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Journal articles on the topic 'Greenstone belt'

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Published: 4 June 2021
Last updated: 31 January 2023

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1

St. Seymour, Karen, Andrew Turek, Ronald Doig, Stephen Kumarapeli, and Robert Fogal. "First U–Pb zircon ages of granitoid plutons from the La Grande greenstone belt, James Bay area, New Quebec." Canadian Journal of Earth Sciences 26, no. 5 (May 1, 1989): 1068–73. http://dx.doi.org/10.1139/e89-088.

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Zircon ages from three granitoid plutons are the first to be reported from the La Grande greenstone belt. Two of the dated samples are from highly tectonized, early tectonic plutons that at the present level of erosion are just outside the greenstone belt proper. Their zircon ages of ca. 2740 Ma are emplacement ages or alternatively represent the age of maximum deformation of the greenstone belt. The third sample is from a mildly deformed late tectonic pluton within the greenstone belt. Its zircon age of ca. 2670 Ma probably represents the emplacement age. The above dates and the relationships of the dated plutons to the greenstone belt as a whole suggest that the bulk of the volcanism in the La Grande belt is older than 2.7 Ga. This limiting age indicates that the age of the La Grande "supracrustals" is similar to those of the other greenstone belts in the Superior Province.
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2

Kozlov, N. E., N. O. Sorokhtin, N. E. Kozlova, and Eu V. Martynov. "Geological structure of the Ustoyarvi region (North-Western part of the Russian Arctic)." Vestnik MGTU 25, no. 1 (March 31, 2022): 12–26. http://dx.doi.org/10.21443/1560-9278-2022-25-1-12-26.

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The paper presents data on geology and composition of rocks from the Ustoyarvi region (the North-Western Arctic zone of Russian Federation). Their compositional analysis (including mathematical evaluation of the similarity/difference measure) provided much reliable conclusion that the rocks from this area, which are presumably attributed to the Ustoyarvi structure (Ustoyarvinsky Greenstone Belt) were similar to those from the Ura-Guba area in the Kolmozero-Voronya Belt and continued it. In addition, it has been shown that from west to east lithotectonic units in the adjacent (Suormussky) Block become gradually impregnated with tectonic wedges of rocks of the Ustoyarvi Greenstone Belt. It indicates increasing collisional interaction between rock associations with a varied genesis. P-T formation parameters have been specified for komatiites from greenstone belts, i. e. the Kolmozero-Voronya, Ura-Guba, Ustoyarvi and Western Litsa area. It has been defined that komatiites of the Ustoyarvi Greenstone Belt were formed under pressure of about 5 hPa, komatiites of the Ura-Guba area - about 4.5 hPa, komatiites of the Kolmozero-Voronya - about 2 hPa. Thus, komatiites of the Ustoyarvi Greenstone Belt are more high-pressure formations.
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3

Benn, Keith, Edward W. Sawyer, and Jean-Luc Bouchez. "Orogen parallel and transverse shearing in the Opatica belt, Quebec: implications for the structure of the Abitibi Subprovince." Canadian Journal of Earth Sciences 29, no. 11 (November 1, 1992): 2429–44. http://dx.doi.org/10.1139/e92-191.

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The late Archean Opatica granitoid-gneiss belt is situated within the northern Abitibi Subprovince, along the northern margin of the Abitibi greenstone belt. Approximately 200 km of structural section was mapped along three traverses within the previously unstudied Opatica belt. The earliest preserved structures are penetrative foliations and stretching and mineral lineations recording regional ductile shearing (D1). Late-D1 deformation was concentrated into kilometre-scale ductile fault zones, typically with L > S tectonite fabrics. Two families of lineations are associated with D1, indicating shearing both parallel and transverse to the east-northeast trend of the belt. Lineations trending east-northeast or northwest–southeast tend to be dominant within domains separated by major fault zones. In light of the abundant evidence for early north–south compression documented throughout southern Superior Province, including the Abitibi greenstone belt, D1 is interpreted in terms of mid-crustal thrusting, probably resulting in considerable crustal thickening. Movement-sense indicators suggest that thrusting was dominantly southward vergent. D2 deformation resulted in the development of vertical, regional-scale dextral and sinistral transcurrent fault zones and open to tight upright horizontal folds of D1 fabrics. In the context of late Archean orogenesis in southern Superior Province, the tectonic histories of the Abitibi and Opatica belts should not be considered separately. The Opatica belt may correlate with the present-day mid-crustal levels of the Abitibi greenstone belt, and to crystalline complexes within the Abitibi belt. It is suggested that the Abitibi Subprovince should be viewed, at the regional scale, as a dominantly southward-vergent orogenic belt. This work demonstrates that structural study of granitoid-gneiss belts adjacent to greenstone belts can shed considerable light on the regional structure and structural evolution of late Archean terranes.
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4

Lodge, Robert W. D., Harold L. Gibson, Greg M. Stott, James M. Franklin, and George J. Hudak. "Geodynamic setting, crustal architecture, and VMS metallogeny of ca. 2720 Ma greenstone belt assemblages of the northern Wawa subprovince, Superior Province." Canadian Journal of Earth Sciences 52, no. 3 (March 2015): 196–214. http://dx.doi.org/10.1139/cjes-2014-0163.

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The greenstone belts along the northern margin of the Wawa subprovince of the Superior Province (Vermilion, Shebandowan, Winston Lake, Manitouwadge) formed at ca. 2720 Ma and have been interpreted to be representative of a rifted-arc to back-arc tectonic setting. Despite a common inferred tectonic setting and broad similarities, these greenstone belts have a significantly different metallogeny as evidenced by different endowments in volcanogenic massive sulphide (VMS), magmatic sulphide, and orogenic gold deposits. In this paper, we examine differences in geodynamic setting and crustal architecture as they pertain to the metallogeny of each greenstone belt by characterizing the regional-scale trace-element and isotopic (Nd and Pb) geochemistry of each belt. The trace-element geochemistry of the Vermilion greenstone belt (VGB) shows evidence for a transition from arc-like to back-arc mafic rocks in the Soudan belt to plume-driven rifted arcs in the ultramafic-bearing Newton belt. The Shebandowan greenstone belt (SGB) has a significant proportion of calc-alkalic, arc-like basalts, intermediate lithofacies, and high-Mg andesites, which are characteristic of low-angle, “hot” subduction. Extensional settings within the SGB are plume-driven and associated with komatiitic ultramafic and mid-ocean ridge basalt (MORB)-like basalts. The Winston Lake greenstone belt (WGB) is characterized by a transition from calc-alkalic, arc-like basalts to back-arc basalts upward in the strata and is capped by alkalic ocean-island basalt (OIB)-like basalts. This association is consistent with plume-driven rifting of a mature arc setting. Each of the VGB, SGB, and WGB show some isotopic evidence for the interaction with a juvenile or slightly older differentiated crust. The Manitouwadge greenstone belt (MGB) is characterized by isotopically juvenile, bimodal, tholeiitic to transitional volcanic lithofacies in a back-arc setting. The MGB is the most isotopically juvenile belt and is also the most productive in terms of VMS mineralization. The Zn-rich VMS mineralization within the WGB suggests a relatively lower-temperature hydrothermal system, possibly within a relatively shallow-water environment. The Zn-dominated and locally Au-enriched VMS mineralization, as well as mafic lithofacies and alteration assemblages, are characteristic of relatively shallower-water deposition in the VGB and SGB, and indicate that the ideal VMS-forming tectonic condition may have been compromised by a shallower-water depositional setting. However, the thickened arc crust and compressional tectonics of the SGB suprasubduction zone during hot subduction may have provided a crustal setting more favourable for the magmatic Ni–Cu sulphide and relative gold endowment of this belt.
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5

Anhaeusser, C. R. "The geology and tectonic evolution of the northwest part of the Barberton Greenstone Belt, South Africa: A review." South African Journal of Geology 122, no. 4 (December 1, 2019): 421–54. http://dx.doi.org/10.25131/sajg.122.0033.

