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.

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.

Comportement du système U-Pb dans la monazite et chronologie de la déformation et du métamorphisme des metasédiments du domaine de Kisseynew, orogène trans-hudsonien (Manitoba, Canada)

1999 ◽  
Vol 36 (11) ◽  
pp. 1843-1857 ◽  
Author(s):  
Martin Parent ◽  
Nuno Machado ◽  
Herman Zwanzig
Keyword(s):  
Transition Zone ◽  
Lower Limit ◽  
Amphibolite Facies ◽  
Lake Area ◽  
Central Unit ◽  
Continuous Deformation ◽  
Minimum Age ◽  
Peak Metamorphism ◽  
Flin Flon ◽  
Southern Flank

The Kisseynew domain is the central unit of the Reindeer Zone of the Paleoproterozoic Trans-Hudson Orogen, in Manitoba and Saskatchewan. The southern flank of the domain is a transition zone between the greenschist facies of the volcano-plutonic assemblage of the Flin Flon - Snow Lake belt and the upper amphibolite facies of Kisseynew paragneisses. The Jungle Lake area, in the southern flank of the Kisseynew Domain, comprises mainly quartzofeldspathic gneisses representing continental clastic units of the Missi suite and migmatitic metagraywackes of the Burntwood suite. The area was affected by several phases of deformation, metamorphism, and migmatisation. Detailed mapping and U-Pb geochronology were carried out in order to establish the timing of the deformational and metamorphic phases. The oldest leucosome contains sillimanite formed during peak metamorphism and is associated with F2 folding and S2 fabric. Five single monazites from this leucosome yield ages between 1809 and 1803 Ma taken as the best estimate for the duration of peak metamorphism. Biotite schlieren in diatexites in the Burntwood suite show a S2 fabric folded by F3. Zircon from one of these diatexites yield a crystallization age of 1798+3-2 Ma, considered as the lower limit for the F2 event. Single monazites from the same rock yield ages between 1812 and 1789 Ma, the oldest of which are considered to be inherited. The youngest mobilisate is a pegmatite crosscutting F2 and F3 fabrics and yielded single monazite ages between 1875 and 1788 Ma. The youngest age is taken as the age of the pegmatite and is a minimum age for F3 fabrics. These results, together with those from other areas of the southern Kisseynew Domain, indicate a ca. 30 million year period (1818 and 1785 Ma) of continuous deformation and metamorphism. The data also show the presence of monazite crystals of different ages in the same rock illustrating the need to analyse single grains to obtain geologically meaningful ages.

Metamorphic and structural evolution of the Flin Flon – Athapapuskow Lake area, west-central Manitoba

2020 ◽  
Vol 57 (11) ◽  
pp. 1269-1288
Author(s):  
Manuele Lazzarotto ◽  
David R.M. Pattison ◽  
Simon Gagné ◽  
Paul G. Starr
Keyword(s):  
Regional Metamorphism ◽  
Equilibrium Phase ◽  
Structural Evolution ◽  
Geothermal Gradient ◽  
Island Arc ◽  
Amphibolite Facies ◽  
Ocean Floor ◽  
Lake Area ◽  
Modelling Techniques ◽  
Flin Flon

The Flin Flon – Athapapuskow Lake area, situated in the Flin Flon Greenstone Belt, Manitoba, consists of ocean-floor and island-arc assemblages, deformed and metamorphosed during the Trans-Hudson Orogeny (∼1.86–1.69 Ga). A new map of metamorphic mineral assemblages and isograds has been compiled that reveals a largely coherent regional metamorphic sequence increasing in metamorphic grade from prehnite–pumpellyite to amphibolite facies. Regional metamorphism postdates most of the deformation within the area, with the exception of the reactivation of major block-bounding faults. The regional prograde sequence has been subdivided into 10 metamorphic zones, separated by 9 isograds, that describe the transition from prehnite–pumpellyite to greenschist to amphibolite facies. The formation of contact metamorphic aureoles, pre-dating regional metamorphism, record conditions up to amphibolite facies. Equilibrium phase diagrams for the island-arc (low-Mg) and ocean-floor (high-Mg) assemblages were calculated and allow for the evaluation of the modelling techniques and determination of pressure–temperature conditions. Discrepancies between the modelling predictions and natural observations occur due to (1) limitations in the thermodynamic models for some of the complex minerals (e.g., amphibole); and (2) metastable persistence of some minerals to higher grade due to sluggish reaction kinetics. Notwithstanding these discrepancies, the modelling suggests that metamorphosed mafic rocks in the Flin Flon – Athapapuskow Lake area reached about 430–480 °C and 3.0–4.5 kbar. Peak metamorphic conditions within contact aureoles that preceded regional metamorphism did not exceed 500 °C (at a pressure between 2.7 and 4.4 kbar). The metamorphic field gradient records a transition from 250–300 °C/1.5–2.3 kbar to 430–480 °C/3–4.5 kbar (100–150 °C/kbar), defining a geothermal gradient of approximately 25–31 °C/km.

