The Quaternary Sedimentology of the Severn River area, Hudson Bay Lowlands

Abstract

<p>Quaternary sediments exposed in the banks of the Severn River, Hudson Bay Lowlands, are interpreted as components of four distinct types of depositional complexes. Overconsolidated massive diamicts displaying strong clast fabric orientations and containing channelized, sub-glacial fluvial deposits and glacially shaped clasts, comprise the majority of sediments in the study area. These are interpreted as components of a lodgement till complex. Thin massive diamict units which often display random clast fabric orientations, and laminated fine-grained sediments containing dropstones and diamict clots often occur near the tops of sections. These are interpreted as components of either a glacio-lacustrine or glacio-mairne depositional complex is composed of fossiliferous beach contained in the sediments. An uniquely marine complex, depending on the abundances of formainifera depositional gravels, and estuarine silts and sands. This complex is found only at the very tops of sections, and was probably deposited in the post-glacial Tyrrell Sea. Three distinct ice flow orientations were defined by clast fabric analysis, and measurement of striations on boulder combining these pavements and bedrock surfaces. Three separate lodgement till complexes are identifiedby combining ice flow orientations with data on formainifera abundances, erratic clast lithologies and diamict matrix colours. These lodgement complexes were deposited by ice flowing from three separate ice domes; an earlier Patrician dome, a middle James Bay dome and a younger New Quebec dome.</p>