robert c. sim hbsc thesis abstract

the geology of the thunder bay area exhibits a sequence of flat-lying proterozoic aphebian sedimentary rocks essentially free from tectonic deformation.  these unconformably overly the archean metamorphic rocks.

within the proterozoic sequence lies a pronounced, thin, stratiform lapilli tuff.  the tuff comprises crystal fragments, pumice fragments as well as accretionary lapilli and lapilli of other origins.

there has been a strong post-depositional compaction.  this was recognized from shape (strain) analysis of the accretionary lapilli and from the shape and orientation of the magnetic susceptibility ellipsoid.  a preliminary paleomagnetic investigation indicates a paleolatitude of the time of sedimentation (or diagenesis) of about 66°.