An isotopic study of the Island Lake Greenstone Belt, Manitoba: crustal evolution and progressive cratonization in the late Archean

1992 ◽  
Vol 29 (10) ◽  
pp. 2200-2210 ◽  
Author(s):  
R. K. Stevenson ◽  
A. Turek
Keyword(s):  
Greenstone Belt ◽  
Metamorphic Event ◽  
Superior Province ◽  
Crustal Evolution ◽  
Isotopic Study ◽  
Volcanic Arc ◽  
Lake Region ◽  
Depleted Mantle ◽  
Intrusive Rocks ◽  
Intrusive Suite

Three new U–Pb zircon ages are reported for units within the Island Lake Greenstone Belt in northern Manitoba: the Jubilee Island dacite (2761 ± 12 Ma), the Chapin Bay tonalite (2748 ± 3 Ma), and the Wassagomach tonalité (2778 ± 5 Ma). Rb–Sr data suggest a mild metamorphic event about 2736 ± 67 Ma ago. Basalts within the basal Hayes River Group (2860–2900 Ma) appear to be derived from a time-averaged, Nd-depleted mantle with εNd values between +0.78 and +2.1. Lower εNd values (< +0.31) are found in volcanic and intrusive rocks of the same age, implying contamination by or remelting of preexisting crust to form the more felsic derivatives. εNd values of early tonalitic, trondhjemitic, and granitic plutons (2729–2900 Ma) decrease from +0.31 to −1.8 as the plutons become younger, and are indicative of a period of dominantly intracrustal recycling processes in the Island Lake region. It is suggested that this trend records the evolution of the Island Lake region through extensive intracrustal melting and recycling from a variably contaminated volcanic arc to a small mature craton. Uplift associated with the plutonism resulted in sedimentation of the Island Lake Group (2729–2749 Ma), followed by renewed granitic plutonism of the Late Intrusive Suite (2699–2729 Ma). εNd values of these units range from +3 to −3, suggesting renewed interaction of depleted mantle with the Island Lake crust. This possibly resulted from magmatism associated with the accretion of the Island Lake Terrane to the rest of the Superior Province.

U–Pb zircon ages for rocks from the Island Lake greenstone belt, Manitoba

1986 ◽  
Vol 23 (1) ◽  
pp. 92-101 ◽  
Author(s):  
A. Turek ◽  
T. M. Carson ◽  
Patrick E. Smith ◽  
W. R. Van Schmus ◽  
W. Weber
Keyword(s):  
Greenstone Belt ◽  
Quartz Diorite ◽  
Superior Province ◽  
Intrusive Complex ◽  
Quartz Porphyry ◽  
Zircon Age ◽  
Metasedimentary Rocks ◽  
Intrusive Rocks ◽  
Granitoid Rocks

The Archean Hayes River Group of the Island Lake greenstone belt (Superior Province, Sachigo Subprovince) comprises mafic to felsic metavolcanics, subvolcanics, and associated metasedimentary rocks. The Hayes River Group is intruded by granitoid rocks belonging to the early intrusive complex. One such pluton, the Bella Lake tonalite, is intrusive into the metabasalt of the Hayes River Group and has a U–Pb zircon age of 2886 ± 15 Ma. Similar intrusives of this complex, either internal or marginal to the greenstone belt, yield zircon ages of 2801 ± 8 Ma (Pipe Point tonalit) and 2768 ± 22 Ma (Linklater Island prophyry). This suggests that the early intrusive complex was emplaced over an ~ 120 Ma long interval by at least three separate intrusive episodes.Subsequent to the emplacement of the early intrusive complex, the isoclinally folded Hayes River Group and the early intrusive complex were uplifted, eroded, and followed by the unconformable deposition of the Island Lake Group, comprising fluvial to marine metasedimentary rocks. The stratigraphically lower part of the Island Lake Group is bracketed by the 2768 ± 22 Ma age of the Linklater Island porphyry and the 2729 ± 3 Ma age obtained for the late tectonic suite—the Pipe Point quartz diorite and feldspar porphyry. A feldspar quartz porphyry belonging to the post-tectonic intrusive rocks intrudes higher stratigraphic levels and has been dated at 2699 ± 4 Ma (Horseshoe Island quartz feldspar porphyry).