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AbstractFormations on the northwestern flank of the Barberton Greenstone Belt have hosted over 85% of all the gold recovered from the ca. 3550 to 3000 Ma Barberton Supergroup since early discoveries in 1872. This sector of the greenstone belt also happens to coincide with a complex tectonic architecture resulting from successive stages of folding and faulting superimposed onto a complex lithostratigraphy. Of particular importance has been the influence of two diapiric granitoid intrusions that caused added structural complexity following their emplacement ca. 3227 to 3250 Ma. Of these the larger Kaap Valley Pluton invaded the area north of present day Barberton town causing the separation of the greenstones into a northern arm (Jamestown Schist Belt) and a southern sector which remained attached to the main greenstone belt (Moodies Hills). The ballooning pluton produced vertical as well as horizontal flattening stresses, the latter reactivating earlier high-angle faults and resulting in subhorizontal strike-slip movements, particularly along the Barbrook Fault Zone, which acted as a right-lateral strike-slip fault. Formations north of this fault were buckled, following progressive deformation in the region known as the Sheba Hills, into major synclinal folds (Eureka and Ulundi Synclines) with folded axial planes that dip steeply to the south, southeast or east. The second granitoid intrusion (Stentor Pluton), which has been extensively modified by subsequent magmatic events, caused significant flattening of greenstone belt rocks in the northeastern part of the Barberton Greenstone Belt (Three Sisters region) as well as in other areas rimming the granitic body. Combined, the two plutons produced a wide range of interference and reactivated structures particularly affecting a triangular region extending from the Jamestown Schist Belt into the area occupied by the New Consort Gold Mine and areas to the east. This paper attempts to outline, in the simplest manner, the geological and structural evolution of the main gold-producing region of the Barberton Goldfield. The principal aim is therefore to highlight the structural influence of the diapiric plutonism and the manner in which the plutons contributed significantly to the horizontal reactivation of pre-existing regional faults, which in turn, resulted in the progressive deformation of a heterogeneous lithological terrane.
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6

Pouclet, André, Siaka Doumbia, and Max Vidal. "Geodynamic setting of the Birimian volcanism in central Ivory Coast (western Africa) and its place in the Palaeoproterozoic evolution of the Man Shield." Bulletin de la Société Géologique de France 177, no. 2 (March 1, 2006): 105–21. http://dx.doi.org/10.2113/gssgfbull.177.2.105.

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Abstract Palaeoproterozoic volcanic formations having different geochemical features are described in the Katiola-Marabadiassa area (Central Ivory Coast). They consist of (i) metamorphic mafic rocks belonging to the greenstone belts, (ii) rhyodacites intruded into the greenstone belts and interpreted as sub-volcanic apophyses of TTG plutons, and (iii) calc-alkaline andesitic lava interbedded in the lower sedimentary pile of the Bandama Basin. The greenstone belt rocks have a magmatic signature of ocean floor tholeiites. They were generated from moderate partial melting of a fairly depleted spinel lherzolite source. The rhyodacites show the same compositions as the TTG granitoids of the belt. These TTGs generated from melting of garnet-bearing amphibolite, derived from subducted oceanic crust, but also from peridotite melting of the fertilized mantle wedge. The andesites show a common composition of active continental margin potassic calc-alkaline lavas. However, they do not constitute a volcanic belt, but belong to an intracontinental basin settled in a wrench tectonic system. They probably generated from remelting of sub-crustal metasomatised mantle. The tectono-magmatism story of the Katiola-Marabadiassa area comprises four stages. A similar evolution is found in other belt-and-basin areas in Ivory Coast. A review of lithostratigraphic and chronological data of the Birimian terrains leads us to compare the four-stage model of the Central Ivory Coast to the West-African Palaeoproterozoic evolution. The first stage corresponds to ocean crust formation, by mid-ocean ridge accretion and volcanic arc building. The second stage, partly overlapping the previous one, is convergent and lasted from oceanic crust stacking to TTG and associated greenstone belt formation. It led to a protocontinental crust accretion by docking of granitized blocks, from ca 2200 Ma to 2110 Ma. The third stage corresponds to the formation of intracontinental basins by reorganization of the granitoid-greenstone shields and of the remnant oceanic basins, between 2118 Ma and 2093 Ma. It was associated with calc-alkaline magma production. The fourth stage is characterized by transtensional stress, with the closure of the basins by left-lateral wrenching along N-S faults, and by emplacement of new potassic granitoids until 2072 Ma.
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7

Dostal, J., C. Dupuy, and J. L. Poidevin. "Geochemistry of Precambrian basaltic rocks from the Central African Republic (Equatorial Africa)." Canadian Journal of Earth Sciences 22, no. 5 (May 1, 1985): 653–62. http://dx.doi.org/10.1139/e85-072.

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The two Archaean greenstone belts (Bandas and Bogoin) in the Central African Republic (Equatorial Africa) are 250 and 150 km long. The metavolcanic rocks in the belts are predominantly komatiitic and tholeiitic basalts. Komatiites include both Al-depleted and Al-undepleted types. The komatiites and light-REE-depleted tholeiites were probably derived from a similar upper mantle source. However, the tholeiitic basalts enriched in light REE from the upper volcanic strata of the Bandas belt were generated from a different source. The dolerites from Proterozoic dyke swarms and sills differ from the basalts mainly in their abundances and ratios of several incompatible elements such as K, Rb, Th, and light REE. They were derived from a distinct, incompatible-element-enriched upper mantle source.The average background gold levels in the Bandas belt and dolerite dyke swarms are comparable to those in equivalent rocks from North America. The exception is the Bogoin greenstone belt, which has anomalously high gold abundances.
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8

Phillips, G. Neil, David I. Groves, and Isobel J. Brown. "Source requirements for the Golden Mile, Kalgoorlie: significance to the metamorphic replacement model for Archean gold deposits." Canadian Journal of Earth Sciences 24, no. 8 (August 1, 1987): 1643–51. http://dx.doi.org/10.1139/e87-158.

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The Golden Mile at Kalgoorlie represents a giant Archean hydrothermal gold system localized by ductile shear zones and hosted mainly by a differentiated tholeiitic sill. Chlorite, carbonate, and pyrite alteration zones cover the whole mineralized area (1 km × 3 km), and calculations suggest that for the Golden Mile (production around 1200 t Au), the amounts of components added to these alteration zones are 340 Mt CO2, 20 Mt K, and 5 Mt S. If one adopts a metamorphic-replacement model for gold mineralization in which all ore components derive from devolatilization of greenstones at amphibolite facies or above, these data suggest that a source area involving a 5 km thick greenstone slab of area 8 km × 8 km could produce the necessary CO2, K, S, H2O, and Au. This is considered a reasonable volume of greenstone belt, and under such a model the minimum spacing of large gold deposits would be approximately 20 km along strike.Neither special Au-enriched source rocks nor unreasonably large volumes of greenstone belt are required to produce a giant gold deposit. Instead, the most critical parameters are suitable structural environments providing focussing of fluids and multiple channelways through specific Fe-rich, low-tensile-strength host rocks to ensure efficient depositional mechanisms.
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9

EVINS, P. M., and K. LAAJOKI. "Early Proterozoic nappe formation: an example from Sodankylä, Finland, Northern Baltic Shield." Geological Magazine 139, no. 1 (January 2002): 73–87. http://dx.doi.org/10.1017/s0016756801006094.

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The Central Lapland Greenstone belt comprises rift-related metavolcanic and metasedimentary rocks representing one of the largest supracrustal belts in the Baltic Shield. The Sodankylä area in the central part of the belt represents a complex thrust duplex within a nappe overlying Belomorian Archaean basement and autocthonous Luirojoki calc-silicate rocks. Here, an early D1 schistosity is axial planar to at least three coaxial generations of southward-verging, subhorizontal, E–W-plunging D1 folds associated with major southwards thrusting. D2 is represented by broad, map-scale, upright, NE-trending folds in the south and crenulations in the north. Staurolite-grade metamorphism represented by post-tectonic andalusite + staurolite + kyanite assemblages occurred after D2 folding. Later D3 deformation was limited to local NW-trending folds and sinistral faults. The internal nappe-like structure of the Central Lapland Greenstone belt suggests that it represents the foreland of a large collisional complex cored by the Lapland Granulite belt.
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10

Inza, Coulibaly, Kouamelan Alain Nicaise, Djro Sagbrou Chérubin, and Coulibaly Yacouba. "Petrographie Des Volcanites Et Plutonites De La Partie Sud Du Sillon Volcano-Sedimentaire De Toumodi-Fetekro (Cote D’ivoire)." European Scientific Journal, ESJ 13, no. 30 (October 31, 2017): 199. http://dx.doi.org/10.19044/esj.2017.v13n30p199.

