Hudson Platform – Introduction

Abstract Hudson Platform, in the central part of the Canadian Shield, covers an area of 971 250 km. Its margins have been greatly eroded, so that most of its sedimentary cover now resides in two linked cratonic basins, Hudson Bay Basin and Moose River Basin. Most of this area is covered by water of Hudson and James bays (608 650 km2). Onshore in the south, parts of the platform form Hudson Bay Lowland (323 750 km2) and in the north, Southampton, Coats, and Mansel islands form Southampton Plain (38 850 km2). A northeast-trending positive area, Cape Henrietta Maria Arch (Sanford et al., 1968; the Patricia Arch of Nelson and Johnson, 1966) divides Hudson Platform into two Phanerozoic sedimentary basins, Moose River Basin in the southeast and Hudson Bay Basin in the northwest (Fig. 7.1, 7.2). These basins are largely defined by post-Devonian movements; their largely common histories involve periods in which they were depocentres alternating with periods in which they were parts of a vast, undifferentiated platform. Thus, the two basins are in part depocentres, in part syndepositional and post-depositional structural basins, and in part basins of preservation. The most reliable thickness measurements are those based on drilling. In Moose River Basin, which developed within the platform somewhat later than Hudson Bay Basin, Ordovician, Silurian, Devonian, Middle Jurassic, and Lower Cretaceous rocks have a total thickness of about 760 m in the central part.