The geology and geochemistry of an Early Proterozoic volcanic-arc association at Cartwright Lake: Lynn Lake greenstone belt, northwestern Manitoba

1989 ◽  
Vol 26 (4) ◽  
pp. 716-736 ◽  
Author(s):  
D. C. Peck ◽  
T. E. Smith
Keyword(s):  
Mafic Magma ◽  
Lake Area ◽  
Garnet Lherzolite ◽  
Calc Alkaline ◽  
Volcanic Arc ◽  
Early Proterozoic ◽  
Intrusive Rocks ◽  
Geochemical Variations ◽  
Arc Setting ◽  
Lynn Lake

The geology of the Cartwright Lake area consists of a >2 km thick conformable sequence of Early Proterozoic supracrustal rocks intruded by calc-alkaline granitoid plutons. The supracrustal succession comprises a basal series of tholeiitic basalts, an overlying bimodal sequence, and an uppermost series of calc-alkaline andesites. The bimodal sequence incorporates abundant tholeiitic basalts and associated mafic tuffs, lesser felsic hyaloclastites and pyroclastics, and minor interflow greywacke–mudstone turbidites.Petrogenetic models involving trace-element concentrations indicate that most of the extrusive and intrusive rocks were derived from similar parent magmas that formed by extensive partial melting of a garnet lherzolite upper-mantle source. The parent liquids fractionated along an early tholeiitic trend and a later calc-alkaline trend, producing the observed geochemical variations in the mafic and intermediate volcanic assemblages. Ponding of mafic magma at the base of the crust may have promoted crustal fusion, thereby generating felsic liquids, which erupted and formed the dacite–rhyolite suite.The geology and geochemistry of the volcanic assemblages are consistent with a subduction-related origin in a volcanic-arc setting. The majority of geochemical evidence favours the interpretation that the Cartwright Lake segment of the arc developed on relatively thin sialic crust.

Provenance of igneous clasts in conglomerates of the Archaean Timiskaming Group, Kirkland Lake area, Abitibi greenstone belt, Canada

1994 ◽  
Vol 31 (12) ◽  
pp. 1749-1762 ◽  
Author(s):  
Marc I. Legault ◽  
Keiko Hattori
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Hydrothermal Activity ◽  
Tholeiitic Basalt ◽  
Coarse Grained ◽  
Alkaline Magmatism ◽  
Lake Area ◽  
Calc Alkaline ◽  
Intrusive Rocks ◽  
Strike Slip Movement

Four types of igneous clasts from Timiskaming conglomerates of the Kirkland Lake area are identified: calc-alkaline porphyry, trachyte (K2O + N2O > 7.25 wt.%), trondhjemite, and tholeiitic basalt. Clasts derived from quartz–carbonate veins and carbonatized porphyries and komatiites indicate CO2-rich hydrothermal activity along the Larder Lake – Cadillac Fault before sedimentation. Calc-alkaline porphyry, the predominant clast, is similar in appearance to feldspar porphyry intrusions widely exposed in the area, but the two are not related. The porphyry clasts are cogenetic with diorite–granodiorite intrusions and volcanic rocks of the greenstone belt. Andesite clasts are only observed near the base of the assemblage, and the ratio of basalt to andesite increases up stratigraphic sections. The change suggests progressive erosion of arc-related volcanic rocks during sedimentation. Composition, texture, and mineralogy of the trondhjemite clasts are consistent with their derivation from the marginal phases of the Round Lake batholith. Intrusive rocks of the Timiskaming Group (coarse-grained holocrystalline syenitic–monzonitic rocks, biotite-bearing feldspar porphyries, and mica-rich lamprophyres) were not observed in the clasts, which suggests sedimentation prior to unroofing of these rocks. Sedimentation of the conglomerates postdated unroofing of underlying plagioclase porphyry (~2685 Ma), but predated unroofing of Timiskaming intrusions. The distribution of alkaline clasts only in proximity to the fault implies that alkaline magmatism was confined along the fault. Derivation of clasts from both sides of the fault and proximity of inferred sources support a pull-apart basin for sedimentation with minor strike-slip movement during and after the sedimentation.

scholarly journals Syn-collisional pan-African granite in the northern part Birnin Gwari schist belt in NW Nigeria

