Rb/Sr isochrons for some Precambrian rocks in the Hanson Lake area, Saskatchewan

1970 ◽  
Vol 7 (2) ◽  
pp. 338-345 ◽  
Author(s):  
L. C. Coleman
Keyword(s):  
Analytical Data ◽  
Lake Area ◽  
Geological Evidence ◽  
Precambrian Rocks ◽  
Granite Intrusion

Rb–Sr whole rock analyses of rocks from the Hanson Lake area; Saskatchewan, combined with geological evidence suggest that there were three thermal events in that region during Precambrian time. During Archean time, a period of volcanism about 2520 m.y. ago was followed by a period of granite intrusion about 2445 m.y. ago. During Aphebian time, the rocks of the area were intruded by pegmatites about 1800 m.y. ago. If the analytical data alone are considered, the two earlier events should be considered as one that took place about 2425 m.y. ago.

Isotopic Studies of Ore-Leads in the Hanson Lake-Flin Flon-Snow Lake Mineral Belt Saskatchewan and Manitoba

1972 ◽  
Vol 9 (5) ◽  
pp. 500-513 ◽  
Author(s):  
D. F. Sangster
Keyword(s):  
Volcanic Rocks ◽  
Massive Sulfide ◽  
Good Evidence ◽  
Lake Area ◽  
Sulfide Ores ◽  
Geological Evidence ◽  
Isotopic Studies ◽  
Mineral Belt ◽  
Flin Flon ◽  
Host Rocks

Lead isotope abundances in 4 stratabound sulfide ores are presented and show characteristics of being single-stage lead deposits. Model ages based on these data range from 1780 ± 44 to 1900 ± 44 m.y. and are considered to be close approximations of the time of ore formation. Geological evidence in the massive sulfide deposits suggests they are coeval with their host rocks, which are predominantly volcanics of the Amisk Group. If this assumption is correct the average model lead age of the ores is essentially the age of the enclosing rocks. Within error limits the results are in good agreement with published Rb-Sr ages for Amisk rocks of the Flin Flon area, and with U-Pb ages in zircons of rhyolites, which also contain similar, massive sulfide ores in the Churchill Province of Arizona. This is considered to be good evidence that the Hanson Lake-Flin Flon-Snow Lake volcanic mineral belt, previously regarded as Archean, is Aphebian in part.A previously published Archean, Rb-Sr isochron for volcanic rocks in the Hanson Lake area may indicate that Amisk-type rocks are a folded complex of both Aphebian and Archean lithologies. The suggested Aphebian age of the Amisk-Missi Groups and their equivalents, indicates they are possibly eugeosynclinal equivalents of the miogeosynclinal Hurwitz sediments.

Pedogenesis of the Precambrian Rocks in the Hanson Lake Area, East-Central Saskatchewan

1971 ◽  
Vol 8 (7) ◽  
pp. 820-843
Author(s):  
J. W. Gaskarth
Keyword(s):  
Basal Part ◽  
Lake Area ◽  
Chemical Analyses ◽  
East Central ◽  
Precambrian Rocks ◽  
Metavolcanic Rocks ◽  
Orogenic Cycle ◽  
Silicate Rocks ◽  
Lower Group ◽  
Chemical Evidence

Precambrian rocks in the Hanson Lake area occur in two main groups. The first (Lower Group) consists of quartz dioritic rocks, migmatites, and agmatites which occur in two large anticlinal complexes. These rocks are overlain by and concordant with a complicated sequence of supracrustal rocks which comprise the second group (Upper Group). The basal part of the Upper Group is basaltic and the rest is made up of basaltic, andesitic, dacitic, and rhyolitic fragmental metavolcanic rocks, dacitic metalavas, calc-silicate rocks, and graywacke-type metasediments. Other rocks in the area include several bodies of intrusive granite, one of which has a mass of magnetite – amphibole – epidote rock associated with it, a body of metapyroxenite, and a number of apparently intrusive amphobolite bodies. Both beryliferous and non-beryliferous pegmatites are abundant and occur mainly within the rocks of the Lower Group.An interpretation of the petrogenesis, consistent with the available petrographic, structural, and chemical evidence (46 new chemical analyses are presented), suggests that the Upper and Lower Groups were originally parts of a conformable supracrustal sequence. The lower parts of the sequence (Lower Group) were migmatized, partially melted, and mobilized during a complicated orogenic cycle.

