The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Robert W. Luth - One of the best experts on this subject based on the ideXlab platform.
-
Melting phase relations of a mica–clinopyroxenite from the Milk River area, southern Alberta, Canada
Contributions to Mineralogy and Petrology, 2013Co-Authors: Sean P. Funk, Robert W. LuthAbstract:Melting experiments were conducted on a mica–clinopyroxenite xenolith brought up in a Minette dyke in southern Alberta, Canada, near Milk River. Both the Minettes and mica–clinopyroxenite xenoliths were studied by Buhlmann et al. (Can J Earth Sci 37:1629–1650, 2000 ), who hypothesized that the Minettes formed by partial melting of a mantle source containing clinopyroxene + phlogopite ± olivine, at pressures ≥1.7 GPa. In liquidus experiments performed on the most primitive Minette in our previous study (Funk and Luth in Contrib Mineral Petrol 164:999–1009, 2012 ), we found a multiple saturation point where olivine and orthopyroxene coexisted with liquid at 1.77 GPa and 1,350 °C. We argued that the Minette originally formed by partial melting of clinopyroxene + phlogopite, but had re-equilibrated with a harzburgite during ascent. In the current study, we wanted to test both the source region hypothesis of Buhlmann et al. and our re-equilibration hypothesis by studying the near-solidus phase equilibria of a mica + clinopyroxene assemblage. We found the solidus for our xenolith has a steep slope in P–T space and lies at temperatures above those of a normal cratonic geotherm, implying that this mica–clinopyroxenite is stable in the cratonic mantle. Melting could occur at greater depths, where the solidus is extrapolated to cross the geotherm or must be induced either by raising the temperatures of the surrounding rocks or by introducing hydrous fluids into the source. Our melts are in equilibrium with clinopyroxene and olivine. The compositions of the liquids derived from melting this xenolith are similar to madupitic lamproites from the Leucite Hills, Wyoming, studied by Carmichael (Contrib Mineral Petrol 15:24–66, 1967 ) and Barton and Hamilton (Contrib Mineral Petrol 66:41–49, 1978 ; Contrib Mineral Petrol 69:133–142, 1979 ). Barton and Hamilton (Contrib Mineral Petrol 69:133–142, 1979 ) proposed that the madupitic lamproites may have come from a source containing mica and pyroxene. This study supports their hypothesis. The composition of the most primitive Minette from southern Alberta lies between our experimental melt and a population of representative mantle orthopyroxenes. We conclude from our study that the Milk River Minettes were likely derived from a source containing phlogopite, clinopyroxene and trace amounts of apatite, which formed olivine upon melting. During ascent, the melts changed composition by reacting with orthopyroxene.
-
An experimental study of a Minette from the Milk River area, southern Alberta, Canada
Contributions to Mineralogy and Petrology, 2012Co-Authors: Sean P. Funk, Robert W. LuthAbstract:Buhlmann et al. (Can J Earth Sci 37: 1629–1650, 2000) studied the Minettes and xenoliths from the Milk River area of southern Alberta, Canada. Based on previous work, they hypothesized that the Minettes were derived from a source containing phlogopite + clinopyroxene ± olivine, at pressures ≥1.7 GPa. To test this hypothesis, liquidus experiments were performed on a primitive Minette between 1.33 and 2.21 GPa and between 1,300 and 1,400 °C to constrain the mineralogy of its source region. We found a multiple saturation point along the liquidus at 1.77 GPa and 1,350 °C, where the liquid coexists with orthopyroxene and olivine. Neither phlogopite nor clinopyroxene were found to be liquidus phases, which is inconsistent with Buhlmann et al.’s hypothesis. We suggest that our Minette is not primary, but had re-equilibrated with harzburgitic mantle subsequent to formation. In such a scenario, partial melting of a veined source containing mica and clinopyroxene occurred at or near the base of the Wyoming craton (~200 km). Minimal heating or the introduction of hydrous fluids into the source would be required to induce partial melting. Rapid ascent rates, coupled with slow cooling rates, of the “primary Minette magma” would preserve the high temperature observed in our experiments. At ~58 km, our “primary Minette magma” likely stalled and re-equilibrated with the harzburgite surroundings.
