Cenozoic plate boundary evolution in the South Island of New Zealand: New thermochronological constraints

摘要: [1] Thermochronological investigations of samples collected west the Alpine Fault zone provide new insight into early development Australian-Pacific (AUS-PAC) plate boundary through New Zealand that is not preserved elsewhere in modern orogenic system South Island. The 40Ar/39Ar, fission track, and (U-Th)/He ages for these span Cenozoic direct constraints on timing character two discrete episodes evolution this tectonic boundary. initial propagation AUS-PAC Island Miocene expressed as short-lived, geographically localized cooling, which we infer to be due exhumation, beginning at 23–25 Ma. This consistent with an initially distributed deformation, progressively localizing onto fault structures developing primacy strain accommodation over time. Regionally synchronous rapid cooling 8 Ma corroborates association present obliquely convergent a marked change Pacific motion Subsequent increases rate regionally prominent 5 thermochronologic signal illuminate progressive adaptation period ∼3 Myr, culminating extant regime.