Age of the Early Precambrian Rocks of the Saganaga Lake – Northern Light Lake Area, Ontario–Minnesota

1971 ◽  
Vol 8 (9) ◽  
pp. 1110-1124 ◽  
Author(s):  
G. N. Hanson ◽  
S. S. Goldich ◽  
J. G. Arth ◽  
D. H. Yardley
Keyword(s):  
Hydrothermal Alteration ◽  
Low Grade ◽  
Lake Area ◽  
Geologic History ◽  
Pyroclastic Material ◽  
Local Conditions ◽  
Precambrian Rocks ◽  
Sequence Of Events ◽  
Mineral Data ◽  
Volcanic Pile

Whole-rock Rb–Sr isochron and mineral ages from the Saganaga Lake – Northern Light Lake area on the Ontario–Minnesota boundary indicate a major orogeny at 2700 m.y. ago. The sequence of events reconstructed in the geologic history started with the eruption of a volcanic pile of flows and pyroclastic material. During metamorphism and folding the basalt flows were converted to amphibolite and an interlayered series to the Northern Light Gneiss, which is now principally trondhjemite with lesser amounts of amphibolite and metarhyolite. The greenstones and the Northern Light Gneiss were intruded by the Saganaga Granite (tonalite), and the tonalite and the Northern Light Gneiss, in turn, were intruded by a syenodioritic phase of the lcarus pluton.The whole-rock isochron ages for the Northern Light Gneiss, the Saganaga tonalite, and the lcarus pluton are 2740, 2710, and 2690 m.y., respectively. Large uncertainties are attached to these values because of the unfavorable Rb/Sr ratios, but the mineral data that include Rb–Sr, K–Ar, and U–Pb analyses, together with geologic observations, permit dating of the Saganaga tonalite at 2700 ± 50 m.y.Mineral ages from this study and some published by the Geological Survey of Canada cluster in the range from 2650 to 2600 m.y. ago and may indicate h low-grade event or an epeirogenetic effect that dates the time of uncovering and stabilization of the region. Mineral ages in the range from 2600 to 2400 m.y. and at approximately 1800 m.y. ago may be partially reset and probably reflect local conditions of faulting and shearing associated with hydrothermal alteration, later low-grade metamorphism, and possibly recent weathering. Similarly, faults and sheared zones probably were effective in localizing the intrusion of dikes that occurred at various times between 2700 and 1100 m.y. ago.

HREM interface studies in SiC-whisker-reinforced Al2O3 and Si3N4 ceramics

1988 ◽  
Vol 46 ◽  
pp. 734-735
Author(s):  
W. Braue ◽  
R.W. Carpenter ◽  
D.J. Smith
Keyword(s):  
Analytical Data ◽  
Base Material ◽  
High Strength ◽  
Ceramic Composites ◽  
Good Thermal Stability ◽  
All Ceramic ◽  
Sic Whiskers ◽  
Base Composite ◽  
C 30 ◽  
Si3n4 Ceramics

Whisker and fiber reinforcement has been established as an effective toughening concept for monolithic structural ceramics to overcome limited fracture toughness and brittleness. SiC whiskers in particular combine both high strength and elastic moduli with good thermal stability and are compatible with most oxide and nonoxide matrices. As the major toughening mechanisms - crack branching, deflection and bridging - in SiC whiskenreinforced Al2O3 and Si3N41 are critically dependent on interface properties, a detailed TEM investigation was conducted on whisker/matrix interfaces in these all-ceramic- composites.In this study we present HREM images obtained at 400 kV from β-SiC/α-Al2O3 and β-SiC/β-Si3N4 interfaces, as well as preliminary analytical data. The Al2O3- base composite was hotpressed at 1830 °C/60 MPa in vacuum and the Si3N4-base material at 1725 °C/30 MPa in argon atmosphere, respectively, adding a total of 6 vt.% (Y2O3 + Al2O3) to the latter to promote densification.

Developing GIS portal to ensure sanitary and epidemiological surveillance of transferring radio engineering objects

2020 ◽  
Vol 99 (4) ◽  
pp. 344-350
Author(s):  
Evgeny V. Zibarev ◽  
A. S. Afanasev ◽  
O. V. Slusareva ◽  
T. I. Muragimov ◽  
V. A. Stepanets ◽  
...  
Keyword(s):  
Electromagnetic Fields ◽  
Analytical Data ◽  
Base Stations ◽  
Epidemiological Surveillance ◽  
Graphical Form ◽  
Residential Areas ◽  
Information Portal ◽  
Radiofrequency Electromagnetic Fields ◽  
Online Mode ◽  
Automated Processes

In recent years, in the Russian Federation there has been an increase in the levels of radiofrequency electromagnetic fields in residential areas, including due to an increase in the number of base stations (BS). The purpose of sanitary and epidemiological surveillance at the stages of placement and commissioning of base stations (BS) is to prevent their adverse effects on public health. The increase in the number of base stations, together with the advent of new electronic equipment and antennas, provide opportunities for improving the processes of their accounting at the stage of placement and monitoring of the levels of radiofrequency electromagnetic fields at the operation stage. This automation tool can be a geo-information portal for providing sanitary and epidemiological surveillance of cellular base stations. The prototype of the geo-information portal allows both calculating the size of sanitary protection zones (SPZ) and building restriction zones (RZ) from the BS in online mode, displaying the results of calculations in graphical form and issuing sanitary and epidemiological conclusions for the placement and operation of base stations. The geo-information portal has the ability to synchronize with the data of the radio frequency center. Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing will be able to receive up-to-date analytical data. There will be completely automated processes of collecting, processing and storing information on BS.

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