-
Minette bodies and cognate mica-clinopyroxenite xenoliths from the Milk River area, southern Alberta: records of a complex history of the northernmost part of the Archean Wyoming craton
Canadian Journal of Earth Sciences, 2000Co-Authors: Arndt L. Buhlmann, Patricia A. Cavell, Ronald A. Burwash, Robert A. Creaser, Robert W. LuthAbstract:Minettes exposed in southern Alberta near the Milk River are the northern outliers of the Eocene Sweet Grass Hills igneous complex of the Montana alkalic igneous province. These Minettes often contain coarse-grained xenoliths of phlogopite + clinopyroxene ± apatite. The parent magmas of the Minettes were generated at pressures 17 kbar in equilibrium with clinopyroxene + phlogopite ± olivine. Fractional crystallization and mixing provided a spectrum of evolved Minettes and cumulates, the latter of which were sampled by subsequent Minette magmas as xenoliths. Two xenoliths were dated at 49.0 ± 0.8 Ma and 52 ± 1.7 Ma. The host dyke of the latter xenolith gave an age of 50 ± 0.3 Ma. The Minettes and their xenoliths have overlapping values of 87Sr/86Sri, eNdT, 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb, similar to those of alkaline igneous rocks from farther south in the Montana alkalic igneous province. The Sweet Grass Hills lie north of the Great Falls Tectonic Zone, previously interpreted as a Proterozoic su...
Sean P. Funk - One of the best experts on this subject based on the ideXlab platform.
-
Melting phase relations of a mica–clinopyroxenite from the Milk River area, southern Alberta, Canada
Contributions to Mineralogy and Petrology, 2013Co-Authors: Sean P. Funk, Robert W. LuthAbstract:Melting experiments were conducted on a mica–clinopyroxenite xenolith brought up in a Minette dyke in southern Alberta, Canada, near Milk River. Both the Minettes and mica–clinopyroxenite xenoliths were studied by Buhlmann et al. (Can J Earth Sci 37:1629–1650, 2000 ), who hypothesized that the Minettes formed by partial melting of a mantle source containing clinopyroxene + phlogopite ± olivine, at pressures ≥1.7 GPa. In liquidus experiments performed on the most primitive Minette in our previous study (Funk and Luth in Contrib Mineral Petrol 164:999–1009, 2012 ), we found a multiple saturation point where olivine and orthopyroxene coexisted with liquid at 1.77 GPa and 1,350 °C. We argued that the Minette originally formed by partial melting of clinopyroxene + phlogopite, but had re-equilibrated with a harzburgite during ascent. In the current study, we wanted to test both the source region hypothesis of Buhlmann et al. and our re-equilibration hypothesis by studying the near-solidus phase equilibria of a mica + clinopyroxene assemblage. We found the solidus for our xenolith has a steep slope in P–T space and lies at temperatures above those of a normal cratonic geotherm, implying that this mica–clinopyroxenite is stable in the cratonic mantle. Melting could occur at greater depths, where the solidus is extrapolated to cross the geotherm or must be induced either by raising the temperatures of the surrounding rocks or by introducing hydrous fluids into the source. Our melts are in equilibrium with clinopyroxene and olivine. The compositions of the liquids derived from melting this xenolith are similar to madupitic lamproites from the Leucite Hills, Wyoming, studied by Carmichael (Contrib Mineral Petrol 15:24–66, 1967 ) and Barton and Hamilton (Contrib Mineral Petrol 66:41–49, 1978 ; Contrib Mineral Petrol 69:133–142, 1979 ). Barton and Hamilton (Contrib Mineral Petrol 69:133–142, 1979 ) proposed that the madupitic lamproites may have come from a source containing mica and pyroxene. This study supports their hypothesis. The composition of the most primitive Minette from southern Alberta lies between our experimental melt and a population of representative mantle orthopyroxenes. We conclude from our study that the Milk River Minettes were likely derived from a source containing phlogopite, clinopyroxene and trace amounts of apatite, which formed olivine upon melting. During ascent, the melts changed composition by reacting with orthopyroxene.
