Basic lavas of the Archean La Grande Greenstone belt: Products of polybaric fractionation and crustal contamination

1988 ◽  
Vol 100 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Thomas Skulski ◽  
Andrew Hynes ◽  
Don Francis
Keyword(s):  
Greenstone Belt ◽  
Crustal Contamination ◽  
Polybaric Fractionation

Stratigraphy, structure, and geochronology of the 3.0–2.7 Ga Wallace Lake greenstone belt, western Superior Province, southeast Manitoba, Canada

2006 ◽  
Vol 43 (7) ◽  
pp. 929-945 ◽  
Author(s):  
C Sasseville ◽  
K Y Tomlinson ◽  
A Hynes ◽  
V McNicoll
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Shear Zones ◽  
Iron Formation ◽  
Superior Province ◽  
Lake Winnipeg ◽  
The North ◽  
Southern Margin ◽  
Plume Magmatism

In western Superior province, the North Caribou terrane (NCT) constitutes a Mesoarchean proto-continent heavily overprinted by Neoarchean magmatism and deformation resulting from the western Superior Province accretion. Locally, along the southern margin of the NCT, Mesoarchean (~3.0 Ga) rift sequences are preserved. These sequences are of key importance to our understanding of the early tectonic evolution of continental crust. The Wallace Lake greenstone belt is located at the southern margin of the NCT and includes the Wallace Lake assemblage, the Big Island assemblage, the Siderock Lake assemblage, and the French Man Bay assemblage. The Wallace Lake assemblage exposes one of the best-preserved Mesoarchean rift sequences along the southern margin of the NCT. The volcano-sedimentary assemblage (3.0–2.92 Ga) exposes arkoses derived from the uplift of a tonalite basement in a subaqueous environment, capped by carbonate and iron formation. Mafic to ultramafic volcanic rocks exhibiting crustal contamination and derived from plume magmatism cap this rift sequence. The Wallace Lake assemblage exhibits D1 Mesoarchean deformation. The Big Island assemblage comprises mafic volcanic rocks of oceanic affinity that were docked to the Wallace Lake assemblage along northwest-trending D2 shear zones. The timing of volcanism and docking of the Big Island assemblage remain uncertain. The Siderock Lake and French Man Bay assemblages were deposited in strike-slip basins related to D3 and D4 stages of movement of the transcurrent Wanipigow fault (<2.709 Ga). Regionally, the Wallace Lake assemblage correlates with the Lewis–Story Rift assemblage observed in Lake Winnipeg, whereas the Big Island assemblage appears to correlate with the Black Island assemblage observed in the Lake Winnipeg area. Thus, the North Caribou terrane appears to preserve vestiges of a Mesoarchean rifted succession together with overlying Neoarchean allochthonous, juvenile, volcanic successions over a considerable distance along its present-day southern margin.

Geochemistry and isotope studies of the metavolcanic rocks of Shimoga greenstone belt, Western Dharwar craton - an effort to deduce the Petrogenesis.

2020 ◽  
Author(s):  
Anshuman Giri ◽  
Rajagopal Anand
Keyword(s):  
Fractional Crystallization ◽  
Greenstone Belt ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Dharwar Craton ◽  
Metavolcanic Rocks ◽  
Depleted Mantle ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

&lt;p&gt;The archaean greenstone belts, dominated by mafic to felsic volcanic rocks followed by younger granitic intrusions occurs associated with volcano-sedimentary sequences. The Dharwar Super group (2600 to 2900 Ma) of rocks in western Dharwar craton, underlie the older TTG gneisses. The Shimoga greenstone belt (SGB) of WDC constitute the basal polymictic conglomerate along with quartzite, pyroclastic rocks, carbonaceous rocks, greywacke-argillite sequences with a thick pile of mafic and felsic metavolcanic rocks (BADR). These rocks are suffered from greenschist to lower amphibolite grade of metamorphism. The Medur metavolcanic volcanic rocks give an age of 2638 &amp;#177; 66 Ma (1), whereas the Daginakatte felsic volcanic rocks give an age of 2601 &amp;#177; 6 Ma (2). The present studied age of 2638 &amp;#177; 66 Ma, tells about the cessation of mafic magmatism in WDC. The metavolcanic rocks of the Medur formation are tholeiitic to calc-alkaline in nature. These rocks show flat to LREE enriched REE pattern with negative europium anomaly. And also show enrichment in LILE and depletion in HFSE elements with significant Nb-Ta anomaly. The geochemical and the isotope data suggest the involvement of partial melting of the depleted mantle by the slab components and assimilation fractional crystallization (AFC) processes for the magma generation. The SGB metavolcanic rocks have 143Nd/144Nd ratios (0.511150 to .513076) and &amp;#949;Nd values of -3.1 to -5.5 and the negative &amp;#949;Nd values &amp;#160;for the rocks is due to the crustal contamination of the magma in a shallow marine subduction setting. The parental magmas were derived from melting in the mantle wedge fluxed by slab derived fluids and slab components followed by assimilation fractional crystallization (AFC) processes involving continental crust in an active continental margin.&lt;/p&gt;&lt;ul&gt;&lt;li&gt;(1) Giri et al., 2019. Lithos, &lt;strong&gt;330-331&lt;/strong&gt;, 177-193&lt;/li&gt; &lt;li&gt;(2) Trendall et al., 1997a. J. Geol. Soc. India, &lt;strong&gt;50&lt;/strong&gt;, 25-50.&lt;/li&gt; &lt;/ul&gt;