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The southern part of Toumodi-Fètêkro greenstone belt is located in the Center - Southeast of Ivory Coast. Petrographic study of volcanic and plutonic rocks shows three units. The first unit is composed of basaltic to rhyolitic lavas which imply effusive character. Then we have volcanosedimentary unit composed of pyroclastic formations (lapilli tuff, breccia, ash deposit and ignimbrites) and the pillow-lavas. Indeed, the presence of this last shows clearly that an explosive volcanism and a submarine effusive volcanism have occurred during during the setting of Toumodi-Fètêkro belt. Plutonic unit is constituted of gabbroic to granitic rocks. Sericite, chlorite, epidote observed in these rocks are consistent with the impacts of greenschist facies metamorphism. The rocks of the southern part of the Toumodi-Fètêkro greenstone belt are formed in a subduction context rather than in oceanic plateaus context because of the old inheritance, sometimes of Archean age, found somewhere in theBirimiandomain. The lithologies of the southern part of Toumodi-Fètêkro meet elsewhere in the other Birimian greenstone belts. Also, these lithologies are affected by a hydrothermal alteration due to the abundant veins of quartz, carbonates, sericite, chlorite, epidote, sulphides and oxides. However, volcanic show in some places amphibolit facies metamorphism.
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11

Kioe-A-Sen, Nicole M. E., Manfred J. van Bergen, Theo E. Wong, and Salomon B. Kroonenberg. "Gold deposits of Suriname: geological context, production and economic significance." Netherlands Journal of Geosciences - Geologie en Mijnbouw 95, no. 4 (November 3, 2016): 429–45. http://dx.doi.org/10.1017/njg.2016.40.

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AbstractGold has been a major economic asset for Suriname for more than a century. The long history of gold mining, concentrated in large parts of a greenstone belt in the northeast of the country, began with small-scale artisanal extraction activities and has recently seen the development of major open-pit operations. Despite the range of mining activities, Suriname's gold deposits and occurrences are under-explored from a scientific point of view. Primary gold mineralisations in the greenstone belt occur in multiple forms, and although their origin is commonly related to the Palaeoproterozoic Trans-Amazonian orogeny, the controls of ore formation in specific cases often remain obscure. This contribution presents an abridged overview of currently available information on the geological setting and characteristics for some of the main deposits where gold is extracted. In view of the consistent link between gold metallogeny and granitoid–greenstone belts in the northern Guiana Shield, the mineralised settings in Suriname are discussed in a regional context.
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12

Corfu, Fernando, and Shoufa Lin. "Geology and U-Pb geochronology of the Island Lake greenstone belt, northwestern Superior Province, Manitoba." Canadian Journal of Earth Sciences 37, no. 9 (September 1, 2000): 1275–86. http://dx.doi.org/10.1139/e00-043.

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Mapping and U-Pb geochronology have been used to examine the tectonic and depositional history of the Archean Island Lake greenstone belt in the northwestern Superior Province. The Island Lake greenstone belt comprises two main supracrustal successions, the older Hayes River Group and the younger Island Lake Group. Zircon data for two volcanic units from the Hayes River Group provide identical ages of 2852 ± 1.5 Ma, whereas a turbidite of this group contains a detrital zircon population with ages between 2858 and 2847 Ma. Younger intrusive events include the emplacement of tonalite in the southern batholith at 2825 ± 2 Ma and the Whiteway Island gabbro at 2807 ± 1 Ma. A wacke at the base of the Island Lake Group is dominated by detrital zircon grains yielding ages between 2830 and 2821 Ma, the latter defining a maximum age of sedimentation. A relatively early time of deposition of the lower stratigraphic sections of the Island Lake Group is also supported by an age of 2744 ± 2 Ma obtained for a crosscutting tonalite. By contrast, two turbidite horizons from higher stratigraphic levels of the Island Lake Group contain detrital zircon populations with ages mostly younger than 2730 Ma, the youngest zircon grains providing maximum ages of sedimentation at 2722 and 2712 Ma, respectively. Our results confirm the protracted evolution of the greenstone belt and show in particular that major sedimentary processes were active throughout the main stages of volcanism of the belt. This pattern of protracted sedimentation is comparable to that observed in other greenstone belts of the northwestern Superior Province, all of which developed on pre-Kenoran crust.
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13

Hofmann, A., C. R. Anhaeusser, and X.-H. Li. "Layered ultramafic complexes of the Barberton Greenstone Belt – age constraints and tectonic implications." South African Journal of Geology 124, no. 1 (March 1, 2021): 7–16. http://dx.doi.org/10.25131/sajg.124.0002.

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Abstract Layered ultramafic–mafic complexes are a common component of the stratigraphically uppermost part of the Onverwacht Group of the Barberton Greenstone Belt. Associated with the Mendon Formation in the south and the Weltevreden Formation in the north, they represent an assemblage of thick differentiated flows and shallow synvolcanic intrusions ranging in composition from dunite to gabbro. U-Pb zircon dating of gabbro from the Sawmill and the Mundt’s Concession ultramafic complexes from the northern part of the Barberton Greenstone Belt yielded ages of 3 258 ± 8 Ma and 3 244 ± 11 Ma, respectively. The ultramafic complexes are thus regarded to have been emplaced during a magmatic flare-up in the final stage of Weltevreden Formation volcanism, post-dating ultramafic magmatism in the southern part of the belt by several millions of years and thus suggesting diachronous evolution of the Onverwacht Group in the Barberton Greenstone Belt.
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14

Abraham, A. P. G., D. W. Davis, S. L. Kamo, and E. T. C. Spooner. "Geochronological constraints on late Archean magmatism deformation and gold–quartz vein mineralization in the northwestern Anialik River greenstone belt and igneous complex, Slave Province, N.W.T." Canadian Journal of Earth Sciences 31, no. 8 (August 1, 1994): 1365–83. http://dx.doi.org/10.1139/e94-119.

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Three phases of the Anialik River igneous complex (ARIC) give U–Pb zircon ages in the range −2705–2683 Ma, and three units from the adjacent northwestern Anialik River greenstone belt (ARGB) give ca. 2678 Ma ages. Titanite from unsheared ARIC rocks crystallized during localized metamorphism and deuteric alteration between 2693 and 2683 Ma. Hydrothermal titanite in wall rocks to gold-mineralized shear zones crystallized during early shear zone development (2670 ± 1 Ma) and was subsequently locally altered to rutile, with gold occurring within the rutile-bearing assemblage. Unaltered second-generation hydrothermal titanite, overgrowing the rutile assemblage, crystallized during later brittle–ductile movement (2656 ± 2 Ma) and provides a minimum age for gold mineralization. Relatively high 207Pb/204Pb ratios of Pb in gold-associated galena suggest that it was partly derived from significantly older crustal material, possibly underlying the igneous complex and greenstone belt. This interpretation is consistent with other evidence for the existence of > 3.0 Ga crustal rocks to the west of the study area. A late crosscutting granite gives an age of [Formula: see text] and is therefore part of the Pan-Slave tectono-thermal event. These results, and other data for the Slave Province, indicate temporal variations in the development and deformation of predeformational greenstone belts. The new ages show that regional deformation and metamorphism in the northwestern Slave Province followed shortly after major magmatism, and that gold mineralization might have occurred during the late Archean accretion of the greenstone belt and igneous complex to an older crustal domain to the west.
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15

Vrevskii, A. B. "Non-subduction petrological mechanisms for the growth of the neoarcheam continental crust of the Kola–Norwegian terrane, Fennoscandian shield: geological and isotope-geochemical evidence." Петрология 27, no. 2 (April 2, 2019): 161–86. http://dx.doi.org/10.31857/s0869-59032161-186.