-
An experimental study of a Minette from the Milk River area, southern Alberta, Canada
Contributions to Mineralogy and Petrology, 2012Co-Authors: Sean P. Funk, Robert W. LuthAbstract:Buhlmann et al. (Can J Earth Sci 37: 1629–1650, 2000) studied the Minettes and xenoliths from the Milk River area of southern Alberta, Canada. Based on previous work, they hypothesized that the Minettes were derived from a source containing phlogopite + clinopyroxene ± olivine, at pressures ≥1.7 GPa. To test this hypothesis, liquidus experiments were performed on a primitive Minette between 1.33 and 2.21 GPa and between 1,300 and 1,400 °C to constrain the mineralogy of its source region. We found a multiple saturation point along the liquidus at 1.77 GPa and 1,350 °C, where the liquid coexists with orthopyroxene and olivine. Neither phlogopite nor clinopyroxene were found to be liquidus phases, which is inconsistent with Buhlmann et al.’s hypothesis. We suggest that our Minette is not primary, but had re-equilibrated with harzburgitic mantle subsequent to formation. In such a scenario, partial melting of a veined source containing mica and clinopyroxene occurred at or near the base of the Wyoming craton (~200 km). Minimal heating or the introduction of hydrous fluids into the source would be required to induce partial melting. Rapid ascent rates, coupled with slow cooling rates, of the “primary Minette magma” would preserve the high temperature observed in our experiments. At ~58 km, our “primary Minette magma” likely stalled and re-equilibrated with the harzburgite surroundings.
Heinz J. Tobschall - One of the best experts on this subject based on the ideXlab platform.
-
Sr, Nd, Pb and O Isotopes of Minettes from Schirmacher Oasis, East Antarctica: a Case of Mantle Metasomatism involving Subducted Continental Material
Journal of Petrology, 2001Co-Authors: Marion Hoch, Mark Rehkämper, Heinz J. TobschallAbstract:Numerous Minette dykes intersect the Precambrian crystalline baseINTRODUCTION ment of Schirmacher Oasis, East Antarctica. This study presents Minette magmas are generally thought to represent smallnew Sr, Nd, Pb and O isotope data for 11 Minette samples from degree melts that form at depths of >50–150 km within four different dykes. The samples are characterized by relatively the lithospheric mantle. The deep origin of such lamhigh Sr/Sr (0·7077–0·7134), Pb/Pb (15·45–15·55) prophyric magmas is indicated by entrained mantle xenoand Pb/Pb (37·8–39·8), combined with low Nd/Nd liths of spinel peridotite or garnet peridotite composition, ( Nd =−6·5 to−25·1) and variable Pb/Pb (16·8–18·1). and the geochemistry of the magmas (e.g. Rogers et al., The O values are high, ranging from +6·5 to +9·5‰ 1982; Stille et al., 1989; Wyman & Kerrich, 1993; Carlson SMOW. Rb/Sr whole-rock–biotite isochrons suggest an age of & Irving, 1994; Carmichael et al., 1996). Minettes typically >455 Ma for emplacement of the Minette dykes. The major and display intermediate to basic compositions with high compatible element geochemistry of the Minettes indicates derivation contents of MgO, Cr and Ni, and high mg-number. of the magmas from a mantle source. The enriched isotopic and Additionally, however, Minettes are also characterized trace element signatures of the dykes cannot be due to contamination by high concentrations of large ion lithophile elements of the ascending magmas by continental crust. Rather, the geochemical (LILE), particularly Ba, Sr and Rb, and they are enriched characteristics of the Minettes are most reasonably explained by in light rare earth elements (LREE). Thus Minettes display partial melting of a lithospheric mantle source that was enriched high abundances of both compatible and highly inby metasomatic fluids derived from recycled continental crust. If compatible trace elements. This requires the involvement mantle enrichment took place just before dyke emplacement, the of at least two distinct source components for the genisotopic systematics of the Minettes must be inherited directly from eration of Minette magmas: (1) a peridotitic mantle resthe metasomatic agents, and this would indicate derivation of the ervoir and (2) a component enriched in LILE and LREE. fluids from recycled lower continental crust. It is conceivable that the enrichment of incompatible trace elements results from the contamination of the magmas with crustal materials during dyke emplacement.