Low-pressure regional amphibolite-facies to granulite-facies metamorphism of the Paleoproterozoic Thompson Nickel Belt, Manitoba

2012 ◽  
Vol 49 (10) ◽  
pp. 1117-1153 ◽  
Author(s):  
Chris G. Couëslan ◽  
David R.M. Pattison
Keyword(s):  
Regional Scale ◽  
Granulite Facies ◽  
Amphibolite Facies ◽  
Iron Formation ◽  
The West ◽  
Mafic Rocks ◽  
Temperature Conditions ◽  
Mineral Assemblages ◽  
Facies Zone ◽  
Superior Craton

The Thompson Nickel Belt is a ca. 35 km × 400 km northeast-trending segment of the northwest margin of the Archean Superior craton in Manitoba, bounded to the west by the Paleoproterozoic Reindeer Zone. The belt was metamorphosed and deformed during the Trans-Hudson orogeny (ca. 1.9–1.7 Ga). Mineral assemblages in metamorphosed pelite, aluminous greywacke, mafic igneous rock, iron formation, and ferruginous wacke define regional metamorphic domains, separated by mineral isograds, that are subparallel to the strike of the belt and to regional-scale D3 structures. An elongate, ca. 5 km × 73 km, central zone of middle amphibolite-facies rocks is characterized by the following: muscovite-bearing mineral assemblages in pelites containing combinations of staurolite, andalusite, and sillimanite; muscovite-free, staurolite + cordierite + garnet-bearing mineral assemblages in greywackes; hornblende-bearing mineral assemblages in mafic metaigneous rocks; and grunerite-bearing mineral assemblages in iron formation. Pressure–temperature (P–T) conditions of the middle amphibolite-facies zone are ca. 550–620 °C and 3.0–5.0 kbar (1 kbar = 100 MPa), with pressure increasing to the northeast. The middle amphibolite-facies zone is bordered to the east and west by an upper amphibolite-facies zone, ca. 5 km wide on the east and ca. 3–5 km on the west. The upper amphibolite-facies zone is characterized by variably migmatitic K-feldspar + sillimanite-bearing mineral assemblages in pelites; migmatitic, garnet + cordierite + sillimanite-bearing mineral assemblages in greywackes; orthopyroxene-free, hornblende-bearing mineral assemblages in mafic rocks; and orthopyroxene-bearing mineral assemblages in iron formations. Pressure–temperature conditions of the upper amphibolite-facies zone are ca. 640–710 °C and 3.0–5.5 kbar in the southeast, and 675–755 °C and 4.5–6.0 kbar in the northwest. The outermost metamorphic zone is of the granulite facies, characterized by migmatitic garnet + cordierite + K-feldspar-bearing assemblages in pelites and greywackes, orthopyroxene + clinopyroxene ± garnet-bearing mineral assemblages in mafic rocks, and orthopyroxene + K-feldspar-bearing mineral assemblages in iron formation in which biotite is unstable. Pressure–temperature conditions of the granulite-facies zone are ca. 775–830 °C and 5.0–7.0 kbar. The P–T paths in the Thompson Nickel Belt appear to be broadly clockwise, except for some domains where they are close to isobaric. The peak P–T conditions, combined with local but widespread development of andalusite, imply relatively steep geothermal gradients of ca. 33–51 °C/km during metamorphism. Regional bathozones (domains of uniform peak-metamorphic pressure) correspond in general but not in detail with the metamorphic-facies zones. They reveal an increase in pressure towards the northeast, suggesting greater degrees of postmetamorphic exhumation in that region. Microstructural analysis suggests that peak metamorphism coincided with, and possibly outlasted, the D2 deformation event. Metamorphic isograds were deformed by D3–D4 structures. These features are consistent with a tectonic model in which the Superior craton moved in a northwest or west-northwest direction relative to the Reindeer Zone, with greatest convergence and tectonic burial occurring at the Thompson promontory.