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The paper reports new data on the composition and age of the Neoarchean calc-alkaline volcanic rocks of the Uraguba–Kolmozero–Voron’ya greenstone belt (UKV GB). Petrological-geochemical modeling indicates a polygenetic origin of primary melts of the basalt–andesite–dacite association and non-subduction geodynamic mechanisms for the crustal growth in the largest greenstone belt of the Kola–Norwegian Block of the Fennoscandian shield.
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16

Diener, J. F. A., and A. Dziggel. "Can mineral equilibrium modelling provide additional details on metamorphism of the Barberton garnet amphibolites?" South African Journal of Geology 124, no. 1 (March 1, 2021): 211–24. http://dx.doi.org/10.25131/sajg.124.0003.

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Abstract The Stolzburg domain to the south of the Barberton Greenstone Belt preserves evidence for a 3.23 Ga subduction–collision tectonic event. Garnet amphibolite greenstone remnants have previously yielded conventional thermobarometric P-T estimates of 12 to 15 kbar at 600 to 650°C, 8 to 11 kbar at 650 to 700°C and 7.5 to 8.5 kbar at 560 to 640°C from, respectively, the Inyoni shear zone along the western margin of the Stolzburg domain, the central part of the domain and from the Tjakastad schist belt on the boundary with the main body of the Barberton Greenstone Belt. Pseudosection calculations constrain the stability conditions of the peak metamorphic assemblages at the three localities to be 10 kbar at 675 to 690°C, ~10 kbar at 700°C and ~7 and 10 kbar at 660°C respectively. Although it is possible that the peak metamorphic assemblages may be displaced to somewhat lower conditions if Mn is considered in the calculations, these estimates are generally in good agreement with existing estimates, and confirm that the Stolzburg domain exposes an intact mid- to lower-crustal section that was metamorphosed in a relatively cool environment at 3.23 Ga. Our results do not support previously documented higher-pressure conditions, and we contend that the mineral assemblages used to derive these estimates can equally reflect the conditions determined here. The presence of albite-epidote inclusion assemblages in garnet indicates that the likely prograde path involved a component of heating at depth, which is typical of subduction–collision environments and markedly different from the heating–burial paths expected for sinking greenstones in a vertical tectonic model.
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17

Schwerdtner, W. M. "Preliminary estimates of the amount of continuous horizontal shortening across an Archean greenstone belt." Canadian Journal of Earth Sciences 22, no. 4 (April 1, 1985): 506–13. http://dx.doi.org/10.1139/e85-052.

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Simple two-dimensional techniques are used to make an estimate of the total shortening across a narrow greenstone belt in northwestern Ontario. The techniques are based on the basic principle of restoring the predeformational geometry of a horizontal traverse across the belt. Depending on the technique used this traverse is a string of line elements or a chain of finite elements. The strain ratios available for the restoration are minimal values and need to be increased significantly to obtain realistic results. Depending on the strain values selected for the restoration, amounts of horizontal shortening range from 17 to 49%. The actual amount remains unknown, but is thought to be < 50%.In view of the apparent variation in longitudinal strain along the greenstone belt, a three-dimensional treatment seems to be necessary. This would require that strain measurements be taken systematically throughout, rather than along a single traverse across, a greenstone belt segment.
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18

Turek, A., R. Keller, and W. R. Van Schmus. "U–Pb zircon ages of volcanism and plutonism in the Mishibishu greenstone belt near Wawa, Ontario." Canadian Journal of Earth Sciences 27, no. 5 (May 1, 1990): 649–56. http://dx.doi.org/10.1139/e90-062.

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The Mishibishu greenstone belt, located 40 km west of Wawa, is a typical Archean greenstone belt and is probably an extension of the Michipicoten belt. This belt is composed of basic to felsic metavolcanic rocks of tholeiitic to calc-alkaline affinity and of metasedimentary rocks ranging from conglomerate to argillite. Granitoids, diorites, and gabbros intrude and embay supracrustal rocks as internal and external plutons.Six U–Pb zircon ages have been obtained on rocks in this area. The oldest is 2721 ± 4 Ma for the Jostle Lake tonalite. The bulk of the volcanic rocks formed by 2696 ± 17 Ma, which is the age of the Chimney Point porphyry at the top of the volcanic pile. The Pilot Harbour granite has a similar age of 2693 ± 7 Ma. The age of the Tee Lake tonalite is 2673 ± 12 Ma, and the age of the Iron. Lake gabbro is 2671 ± 4 Ma. The youngest age for volcanics in this part of the Superior Province is 2677 ± 7 Ma, obtained from, the David Lakes pyroclastic breccia. these ages agree with those reported for the adjacent Michipicoten and Gamitagama belts.
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Fedo, Christopher M., Kenneth A. Eriksson, and Tom G. Blenkinsop. "Geologic history of the Archean Buhwa Greenstone Belt and surrounding granite–gneiss terrane, Zimbabwe, with implications for the evolution of the Limpopo Belt." Canadian Journal of Earth Sciences 32, no. 11 (November 1, 1995): 1977–90. http://dx.doi.org/10.1139/e95-151.

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The Buhwa Greenstone Belt (BGB) of southern Zimbabwe is the only major greenstone belt in the Archean Zimbabwe Craton directly adjacent to the granulite-facies rocks that constitute the Northern Marginal Zone of the Limpopo Belt. The deformational history and assembly of the BGB shed light on the evolution of the Northern Marginal Zone – Zimbabwe Craton transition. Assembly of the region began with deposition of the dominantly sedimentary cover succession at ~3.0 Ga on banded gneisses of the ~3.5 Ga Tokwe segment. At ~2.9 Ga the northern margin of the greenstone belt experienced kilometres of ductile, oblique-slip, dextral shearing. This shear zone was later intruded by the granitic to tonalitic ~2.9 Ga Chipinda batholith. The remaining events recognized in the region occurred during the time span 2.9–2.5 Ga. Northwest-directed thrusting of the Northern Marginal Zone over the Zimbabwe Craton took place along a collection of discrete, typically metre-wide shear zones, which collectively form the tectonic break between the Zimbabwe Craton and the Northern Marginal Zone. In response to thrusting, the cover succession and surrounding granitoids were folded and underwent regional greenschist-facies metamorphism. Two suites of potassic granites were emplaced north and south of the greenstone belt towards the end of thrusting. Plutonism was followed by conjugate faulting and later filling of the fractures by the Great Dyke of Zimbabwe. The youngest events may have occurred between ~2.5 and ~2.0 Ga, and include sinistral shearing along the southern margin of the belt, transecting cleavage formation, and open folding as a result of northeast-directed crustal shortening.
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Parks, Jen, Shoufa Lin, Don Davis, and Tim Corkery. "New high-precision U–Pb ages for the Island Lake greenstone belt, northwestern Superior Province: implications for regional stratigraphy and the extent of the North Caribou terrane." Canadian Journal of Earth Sciences 43, no. 7 (July 1, 2006): 789–803. http://dx.doi.org/10.1139/e06-044.

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A combined U–Pb and field mapping study of the Island Lake greenstone belt has led to the recognition of three distinct supracrustal assemblages. These assemblages record magmatic episodes at 2897, 2852, and 2744 Ma. Voluminous plutonic rocks within the belt range in age from 2894 to 2730 Ma, with a concentration at 2744 Ma. U–Pb data also show that a regional fault that transects the belt, the Savage Island shear zone, is not a terrane-bounding structure. The youngest sedimentary group in the belt, the Island Lake Group, has an unconformable relationship with older plutons. Sedimentation in this group is bracketed between 2712 and 2699 Ma. This group, and others similar to it in the northwestern Superior Province, is akin to Timiskaming-type sedimentary groups found throughout the Superior Province and in other Archean cratons. These data confirm that this belt experienced a complex geological history that spanned at least 200 million years, which is typical of greenstone belts in this area. Age correlations between the Island Lake belt and other belts in the northwest Superior Province suggest the existence of a volcanic "megasequence". This evidence, in combination with Nd isotopic data, indicates that the Oxford–Stull domain, and the Munro Lake, Island Lake, and North Caribou terranes may have been part of a much larger reworked Mesoarchean crustal block, the North Caribou superterrane. It appears that the Superior Province was assembled by accretion of such large independent crustal blocks, whose individual histories involved extended periods of autochthonous development.
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21

Pan, Yuanming, and Michael E. Fleet. "Polymetamorphism in the Archean Hemlo – Heron Bay greenstone belt, Superior Province: P–T variations and implications for tectonic evolution." Canadian Journal of Earth Sciences 30, no. 5 (May 1, 1993): 985–96. http://dx.doi.org/10.1139/e93-082.