-
Minettes from Schirmacher Oasis, East Antarctica — indicators of an enriched mantle source
Antarctic Science, 1998Co-Authors: Marion Hoch, Heinz J. TobschallAbstract:Minette dykes intersect the Precambrian crystalline basement of Schirmacher Oasis, East Antarctica. The rocks have intermediate to basic compositions, showing shoshonitic to ultrapotassic character. The samples show enhanced concentrations of compatible elements and high mg# combined with extreme enrichments in LILE (especially Ba) and LREE. Mantle-normalized trace element patterns are characterized by coupled relative depletions of Nb and Ti and strong fractionations between LILE and HFSE. The Minettes display fractionated chondrite-normalized REE patterns with high and varying LREE concentrations in contrast to relative low and nearly constant HREE contents. High magma-ascent and cooling rates of lamprophyric magmas argue against a fundamental change of the primary geochemical signatures in Minette magmas by interactions with the continental crust during ascent. The major and trace element abundances of the studied Minettes point to varying degrees of partial melting of a mantle source, which was enriched in LILE and LREE during or before the melting event. Incompatible element signatures argue for the involvement of subducted pelagic sediments.
Marion Hoch - One of the best experts on this subject based on the ideXlab platform.
-
Sr, Nd, Pb and O Isotopes of Minettes from Schirmacher Oasis, East Antarctica: a Case of Mantle Metasomatism involving Subducted Continental Material
Journal of Petrology, 2001Co-Authors: Marion Hoch, Mark Rehkämper, Heinz J. TobschallAbstract:Numerous Minette dykes intersect the Precambrian crystalline baseINTRODUCTION ment of Schirmacher Oasis, East Antarctica. This study presents Minette magmas are generally thought to represent smallnew Sr, Nd, Pb and O isotope data for 11 Minette samples from degree melts that form at depths of >50–150 km within four different dykes. The samples are characterized by relatively the lithospheric mantle. The deep origin of such lamhigh Sr/Sr (0·7077–0·7134), Pb/Pb (15·45–15·55) prophyric magmas is indicated by entrained mantle xenoand Pb/Pb (37·8–39·8), combined with low Nd/Nd liths of spinel peridotite or garnet peridotite composition, ( Nd =−6·5 to−25·1) and variable Pb/Pb (16·8–18·1). and the geochemistry of the magmas (e.g. Rogers et al., The O values are high, ranging from +6·5 to +9·5‰ 1982; Stille et al., 1989; Wyman & Kerrich, 1993; Carlson SMOW. Rb/Sr whole-rock–biotite isochrons suggest an age of & Irving, 1994; Carmichael et al., 1996). Minettes typically >455 Ma for emplacement of the Minette dykes. The major and display intermediate to basic compositions with high compatible element geochemistry of the Minettes indicates derivation contents of MgO, Cr and Ni, and high mg-number. of the magmas from a mantle source. The enriched isotopic and Additionally, however, Minettes are also characterized trace element signatures of the dykes cannot be due to contamination by high concentrations of large ion lithophile elements of the ascending magmas by continental crust. Rather, the geochemical (LILE), particularly Ba, Sr and Rb, and they are enriched characteristics of the Minettes are most reasonably explained by in light rare earth elements (LREE). Thus Minettes display partial melting of a lithospheric mantle source that was enriched high abundances of both compatible and highly inby metasomatic fluids derived from recycled continental crust. If compatible trace elements. This requires the involvement mantle enrichment took place just before dyke emplacement, the of at least two distinct source components for the genisotopic systematics of the Minettes must be inherited directly from eration of Minette magmas: (1) a peridotitic mantle resthe metasomatic agents, and this would indicate derivation of the ervoir and (2) a component enriched in LILE and LREE. fluids from recycled lower continental crust. It is conceivable that the enrichment of incompatible trace elements results from the contamination of the magmas with crustal materials during dyke emplacement.