A retrogressive sapphirine-cordierite-talc paragenesis in a spinel-orthopyroxenite from southern Karnataka, India

1993 ◽  
Vol 57 (387) ◽  
pp. 273-288 ◽  
Author(s):  
C. R. L. Friend ◽  
A. S. Janardhan ◽  
N. Shadakshara Swamy
Keyword(s):  
Dharwar Craton ◽  
Amphibolite Facies ◽  
Coarse Grained ◽  
Cooling History ◽  
Metamorphic History ◽  
Gneiss Complex ◽  
Igneous Origin ◽  
Mineral Assemblages ◽  
History Of ◽  
Granoblastic Texture

AbstractWithin amphibolite facies Peninsular gneisses in the south of the Dharwar craton, units of Sargur supracrustal rocks contain ultrabasic enclaves. One of these enclaves is an orthopyroxenite which comprises bronzite, spinel and minor phlogopite preserving coarse-grained, relic textures of probable igneous origin. After incorporation into the gneisses the enclave evolved through several distinct stages, elucidation of which allow an assessment of its metamorphic history.Firstly, deformation during closed system, anhydrous recrystallisation caused the coarse-grained textures to be partially overprinted by similar mineral assemblages but with a granoblastic texture. Secondly, open system hydration caused retrogression of the bronzite to alumino-gedrite at the margins of the enclave. Subsequently, the penetration of these fluids along grain boundaries caused reactions between spinel and bronzite to produce reaction pockets carrying assemblages of peraluminous sapphirine associated with cordierite and talc. The differences in the mineral assemblages in each pocket coupled with slight variations in their chemistry, suggest that equilibrium did not develop over the outcrop. Because sapphirine + magnesite is present in some pockets, it is evident that CO2 was also a component of the fluid.Phase relations from the MASH portion of the FMASH system, to which the chemistry of the reaction pockets approximates, suggest that the hydrous metamorphism causing the changes depended upon the assemblage enstatite + spinel + vapour which exists at PT conditions above the position of I16, ∼760°C at 3 kbar and below I21 at ∼765°C at 5.6 kbar (Seifert, 1974, 1975), where sapphirine is replaced by kornerupine. The suggested path of reaction occurred between I18 and I21. Subsequent reactions related to I20 cause the formation of cordierite. Talc formation has to be modelled in a different reaction grid.The metamorphism recorded by these reactions is thus at a maximum of amphibolite facies and is interpreted to have formed during the uplift and cooling history of the gneiss complex when hydrous fluids were free to migrate. Given the complex high-grade metamorphic history of this part of the Dharwar craton this event is likely to be late Archaean or Palaeoproterozoic in age.

Coeval sedimentation, magmatism, and fold-thrust belt development in the Trans-Hudson Orogen: geochronological evidence from the Wekusko Lake area, Manitoba, Canada

1999 ◽  
Vol 36 (2) ◽  
pp. 293-312 ◽  
Author(s):  
Kevin M Ansdell ◽  
Karen A Connors ◽  
Richard A Stern ◽  
Stephen B Lucas
Keyword(s):  
Regional Metamorphism ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Lake Area ◽  
Thrust Belt ◽  
Fold And Thrust Belt ◽  
Minimum Age ◽  
Flin Flon ◽  
Felsic Volcanic

Lithological and structural mapping in the east Wekusko Lake area of the Flin Flon Belt, Trans-Hudson Orogen, suggested an intimate relationship between magmatism, fluvial sedimentation, and initiation of fold and thrust belt deformation. Conventional U-Pb geochronology of volcanic rocks in fault-bounded assemblages provides a minimum age of 1876 ± 2 Ma for McCafferty Liftover back-arc basalts, and ages of between 1833 and 1836 Ma for the Herb Lake volcanic rocks. A rhyolite which unconformably overlies Western Missi Group fluvial sedimentary rocks has complex zircon systematics. This rock may be as old as about 1856 Ma or as young as 1830 Ma. The sedimentary rocks overlying this rhyolite are locally intercalated with 1834 Ma felsic volcanic rocks, and yield sensitive high resolution ion microprobe (SHRIMP) U-Pb and Pb-evaporation detrital zircon ages ranging from 1834 to 2004 Ma. The Eastern Missi Group is cut by an 1826 ± 4 Ma felsic dyke, and contains 1832-1911 Ma detrital zircons. The dominant source for detritus in the Missi Group was the Flin Flon accretionary collage and associated successor arc rocks. The fluvial sedimentary rocks and the Herb Lake volcanic rocks were essentially coeval, and were then incorporated into a southwest-directed fold and thrust belt which was initiated at about 1840 Ma and active until at least peak regional metamorphism.

