Geology and thermotectonic evolution of the western margin of the Trans-Hudson Orogen: evidence from the eastern sub-Athabasca basement, Saskatchewan

Citations Over TimeTop 17% of 2005 papers

Abstract

In the Cree Lake Zone of northern Saskatchewan, reworked Archean orthogneisses are overlain by a highly deformed supracrustal sequence, the Paleoproterozoic Wollaston Group. This package of rocks was deformed and metamorphosed during the ca. 1.8 Ga continent–continent collision of the Trans-Hudson Orogen (THO), forming the Wollaston fold–thrust belt that underlies the eastern Athabasca Basin. The Hudsonian structural, metamorphic, and magmatic evolution of the Wollaston fold-thrust belt in the eastern Athabasca area involved six major stages. (1) Early collisional stage, D P1 at 1860–1835 Ma, involved burial of Wollaston Group metasediments from surface to depths equivalent to 3–5vkbar (1 kbar = 100 MPa) by thrust-pile stacking or imbrication tectonics, prograde metamorphism with garnet growth and development of early leucosomes, and emplacement of ca. 1840 Ma grey granite suite. (2) Collisional stage, D P2a at 1835–1820 Ma, involved continued deeper burial of Wollaston Group metasediments along a prograde P–T–t (pressure–temperature–time) path at depths equivalent to peak pressures of 6–9 kbar and approaching peak temperatures (750–825 °C), mafic magma underplating in the lower crust, initiation of large-scale crustal melting, emplacement of 1835–1820 Ma tholeiitic to calc-alkaline intrusions, and initiation of strike-slip tectonics. (3) Oblique collisional stage, D P2b at 1820–1805 Ma, involved strong transpressional tectonics with NE–SW shearing and NW–SE shortening, partitioned high-strain ductile flow, kilometre-scale fold development, initiation of exhumation, attainment of peak temperatures (750–825 °C), and essentially isothermal decompression with decompressional melting and intrusion of the main pulse of leucogranites and granitic pegmatites. (4) Late oblique collisional stage, D P3 at 1805–1775 Ma, caused development of amphibolite-facies dextral strike-slip shear zones and retrograde movement of older shear zones. It included apparent rotation of the main shortening axis and development of accommodation features due to vertical uplift (i.e., extension). (5) Post-collisional stage, D P4 at 1775–1760 Ma, involved continued localized adjustments along an essentially isobaric cooling path and produced NNE-trending, sinistral, oblique-slip reverse faults with reactivation of older shear zones. (6) Late post-collisional stage, D P5, produced north- to northwest-trending sinistral faults, including the Tabbernor fault system. Extension and tectonic extrusion during D P4 and D P5 were significant and resulted in orogenic collapse and formation of the Athabasca Basin at ca. 1750–1680 Ma.

Related Papers

• → Structural styles and regional tectonic setting of the “Gela Nappe” and frontal part of the Maghrebian thrust belt in Sicily(1999)107 cited
• → Metamorphism and crustal stacking in the North Indian Plate, North Pakistan(1989)61 cited
• → Kinematics and geochronology of Early Cretaceous thrusting in the northwestern paleozoic of Graz (Eastern Alps)(1988)19 cited
• → CRUSTAL ANATEXIS AND GRANITE GENESIS IN THE SOCORRO-GUAXUPÉ THRUST NAPPE, SOUTHEASTERN BRAZIL: SOME CONSTRAINTS FROM ELEMENTAL GEOCHEMISTRY(1997)7 cited
• → Re-imbrication of the Hawasina allochthons in the Sufrat ad Dawh range, Oman Mountains(1987)11 cited