-
Minettes from Schirmacher Oasis, East Antarctica — indicators of an enriched mantle source
Antarctic Science, 1998Co-Authors: Marion Hoch, Heinz J. TobschallAbstract:Minette dykes intersect the Precambrian crystalline basement of Schirmacher Oasis, East Antarctica. The rocks have intermediate to basic compositions, showing shoshonitic to ultrapotassic character. The samples show enhanced concentrations of compatible elements and high mg# combined with extreme enrichments in LILE (especially Ba) and LREE. Mantle-normalized trace element patterns are characterized by coupled relative depletions of Nb and Ti and strong fractionations between LILE and HFSE. The Minettes display fractionated chondrite-normalized REE patterns with high and varying LREE concentrations in contrast to relative low and nearly constant HREE contents. High magma-ascent and cooling rates of lamprophyric magmas argue against a fundamental change of the primary geochemical signatures in Minette magmas by interactions with the continental crust during ascent. The major and trace element abundances of the studied Minettes point to varying degrees of partial melting of a mantle source, which was enriched in LILE and LREE during or before the melting event. Incompatible element signatures argue for the involvement of subducted pelagic sediments.
Brian Cousens - One of the best experts on this subject based on the ideXlab platform.
-
Petrology and geochronology of Paleoproterozoic intrusive
2015Co-Authors: J. M. J. Scott, T D Peterson, William J. Davis, C W Jefferson, Brian CousensAbstract:We investigated the age and petrology of Paleoproterozoic granitic intrusions in the area of the Kiggavik uranium exploration camp, near the southeast margin of the Aberdeen subbasin of the Thelon Basin. A subset of these intrusions (e.g., the Lone Gull stock) is spatially associated with and mineralized by basement hosted, unconformity-related uranium deposits. Surface (outcrop) samples have field relations, textures, and compositions consistent with Hudson Suite granitoids and mixtures of monzogranite with Minette. We obtained U-Pb (zircon) ages ranging from ca. 1818 to 1840 Ma, within the known range of the Hudson Suite and cogenetic Minettes of the Baker Lake Group (1.80-1.84 Ga). Core samples of granitic rocks adjacent to mineralized zones are more complex and indicate an influence from the younger Nueltin Granite (Kivalliq Igneous Suite, ca. 1.77-1.73 Ga). One sample from the Lone Gull stock contains two zircon populations in texturally distinctive domains, one at 1806 ± 41 Ma and the other at 1748 ± 9.4 Ma. A porphyritic hypabyssal syenite below the Bong deposit yielded a U-Pb zircon age of 1837.8 ± 7.7 Ma and a U-Pb titanite age of 1758.5 ± 44 Ma. We recognize a Kivalliq-age overprint in the form of metasomatism and partial remelting or melt infiltration in the drill core samples, which is not evident at the surface and is consistent with the presence of a Nueltin Granite intrusive complex at depth. The geochemistry and primary igneous textures of the Bong syenite, including its euhedral zircons, resemble those of lava flows near the base of the Baker Lake Group, and we recognize a mixed magma (i.e., Martell Syenite) continuum between intrusive Hudson granitoids and Minette with extrusive equivalents in the lower felsic Minette member of the Christopher Island Formation.