Geology, lithogeochemistry, and significance of porphyry intrusions associated with gold mineralization within the Timmins–Porcupine gold camp, Canada

2019 ◽  
Vol 56 (4) ◽  
pp. 399-418 ◽  
Author(s):  
Peter J. MacDonald ◽  
Stephen J. Piercey
Keyword(s):  
Partial Melting ◽  
Greenstone Belt ◽  
Deformation Zone ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Crustal Thickening ◽  
Abitibi Greenstone Belt ◽  
Crustal Structures ◽  
Intrusive Rocks ◽  
Intrusive Suite

The Timmins–Porcupine gold camp, Abitibi greenstone belt, is host >60 Moz of Au with many gold deposits spatially associated with porphyry intrusions and the Porcupine–Destor deformation zone (PDDZ). Porphyry intrusions form three suites. The Timmins porphyry suite (TIS) consists of high-Al tonalite–trondjhemite–granodiorite (TTG) with calc–alkalic affinities and high La/Yb ratios and formed during ∼2690 Ma D1-related crustal thickening and hydrous partial melting of mafic crust where garnet and hornblende were stable in the residue. The Carr Township porphyry intrusive suite (CIS) and the granodiorite intrusive suite (GIS) also have high-Al TTG, calc-alkalic affinities, but were generated 10–15 million years after the TIS; the CIS were generated at shallower depths (during postorogenic extension?) with no garnet in the crustal residue, whereas the GIS formed during D2 thrust-related crustal thickening and partial melting where garnet was stable in the residue. Gold mineralization is preferentially associated with the TIS, and to a lesser extent the GIS, proximal to the PDDZ. Intrusions near mineralization have abundant sericite, carbonate, and sulphide alteration. These intrusions exhibit low Na2O and Sr, and high Al2O3/Na2O, K2O, K2O/Na2O, Rb, and Cs, (i.e., potassic alteration); sulfide- and carbonate-altered porphyries have high (CaO + MgO + Fe2O3)/Al2O3 and LOI values. Although porphyries are not genetically related to gold mineralization, they are spatially related and are interpreted to reflect the emplacement of intrusions and subsequent Au-bearing fluids along the same crustal structures. The intrusive rocks also served as structural traps, where gold mineralization precipitated in dilatant structures along the margins of intrusions during regional (D3?) deformation.

Neodymium isotope geochemistry of felsic volcanic and intrusive rocks from the Yukon–Tanana Terrane in the Finlayson Lake Region, Yukon, Canada

2003 ◽  
Vol 40 (1) ◽  
pp. 77-97 ◽  
Author(s):  
Stephen J Piercey ◽  
James K Mortensen ◽  
Robert A Creaser
Keyword(s):  
Isotope Geochemistry ◽  
Volcanic Rocks ◽  
Lake Region ◽  
Volcanogenic Massive Sulphide ◽  
Depleted Mantle ◽  
Intrusive Rocks ◽  
Felsic Volcanic ◽  
Back Arc ◽  
Finlayson Lake ◽  
Felsic Rocks

Devonian–Mississippian felsic rocks from the Finlayson Lake region have variable geochemical and Nd isotopic characteristics that provide insights into the tectonic and metallogenic evolution of the Yukon–Tanana terrane (YTT), and the northern Cordillera. Late Devonian (~365–360 Ma) calc-alkaline and tholeiitic arc felsic rocks in the mafic-dominated Fire Lake unit yield εNd350 = –4.8 and +0.1, respectively, and have 1.49–1.94 Ga depleted mantle model ages (TDM). Devonian–Mississippian (~360–356 Ma) felsic volcanic (Kudz Ze Kayah unit, Wolverine succession) and intrusive rocks (Grass Lakes suite) associated with volcanogenic massive sulphide (VMS) deposits have εNd350 = –7.8 to –9.5 with TDM = 1.59–2.25 Ga. A granitoid sample from the Early Mississippian (~350–345 Ma) Simpson Range plutonic suite has εNd350 = –12.9 and TDM = 2.01 Ga, similar to previously reported values for this suite. The VMS-associated Grass Lakes suite of granitoids has higher high field strength element (HFSE) and rare-earth element (REE) contents, and higher Zr/Sc, Zr/TiO2, Nb/La, and Zr/La values relative to the Simpson Range plutonic suite; these geochemical features are similar to coeval VMS-associated felsic volcanic rocks in the Kudz Ze Kayah unit. The identification of similar HFSE–REE-enriched felsic volcanic and subvolcanic intrusive rocks may aid in delineating prospective regions for VMS mineralization in the YTT and other continental-margin arc to back-arc environments. The geochemical and Nd isotopic data for these YTT felsic rocks suggest that they reflect episodic mid-Paleozoic arc (Fire Lake unit; Simpson Range plutonic suite) and back-arc magmatism (Kudz Ze Kudz unit; Wolverine succession) built upon a transitional basement with variable, but significant, influence from evolved (Proterozoic) crustal materials.

