The Early Oligocene Oregon Coast Range Intrusions (OCRI) consist of gabbroic rocks and lesser alkalic intrusive bodies that were emplaced in marine sedimentary units and volcanic sequences within a Tertiary Cascadia forearc basin. The alkalic intrusions include nepheline syenite, camptonite, and alkaline basalt. The gabbros occur as dikes and differentiated...
Eleven sedimentary and volcanic rock units are mapped and described in the thesis area, and chronicle the dynamic geologic history of the Tillamook embayment from the Oligocene through the middle Mlocene. The
oldest unit is the Zemorrian to early Saucesian Smuggler Cove formation, a bathyal tuffaceous mudstone with some thin-...
An ancient delta complex is partly recorded by the upper seven
formations of the Cretaceous Nanaimo Group exposed on Mayne and
Samuel Islands of southwestern British Columbia. Features especially
suggestive of deltaic sedimentation here are: upward-coarsening
marine to fluvial sequences, cyclic repetition of facies, subaqueous
slumping, fluvial-marine interfingering, facies changes,...
There are seven stratigraphic units exposed in the Picture
Gorge quadrangle, a 204-square mile area in east-central Oregon.
isolated exposures of pre-Cretaceous serpentinites, metalimestones,
and other metamorphic rocks record marine deposition
of sands silts, and limy sediments followed by burial, lithification,
peridotite intrusion, and several periods of deformation. Intrusion
and...