-
Petrology and geochronology of Paleoproterozoic intrusive rocks, Kiggavik uranium camp, Nunavut
Canadian Journal of Earth Sciences, 2015Co-Authors: J. M. J. Scott, T D Peterson, William J. Davis, C W Jefferson, Brian CousensAbstract:We investigated the age and petrology of Paleoproterozoic granitic intrusions in the area of the Kiggavik uranium exploration camp, near the southeast margin of the Aberdeen subbasin of the Thelon Basin. A subset of these intrusions (e.g., the Lone Gull stock) is spatially associated with and mineralized by basement hosted, unconformity-related uranium deposits. Surface (outcrop) samples have field relations, textures, and compositions consistent with Hudson Suite granitoids and mixtures of monzogranite with Minette. We obtained U–Pb (zircon) ages ranging from ca. 1818 to 1840 Ma, within the known range of the Hudson Suite and cogenetic Minettes of the Baker Lake Group (1.80–1.84 Ga). Core samples of granitic rocks adjacent to mineralized zones are more complex and indicate an influence from the younger Nueltin Granite (Kivalliq Igneous Suite, ca. 1.77–1.73 Ga). One sample from the Lone Gull stock contains two zircon populations in texturally distinctive domains, one at 1806 ± 41 Ma and the other at 1748 ...
-
proterozoic 1 85 1 75 ga igneous suites of the western churchill province granitoid and ultrapotassic magmatism in a reworked archean hinterland
Precambrian Research, 2002Co-Authors: T D Peterson, O Van Breemen, Hamish Sandeman, Brian CousensAbstract:Paleoproterozoic igneous rocks in the Archean hinterland of the Paleoproterozoic Trans-Hudson orogen (THO) consist of voluminous late syn-orogenic to post-orogenic monzonite to granite (Hudson granitoids; ≈1850–1810 Ma), and contemporaneous ultrapotassic lamprophyre dykes and volcanic rocks (Dubawnt Minettes) that are interbedded with alluvial fan and fluvial deposits (Baker Lake Group, lower Dubawnt Supergroup). They were followed at approximately 1750 Ma by rapakivi granite (Nueltin granite) and porphyritic rhyolite associated with aeolian sandstone (Pitz Formation, middle Dubawnt Supergroup). The tectonic cycle ended with the deposition of conglomerates and sandstones in a large sag basin (Thelon Formation, upper Dubawnt Supergroup, ≈1.72 Ga). The Hudson granitoids, which are strongly concentrated northwest of the THO, were broadly synchronous with terminal collision between the Archean Churchill and Superior cratons and the development of NE-trending ductile structures in the Western Churchill Province (WCP) that may be related to tectonic escape to the northeast. They were emplaced at mid-crustal level and no volcanic equivalents are preserved. Fault-bounded basins containing the Minette volcanic rocks are located farther west in a domain dominated more by brittle faulting. The Nueltin granites, emplaced during a period of active extensional faulting, are present in a band extending southwest from the Minette basins toward a preserved remnant of the sag basin (the Athabasca basin). Hudson granitoids are largely absent from this band but reappear west of it, indicating a higher crustal level of exposure in a downdropped Nueltin ‘corridor’. The Nd isotope composition of the three suites is similar (Minettes: eNd,1830 Ma=−5 to −11; Hudson granitoids: eNd,1830 Ma=−7 to −13.5; Nueltin suite: eNd,1750 Ma=−7 to −10.5), and they have late Archean model ages that match those of average Archean WCP rocks. The Hudson granitoids are rich in inherited Archean zircon, and both granitoid suites are interpreted as crustal melts. Some Nueltin granites and Pitz rhyolites are mingled with basalt, and the Nueltin suite fits a commonly cited model for rapakivi granite production, which postulates injection of basalt into extending, brittly faulted crust. The Hudson granitoids are similar to late syn- to post-orogenic plutons in numerous other collisional hinterlands, which are typically associated with ultrapotassic lamprophyres. The Minettes, which have high mg# and bear mantle xenocrysts, must have a mantle source component, and their source region could have been subduction-enriched lithospheric mantle. However, their source had only slightly lower time-integrated LREE enrichment than did that of the granitoids, and the incompatible element signatures of the two suites are strikingly similar. The Minette source region may have been in a zone of mixed crust and upper mantle, formed during a shortening event which resulted in crustal thickening and subsequent melting at mid-crustal layers to form the Hudson granitoid plutons. The generation and emplacement of Minette melts may have been promoted by extension related to a combination of slab breakoff, gravitational collapse of thickened crust, and strike-slip faulting in the deforming hinterland. Subsequent anorogenic rapakivi granite-basalt activity may have been triggered by lithospheric mantle delamination. The hinterland tectonic cycle of the WCP was repeated in other large Archean terranes that were deformed during the early Proterozoic, but the igneous and sedimentary record is unusually complete in the WCP.
