| Popis: |
The Sudbury Basin is a unique, regional geologic and geomorphologic feature situated on the southern Canadian Shield at the nexus of three geological provinces and three physiographic zones. Its broad form is attributable to its meteorite impact origin (1,850 Ma) and subsequent northwestward directed stresses and deformation during the Penokean Orogeny. The main basin measures 27 km × 60 km with its structural axis aligned northeast-southwest. The basin floor is generally flat and gently sloping toward the southwest due in part to impact/fallback processes and subsequent Precambrian sedimentation, and in part due to more recent Quaternary infilling. The basin rim and surrounding uplands rise to more than 150 m above the basin floor and exhibit a much more rugged topography, numerous lakes and largely deranged drainage patterns. The basin was covered by Laurentide/Labrador ice during the late Wisconsinan and influenced flow rate and direction at least during deglaciation. The basin also acted as a pinning point for the retreating Wisconsinan ice and a low area making up, for a time, an embayment of glacial Lake Algonquin. As a result, a wide range of glacial, glacilacustrine and meltwater-related landforms and deposits are represented in the area despite the relative paucity of surficial materials characteristic of much of the Canadian Shield. The geology and landforms of the area have strongly influenced human settlement based on logging, agriculture and especially mining of the Cu- and Ni-rich ores of the Sudbury Structure. In turn, human activity has left an indelible mark on over 1000 km2 of the landscape through contamination and acidification of soils, severe vegetation damage or loss, altered hydrology, and enhanced weathering, erosion and sediment redistribution in some areas. |
