Suture-zone geometry along an irregular Paleoproterozoic margin; the Superior boundary zone, Manitoba, Canada
Suture-zone geometry along an irregular Paleoproterozoic margin; the Superior boundary zone, Manitoba, Canada
Geology (Boulder) (August 2002) 30 (8): 735-738
- boundary conditions
- Canada
- Canadian Shield
- continental lithosphere
- continental margin
- cratons
- crust
- decollement
- deep seismic sounding
- geometry
- geophysical methods
- geophysical profiles
- geophysical surveys
- Hudsonian Orogeny
- imbricate tectonics
- Kisseynew Complex
- Lithoprobe
- lithosphere
- Manitoba
- mantle
- North America
- orogenic belts
- orogeny
- Paleoproterozoic
- plate collision
- plate tectonics
- Precambrian
- Proterozoic
- reflection methods
- Reindeer Zone
- seismic methods
- seismic profiles
- subduction
- Superior Province
- surveys
- suture zones
- tectonics
- Thompson nickel belt
- upper mantle
- upper Precambrian
- Western Canada
Lithoprobe acquired a 190-km-long deep seismic reflection profile across the Superior boundary zone at the eastern margin of the Paleoproterozoic Trans-Hudson orogen. The profile is located approximately 250 km south of a major promontory along the ancient margin of the Superior craton and complements earlier profiles closer to the promontory. The new data image the remnants of a craton-verging thrust belt, younger than 1864 Ma, within the Superior boundary zone extending to a maximum depth of 15 km above a shallowly west dipping basal decollement. Across the surface suture zone, a dip reversal to east-dipping reflections occurs within the adjacent Reindeer zone, where a crustal-scale imbricate stack is imaged. Reindeer zone lower crust and upper mantle extend eastward beneath the Superior craton margin for 40-100 km. Preservation of a foreland thrust belt within the Superior boundary zone is explained as a result of reduced collisional convergence and subsequent exhumation within a reentrant flanking the Thompson promontory.