The Amisk Group: An Aphebian(?) Island Arc Deposit

1975 ◽  
Vol 12 (12) ◽  
pp. 2021-2035 ◽  
Author(s):  
Mel R. Stauffer ◽  
A. C. Mukherjee ◽  
J. Koo
Keyword(s):  
Major Element ◽  
Regional Metamorphism ◽  
Island Arc ◽  
Lava Flows ◽  
Chemical Analyses ◽  
Pyroclastic Rocks ◽  
Andesitic Lava ◽  
Ore Bodies ◽  
Flin Flon ◽  
Garnet Zone

The Amisk Group (Aphebian?) near Flin Flon, Manitoba, consists dominantly of andesitic lava flows and pyroclastic rocks, with minor basalt, dacite, rhyolite, and epiclastic rocks. These have undergone regional metamorphism ranging from chlorite to garnet zone, and locally have been sheared intensely.Major element chemical analyses indicate that intensely sheared Amisk rocks near the Flin Flon and Schist Lake Cu–Zn ore bodies have undergone considerable metasomatism. The unsheared, regionally metamorphosed rocks have undergone significantly less metasomatism, and the compositions of the least-altered of these suggest an island arc tholeiite chemical affinity.The lithology, primary structures, and major-element compositions of lavas within the Amisk Group suggest deposition may have been in an island arc environment.

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.

Major-Element Chemical Analyses

1979 ◽  
Author(s):  
D.A. Wood ◽  
J. Varet ◽  
H. Bougault ◽  
O. Corre ◽  
J.L. Joron ◽  
...  
Keyword(s):  
Major Element ◽  
Chemical Analyses

A Kaolin-smectite interstratification sequence from a red and black complex

Clay Minerals ◽  
1991 ◽  
Vol 26 (3) ◽  
pp. 343-358 ◽  
Author(s):  
C. Bühmann ◽  
P. L. C. Grubb
Keyword(s):  
Major Element ◽  
Element Composition ◽  
Chemical Analyses ◽  
Sand Content ◽  
Major Element Composition ◽  
Genetic Link ◽  
Sequential Development ◽  
Mineral Compositions

AbstractThe sequential development of kaolin by progressive alteration of smectite, involving kaolin-smectite interstratifications as a genetic link is described from a red and black complex. Mineral compositions were studied using XRD, DTA and XRF techniques. The basalt-derived soils are situated along a 600 m transect and grade in colour from dark grey (10 YR 3/1) to red (5 YR 3/3). The kaolin proportions in the interstratification increase almost linearly with increasing reddening up to ∼80%. Whole-soil chemical analyses exhibit no significant variations in the major element composition, but dithionite extractable Fe increases along the transect from 1% to 4·16%. Hematite and goethite are the only secondary iron phases. Topographic differences are slight but sub-surface bedrock contours plus appreciable variations in sand content between red and black soils could be genetically significant.

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.

Gneissic Alkalic Rocks and Carbonatites in the Frenchman's Cap Gneiss Dome, Shuswap Complex, British Columbia

1974 ◽  
Vol 11 (2) ◽  
pp. 304-318 ◽  
Author(s):  
W. J. McMillan ◽  
J. M. Moore Jr.
Keyword(s):  
Regional Metamorphism ◽  
Lava Flows ◽  
High Grade ◽  
Metamorphic Complex ◽  
Sedimentary Deposits ◽  
Gneiss Domes ◽  
The Core ◽  
Igneous Origin ◽  
Eastern Border ◽  
Shuswap Metamorphic Complex

Frenchman's Cap dome is one of a series of gneiss domes along the eastern border of the high-grade Shuswap metamorphic complex. The granitic gneisses which compose the core of the dome are enclosed in an envelope of metasedimentary rocks.Before Shuswap metamorphism and deformation, the rocks of the sedimentary envelope were intruded by concordant bodies of alkalic rocks and carbonatite. Other carbonatite bodies appear to have formed at or extruded onto the surface. It is not certain whether these are exhalative sedimentary deposits, lava flows, or pyroclastic deposits.Criteria which can be used to distinguish igneous alkalic rocks from those of metasomatic origin were almost entirely destroyed by regional metamorphism. A few relict igneous textures show that at least some of the alkalic gneisses are of igneous origin.

Lithogeochemistry of volcano-plutonic assemblages of the southern Hanson Lake Block and southeastern Glennie Domain, Trans-Hudson Orogen: evidence for a single island arc complex

1999 ◽  
Vol 36 (2) ◽  
pp. 209-225 ◽  
Author(s):  
Ralf O Maxeiner ◽  
Tom II Sibbald ◽  
William L Slimmon ◽  
Larry M Heaman ◽  
Brian R Watters
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Oceanic Island ◽  
Island Arc ◽  
Island Arcs ◽  
Calc Alkaline ◽  
East Central ◽  
South Central ◽  
Volcaniclastic Rocks ◽  
Flin Flon