2020 ◽  
Vol 8 (2) ◽  
pp. 197
Author(s):  
Kehinde Oluyede ◽  
Urs Klötzli
Keyword(s):  
Mafic Magma ◽  
Biotite Granite ◽  
Trace Element Data ◽  
Schist Belt ◽  
Calc Alkaline ◽  
Fractionation Factor ◽  
Volcanic Arc ◽  
Pan African ◽  
High K ◽  
Ree Patterns

Syn-collisional granite in the northern part of the Birnin Gwari schist belt consists dominantly of granite and lesser granodiorite and quartzolite. Petrographic and ge¬ochemical data revealed three granite groups: the biotite-hornblende granite (quartzolite - BHG); the biotite granite (BG) and the biotite-muscovite granite (BMG). The rocks generally have calc-alkaline and high-K calc-alkaline affinities, and calc-alkalic to alkali-calcic, peraluminous and ferroan and magnesian geochemistry. They are characterized by LILE enrichment, high LREE fractionation factor [(La/Yb) (6.74 to 45.14] with weak to moderate negative Eu (Eu/Eu* = 0.38 to 0.62) and strong negative Nb, P and Ti anomalies. Variation in the behavior of lithophile elements (Ba, Sr and Rb) revealed diverse granite trend such as “high and low Ba-Sr”; “normal”, “anomalous” “strongly differentiated” and “granodiorite and quartz diorite” granite. Their display of similar trace elements and REE patterns suggest they are cogenetic. Major and trace element data indicate differentiation of a mafic magma and partial melting of crustal components inherited from shale-greywacke and quartzose sedimentary protoliths in volcanic arc and post collisional settings. The field and geochemical characteristics of this granite suggest that they are similar to other granites in schist belts in other parts of Nigeria, forming the lateral continuation of the same Pan-African magmatic belt.   

Geochemistry and geodynamic constraint of volcanic and plutonic magmatism within the Banfora Belt (Burkina-Faso, West-Africa): contribution to mineral exploration

2020 ◽  
pp. SP502-2019-86
Author(s):  
Hermann Ilboudo ◽  
Sâga Sawadogo ◽  
Gounwendmanaghre Hubert Zongo ◽  
Seta Naba ◽  
Urbain Wenmenga ◽  
...  
Keyword(s):  
Fractional Crystallization ◽  
Mineral Exploration ◽  
Volcanic Rocks ◽  
Mafic Magma ◽  
Calc Alkaline ◽  
High K ◽  
Tectonic Settings ◽  
Arc Setting ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

AbstractPredominant volcano-plutonic (mafic–felsic) activity is expressed in the eastern Banfora Belt. The geochemical signature shows different geodynamic settings: (1) mafic rocks are tholeiitic, subalkaline and show high-Mg tendency, whereas pyroxenolite (MgO c. 15.4 wt%) has komatiite affinity; (2) felsic volcanic rocks are subalkaline; and (3) granitoids surrounding the Banfora Belt are alkaline to calc-alkaline, high K, peraluminous to metaluminous. The geochemistry of mafic volcanic rocks shows an unusual evolution from Mid Oceanic Ridge Basalt to Arc-related. The Western Granite and Eastern Granites were emplaced by fractional crystallization and partial melting, respectively, but sourced from igneous protolith (I-type magma) in a volcanic arc setting. The Sodingue granite was emplaced by fractional crystallization from A-type magma in a ‘within-plate setting’. Two-mica S-type granites located at the central portion of the belt relate to syn-collisional fractional crystallization. The paper highlights the complexity of the magma process through a diversity of sources, geochemical patterns and tectonic settings. An emphasis on the komatiite affinity of mafic magma is a challenge for related commodities, such as copper and gold resources.

scholarly journals Mineral chemistry and geothermobarometry of gabbroic rocks from the Gysel area, Alborz mountains, north Iran

2020 ◽  
Vol 33 (02) ◽  
pp. 392-408
Author(s):  
Farzaneh Farahi ◽  
Saeed Taki ◽  
Mojgan Salavati
Keyword(s):  
Electron Microprobe ◽  
Parental Magma ◽  
Mineral Chemistry ◽  
Olivine Gabbro ◽  
Calc Alkaline ◽  
Plagioclase Composition ◽  
Volcanic Arc ◽  
Rock Samples ◽  
Central Alborz ◽  
Arc Setting

