At least 105% nearly east-west extension of late Cenozoic age has been accommodated by down-to-the-east normal and oblique-slip faults in the central Wassuk Range. One northwest striking, right-lateral strike-slip fault probably contributes an additional component of WNW-ESE slip. Movement on the normal and oblique-slip faults in this area tilt the...
The Tobin Range of central Nevada lies in the Basin and Range extensional province near the transition between more extended terrane (>50%) to the south and east, and generally less extended terrane to the north and west. Geologic mapping, 40Ar/39Ar dating and whole-rock geochemical analysis were employed to establish the...
Periodic violent eruptions from many different centers during Cenozoic time deposited vast quantities of pyroclastic material as ash-flow tuffs over most of Oregon, although the Coast Ranges and isolated patches elsewhere in the state appear to have been spared these recurring inundations. Eruptions occurred at different times throughout the Cenozoic,...
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...