scholarly journals Proposals for time classification and correlation of precambrian rocks and events in Canada and adjacent areas of the Canadian Shield part 1 : a time classification of precambrian rocks and events

1982 ◽  
Author(s):  
C H Stockwell
Keyword(s):  
Canadian Shield ◽  
Precambrian Rocks

The densities of Precambrian rocks from northern Manitoba

1968 ◽  
Vol 5 (3) ◽  
pp. 433-438 ◽  
Author(s):  
R. A. Gibb
Keyword(s):  
Rock Type ◽  
Gravity Anomalies ◽  
Average Density ◽  
Canadian Shield ◽  
Granitic Rocks ◽  
Precambrian Rock ◽  
Average Composition ◽  
Precambrian Rocks ◽  
Surface Rock ◽  
Greenstone Belts

To assist in the interpretation of gravity anomalies in northern Manitoba and northeastern Saskatchewan, a part of the western Canadian Shield, the average densities of 2004 Precambrian rock samples, grouped according to rock type, are tabulated. Relatively positive anomalies may be expected over greenstone belts (2.85 g/cm3), sedimentary gneisses (2.79 g/cm3), granulites (2.73 g/cm3), and mafic to ultramafic intrusions—diorite (2.77 g/cm3), gabbro (3.00 g/cm3), and peridotite (3.19 g/cm3), whereas negative anomalies may be expected over granitic rocks (2.64 g/cm3). These results are consistent with results from other areas.The average composition of a slab of surface rock in this part of the western Canadian Shield is shown to be granodioritic with an average density of 2.67 g/cm3.

Some Problems of Classification in the Canadian Pre-Cambrian Shield.

1927 ◽  
Vol 64 (1) ◽  
pp. 1-7 ◽  
Author(s):  
M. E. Wilson
Keyword(s):  
Lake Superior ◽  
Field Work ◽  
Canadian Shield ◽  
Geological Survey ◽  
Considerable Difficulty ◽  
North West ◽  
Southern Border ◽  
Positive Correlations ◽  
Vast Area

The region lying along the southern border of the Canadian Shield, the St. Lawrence basin, to which by far the greater part of the field work so far performed in this vast area has been confined, is divided into four geographically separate sub-provinces, in each of which the succession of formations is so different that few positive correlations of either formations or unconformities in different sub-provinces can be made. It is probable, however, that all geologists familiar with this region are agreed that there is a palaeoplain at the base of the Huronian that originally at least extended over the southern part of the Canadian Shield. If the existence of this palaeoplain be assumed as established then there are two major problems in Pre-Cambrian classification in this region that remain unsolved: (1) What is the position of the pre-Huronian palaeoplain in the succession of formations present in the sub-province north-west of Lake Superior and in the Grenville sub-province? and (2) is there a second erosion plain within the pre-Huronian complex, and, if so, can it be used satisfactorily for the classification of the pre-Huronian into two major divisions equivalent in rank to the Huronian?The purpose of this paper has been to point out (1) that there is no present agreement regarding the solution of either of these problems; (2) that the existence of a widespread unconformity within the pre-Huronian complex of the St. Lawrence province is, as yet, only a hypothesis, and (3) that there are only two logical courses to be followed in the classification of the Pre-Cambrian formations of the Canadian Shield, either to adopt the dual classification or to use it tentatively in the manner indicated in the accompanying table, until the existence of the second widespread unconformity is established or disproved. It may be suggested, however, that since considerable difficulty is being encountered in applying the dual classification even within the St. Lawrence province, it may be more practical to adopt the dual classification for the major divisions of the Pre-Cambrian notwithstanding the possible presence of an unconformity within the pre-Huronian complex.In conclusion the writer wishes to express his indebtedness to his colleagues of the Geological Survey of Canada, W. H. Collins, F. J. Alcock, T. L. Tanton, and J. F. Wright, for criticism of the columns in the table of formations having reference to the different sub-provinces with which they are especially familiar.

GENETIC CLASSIFICATION OF ARCHEAN LODE GOLD DEPOSITS

2020 ◽  
pp. 11-21
Author(s):  
A. N. Glukhov
Keyword(s):  
Spatial Distribution ◽  
Gold Deposits ◽  
Canadian Shield ◽  
Genetic Classification ◽  
Lode Gold ◽  
Genetic Types ◽  
Tectonic Position ◽  
Lode Gold Deposits ◽  
Rock Lithology

Main features of the Archean gold deposits spatial distribution are outlined. Geology and ore composition of two deposits within the Canadian shield distinguished by tectonic position and host rock lithology are described. Delineation of two separate genetic types of the Archean gold deposits, orogenic and granitoid-related, similar to Phanerozoic accretion-collision belts is validated on that basis.

Note on the spectral classification of carbon stars in the photographic infrared region

1966 ◽  
Vol 24 ◽  
pp. 21-23
Author(s):  
Y. Fujita
Keyword(s):  
Infrared Region ◽  
Spectral Classification ◽  
Carbon Stars

We have investigated the spectrograms (dispersion: 8Å/mm) in the photographic infrared region fromλ7500 toλ9000 of some carbon stars obtained by the coudé spectrograph of the 74-inch reflector attached to the Okayama Astrophysical Observatory. The names of the stars investigated are listed in Table 1.

Diagnostic Value of Electron Microscopy in Soft Tissue Tumors

1970 ◽  
Vol 28 ◽  
pp. 220-221
Author(s):  
Gerald Fine ◽  
Azorides R. Morales
Keyword(s):  
Cardiac Myxoma ◽  
Osteogenic Sarcoma ◽  
Diagnostic Value ◽  
Soft Tissue Tumors ◽  
Amelanotic Melanoma ◽  
Growth Patterns ◽  
Light Microscopic Level ◽  
Mesenchymal Tumors ◽  
Good Agreement

For years the separation of carcinoma and sarcoma and the subclassification of sarcomas has been based on the appearance of the tumor cells and their microscopic growth pattern and information derived from certain histochemical and special stains. Although this method of study has produced good agreement among pathologists in the separation of carcinoma from sarcoma, it has given less uniform results in the subclassification of sarcomas. There remain examples of neoplasms of different histogenesis, the classification of which is questionable because of similar cytologic and growth patterns at the light microscopic level; i.e. amelanotic melanoma versus carcinoma and occasionally sarcoma, sarcomas with an epithelial pattern of growth simulating carcinoma, histologically similar mesenchymal tumors of different histogenesis (histiocytoma versus rhabdomyosarcoma, lytic osteogenic sarcoma versus rhabdomyosarcoma), and myxomatous mesenchymal tumors of diverse histogenesis (myxoid rhabdo and liposarcomas, cardiac myxoma, myxoid neurofibroma, etc.)

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