The gabbroic rocks in the Gysel area of the Central Alborz Mountains in north Iran are intruded into the Eocene Volcano-sedimentary units. The main gabbroic rocks varieties include gabbro porphyry, olivine gabbro, olivine dolerite and olivine monzo-gabbro. The main minerals phases in the rocks are plagioclase and pyroxene and the chief textures are sub-hedral granular, trachytoidic, porphyritic, intergranular and poikilitic. Electron microprobe analyses on minerals in the rock samples shows that plagioclase composition ranges from labradorite to bytonite, with oscillatory and normal chemical zonings. Clinopyroxene is augite and orthopyroxene is hypersthene to ferro-hypersthene. Thermometry calculations indicate temperatures of 650˚C to 750˚C for plagioclase crystallization and 950˚C to 1130˚C for pyroxene crystallization. Clinopyroxene chemistry reveals sub-alkaline and calc-alkaline nature for the parental magma emplaced in a volcanic arc setting.

INTRUSIVE ROCKS OF THE GAME LAKE AREA AND IMPLICATIONS FOR THE ORIGIN OF THE SNOWCAMP OPHIOLITE

2017 ◽  
Author(s):  
Brittany M. DePasquale ◽  
◽  
Nuredin Kozenjic ◽  
Adam Schoonmaker
Keyword(s):  
Lake Area ◽  
Intrusive Rocks

Magnetic field characterization of Macolod Corridor (Luzon, Philippines): New perspectives on rifting in a volcanic arc setting

2021 ◽  
pp. 229179
Author(s):  
Rurik S.P. Austria ◽  
Nathaniel E. Parcutela ◽  
Edd Marc L. Reyes ◽  
Leo T. Armada ◽  
Carla B. Dimalanta ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Volcanic Arc ◽  
Arc Setting

Rare earth element concentrations in Quaternary volcanic rocks of southwestern British Columbia

1984 ◽  
Vol 21 (6) ◽  
pp. 731-736 ◽  
Author(s):  
Nathan L. Green ◽  
Paul Henderson
Keyword(s):  
British Columbia ◽  
Earth Element ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Lake Area ◽  
Calc Alkaline ◽  
Lower Light ◽  
The Individual ◽  
High Level ◽  
Ree Patterns

A suite of hy-normative hawaiites, ne-normative mugearite, and calc-alkaline andesitic rocks from the Garibaldi Lake area exhibits fractionated, slightly concave-upward REE patterns (CeN/YbN = 4.5–15), heavy REE contents about 5–10 times the chondritic abundances, and no Eu anomalies. It is unlikely that the REE patterns provide information concerning partial melting conditions beneath southwestern British Columbia because they have probably been modified substantially by upper crustal processes including crustal contamination and (or) crystal fractionation. The REE contents of the Garibaldi Lake lavas are not incompatible with previous interpretations that (1) the hawaiites have undergone considerable fractionation of olivine, plagioclase, and clinopyroxene; and (2) the individual andesitic suites were derived from separate batches of chemically distinct magma that evolved along different high-level crystallization trends. In general, however, the andesites are characterized by lower light REE contents than the basaltic andesites. These differences in LREE abundances may reflect different amounts of LREE-rich accessory phases, such as apatite, sphene, or allanite, assimilated from the underlying quartz diorites.

scholarly journals Tectono-magmatic evolution of the younger Gardar southern rift, South Greenland

2013 ◽  
Vol 29 ◽  
pp. 1-24 ◽  
Author(s):  
Brian G.J. Upton
Keyword(s):  
Mafic Magma ◽  
Dyke Swarm ◽  
Small Scale ◽  
Alkaline Magmatism ◽  
East African ◽  
The North ◽  
Intrusive Rocks ◽  
Alkali Granites ◽  
African Rift ◽  
Very High

