Extension across the Eocene Okanagan crystal shear in southern British Columbia

Fission-track evidence for Cenozoic uplift of the Nelson batholith, southeastern British Columbia

“…The high-grade metamorphic core complexes in southern British Columbia and northeastern Washington have been shown to be bounded by shallowly dipping brittle-ductile mylonite zones that were the locus of significant extension (Cheney 1980;Rhodes and Cheney 1981;Harms 1982;Harms and Price 1983;Corbett and Simony 1984;Tempelman-Kluit and Parkinson 1986;Can-et al 1987;Parrish et al 1988). Extension is tightly constrained to Eocene time by intrusive cross-cutting relations with the mylonites and by dates of the mylonites (Rhodes and Cheney 1981;Harms 1982;Harms and Price 1983;Corbett and Simony 1984;Tempelman-Kluit and Parkinson 1986;Carr et al 1987;Parrish et al 1988).…”

“…Extension is tightly constrained to Eocene time by intrusive cross-cutting relations with the mylonites and by dates of the mylonites (Rhodes and Cheney 1981;Harms 1982;Harms and Price 1983;Corbett and Simony 1984;Tempelman-Kluit and Parkinson 1986;Carr et al 1987;Parrish et al 1988). Eocene extension was accompanied by significant amounts of uplift, resulting in the tectonic denudation of high-grade metamorphic terranes.…”

“…Geologic setting Although it has long been known that southeastern British Columbia was tectonically active during the Tertiary (Ewing 1981), it is only recently that large-scale Early and Middle Eocene normal faulting in the area has been recognized (Price 1979;Hams and Price 1983;Lane 1984;Tempelman-Kluit and Parkinson 1986;Carr et al 1987;Parrish et al 1985bParrish et al , 1988. In particular, many of the faults bounding the metamorphic core complexes in southeastern British Columbia and northern Washington have been shown to have significant normal displacement in Eocene time.…”

“…For the period from 40 to 20 Ma, the sample cooled approximately 70°C from the closure temperature of zircon (175°C) to the closure temperature of apatite (105"), yielding an average cooling rate of 3.5"C Ma-'. Cooling rates during Eocene time were much higher (15°C Ma-') and were the result of rapid uplift during I that time (Archibald et al 1984;Parrish 1984;Oblitch 1985;Hamson 1985;Parkinson 1985;Tempelman-Kluit and Parkinson 1986;Carr et al 1987;Pamsh et al 1988).…”

Eocene sedimentation and volcanism in the Fig Lake Graben, southwestern British Columbia

“…In the last few years, Eocene extension of southern British Columbia has become an important theme in the literature (e.g., Monger 1985;Bardoux 1985;Parrish et al 1985;Tempelman-Kluit and Parkinson 1986;Carr et al 1987;Brown and Journeay 1987;. J.…”