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The tectono-metamorphic history of the late Archean (2800–2600 Ma) Hemlo – Heron Bay greenstone belt in the Superior Province has been delineated from textural relationships, mineral chemistry, and P–T paths in metapelites, cordierite–orthoamphibole rocks, and metabasites from the White River exploration property, Hemlo area, Ontario. An early low-temperature, medium-pressure metamorphism (about 500 °C and 6–6.5 kbar (1 kbar = 100 MPa)) is indicated by the occurrence of relict kyanite and staurolite porphyroblasts and zoned garnet porphyroblasts in metapelites and the presence of zoned calcic amphiboles in metabasites. This early metamorphism appears to have been coeval with the previously documented D1 deformation that is associated with, for example, low-angle thrusts. A second regional metamorphism predominates in the Hemlo – Heron Bay greenstone belt and is generally of relatively low grade, at about 510–530 °C and 3.2–3.5 kbar, over most of the study area and increases to medium grade (550–650 °C and 4–5 kbar) towards the southern margin with the Pukaskwa Gneissic Complex and along the central axis enclosing the Hemlo Shear Zone. The second regional metamorphism was contemporaneous with the D3 deformation and was probably related to plutonism. This type of polymetamorphism in the Hemlo – Heron Bay greenstone belt may be equivalent to those in Phanerozoic subduction complexes and therefore supports the arc–arc accretion model for the development of the southern Superior Province. Although the Hemlo – Heron Bay greenstone belt most likely represents a single tectonic environment (an oceanic island arc), the restricted occurrence of the relict kyanite and staurolite indicates that the central portion of this Archean greenstone belt probably was at a deeper crustal level at the time of the first metamorphic event.
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22

Jackson, S. L., and R. H. Sutcliffe. "Central Superior Province geology: evidence for an allochthonous, ensimatic, southern Abitibi greenstone belt." Canadian Journal of Earth Sciences 27, no. 4 (April 1, 1990): 582–89. http://dx.doi.org/10.1139/e90-054.

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Published U–Pb geochronological, geological, and petrochemical data suggest that there are late Archean ensialic greenstone belts (GB) (Michipicoten GB and possibly the northern Abitibi GB), ensimatic greenstone belts (southern Abitibi GB and Batchawana GB), and possibly a transitional ensimatic–ensialic greenstone belt (Swayze GB) in the central Superior Province. This lateral crustal variability may preclude simple correlation of the Michipicoten GB and its substrata, as exposed in the Kapuskasing Uplift, with that of the southern Abitibi GB. Furthermore, this lateral variability may have determined the locus of the Kapuskasing Uplift. Therefore, although the Kapuskasing Uplift provides a useful general crustal model, alternative models of crustal structure and tectonics for the southern Abitibi GB warrant examination.Thrusting of a juvenile, ensimatic southern Abitibi GB over a terrane containing evolved crust is consistent with (i) the structural style of the southern Abitibi GB; (ii) juvenile southern Abitibi GB metavolcanic rocks intruded by rocks having an isotopically evolved, older component; and (iii) Proterozoic extension that preserved low-grade metavolcanic rocks within the down-dropped Cobalt Embayment, which is bounded by higher grade terranes to the east and west.
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23

Goodwin, A. M., M. B. Lambert, and O. Ujike. "Geochemical and metallogenic relations in volcanic rocks of the southern Slave Province: implications for late Neoarchean tectonics." Canadian Journal of Earth Sciences 43, no. 12 (December 1, 2006): 1835–57. http://dx.doi.org/10.1139/e06-074.

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Late Neoarchean volcanic belts in the southern Slave Province include (1) in the east, the Cameron River – Beaulieu River belts, which are characterized by stratigraphically thin, flow-rich, classic calc-alkaline, arc-type sequences with accompanying syngenetic volcanogenic massive sulphide deposits; and (2) in the west, the Yellowknife belt, which is characterized by stratigraphically thick, structurally complex, pyroclastic-rich, adakitic, back-arc basin-type sequences, with accompanying epigenetic lode-gold deposits. The volcanic belt association bears persuasive chemical evidence of subduction-initiated magma generation. However, the greenstone belts, together with coeval matching patterned belts in Superior Province of the southern Canadian Shield, bear equally persuasive evidence of prevailing autochthonous–parautochthonous relations with respect to component stratigraphic parts and to older gneissic basement. The eastern and western volcanic belts in question are petrogenetically ascribed to a "westerly inclined" (present geography) subduction zone(s) that produced shallower (east) to deeper (west), slab-initiated, mantle wedge-generated, parent magmas. This early stage microplate tectonic process involved modest mantle subduction depths, small tectonic plates, and small sialic cratons. In the larger context of Earth's progressively cooling, hence subduction-deepening mantle, this late Neoarchean greenstone belt development (2.73–2.66 Ga) merged with the massive end-Archean tonalite–trondhjemite–granodiorite–granite (TTGG) "bloom" (2.65–2.55 Ga), resulting in greatly enhanced craton stability. Successive subduction-deepening, plate-craton-enlarging stages, with appropriate metallotectonic response across succeeding Proterozoic time and beyond, led to modern-mode plate tectonics.
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24

Lacroix, S., and E. W. Sawyer. "An Archean fold-thrust belt in the northwestern Abitibi Greenstone Belt: structural and seismic evidence." Canadian Journal of Earth Sciences 32, no. 2 (February 1, 1995): 97–112. http://dx.doi.org/10.1139/e95-009.

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An integration of structural field data and Lithoprobe seismic reflection line 28 in the northwestern Abitibi Greenstone Belt (AGB) reveals a crustal-scale, south-to southwest-vergent thrusting event that developed "in sequence" above a shallowly (15°) north-dipping sole thrust at a mid-crustal level. Seismic reflector geometry above this décollement suggests a mid crust (6–20 km depth) dominated by low-angle thrusts with smooth trajectory ramps and culmination folds or antiformal stacks, similar to the structural style of neighbouring high-grade plutonic–gneissic (Opatica) and sedimentary (Pontiac) subprovinces. In contrast, low-to high-angle east–west-trending thrusts at the upper-crust greenstone belt level (6–9 km depth) are interpreted to be listric. They occur in two fault systems, the Chicobi and Taibi, that resemble "imbricate fan" systems. The contrasting structural geometry of the upper and mid crust is interpreted as variations in level through the thrust stack, and resembles Paleozoic mountain belts where the upper AGB would represent a ductile–brittle fold–thrust belt. However, the structural evolution of the AGB has been complicated by earlier intrusive–metamorphic contacts or set of thrusts beneath it, and (or) younger out-of-sequence thrusts with north-vergent backthrusts. Also, south-to southwest-vergent thrusts were reactivated, folded, and steepened during a younger dextral strike-slip event.
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25

Turek, A., R. Keller, W. R. Van Schmus, and W. Weber. "U–Pb zircon ages for the Rice Lake area, southeastern Manitoba." Canadian Journal of Earth Sciences 26, no. 1 (January 1, 1989): 23–30. http://dx.doi.org/10.1139/e89-003.