Petrogenesis of the Boundary intrusions in the Flin Flon area of Saskatchewan and Manitoba

1977 ◽  
Vol 14 (3) ◽  
pp. 444-455 ◽  
Author(s):  
Eric C. Syme ◽  
Richard W. Forester
Keyword(s):  
Basaltic Magma ◽  
Molar Ratio ◽  
Chemical Characteristics ◽  
Olivine Gabbro ◽  
Metasedimentary Rocks ◽  
Metavolcanic Rocks ◽  
Flin Flon ◽  
Group 2 ◽  
The Town ◽  
Felsic Rocks

The Aphebian Boundary intrusions are a group of lensoid, ultramafic to felsic rocks which occur in a N–NW trending zone 10 km long by 4 km wide centred on the town of Flin Flon. The intrusions were emplaced into Amisk metavolcanic rocks and Missi metasedimentary rocks. Field relationships, petrography, and chemical characteristics of the Boundary intrusions indicate that they are composed of three compositionally distinct, sequentially emplaced groups. From oldest to youngest, these are (1) a mafic augite- and biotite-bearing mela-dioritic group, (2) a felsic group ranging from leucodiorite to granodiorite, and (3) an olivine-bearing (wehrlite to olivine gabbro) group. The mafic group crystallized at relatively high [Formula: see text] and [Formula: see text], such that successive differentiates have increasing MgO/FeO ratios. Molar ratio diagrams clearly indicate that fractionation of augite, minor magnetite, and possibly subordinate olivine can account for the observed chemical variation of approximately 80% of this group, whereas the olivine-bearing group could only have formed by crystal fractionation of subequal amounts of olivine and clinopyroxene, and minor magnetite. The felsic group is chemically similar to the post-Missi granodioritic plutons and cannot represent SiO2-rich residual liquids produced solely by fractionation of augite and olivine from a basaltic magma.

Paleomagnetism of the Flin Flon – Snow Lake Greenstone Belt, Manitoba and Saskatchewan

1975 ◽  
Vol 12 (8) ◽  
pp. 1272-1290 ◽  
Author(s):  
J. K. Park
Keyword(s):  
Greenstone Belt ◽  
Amphibolite Facies ◽  
Retrograde Metamorphism ◽  
General Direction ◽  
Thermoremanent Magnetization ◽  
Flin Flon ◽  
K 12 ◽  
Very High

The Flin Flon – Snow Lake greenstone belt is of Archean or Aphebian age and has been metamorphosed to greenschist or low amphibolite facies during the Hudsonian orogeny. It contains four rock units — the Amisk Group, the Missi Group, metadiorite and metagabbro bodies, and the Boundary Intrusions. The rocks contain two main magnetizations, an early B magnetization and a later A magnetization. Both magnetizations contain reversals. The A magnetization (43 sites, direction 168°, +73°, k = 17, α95 = 5°, pole 24°N, 095°W) is found in all rock units. It can be divided into three parts (1, 2 and 3) which have the same general direction, but which are significantly different from one another. It is suggested that A1 is a viscous partial thermoremanence (vptrm), and A2 possibly a chemical remanence (crm). Both are considered to have been acquired during uplift (1600–1700 m.y.) following the Hudsonian orogeny. A3 is possibly a crm acquired during late fault movements and appears to be carried by hematite developed during retrograde metamorphism. A3 is considered to be about 1600 m.y. old. The B magnetization (7 sites, 129°, +04°, k = 12, α95 = 18°, pole 20°S, 046°W) occurs in all rock units except the Missi. It is particularly well developed in the Boundary Intrusions where it is considered to be a primary thermoremanent magnetization (trm). In other rock units B is considered to be a vptrm acquired during heating at the time of emplacement of the Boundary Intrusions. The B magnetization is considered to be about 1800 m.y. old. Some enigmatic magnetizations with very high blocking temperatures above 700 °C were observed. Formulas for calculating the coercivities in rocks with more than one magnetization are given.

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