study of the depositional environments of the halfway formation, british columbia, canada
abstract
the upper sands of the discontinuous halfway formation
to the northeast of fort st. john were formed as barrier
islands deposited perpendicular,or nearly perpendicular to
the dip of the paleoslope of the western canadian
sedimentary basin. these upper sands of the area of study
were deposited during a transgressive phase of the triassic
sea to the northeast,and formed the basal unit of an
onlapping sequence comprising the halfway and the charlie
lake formations that disconformably overstepped the
erosional surface on the silty dolomite of the doig
formation. the weasel sand body was deposited during a
pause in the transgression,and then was submerged by a rapid rise in sea level. the wildmint to beatton barrier islands
trend was deposited during a second pause in the
transgression.these barrier islands would appear to have
been deposited under arid conditions resulting in restricted
lagoonal environments. the lower sands of the discontinuous
halfway formation which only occur at a few locations in
southern willow and wildmint ,would appear to have resulted
from tidal inlet action that eroded channels into the doig
formation below the base of the upper sands forming the
barrier island complex. these later were filled with sand. then this barrier island trend was submerged by renewed
transgression of the triassic sea.the source of the
sediments comprising the discontinuous halfway formation
probably was to the north and northeast of the area of
study.
collections
- retrospective theses [1604]