Abstract

The Apollo structure of Torfino Basin, Vancouver Island continental shelf, represents a gentle fold that developed within Neogene marine mudstones and siltstones during the Pleistocene. Interpretations derived from side-scan sonar, single and multichannel seismic, and 3.5 kHz profiles, in addition to observations made during submersible traverses as well as lithostratigraphic and biostratigraphic information from dart cores and the Shell Anglo Apollo J-14 well, provide the basis for a structural and kinematic analysis of the structure.At the surface the structure is expressed as a curvilinear anticline, the axis of which is offset by a left-lateral wrench fault. Rotated conjugate left-lateral and minor right-lateral shears developed from the main wrench and dislocate strata within the structure's core. The anticline developed above a shallow detachment surface enclosed within the Neogene and Pleistocene successions. Motion along this surface was possibly induced by earthquake activity associated with the Nootka Fault and thus the structure possibly represents the effects of a gravitational slide.

You do not currently have access to this article.