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The Archean Rice Lake greenstone belt in southeastern Manitoba is made up of mafic to felsic volcanic rocks and associated intrusive and metasedimentary rocks. The belt is flanked to the north by the Wanipigow River granitic complex and to the south by the Manigotagan gneissic belt. The Ross River quartz diorite pluton is intrusive into the centre of the greenstone belt. U–Pb zircon ages indicate a major volcanic and plutonic event in the area at 2730 Ma. Ages for two volcanic units of the Rice Lake Group are 2731 ± 3 and 2729 ± 3 Ma. The Ross River pluton yields an age of 2728 ± 8 Ma and the Gunnar porphyry gives an age of 2731 ± 13 Ma; both intrude rocks of the Rice Lake Group. Granitic rocks of the Wanipigow River granitic complex give ages of 2731 ± 10 and 2880 ± 9 Ma, while a post-tectonic granite in the Manigotagan gneissic belt has an age of 2663 ± 7 Ma.
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26

DЕRIABIN, M. I. "THE PULSE DEVELOPMENT OF URALS GREENSTONE BELT." Geological Journal, no. 1 (February 23, 2012): 99–107. http://dx.doi.org/10.30836/igs.1025-6814.2012.1.139181.

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27

Brake, C. R. "Tholeiitic Magmatism in the Belingwe Greenstone Belt." Mineralogical Magazine 58A, no. 1 (1994): 113–14. http://dx.doi.org/10.1180/minmag.1994.58a.1.62.

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28

Slater, K. R., and S. J. Haydon. "Copper occurrences in the Heathcote Greenstone belt." ASEG Extended Abstracts 1999, no. 1 (December 1999): 99–112. http://dx.doi.org/10.1071/asegspec11_07.

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29

BARBOSA, JOHILDO S. F., and PIERRE SABATÉ. "Geological features and the Paleoproterozoic collision of four Archean crustal segments of the São Francisco Craton, Bahia, Brazil: a synthesis." Anais da Academia Brasileira de Ciências 74, no. 2 (June 2002): 343–59. http://dx.doi.org/10.1590/s0001-37652002000200009.

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Recent geological, geochronological and isotopic research has identified four important Archean crustal segments in the basement of the São Francisco Craton in the State of Bahia. The oldest Gavião Block occurs in the WSW part, composed essentially of granitic, granodioritic and migmatitic rocks. It includes remnants of TTG suites, considered to represent the oldest rocks in the South American continent (~ 3,4Ga) and associated Archean greenstone belt sequences. The youngest segment, termed the Itabuna-Salvador-Curaçá Belt is exposed along the Atlantic Coast, from the SE part of Bahia up to Salvador and then along a NE trend. It is mainly composed of tonalite/trondhjemites, but also includes stripes of intercalated metasediments and ocean-floor/back-arc gabbros and basalts. The Jequié Block, the third segment, is exposed in the SE-SSW area, being characterized by Archean granulitic migmatites with supracrustal inclusions and several charnockitic intrusions. The Serrinha Block (fourth segment) occurs to the NE, composed of orthogneisses and migmatites, which represent the basement of Paleoproterozoic greenstone belts sequences. During the Paleoproterozoic Transamazonian Orogeny, these four crustal segments collided, resulting in the formation of an important mountain belt. Geochronological constrains indicate that the regional metamorphism resulting from crustal thickening associated with the collision process took place around 2.0 Ga.
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30

Corkery, M. T., D. W. Davis, and P. G. Lenton. "Geochronological constraints on the development of the Cross Lake greenstone belt, northwest Superior Province, Manitoba." Canadian Journal of Earth Sciences 29, no. 10 (October 1, 1992): 2171–85. http://dx.doi.org/10.1139/e92-172.

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Recent 1: 20 000 mapping combined with 11 age determinations from metavolcanic, metaplutonic, and metasedimentary rocks in the Cross Lake greenstone belt provide a framework for interpreting the stratigraphic, structural, intrusive, and metamorphic evolution of the belt. These data, in combination with U–Pb ages from adjacent granitoid domains, are used to model a cratonizing event in the northwest Superior Province.The Cross Lake greenstone belt is made up of three distinct unconformable groups of supracrustal rocks: (i) the Pipestone Lake Group (2760 Ma), a thick sequence of pillowed and massive tholeiitic basalt flows and related high level gabbros, inter-preted as a back-arc spreading sequence; (ii) the Gunpoint Group (2730 Ma), a fining-upward sequence of clastic sediments interbedded with rhyodacitic fragmental volcanic rocks; and (iii) the Cross Lake Group (<2710 Ma), a fining-upward, fluvial–marine clastic sedimentary sequence, with shoshonitic volcanic rocks near the top, deposited in a restricted basin. Angular unconformities occur between (i) the Pipestone Lake Group and the overlying Gunpoint and Cross Lake groups, and (ii) the Gunpoint Group and the younger Cross Lake Group.The greenstone belt is flanked by the plutonic Molson Lake Domain on the south and the largely metaplutonic Pikwitonei and granite–greenstone Gods Lake domains on the northwest. The northern contact is a major northeast-trending fault system with a dextral strike-slip component and vertical component indicative of relative uplift of the northwest side. The southern contact is a much broader zone of deformation in which a number of east-southeast-trending dextral fault zones imbricate Pipestone Lake and Gunpoint Group supracrustal rocks and, to a lesser extent, Molson Lake plutonic rocks.
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31

Kroonenberg, S. B., E. W. F. de Roever, L. M. Fraga, N. J. Reis, T. Faraco, J. M. Lafon, U. Cordani, and T. E. Wong. "Paleoproterozoic evolution of the Guiana Shield in Suriname: A revised model." Netherlands Journal of Geosciences - Geologie en Mijnbouw 95, no. 4 (May 12, 2016): 491–522. http://dx.doi.org/10.1017/njg.2016.10.

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AbstractThe Proterozoic basement of Suriname consists of a greenstone–tonalite–trondhjemite–granodiorite belt in the northeast of the country, two high-grade belts in the northwest and southwest, respectively, and a large granitoid–felsic volcanic terrain in the central part of the country, punctuated by numerous gabbroic intrusions. The basement is overlain by the subhorizontal Proterozoic Roraima sandstone formation and transected by two Proterozoic and one Jurassic dolerite dyke swarms. Late Proterozoic mylonitisation affected large parts of the basement. Almost 50 new U–Pb and Pb–Pb zircon ages and geochemical data have been obtained in Suriname, and much new data are also available from the neighbouring countries. This has led to a considerable revision of the geological evolution of the basement. The main orogenic event is the Trans-Amazonian Orogeny, resulting from southwards subduction and later collision between the Guiana Shield and the West African Craton. The first phase, between 2.18 and 2.09 Ga, shows ocean floor magmatism, volcanic arc development, sedimentation, metamorphism, anatexis and plutonism in the Marowijne Greenstone Belt and the adjacent older granites and gneisses. The second phase encompasses the evolution of the Bakhuis Granulite Belt and Coeroeni Gneiss Belt through rift-type basin formation, volcanism, sedimentation and, between 2.07 and 2.05 Ga, high-grade metamorphism. The third phase, between 1.99 and 1.95 Ga, is characterised by renewed high-grade metamorphism in the Bakhuis and Coeroeni belts along an anticlockwise cooling path, and ignimbritic volcanism and extensive and varied intrusive magmatism in the western half of the country. An alternative scenario is also discussed, implying an origin of the Coeroeni Gneiss Belt as an active continental margin, recording northwards subduction and finally collision between a magmatic arc in the south and an older northern continent. The Grenvillian collision between Laurentia and Amazonia around 1.2–1.0 Ga caused widespread mylonitisation and mica age resetting in the basement.
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Isachsen, C. E., and S. A. Bowring. "The Bell Lake group and Anton Complex: a basement – cover sequence beneath the Archean Yellowknife greenstone belt revealed and implicated in greenstone belt formation." Canadian Journal of Earth Sciences 34, no. 2 (February 1, 1997): 169–89. http://dx.doi.org/10.1139/e17-014.

