Deep crustal structure and tectonic history of the Northern Kapuskasing Uplift of Ontario: An integrated petrological‐geophysical study

Percival, John A.; McGrath, Peter

doi:10.1029/tc005i004p00553

Cited by 115 publications

(40 citation statements)

References 31 publications

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“…We suggest that this structure is analogous to the Kapuskasing uplift in the central Superior province. Thought to be a result of Trans-Hudson orogen compression, this structure consists of mid-to lower crustal rocks that have been brought to the surface (Percival and McGrath, 1986;Clowes et al, 1992;Cook and Varsek, 1994). Another analogous location may be in the Athabasca terrane to the north, in the western Churchill province of central Canada, where the lower crust of the Rae domain was thrust above the middle crustal rocks of the Hearne domain during the early stages of the Trans-Hudson Orogeny (Williams and Hanmer, 2006;Dummond et al, 2008).…”

Section: Wy-superior Suture Zonementioning

confidence: 93%

PdS receiver function evidence for crustal scale thrusting, relic subduction, and mafic underplating in the Trans-Hudson Orogen and Yavapai province

Thurner

Margolis

Levander

et al. 2015

Earth and Planetary Science Letters

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The Trans-Hudson Orogen (THO) in the north central United States represents a major suturing event between the Wyoming and Superior Archean provinces. It is bounded to the south by the NE-SW striking Yavapai province, which was accreted along the southeastern margin of North America between 1.71 and 1.68 Ga and was one of a series of major collisional events responsible for the assembly of Laurentia. In this study, PdS teleseismic receiver functions were used to investigate the deep crustal structure associated with these collisions. Using data from over 800 broadband seismic stations distributed throughout the Great Plains/Midcontinent region, we calculated 0.5 Hz receiver functions using 245 M > 6.0 teleseismic events. The receiver functions were then CCP (common conversion point) stacked to create a 3D image volume. Profiles through this image volume show evidence of crustal scale thrusting of the Wyoming province in the west over the Superior province in the east and a relic subduction zone associated with the Yavapai-Superior boundary. We also performed a density analysis of the region using relative amplitude of the 2p1s and 0p1s receiver function phases from 233 stations. These data indicate a relatively low Moho density contrast throughout the THO and northern Yavapai Province associated with a region of thickened crust (>50 km), which we interpret to be evidence of a dense lower crustal layer that is the result of mafic underplating.

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Section: Wy-superior Suture Zonementioning

confidence: 93%

PdS receiver function evidence for crustal scale thrusting, relic subduction, and mafic underplating in the Trans-Hudson Orogen and Yavapai province

Thurner

Margolis

Levander

et al. 2015

Earth and Planetary Science Letters

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“…1983Sills, 1984Sills, 1984Jan & Howie, 1981Hansen el al. 1987Chacko, Ravindra Kumar & Newton 1987Percival & McGrath, 1986Percival & McGrath, 1986Krogh, 1980Ackermand, Lai & Siefert, 1988 comm.) Windley, Ackermand & Herd, 1984Harris & Holland, 1984Van Reenen el al.…”

Section: B Distributionmentioning

confidence: 94%

The origins of granulites: a metamorphic perspective

1989

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Although many recent reviews emphasize a uniformity in granulite pressure-temperature (P-T) conditions and paths, granulites in reality preserve a spectrum of important petrogenetic features which indicate diversity in their modes of formation. A thorough survey of over 90 granulite terranes or occurrences reveals that over 50% of them record P-Tconditions outside the 7.5+ 1 kbar and 8OO + 5O°C average granulite regime preferred by many authors. In particular, an increasing number of very high temperature (900-1000 °C) terranes are being recognized, both on the basis of distinctive mineral assemblages and geothermobarometry. Petrogenetic grid and geothermobarometric approaches to the determination and interpretation of P-T histories are both evaluated within the context of reaction textures to demonstrate that the large range in P-Tconditions is indeed real, and that both near-isothermal decompression (ITD) and near-isobaric cooling (IBC) P-T paths are important. Amphibolite-granulite transitions promoted by the passage of CO 2 -rich fluids, as observed in southern India and Sri Lanka, are exceptional and not representative of fluid-related processes in the majority of terranes. It is considered, on the contrary, that fluid-absent conditions are typical of most granulites at or near the time of their recorded thermal maxima.ITD granulites are interpreted to have formed in crust thickened by collision, with magmatic additions being an important extra heat source. Erosion alone is not, however, considered to be the dominant post-collisional thinning process. Instead, the ITD paths are generated during more rapid thinning (l-2mm/yr exposure) related to tectonic exhumation during moderate-rate or waning extension. IBC granulites may have formed in a variety of settings. Those which show anticlockwise P-T histories are interpreted to have formed in and beneath areas of voluminous magmatic accretion, with or without additional crustal extension. IBC granulites at shallow levels ( < 5 kbar) may also be formed during extension of normal thickness crust, but deeper-level IBC requires more complex models. Many granulites exhibiting IBC at deep crustal levels may have formed in thickened crust which underwent very rapid (5 mm/yr) extensional thinning subsequent to collision. It is suggested that the preservation of IBC paths rather than ITD paths in many granulites is primarily related to the rate and timescale of extensional thinning of thickened crust, and that hybrid ITD to IBC paths should also be observed.Most IBC granulites, and probably many ITD granulites, have not been exposed at the Earth's surface as a result of the tectonic episodes which produced them, but have resided in the middle and lower crust for long periods of time (100-2000 Ma) following these events. The eventual exhumation of most granulite terranes only occur through their incorporation in later tectonic and magmatic events unrelated to their formation.

