The Haughton Impact Structure,Devon Island,Canada: Setting and History of Investigations |
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| Authors: | P Blyth Robertson |
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| Abstract: | Abstract— Although mapped initially as a piercement dome, subsequent discovery of shock metamorphism in clasts of an impact breccia, shatter cones in outcrops of uplifted target rocks and morphological and geophysical characteristics consistent with a complex crater, confirmed a meteorite impact origin for the Haughton structure, Devon Island. Results of three field investigations carried out prior to 1984 defined a complex crater, 20 km in diameter, formed in a lower Paleozoic sedimentary sequence overlying gneisses of the Precambrian basement. The distribution of allochthonous breccia overlying the disturbed target rocks and of the sediments deposited in the crater-filling lake were mapped. A Miocene or possibly Holocene age for the crater was based on paleo-flora and fauna assemblages from the lake sediments. Gravity and magnetic surveys revealed anomalies coincident with the crater, but not interpretable from surface lithologies. Some of the early investigations were of a reconnaissance nature and results and interpretation can only be considered preliminary. Other studies that were carried out in some detail, petrographic investigations in particular, require complementary work for a fuller understanding of their significance. As a result, in 1984 the HISS (Haughton Impact Structure Studies) group carried out a program of detailed geological mapping and sampling, and seismic, gravity, and magnetic surveys in an attempt to improve the definition of the surface and subsurface nature of Haughton, and to formulate a more complete understanding of its formation and subsequent history. Results of these various studies are presented in the eight succeeding papers of this volume. |
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