This paper describes the geology, geochemistry, and age of two amphibolite facies volcano-plutonic assemblages in the southern Hanson Lake Block and southeastern Glennie Domain of the Paleoproterozoic Trans-Hudson Orogen of east-central Saskatchewan. The Hanson Lake assemblage comprises a mixed suite of subaqueous to subaerial dacitic to rhyolitic (ca. 1875 Ma) and intercalated minor mafic volcanic rocks, overlain by greywackes. Similarly with modern oceanic island arcs, the Hanson Lake assemblage shows evolution from primitive arc tholeiites to evolved calc-alkaline arc rocks. It is intruded by younger subvolcanic alkaline porphyries (ca. 1861 Ma), synvolcanic granitic plutons (ca. 1873 Ma), and the younger Hanson Lake Pluton (ca. 1844 Ma). Rocks of the Northern Lights assemblage are stratigraphically equivalent to the lower portion of the Hanson Lake assemblage and comprise tholeiitic arc pillowed mafic flows and felsic to intermediate volcaniclastic rocks and greywackes, which can be traced as far west as Wapawekka Lake in the south-central part of the Glennie Domain. The Hanson Lake volcanic belt, comprising the Northern Lights and Hanson Lake assemblages, shows strong lithological, geochemical, and geochronological similarities to lithotectonic assemblages of the Flin Flon Domain (Amisk Collage), suggesting that all of these areas may have been part of a more or less continuous island arc complex, extending from Snow Lake to Flin Flon, across the Sturgeon-Weir shear zone into the Hanson Lake Block and across the Tabbernor fault zone into the Glennie Domain.

Upper Cretaceous Stratigraphy and Volcanism in the İğneada region, Pontides, NW Turkey

2020 ◽  
Author(s):  
Ezgi Sağlam ◽  
Turgut Duzman ◽  
Aral I. Okay
Keyword(s):  
Upper Cretaceous ◽  
Planktonic Foraminifera ◽  
Lava Flows ◽  
Arc Volcanism ◽  
Magmatic Arc ◽  
Andesitic Lava ◽  
Black Sea Coast ◽  
Nw Turkey ◽  
Sandy Limestone ◽  
Volcaniclastic Rocks

<p>The Pontide Upper Cretaceous magmatic arc can be traced for over 1000 km along the southern Black Sea coast from Georgia to Bulgaria.  The arc extrusive sequence is well-exposed in the İğneada region in Thrace close to the Bulgarian border. The Upper Cretaceous sequence in İğneada region overlies the schists and phyllites of Strandja Massif with an unconformity. It  has a thickness of over 700 meters and consists at the base of Cenomanian shallow marine sandy limestone, which pass up into pelagic limestone, marn and volcanogenic siltstone with Turonian planktonic foraminifera, including <em>Marginotruncana pseudolinneana</em>, <em>Marginotruncana marginata</em>, <em>Whitenella</em> sp., <em>Whitenella praehelvetica</em>, <em>Muricohedbergella</em> sp.  This indicates that the arc volcanism in the region started in the Turonian. The pelagic limestone, marl, and calcareous siltstone series passes up into a volcanic-volcaniclastic sequence of andesitic tuff, lapillistone, agglomerate, andesitic and basaltic-andesitic lava flows. The volcaniclastic rocks are intercalated with lava flows and with rare pelagic limestone and shale beds. Although it is disrupted by several faults, the volcanic sequence can be traced from older to younger along the coast of İğneada. The sequence starts with andesitic volcaniclastic rocks and lava flows, and changes to basaltic-andesitic and then, again to andesitic rocks. The ocean floor alteration, which is found in all volcaniclastic and volcanic rock samples, and the intercalated pelagic limestones show that the rocks were deposited in deep submarine conditions in an intra-arc to fore-arc environment. Campanian (80.6 ±1.5 Ma) U-Pb zircon ages, which are obtained from the andesitic tuffs at the base of the volcanic-volcaniclastic sequence, indicate a continued magmatism from Turonian to Campanian.</p>

Petrology and emplacement of the Los Pinos pluton, southern California

1976 ◽  
Vol 13 (9) ◽  
pp. 1288-1300 ◽  
Author(s):  
M. J. Walawender
Keyword(s):  
Experimental Data ◽  
Volcanic Eruption ◽  
Southern California ◽  
Major Element ◽  
Parent Magma ◽  
Chemical Analyses ◽  
Eastern Margin ◽  
Peninsular Ranges ◽  
Summit Region ◽  
Pelitic Rocks

The Los Pinos gabbro is located on the eastern margin of the gabbro sub-belt of the Peninsular Ranges batholilh. Two lithologic sequences are recognized in this pluton. The outer group consists of bimodal assemblages of hornblende and plagioclase in several textural varieties, whereas the inner group contains a variety of olivine–plagioclase rocks. Symplectitic intergrowths of spinel, amphibole, and orthopyroxene have developed wherever the olivine and plagioclase were in contact. The outer group is generally the older of the two, although there is evidence suggesting that their emplacement overlapped in time. The contact between the two groups is characterized locally by sequences of comb layers up to 65 m thick. Major-element chemical analyses emphasize the differences between the two groups. The outer group is generally richer in total alkalis, titanium, and silica. Variation diagrams suggest that different differentiation mechanisms operated within each group.Textural and published experimental data suggest that the two groups are derived from a parent magma by clinopyroxene fractionation at PT > 5 kbar. The more silicic differentiates were emplaced at shallower levels into a series of regionally metamorphosed pelitic rocks. Volatile streaming in restricted channels along a conduit zone and periodic degassing of the melt, possibly through volcanic eruption, produced the comb layering in the summit region. The remaining fraction intruded along the old conduit zone. Differentiation at these shallower levels (PT < 5 kbar) produced the olivine–plagioclase cumulates. The symplectic intergrowths in these units formed at this shallower level prior to the solidification of the melt.

Sign in / Sign up

Export Citation Format

Share Document