Geology and geochemistry of the Coulee Dam Intrusive Suite and associated younger intrusive rocks, Colville Batholith, Washington

U–Pb zircon ages from Athapuscow aulacogen, East Arm of Great Slave Lake, N.W.T., Canada

Canadian Journal of Earth Sciences ◽

10.1139/e84-136 ◽

1984 ◽

Vol 21 (11) ◽

pp. 1315-1324 ◽

Cited By ~ 38

Author(s):

S. A. Bowring ◽

W. R. Van Schmus ◽

P. F. Hoffman

Keyword(s):

Slave Craton ◽

Great Slave Lake ◽

Intrusive Rocks ◽

Island Group ◽

Minimum Age ◽

Great Bear Magmatic Zone ◽

Intracratonic Basin ◽

Two Phases ◽

Intrusive Suite ◽

Stratigraphic Sequences

Athapuscow aulacogen is an Early Proterozoic intracratonic basin located in the East Arm of Great Slave Lake between the Slave and northwest Churchill provinces. Athapuscow aulacogen comprises three stratigraphic sequences, the Wilson Island Group, the Great Slave Supergroup, and the Et-Then Group. New U–Pb zircon ages provide constraints on the development of the aulacogen.The Blachford Lake Intrusive Suite consists of an older alkaline phase (Hearne Channel Granite) dated at 2175 ± 7 Ma and a younger peralkaline phase (Thor Lake Syenite) dated at 2094 ± 10 Ma, confirming the suggestion that the two phases may not be related. A felsite from the Wilson Island Group has an age of 1928 ± 11 Ma. The Wilson Island Group is intruded by epizonal granites (Butte Island Intrusive Suite), one of which has an age of 1895 ± 8 Ma. The Wilson Island Group and the Butte Island Instrusive Suite are entirely allochthonous with respect to the Slave craton. Rocks of the Great Slave Supergroup overlie mylonitized Wilson Island Group rocks and both were involved in northeast-directed thrusting. The Compton laccoliths intrude rocks of the Great Slave Supergroup, postdate thrusting, and are about 1865 Ma old.The Blachford Lake Intrusive Suite is significantly older than both the rift sequence in Wopmay Orogen (ca. 1900 Ma) and the Wilson Island Group; it probably is genetically unrelated. The age of the Wilson Island Group and Butte Island Intrusive Suite is considerably younger than previous estimates and is close to the minimum age of rifting in Wopmay Orogen. The Compton laccoliths are very similar to intrusive rocks in the Great Bear Magmatic Zone of Wopmay Orogen and may be related to east-dipping subduction beneath the aulacogen.The new ages strengthen the correlations between Athapuscow aulacogen and Wopmay Orogen and suggest a link with events in the Trans-Hudson Orogen to the south.

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

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2018-0091 ◽

2019 ◽

Vol 56 (4) ◽

pp. 399-418 ◽

Cited By ~ 1

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.

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

10.4095/296678 ◽

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

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

Canadian Journal of Earth Sciences ◽

10.1139/e92-174 ◽

1992 ◽

Vol 29 (10) ◽

pp. 2200-2210 ◽

Cited By ~ 13

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.

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