Figure 11.

Backscatter electron images showing locations of in situ ⁴⁰Ar/³⁹Ar spot analyses. (a) High‐angle white mica “fans” preserves late Oligocene dates, whereas foliation‐defining mica records late Oligocene to early Miocene dates. (b) Discrete patches of phengite and paragonite in EV22‐07 defining a single foliation yield late Oligocene dates within error of one another. Phengite in high‐angle fans yields late Eocene dates. (c) Strain shadow preserving and early Oligocene date among foliation‐defining white mica recording late Oligocene to early Miocene dates. (d) Coarse, blocky mica in EV22‐03 overgrowing albite yield late Oligocene to early Miocene dates. Foliation in this sample has disseminated Fe‐oxides and produces scattered late Eocene and older dates. (e, f) Sample EV22‐14.5 exhibits mica microlithons with a spaced crenulation cleavage. Crenulated mica yields early to late Oligocene dates, whereas mica neoblasts intergrown with chlorite provided late Oligocene to early Miocene dates.