Phase relations in metabasites and pressure-temperature conditions at the prehnite-pumpellyite to greenschist facies transition, Flin Flon, Manitoba Canada

1995 ◽  
pp. 67-80 ◽  
Author(s):  
Scott G. Digel ◽  
T. M. Gordon
Keyword(s):  
Phase Relations ◽  
Greenschist Facies ◽  
Temperature Conditions ◽  
Flin Flon ◽  
Facies Transition

Pressure and temperature conditions of metamorphism in the vicinity of three massive sulfide deposits, Flin Flon – Snow Lake belt, Manitoba

1987 ◽  
Vol 24 (11) ◽  
pp. 2305-2315 ◽  
Author(s):  
Pradeep K. Aggarwal ◽  
Bruce E. Nesbitt
Keyword(s):  
Experimental Studies ◽  
Massive Sulfide ◽  
Greenschist Facies ◽  
Maximum Pressure ◽  
Lake Area ◽  
Sulfide Deposits ◽  
Temperature Conditions ◽  
Massive Sulfide Deposits ◽  
Flin Flon ◽  
Temperature And Pressure

Estimates of pressure and temperature conditions of metamorphism in the vicinity of three massive sulfide deposits of the Flin Flon – Snow Lake, Manitoba, greenstone belt have been obtained using mineral assemblages in mafic and felsic metavolcanic rocks. The Flin Flon area around the Centennial deposit, in the western part of the belt, has been metamorphosed to low greenschist facies. Near the Spruce Point deposit, in the central part of the belt, the metamorphic conditions are estimated to be of the upper greenschist facies, with a temperature of 475 ± 75 °C at 2.6 ± 1.2 kbar pressure (1 kbar = 0.1 kPa). The Snow Lake area to the west, in the vicinity of the Anderson Lake deposit, has been metamorphosed to sillimanite grade. In the staurolite–biotite–sillimanite zone, the temperature and pressure conditions were 580 ± 25 °C and 5.25 + 0.75 kbar; in the biotite–sillimanite–almandine zone, the temperature was 620 ± 25 °C at a maximum pressure of 6.2 kbar. Based on the temperature and pressure estimates from the Snow Lake area, it is suggested that experimental studies of the upper stability of staurolite and quartz at low pressure indicate temperatures that are unusually high compared with those indicated by field assemblages.

Superimposed Deformations in the Missi Meta-sedimentary Rocks near Flin Flon, Manitoba

1971 ◽  
Vol 8 (2) ◽  
pp. 217-242 ◽  
Author(s):  
Mel R. Stauffer ◽  
Amar Mukherjee
Keyword(s):  
Sedimentary Rocks ◽  
Greenschist Facies ◽  
Axial Plane ◽  
Small Scale ◽  
Second Phase ◽  
Retrograde Metamorphism ◽  
High Angle ◽  
South Side ◽  
Flin Flon

Within the Flin Flon Basin, Precambrian meta-sandstones and conglomerates belonging to the Missi Group have been complexly deformed as a result of three periods of deformation. The first two periods (P1 and P2) involved folding but no apparent faulting, the last (P3) involved both folding and faulting. Progressive metamorphism (M2), within the greenschist facies, occurred during the second phase (P2) and aided in the formation of a pronounced axial-plane foliation (S2). Small-scale folding and retrograde metamorphism (M3) occurred along faults formed during the last phase (P3).The faults in this area all appear to be high angle, oblique-slip reverse faults and can be interpreted as having formed during a single orogenic event (P3) although there is sequence in their initiation. The net-slip directions of different faults are approximately the same, and plunge moderately to the southeast, with either the east or south side upthrown, depending on the attitude of the fault.

scholarly journals Amphibole CPO in retrograded gabbro from the Lyngen Magmatic Complex (Northern Scandinavian Caledonides, Norway).

2021 ◽  
Author(s):  
Marina Galindos Alfarache ◽  
Holger Stünitz ◽  
Jiří Konopásek ◽  
Amicia Lee
Keyword(s):  
Low Temperature ◽  
Large Scale ◽  
Greenschist Facies ◽  
Amphibolite Facies ◽  
Preferential Growth ◽  
Magmatic Complex ◽  
Temperature Conditions ◽  
Preferred Direction ◽  
Regional Deformation ◽  
Predominant Type