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U–Pb zircon and monazite geochronology indicates the presence of a >2.93 Ga basement (Anton Complex) and >2.8 Ga cover sequence (Bell Lake group) beneath the 2.70 to >2.72 Ga Kam Group of the Yellowknife greenstone belt in the southern Slave Province. The Bell Lake group comprises remnants of a quartzite – rhyolite – banded iron formation succession. The ages of detrital zircons from the quartzite unit constrain its deposition to be younger than 2.92 and range up to 3.7 Ga. U–Pb ages for gneisses beneath the Bell Lake group are in excess of 2.93 Ga and they are locally overlain by the quartzite. The contact between the tholeiitic to calc-alkaline Kam Group and the Bell Lake group is poorly exposed and equivocal. Approximately 6 km higher in the section, the Ranney chert, a felsic volcaniclastic layer, separates 2.70 – 2.72 Ga tholeiitic to calc-alkaline upper Kam Group rocks from a lower tholeiitic section containing sheeted-dike complexes. Zircons from the Ranney chert yield Pb –Pb ages ranging from 2.72 to >2.8 Ga. The older ages suggest proximity of older basement during deposition of mostly tholeiitic lower Kam Group volcanic rocks in an extensional setting, followed by deposition of the upper Kam Group, which is more arc-like in character, on this earlier-formed tholeiitic crust beginning at 2.72 Ga.
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Kusky, Timothy M., and Pamela A. Winsky. "Structural relationships along a greenstone/shallow water shelf contact, Belingwe greenstone belt, Zimbabwe." Tectonics 14, no. 2 (April 1995): 448–71. http://dx.doi.org/10.1029/94tc03086.

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34

Kalinin, Arkady, Oleg Kazanov, Vladimir Bezrukov, and Vsevolod Prokofiev. "Gold Prospects in the Western Segment of the Russian Arctic: Regional Metallogeny and Distribution of Mineralization." Minerals 9, no. 3 (February 26, 2019): 137. http://dx.doi.org/10.3390/min9030137.

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Location of the deposits and occurrences of gold mineralization in metamorphic complexes of the Kola region is controlled by tectonic zones at the regional scale at the boundaries of major segments of the Fennoscandian Shield. Three zones are the most important: (1) the system of Neoarchean greenstone belts Kolmozero–Voron’ya–Ura-guba along the southern boundary of the Murmansk craton; (2) the suture, delineating the core of the Lapland–Kola orogeny in the north; and (3) the series of overthrusts and faults at the eastern flank of the Salla–Kuolajarvi belt. Gold deposits and occurrences are located within greenstone belts of Neoarchean and Paleoproterozoic age, and hosted by rocks of different primary compositions (mafic metavolcanics, diorite porphyry, and metasedimentary terrigenous rocks). The grade of metamorphism varies from greenschist to upper amphibolite facies, but the mineralized rocks are mainly lower amphibolite metamorphosed, close to the transition from greenschist to amphibolite facies. Gold deposits and occurrences in the northeastern part of the Fennoscandian Shield formed during two periods: the Neoarchean 2.7–2.6 Ga and the Paleoproterozoic 1.9–1.7 Ga. According to paleo-geodynamic reconstructions, these were the periods of collisional and accretionary orogeny in the region. Those Archean greenstone belts, which were reworked in the Paleoproterozoic (e.g., Strel’na and Tiksheozero belts), can contain gold deposits of Paleoproterozoic age.
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35

Corfu, F., and R. P. Sage. "U–Pb age constraints for deposition of clastic metasedimentary rocks and late-tectonic plutonism, Michipicoten Belt, Superior Province." Canadian Journal of Earth Sciences 29, no. 8 (August 1, 1992): 1640–51. http://dx.doi.org/10.1139/e92-129.

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The study investigates the ages of clastic metasedimentary rocks and of late-tectonic alkalic to calc-alkalic intrusions and puts constraints on the timing of major deformation in the Michipicoten greenstone belt of the Wawa Subprovince. A trondhjemitic boulder in the Doré conglomerate of the southern metasedimentary belt is dated at 2698 ± 2 Ma. This is a maximum age of sedimentation that is also supported by ages of detrital zircons in the matrix and may directly reflect the time of synvolcanic deposition. Detrital zircons in metapsammites of the central and northern sedimentary belts yield younger ages of 2682 ± 3 and 2680 ± 3 Ma, respectively, suggesting that sedimentation occurred significantly later in the northern than in the southern parts of the greenstone belt. The ≤2682 Ma sedimentary rocks were affected by multiphase deformation that is related to the development of a large-scale recumbent fold and superimposed folds and faults. This tectonism was followed by the emplacement of the granodioritic Troupe Lake and Maskinonge Lake stocks that yield identical zircon and titanite ages of 2671 ± 2 Ma. The structurally older and deformed Herman Lake nepheline syenite has an imprecise titanite age of [Formula: see text]. The isotopic composition of Pb in feldspar of these intrusions is relatively evolved and, in light of geochemical considerations, may reflect provenance of the melts from enriched mantle reservoirs.
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36

Tomlinson, K. Y., R. P. Hall, D. J. Hughes, and P. C. Thurston. "Geochemistry and assemblage accretion of metavolcanic rocks in the Beardmore–Geraldton greenstone belt, Superior Province." Canadian Journal of Earth Sciences 33, no. 11 (November 1, 1996): 1520–33. http://dx.doi.org/10.1139/e96-115.

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The Beardmore–Geraldton greenstone belt lies between the Wabigoon volcanic arc (Onaman–Tashota terrane) and the Quetico metasedimentary subprovince and thus has an important bearing on the accretionary model that has been proposed for the amalgamation of these terranes. This paper presents geochemical evidence for the petrogenetic affinities of the volcanic units of the western half of the Beardmore–Geraldton greenstone belt. These data suggest that the metavolcanic rocks of the greenstone belt form a series of distinct packages. Trace element data are used to demonstrate the similarities and differences of each unit of lavas and to characterize their source region and likely tectono-magmatic setting. The data indicate that three separate fragments of volcanic crust representing oceanic crust, arc crust, and back-arc crust formed in a small arc system and were juxtaposed prior to collision with the Wabigoon arc. These fragments of crust were then accreted to the Wabigoon arc where sedimentation was followed by thrusting and folding resulting in shortening of the belt. Delamination of the volcanic units is thought to have been responsible for the preservation of just the pillow lava sequence of oceanic crust. Lower crustal or crust–mantle delamination of the Wawa arc and underplating of the Quetico are thought to have been responsible for the late and long-lived, high-grade metamorphic event in the Quetico and such "flake tectonics" are thought to have been an important process in the interaction between the Wabigoon, Quetico, and Wawa subprovinces.
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37

Beakhouse, Gary P., Shoufa Lin, and Sandra L. Kamo. "Magmatic and tectonic emplacement of the Pukaskwa batholith, Superior Province, Ontario, CanadaThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh." Canadian Journal of Earth Sciences 48, no. 2 (February 2011): 187–204. http://dx.doi.org/10.1139/e10-048.

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The Neoarchean Pukaskwa batholith consists of pre-, syn-, and post-tectonic phases emplaced over an interval of 50 million years. Pre-tectonic phases are broadly synvolcanic and have a high-Al tonalite–trondhjemite–granodiorite (TTG) affinity interpreted to reflect derivation by partial melting of basaltic crust at lower crustal or upper mantle depths. Minor syn-tectonic phases slightly post-date volcanism and have geochemical characteristics suggesting some involvement or interaction with an ultramafic (mantle) source component. Magmatic emplacement of pre- and syn-tectonic phases occurred in the midcrust at paleopressures of 550–600 MPa and these components of the batholith are thought to be representative of the midcrust underlying greenstone belts during their development. Subsequent to emplacement of the syntectonic phases, and likely at approximately 2680 Ma, the Pukaskwa batholith was uplifted as a structural dome relative to flanking greenstone belts synchronously with ongoing regional sinistral transpressive deformation. The driving force for vertical tectonism is interpreted to be density inversion (Rayleigh–Taylor-type instabilities) involving denser greenstone belts and underlying felsic plutonic crust. The trigger for initiation of this process is interpreted to be an abrupt change in the rheology of the midcrust attributed to introduction of heat from the mantle attendant with slab breakoff or lithospheric delamination following the cessation of subduction. This process also led to partial melting of the intermediate to felsic midcrust generating post-tectonic granitic phases at approximately 2667 Ma. We propose that late density inversion-driven vertical tectonics is an inevitable consequence of horizontal (plate) tectonic processes associated with greenstone belt development within the Superior Province.
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SANISLAV, I. V., P. H. G. M. DIRKS, Y. A. COOK, T. G. BLENKINSOP, and S. L. KOLLING. "A Giant Gold System, Geita Greenstone Belt, Tanzania." Acta Geologica Sinica - English Edition 88, s2 (December 2014): 110–11. http://dx.doi.org/10.1111/1755-6724.12368_21.