-
Proterozoic (1.85–1.75 Ga) igneous suites of the Western Churchill Province: granitoid and ultrapotassic magmatism in a reworked Archean hinterland
Precambrian Research, 2002Co-Authors: T D Peterson, O Van Breemen, Hamish Sandeman, Brian CousensAbstract:Paleoproterozoic igneous rocks in the Archean hinterland of the Paleoproterozoic Trans-Hudson orogen (THO) consist of voluminous late syn-orogenic to post-orogenic monzonite to granite (Hudson granitoids; ≈1850–1810 Ma), and contemporaneous ultrapotassic lamprophyre dykes and volcanic rocks (Dubawnt Minettes) that are interbedded with alluvial fan and fluvial deposits (Baker Lake Group, lower Dubawnt Supergroup). They were followed at approximately 1750 Ma by rapakivi granite (Nueltin granite) and porphyritic rhyolite associated with aeolian sandstone (Pitz Formation, middle Dubawnt Supergroup). The tectonic cycle ended with the deposition of conglomerates and sandstones in a large sag basin (Thelon Formation, upper Dubawnt Supergroup, ≈1.72 Ga). The Hudson granitoids, which are strongly concentrated northwest of the THO, were broadly synchronous with terminal collision between the Archean Churchill and Superior cratons and the development of NE-trending ductile structures in the Western Churchill Province (WCP) that may be related to tectonic escape to the northeast. They were emplaced at mid-crustal level and no volcanic equivalents are preserved. Fault-bounded basins containing the Minette volcanic rocks are located farther west in a domain dominated more by brittle faulting. The Nueltin granites, emplaced during a period of active extensional faulting, are present in a band extending southwest from the Minette basins toward a preserved remnant of the sag basin (the Athabasca basin). Hudson granitoids are largely absent from this band but reappear west of it, indicating a higher crustal level of exposure in a downdropped Nueltin ‘corridor’. The Nd isotope composition of the three suites is similar (Minettes: eNd,1830 Ma=−5 to −11; Hudson granitoids: eNd,1830 Ma=−7 to −13.5; Nueltin suite: eNd,1750 Ma=−7 to −10.5), and they have late Archean model ages that match those of average Archean WCP rocks. The Hudson granitoids are rich in inherited Archean zircon, and both granitoid suites are interpreted as crustal melts. Some Nueltin granites and Pitz rhyolites are mingled with basalt, and the Nueltin suite fits a commonly cited model for rapakivi granite production, which postulates injection of basalt into extending, brittly faulted crust. The Hudson granitoids are similar to late syn- to post-orogenic plutons in numerous other collisional hinterlands, which are typically associated with ultrapotassic lamprophyres. The Minettes, which have high mg# and bear mantle xenocrysts, must have a mantle source component, and their source region could have been subduction-enriched lithospheric mantle. However, their source had only slightly lower time-integrated LREE enrichment than did that of the granitoids, and the incompatible element signatures of the two suites are strikingly similar. The Minette source region may have been in a zone of mixed crust and upper mantle, formed during a shortening event which resulted in crustal thickening and subsequent melting at mid-crustal layers to form the Hudson granitoid plutons. The generation and emplacement of Minette melts may have been promoted by extension related to a combination of slab breakoff, gravitational collapse of thickened crust, and strike-slip faulting in the deforming hinterland. Subsequent anorogenic rapakivi granite-basalt activity may have been triggered by lithospheric mantle delamination. The hinterland tectonic cycle of the WCP was repeated in other large Archean terranes that were deformed during the early Proterozoic, but the igneous and sedimentary record is unusually complete in the WCP.