The 1300–1140 Ma Gardar period in South Greenland involved continental rifting, sedimentation and alkaline magmatism. The latest magmatism was located along two parallel rift zones, Isortoq–Nunarsuit in the north and the Tuttutooq–Ilimmaasaq–Narsarsuaq zone in the south addressed here. The intrusive rocks crystallised at a depth of troctolitic gabbros. These relatively reduced magmas evolved through marked iron enrichment to alkaline salic differentiates. In the Older giant dyke complex, undersaturated augite syenites grade into sodalite foyaite. The larger, c . 1163 Ma Younger giant dyke complex (YGDC) mainly consists of structureless troctolite with localised developments of layered cumulates. A layered pluton (Klokken) is considered to be coeval and presumably comagmatic with the YGDC. At the unconformity between the Ketilidian basement and Gardar rift deposits, the YGDC expanded into a gabbroic lopolith. Its magma may represent a sample from a great, underplated mafic magma reservoir, parental to all the salic alkaline rocks in the southern rift. The bulk of these are silica undersaturated; oversaturated differentiates are probably products of combined fractional crystallisation and crustal assimilation. A major dyke swarm 1–15 km broad was intruded during declining crustal extension, with decreasing dyke widths and increasing differentiation over time. Intersection of the dyke swarm and E–W-trending sinistral faults controlled the emplacement of at least three central complexes (Narssaq, South Qôroq and early Igdlerfigssalik). Three post-extensional complexes (Tugtutôq, Ilímaussaq and late Igdlerfigssalik) along the former rift mark the end of magmatism at c . 1140 Ma. The latter two complexes have oblate plans reflecting ductile, fault-related strain. The Tugtutôq complex comprises quartz syenites and alkali granites. The Ilímaussaq complex mainly consists of nepheline syenite crystallised from highly reduced, Fe-rich phonolitic peralkaline (agpaitic) magma, and resulted in rocks with very high incompatible element concentrations. Abundant anorthositic xenoliths in the mafic and intermediate intrusions point to a large anorthosite protolith at depth which is considered of critical importance in the petrogenesis of the salic rocks. Small intrusions of aillikite and carbonatite may represent remobilised mantle metasomites. The petrological similarity between Older and Younger Gardar suites implies strong lithospheric control of their petrogenesis. The parental magmas are inferred to have been derived from restitic Ketilidian lithospheric mantle, metasomatised by melts from subducting Ketilidian oceanic crust and by small-scale melt fractions associated with Gardar rifting. There are numerous analogies between the southern Gardar rift and the Palaeogene East African rift.

Geochemistry of Sainte-Marguerite volcanic rocks: implications for the evolution of Silurian–Devonian volcanism in the Gaspé Peninsula

2008 ◽  
Vol 45 (1) ◽  
pp. 15-29 ◽  
Author(s):  
Alan D’hulst ◽  
Georges Beaudoin ◽  
Michel Malo ◽  
Marc Constantin ◽  
Pierre Pilote
Keyword(s):  
Lower Devonian ◽  
Volcanic Rocks ◽  
Magma Source ◽  
Volcanic Arc ◽  
Lower Silurian ◽  
Trace Element Signature ◽  
Arc Setting ◽  
Back Arc ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

The Lower Devonian Sainte-Marguerite volcanic rocks are part of a Silurian–Devonian volcanic sequence deposited between the Taconian and Acadian orogenies in the Gaspé Peninsula, Quebec, Canada. The Sainte-Marguerite unit includes basaltic and dacitic lava flows with calc-alkaline and volcanic-arc affinities. Such affinities are also recorded by the trace-element signature in Lower Silurian and most Lower Devonian volcanic units of the Gaspé Peninsula. However, most of the other Silurian–Devonian volcanic rocks occurring in the Gaspé Peninsula have been previously interpreted to have erupted in an intracontinental setting. A back-arc setting for the Gaspé Peninsula between the Taconian and Acadian orogenies could account for these subduction volcanic-arc signatures, though a metasomatized lithospheric mantle magma source, unrelated to subduction, cannot be excluded. Lower Silurian and Lower Devonian volcanic rocks in the central part of the Gaspé Peninsula show an arc affinity, whereas Upper Silurian and Lower to Middle Devonian volcanic rocks, located in the south and north of the Gaspé Peninsula, respectively, show a within-plate affinity. The Lower Devonian Archibald Settlement and Boutet volcanic rocks of the southern and northern Gaspé Peninsula, respectively, show a trend toward a within-plate affinity. This suggests that within-plate volcanism migrated from south to north through time in an evolving back-arc environment and that the subduction signature of Lower Silurian and Lower Devonian rocks results from a source that melted only under the central part of the Gaspé Peninsula.

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