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Hudleston, P. J., D. Schultz-Ela, and D. L. Southwick. "Transpression in an Archean greenstone belt, northern Minnesota." Canadian Journal of Earth Sciences 25, no. 7 (July 1, 1988): 1060–68. http://dx.doi.org/10.1139/e88-103.

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Weakly metamorphosed Archean sedimentary and volcanic rocks of the Vermilion district, northern Minnesota, occupy an east–west-trending belt between gneisses of the Vermilion granitic complex to the north and the Giants Range batholith to the south. All the measured strain, a foliation, and a mineral lineation in this belt are attributed to the "main" phase of deformation (D2). Foliation strikes parallel to the belt and dips steeply, and the mineral lineation plunges moderately to steeply east or west and is parallel to the maximum stretching direction, X, and subparallel to fold hinges. An earlier, possibly nappe-forming, event (D1) left little evidence of fabric in the Vermilion district.A number of features indicate that the D2 deformation involved a significant component of dextral strike-slip shear in addition to north–south compression. They include ductile shear zones with sigmoidal foliation patterns, shear bands, asymmetric pressure shadows, and the fact that the asymmetry of the F2 folds is predominantly Z. Other features are more simply explained by a deformation involving simple shear. The S2 cleavage is locally folded, and a new spaced cleavage developed in an orientation similar to that of the old cleavage away from the folds. We consider this the result of a process of continuous shear, with perturbations of flow resulting in folding of S2 and the development of a new foliation axial planar to the folds. The same type of perturbation can lead to the juxtaposition of zones of constrictional and flattening strains, a distinctive feature of the rocks of the Vermilion district otherwise hard to account for. The strain pattern requires a north–south component of shortening in addition to shear. The D2 deformation in the Vermilion district can therefore be characterized as one of transpression: oblique compression between two more rigid lithospheric blocks to the north and south.
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HOFMANN, HANS J., and MARIO MASSON. "Archean stromatolites from Abitibi greenstone belt, Quebec, Canada." Geological Society of America Bulletin 106, no. 3 (March 1994): 424–29. http://dx.doi.org/10.1130/0016-7606(1994)106<0424:asfagb>2.3.co;2.

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Schultz-Ela, D. D., and P. J. Hudleston. "Strain in an Archean greenstone belt of Minnesota." Tectonophysics 190, no. 2-4 (May 1991): 233–68. http://dx.doi.org/10.1016/0040-1951(91)90432-r.

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Liipo, Jussi P., Jouni I. Vuollo, Vesa M. Nykänen, and Tauno A. Piirainen. "Pyrophanite and ilmenite in serpentinized wehrlite from Ensilä, Kuhmo greenstone belt, Finland." European Journal of Mineralogy 6, no. 1 (February 4, 1994): 145–50. http://dx.doi.org/10.1127/ejm/6/1/0145.

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Motta, João Gabriel, and Ilio Rodarte Faria Júnior. "A mineral potential mapping approach for supergene nickel deposits in southwestern São Francisco Craton, Brazil." Brazilian Journal of Geology 46, no. 2 (June 2016): 261–73. http://dx.doi.org/10.1590/2317-4889201620160021.

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ABSTRACT: Southwestern São Francisco Craton makes limit with Brasília thrust-fold belt and involves rocks from Archean to formed during the Brasiliano-Pan Africano Neoproterozoic event, including a mafic-ultramafic belt (Morro do Ferro Greenstone Belt) hosted along the Archean counterpart. This greenstone belt hosts two-nickel deposits (Morro do Níquel and O'Toole, respectively silicate and sulfide types) and occurrences. This study applies an empirical-conceptual model for lateritic nickel deposits formation into geographic information systems with aerogeophysical data (magnetic and gamma-spectrometry) and digital elevation models (terrain relief and slope). Our contribution aims for nickel deposits favorability mapping using a simple mathematical operator over a supporting spatial database translating the conceptual exploration model into evidential layers for geological processes involved on deposit formation. Evidential layers constructed for identification of elements pertaining the supergene nickel mineral system are given by analytic signal amplitude maps, thorium over potassium ratio images, and digital elevation models and slope maps, derived from shuttle radar topography mission digital elevation models. Evidential layers integration through binary layers algebraic sum identified effectively known deposits and occurrences with its outputs highlighting possibilities for unknown resources in this under-explored terrain.
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Van Kranendonk, Martin J. "Cool greenstone drips and the role of partial convective overturn in Barberton greenstone belt evolution." Journal of African Earth Sciences 60, no. 5 (July 2011): 346–52. http://dx.doi.org/10.1016/j.jafrearsci.2011.03.012.

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de Wit, Maarten J. "Archaean greenstone belt tectonism and basin development: some insights from the Barberton and Pietersburg greenstone belts, Kaapvaal Craton, South Africa." Journal of African Earth Sciences (and the Middle East) 13, no. 1 (January 1991): 45–63. http://dx.doi.org/10.1016/0899-5362(91)90043-x.

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Sylvester, Paul J., Kodjo Attoh, and Klaus J. Schulz. "Tectonic setting of late Archean bimodal volcanism in the Michipicoten (Wawa) greenstone belt, Ontario." Canadian Journal of Earth Sciences 24, no. 6 (June 1, 1987): 1120–34. http://dx.doi.org/10.1139/e87-109.

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The tectono-stratigraphic relationships, depositional environments, rock associations, and major- and trace-element compositions of the late Archean (2744–2696 Ma) bimodal basalt–rhyolite volcanic rocks of the Michipicoten (Wawa) greenstone belt, Ontario, are compatible with an origin along a convergent plate margin that varied laterally from an immature island arc built on oceanic crust to a more mature arc underlain by continental crust. This environment is similar to that of the Cenozoic Taupo–Kermadec–Tonga volcanic zone. Michipicoten basaltic rocks, most of which are proximal deposits compositionally similar ([La/Yb]n = 0.63–1.18) to modern oceanic island-arc tholeiites, are interpreted as having formed along the largely submerged island arc. Voluminous Michipicoten rhyolitic pyroclastic rocks ([La/Yb]n = 4.3–18.7, Ybn = 5.7–15.9) probably erupted subaerially from the continental arc, with distal facies deposited subaqueously on the adjacent oceanic island arc and proximal facies deposited in subaerial and shallow subaqueous environments on, or along the flanks of, the continental arc. The compositional similarity between the lower (2744 Ma) and upper (2696 Ma) volcanic sequences of the belt suggests that this island- and continental-arc configuration existed for at least 45 Ma. The Michipicoten belt may be a remnant of a larger, laterally heterogeneous volcanic terrane that also included the Abitibi greenstone belt.
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Jost, Hardy, Vinícius Gomes Rodrigues, Marcelo Juliano de Carvalho, Farid Chemale Junior, and Juliana Charão Marques. "Estratigrafia e geocronologia do greenstone belt de Guarinos, Goiás." Geologia USP. Série Científica 12, no. 2 (August 1, 2012): 31–48. http://dx.doi.org/10.5327/z1519-874x2012000200003.

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Hofmann, A., P. H. G. M. Dirks, and H. A. Jelsma. "Late Archaean foreland basin deposits, Belingwe greenstone belt, Zimbabwe." Sedimentary Geology 141-142 (June 2001): 131–68. http://dx.doi.org/10.1016/s0037-0738(01)00072-0.

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Dostal, Jaroslav, and Wulf U. Mueller. "Deciphering an Archean mantle plume: Abitibi greenstone belt, Canada." Gondwana Research 23, no. 2 (March 2013): 493–505. http://dx.doi.org/10.1016/j.gr.2012.02.005.

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Astaf’ev, B. Yu, S. G. Skublov, V. A. Glebovitskii, I. M. Gembitskaya, O. A. Voinova, and O. A. Levchenkov. "Geochemistry of metasomatic zircons from the Terskii greenstone belt." Doklady Earth Sciences 427, no. 1 (July 2009): 840–45. http://dx.doi.org/10.1134/s1028334x09050298.

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