ERTH 2415 Lecture Notes - Lecture 14: Subduction, Gravimeter, Inuktitut
27 Mar 2018
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Document Summary
Shatter cone: a conical fragment of host rock fractured by the shock wave generated by the impact, striations radiating from the apex, terrestrial rock. Simple craters: small impactor -> simple crater, diameter < 5km, raised rim, concave bottom without a central uplift, meteorites might be found. Complex craters: large impactor -> complex crater, diameter > 5km, collapsed rim, central uplift, no meteorites. 160 impact craters in the world: uneven distribution. 25 impact craters in canada: large territory, rocks of the canadian precambrian shield unchanged over a long period of time, long history of catering, craters are preserved. Why have no craters been found in the rockies: rocks are younger than those of continental interior, rocks are being destroyed by subduction, rocks are buried under lava flows. 3 ma: largest and oldest impact crater in canada, heavily deformed by regional movements along faults, originally: complex circular crater, present day: elliptical structure, site of world famous nickel, copper and platinum deposits.