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“…A strong positive-gravity anomaly is located over the Chapleau and Fraserdale-Moosonee Blocks coextensive with a positive aeromagnetic anomally (Percival & McGrath 1986). The Groundhog River Block is characterized by a strong positive magnetic anomaly, but the gravity high ocurs further to the west.…”

Section: Geologymentioning

confidence: 95%

“…The highest grade rocks in the KU are somewhat older than 2765 Ma for which peak metamorphic conditions are estimated at 6 to 8kb and temperatures of 700-800 "C (Percival 1983). Percival & McGrath (1986) refer to the linear north-northeast belt of geophysical anomalies and granulites as the Kapuskasing zone while the entire region of low-to-high grade metamorphic transition is termed the Kapuskasing Uplift (Fig. 1).…”

Section: Geologymentioning

confidence: 99%

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The conductivity of the crust and mantle beneath the Kapuskasing Uplift: electrical anisotropy in the upper mantle

Kurtz

Craven

Niblett

et al. 1993

Geophysical Journal International

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S U M M A R YThe Kapuskasing Uplift has been interpreted as an oblique cross-section of up to 25km of crust and thus provides the opportunity to examine the properties of exposed mid-to lower-crustal material. A magnetotelluric (MT) survey mapped a remarkably uniform upper crust and provided no evidence for upper crustal conductive zones that could be related to the often observed increase in mid and lower crustal conductivity. The only shallow conductive anomaly is related to the Ivanhoe Lake Cataclastic Zone but its electrical signature does not appear to extend more than one kilometer in depth.A regional apparent resistivity curve was determined from MT data and confirmed by subsequent controlled source electromagnetic surveys. Regional curves are essential for proper structural interpretation but are often difficult to determine because of electric field distortions. The data show a decrease in resistivity at depths below 15 km which is typical of continental crust in many areas of the world.There is a clear difference in orthogonal apparent resistivity and phase curves at periods greater than 10s which is most pronounced in a N65"E and N25"W coordinate frame. Two different models are proposed to explain the data. The first consists of a conducting 2-D slab of approximately 50 km width in the lower crust and striking N65"E. The strike direction is consistent with a number of regional structural trends but there is no other direct supporting evidence for it. The second model invokes either micro or macro electrical anisotropy in the upper mantle. There is considerable evidence for seismic anisotropy in the region. The electrical anisotropy could be the result of preferential conduction along the c-axis of olivine crystals, hydrogen dissolved in the olivine lattice with preferential conduction along the a-axis, or possible alignment of dykes, joints and faults in the upper mantle. If the anisotropy is related to strain induced orientations of crystals or fabric, it will provide evidence for the motions of the mantle associated with plate tectonics.

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Deep crustal structure and tectonic history of the Northern Kapuskasing Uplift of Ontario: An integrated petrological‐geophysical study

Cited by 115 publications

References 31 publications

PdS receiver function evidence for crustal scale thrusting, relic subduction, and mafic underplating in the Trans-Hudson Orogen and Yavapai province

PdS receiver function evidence for crustal scale thrusting, relic subduction, and mafic underplating in the Trans-Hudson Orogen and Yavapai province

The origins of granulites: a metamorphic perspective

The conductivity of the crust and mantle beneath the Kapuskasing Uplift: electrical anisotropy in the upper mantle

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