<p>Deformation of natural mafic rocks by viscous deformation mechanisms can occur even at low temperature conditions. In such instances, crystal plastic mechanisms are not operative, as their activity is restricted to very high temperatures for amphiboles, pyroxenes, and plagioclase. Instead, simultaneous mineral reactions may facilitate deformation at low temperature conditions. The gabbro from the Lyngen Magmatic Complex (LMC) constitutes a good example of such processes, because it has experienced deformation at low temperatures of greenschist to lower amphibolite-facies conditions, and the rock has been transformed from gabbro to greenschist. This study focuses on detailed analysis of deformation processes, metamorphic reactions and fabric development in the LMC gabbro. Most samples are overprinted by epidote amphibolite and greenschist-facies mineral assemblages. Preliminary observations distinguish two different types of amphiboles, which have been interpreted as different generations. The predominant type defines the stretching lineation and shows long prismatic habits whereas the less abundant type crystallized in a sub- to anhedral manner. The metamorphic conditions of growth for each amphibole type is yet not well constrained. However, we initially interpret the former to grow during epidote amphibolite- or greenschist facies-conditions, whereas the latter could represent relict grains from the original magmatic assemblage or products generated at amphibolite- or epidote amphibolite-facies conditions. Further analysis will determine the orientation, geochemistry and metamorphic conditions during growth for both amphibole types. A recent model proposed for eclogites suggests that simultaneous mineral growth and deformation can result in new products growing in a preferred direction. Such preferential growth can generate a shape preferred orientation parallel to the lineation, which results in the formation of crystal preferred orientations (CPO). We aim to test if similar microstructural observations can be translated to the amphiboles of the LMC gabbro. In such case, amphibole CPO’s would not be the product of crystal plasticity but of preferential growth. The large scale deformation of the LMC emphasizes the relevance of these results, as it would demonstrate that the interaction between mineral reactions and deformation can play a major role on regional deformation of large mafic bodies, such as the ocean floor.</p>

Synmetamorphic uranium mineralization from Tiraun, Graubünden, Switzerland

1982 ◽  
Vol 46 (339) ◽  
pp. 173-178 ◽  
Author(s):  
E. von Pechmann ◽  
F. Bianconi
Keyword(s):  
High Temperature ◽  
Northern Italy ◽  
Uranium Mineralization ◽  
Greenschist Facies ◽  
Metamorphic Rocks ◽  
X Ray ◽  
Lattice Constants ◽  
Temperature Conditions

AbstractPetrographic, microscopic, and X-ray investigations of a uranium occurrence near Tiraun, Graubünden, Switzerland, are described. The uranium mineralization occurs in greenschist facies metamorphic rocks of the Tavetsch massif and consists essentially of uraninite of various habits with minor chalcopyrite, linnaeite, millerite, galena, marcasite, pyrite, hematite, magnetite, and skutterudite. The ore structure, characterized by concentrations along foliation planes, boudinage, and rotated (helicitic) textures of uraninite porphyroblasts, is indicative of a synmetamorphic (Alpine) remobilization, recrystallization and enrichment of the ore, which was probably derived from an original ‘protore’ in psephites and psammites (? sandstone-type mineralization) of at least Variscan age. The synmetamorphic emplacement of the ore took place under medium- to high-temperature conditions (approx. 350–400°C), as demonstrated by the lattice constants of the uraninite phases and by the ore paragenesis. Late to postmetamorphic tectonism resulted in a partial remobilization (over cm distances) and redistribution of the ore along veinlets that cut the foliation planes. The characteristics of the ore from Tiraun are similar to those from the synmetamorphic ore from Preit, northern Italy, as described by Cevales (1961).

Pressure–temperature conditions of Early Proterozoic metamorphism during the Trans-Hudson Orogen as determined from rocks straddling the Flin Flon – Kisseynew boundary at Niblock and File lakes, Manitoba

1992 ◽  
Vol 29 (11) ◽  
pp. 2497-2507 ◽  
Author(s):  
William Briggs ◽  
C. T. Foster
Keyword(s):  
Amphibolite Facies ◽  
Lake Area ◽  
Relative Timing ◽  
Early Proterozoic ◽  
Temperature Conditions ◽  
Mineral Assemblages ◽  
Flin Flon ◽  
The Town

The Niblock Lake and File Lake areas straddle the boundary between the Kisseynew gneiss belt and the Flin Flon belt, near the town of Snow Lake, Manitoba. The region contains pelitic schists metamorphosed to lower to middle almandine–amphibolite facies. Metamorphic conditions were studied by examining relative timing of growth of metamorphic minerals by geothermobarometry of selected samples. Calculated temperatures and pressures are compared with those estimated from mineral assemblages and reactions on a petrogenetic grid.Two metamorphic (M1 and M2) and deformation (D1 and D2) phases have been recognized in the Niblock Lake and File Lake areas. M1 (contemporaneous with D1 folding) was characterized by growth of micas but no higher grade minerals. Temperatures and pressures of M1, therefore, were probably less than about 475 °C and 3.5 kbar (1 kbar = 100 MPa). Peak conditions, reached during M2 (late- to post-D2 folding), resulted in growth of garnet, staurolite, sillimanite, and (in the Niblock Lake area) andalusite. In the Niblock Lake area, M2 temperatures range from 525 to 625 °C, with most samples between 550 and 600 °C; pressures range from 2.5 to 5 kbar, with most samples between 2.5 and 4 kbar. In the File Lake area, M2 temperatures range from approximately 560 to 625 °C; pressures range from 3.3 to 4.6 kbar.

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