Improved interpretation of Kapuskasing crustal reflection data by selection of the most effective reprocessing sequences

Hajnal, Z.; Scott, D. H.; Pandit, B.; Reilkoff, B.; West, G. F.

doi:10.1029/gd022p0417

Cited by 1 publication

(1 citation statement)

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“…netic susceptibility of the rocks presently exposed [Gaucher, 1966]. According to Bennett [1969] interpretation of Percival and Card [1983,1985] Hajnal et al [1991] shows no such high replanar fabric of >45 ø, since the ILFZ is a steep fault near fiectivity within the fault zone, indicating that the difference the surface. is unlikely to be due to inadequate processing.…”

Section: Every Raw Shot Gather Was Visually Inspected On Our Sunmentioning

confidence: 99%

Crustal structure of the Kapuskasing uplift from Lithoprobe Near‐vertical/wide‐angle seismic reflection data

Wu¹,

Mereu²

1992

J. Geophys. Res.

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Reprocessing of one LITHOPROBE Kapuskasing deep seismic reflection profile discloses significant new information on the structure of the Kapuskasing Uplift (KU). The shallow structure of the Ivanhoe Lake fault zone (ILFZ), along which the high‐grade granulites of the KU were thrust to the surface, is conspicuously imaged on a seismic section as a series of prominent northwest‐dipping reflections with listric geometry. The new images show that the ILFZ is a steep fault (∼50°) near the surface which quickly flattens out at shallow depths. These reflections coincide with bright positive aeromagnetic anomalies over the fault zone. Direct correlation with geological observations indicates that the high reflectivity and high magnetism associated with the fault zone likely originate from mylonites. The reprocessing also reveals a pronounced midcrustal reflector within the Abitibi greenstone belt (AGB), dipping northwest and plunging under the KU. The existence of such a reflector is independently confirmed by wide‐angle reflection data acquired from a cross‐profile. This reflector is apparently also detected on two other reflection profiles crossing the ILFZ about 80 km to the southwest. Its concave‐down shape and broad lateral extent suggest that it represents underthrusting of the AGB beneath the KU. With these new results, a more complete structural cross‐section can be constructed. It shows that, on the northwest side, the KU was overthrust along the northwest‐dipping ILFZ and, on the southeast side, the AGB was underthrust northwesterly. It seems evident that the KU is a product of intraplate collision during the early Proterozoic and the underthrusting of the AGB is primarily responsible for the emplacement of the KU.

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Section: Every Raw Shot Gather Was Visually Inspected On Our Sunmentioning

confidence: 99%