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.

scholarly journals Mafic intrusive rocks from the Bird River intrusive suite, Bird River greenstone belt, southeast Manitoba

2015 ◽  
Author(s):  
V Bécu ◽  
M G Houlé ◽  
V J McNicoll ◽  
E M Yang ◽  
H P Gilbert
Keyword(s):  
Greenstone Belt ◽  
Intrusive Rocks ◽  
Intrusive Suite

Age and timing of igneous activity in the Temagami greenstone belt, Ontario: a preliminary report

1991 ◽  
Vol 28 (11) ◽  
pp. 1873-1876 ◽  
Author(s):  
R. J. Bowins ◽  
L. M. Heaman
Keyword(s):  
Greenstone Belt ◽  
Preliminary Report ◽  
Superior Province ◽  
Early Proterozoic ◽  
The North ◽  
Intrusive Rocks ◽  
Abitibi Subprovince ◽  
Igneous Activity ◽  
The Town ◽  
Volcanic Cycle

The southernmost remnants of Archean supracrustal and intrusive rocks in eastern Ontario are exposed through a window in the Early Proterozoic Huronian Supergroup near the town of Temagami. U–Pb zircon ages from this area indicate the presence of some of the oldest felsic magmatism so far discovered in this portion of the Superior Province. The Iceland Lake pluton (2736 ± 2 Ma) and a nearby rhyolite flow ([Formula: see text]) are contemporaneous, which establishes that at least some of the intrusive rocks in the region are synvolcanic and coeval with the oldest volcanic cycle. The youngest plutonic activity is the emplacement of a late rhyolite porphyry dike at 2687 ± 2 Ma, an age that is bracketed by the 2675–2700 Ma emplacement ages of late internal plutons found throughout the Abitibi Subprovince. The 2736 Ma dates, however, are older than the nearest portion of the exposed Abitibi, some 120 km to the north near Kirkland Lake.

U–Pb zircon geochronology in the southwestern Abitibi greenstone belt, Superior Province

1989 ◽  
Vol 26 (9) ◽  
pp. 1747-1763 ◽  
Author(s):  
F. Corfu ◽  
T. E. Krogh ◽  
Y. Y. Kwok ◽  
L. S. Jensen
Keyword(s):  
Greenstone Belt ◽  
Gold Mineralization ◽  
Superior Province ◽  
Zircon Geochronology ◽  
Zircon Age ◽  
The Past ◽  
Sedimentary Sequences ◽  
Lake Region ◽  
Apparent Age ◽  
Stratigraphic Thickness

The Abitibi Belt is the largest continuous greenstone belt in the Superior Province of the Canadian Shield. It comprises several composite komatiitic–tholeiitic–calc-alkalic and sedimentary sequences that are folded, transected by major faults, and intruded by various generations of plutonic rocks. Precise U–Pb geochronology has been carried out in the belt for the past decade to solve chronostratigraphic and metallogenetic problems. This paper presents new zircon ages and reassesses previously published ones, now refined by the addition of abraded and concordant zircon analyses.Volcanic and subvolcanic units of the Timmins area yield the following ages: 2727 ± 1.5 Ma for a tuff of the upper Deloro Formation; 2703 ± 1.5 Ma for a tuff of the upper Tisdale Formation; and 2698 ± 4 Ma for the Krist fragmental, assigned to the top of the Tisdale Formation. The age of a dunite intrusive into the upper Deloro Formation is revised at 2707 ± 3 Ma, whereas the Aquarius diorite east of Timmins yields a poorly defined age of 2705 ± 10 Ma. In the Lake Abitibi – Kirkland Lake region, the following dates were obtained: 2713 ± 2 Ma for a porphyritic unit of the Hunter Mine Group; 2714 ± 2 Ma for a rhyolite at the base of the mainly tholeiitic to komatiitic Stoughton–Roquemaure Group; 2701 ± 2 Ma for porphyritic rhyolite of the Blake River Group; 2701 ± 2 Ma for a tuff of the Skead Group; and [Formula: see text] for a pyroclastic unit at the base of the Larder Lake Group. These data are generally consistent with the earlier proposed stratigraphic subdivisions and correlations. However, there are apparent age reversals, for example between the Larder Lake and Skead groups, that could support the concept of thrusting and tectonic thickening to explain particular lithologic relationships and the considerable stratigraphic thickness of the supracrustal sequences in the Abitibi Belt.One part of the study was dedicated to the problem of gold mineralization in the Timmins area. The zircon age of 2690 ± 2 Ma for the Paymaster porphyry, a less well defined but probably identical age for the Preston porphyry, and dates of 2689 ± 1 Ma for the Pearl Lake porphyry, 2691 ± 3 Ma for the Millerton porphyry, and 2688 ± 2 Ma for the Crown porphyry show that these intrusions were formed during a well-defined, short-lived episode unrelated to volcanism; furthermore, a date of [Formula: see text] for an albitite, which predates Au mineralization, demonstrates that Au is spatially but not genetically related to the porphyries.Finally, two ages are reported for late tectonic potassic intrusions: a refined age of 2678 ± 2 Ma for the Garrison stock east of Matheson and a precise zircon (and titanite) age of 2680 ± 1 Ma for the Otto stock near Kirkland Lake.

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