Nd and Pb isotopes from the Lake of the Woods greenstone belt, northwestern Ontario: implications for mantle evolution and the formation of crust in the southern Superior Province

2000 ◽  
Vol 37 (12) ◽  
pp. 1677-1689 ◽  
Author(s):  
John A Ayer ◽  
Jaroslav Dostal
Keyword(s):  
Greenstone Belt ◽  
Crustal Contamination ◽  
Pb Isotopes ◽  
Superior Province ◽  
Elevated Concentration ◽  
Lake Of The Woods ◽  
Metavolcanic Rocks ◽  
Depleted Mantle ◽  
Winnipeg River ◽  
Mantle Reservoir

Nd and Pb isotopes from the Lake of the Woods greenstone belt indicate the presence of three distinct reservoir sources: old enriched crust (>3.0 Ga); pre-2.7 Ga, homogeneous depleted mantle; and post-2.70 Ga heterogeneous mantle. EpsilonNd values of +1.1 to +2.3 for ultramafic to felsic metavolcanic rocks (2.74–2.72 Ga) indicate derivation from depleted mantle. The εNd value of –0.9 for younger turbidite (2.71 Ga), in conjunction with detrital zircon ages ranging from 2.72 to 3.0 Ga, indicates detritus from local greenstone belt sources (depleted mantle) mixed with an older crustal source. Post-2.70 Ga heterogeneity is demonstrated by εNd values ranging from –0.4 to +0.4 in shoshonitic to calc-alkaline metavolcanic rocks and +2.1 in a coeval ultrapotassic pluton. Pb isotopes from the pluton indicate derivation from a depleted mantle reservoir with an initial 207Pb/204Pb of 14.52, an initial 206Pb/204Pb of 13.29, and µ1 of 7.86. Isotopic comparison with post-2.70 Ga potassic suites from across the Superior Province indicates widespread mixing between depleted mantle and enriched end members. The enriched end member has isotopic characteristics of rocks derived from old crustal terrains, such as the Winnipeg River and Opatica subprovinces. This type of isotopic heterogeneity could be the result of crustal contamination or derivation from metasomatized mantle. Contamination of the mantle wedge by influx of fluids derived from partial melting of isotopically evolved, subducted sediments is favoured for the Superior Province potassic suite, because elevated concentration of Sr, Nd, and Pb in conjunction with primitive Mg#s suggest only limited crustal contamination has occurred.

Estructura, metamorfismo y petrología del basamento ígneo-metamórfico de la Sierra de San Luis entre Nogolí y Gasparillo

2003 ◽  
Author(s):  
◽  
Pablo Diego González
Keyword(s):  
Greenstone Belt ◽  
San Luis

El análisis de la evolución estructural, metamórfica y magmática del basamento del sector occidental de la Sierra de San Luis entre Nogolí y Gasparillo permitió identificar al ciclo orogénico Famatiniano dividido en dos etapas: 1) una fase orogénica principal, de edad fundamentalmente ordovícica, y 2) una etapa tardía a pos-orogénica, desarrollada entre el Silúrico y el Carbonífero Temprano. Los procesos anteriores a ellos fueron agrupados como pre-Famatinianos. El evento más antiguo reconocido en el Complejo Metamórfico Nogolí es una sedimentación silicoclástica pelítica y psamítica vinculada a flujos de komatiitas, basaltos komatiíticos y basaltos toleíticos de alto Fe, y a intercalaciones de estratos de Fe bandeado (BIF). La asociación litológica komatiita-BIF dentro de una misma secuencia (típica de un greenstone belt) y una edad Sm-Nd roca total de 1500 Ma para la posible cristalización de los flujos máficos-ultramáficos sugieren una edad mesoproterozoica para el protolito del Complejo Metamórfico Nogolí. La posterior estructuración E-O a NO-SE asociada a metamorfismo relíctico de T alta y P media es asignada a la actividad orogénica del ciclo Pampeano. Se describe un conjunto de tres eventos deformativos, con plegamientos, foliaciones e inyecciones graníticas asociadas. Por otro lado se registra la sedimentación de la Formación San Luis y la Unidad La Alumbrera que habría sido anterior o coetánea con el metamorfismo y la deformación pre-Famatinianos del Complejo Metamórfico Nogolí.

Evidence for Mesoarchean subduction in southern Bundelkhand Craton, India: Geochemical fingerprints from metavolcanics of Kurrat - Girar - Badwar Greenstone Belt

Geochemistry ◽  
2021 ◽  
pp. 125787
Author(s):  
Sikha Hiloidari ◽  
Manavalan Satyanarayanan ◽  
Surya Pratap Singh ◽  
Rajneesh Bhutani ◽  
K.S.V. Subramanyam ◽  
...  
Keyword(s):  
Greenstone Belt
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