/e72-007

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A thin, poorly stratified, polymictic diamictite at the the base of the White Rock Formation (perhaps Caradocian or younger) contains unsorted, clustered, faceted, and grooved clasts apparently dropped into a shaly or sandy lithotope. Ice probably transported these stones from a distant source. Other lithosomes of the formation are of almost every sedimentary/volcanic lithology, shape, and extent. Supermature orthoquartzite may be eolian or beach dune, or intertidal; immature quartzites are channel-fills, probably fluvioglacial; bouldery diamictite may be morainic or glaciomarine. Underlying and overlying conformable formations are thick, graptolitic black slate. White Rock contacts may mark glacio-eustatic lowering and rising of sea-level. Locally at the top of the Halifax Formation, small-scaled folding resulting in detailed and superficial angular discordance with the overlying White Rock. Formation may be ice-thrust phenomena.Both the gross stratigraphic succession and detail of lithosomes of the White Rock Formation are remarkably similar to those of the latest Ordovician (Ashgillian) of northwest Africa. There, this stage records extensive continental glaciation well-established by sedimentology, stratigraphy, paleomagnetism, and paleontology. Ordovician–Silurian glaciation of North America is unknown. If the White Rock Formation is glacio-genetic, then it is Ashgillian and correlative with the Dunn Point Volcanics of northeastern Nova Scotia. Moreover the underlying Halifax Formation could encompass almost all of the Ordovician, and the overlying Kentville perhaps most of the Silurian. Furthermore the hypothesis would be supported that Nova Scotia and the rest of southeastern Canada is a remnant of northwestern Africa.

ISSN:0008-4077    

DOI:10.1139/e72-008

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The marine algae of the post-glacial deposits from the Ottawa Islands, Hudson Bay and Broughton Island off East Baffin Island were examined. A total of 15 non-calcareous species were identified, of which the most abundant at both sites wereSphacelaria plumosaandDesmarestia aculeata. The species assemblages are characteristic of present-day arctic and subarctic floras.

ISSN:0008-4077    

DOI:10.1139/e72-009

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The flow of deep water across the axis of the Mid-Atlantic Ridge through the Charlie–Gibbs Fracture Zone near 52.5 °N was monitored for 7 days during June, 1970 with current meters moored 50 m and 650 m above the bottom in each of the two zonal channels of the fracture. Flow was west-going through the fracture. The mean rate of flow was about 3 cm/s with an oscillatory flow superimposed of semi-diurnal tidal period.

ISSN:0008-4077    

DOI:10.1139/e72-010

出版商:NRC Research Press    

年代:1972

数据来源: NRC