Oligocene-Miocene rocks of the Brechin Burn outlier, Waimakariri valley, Canterbury

Abstract

A varied succession of Oligocene and Miocene, clastic, volcanic, and carbonate rocks form an outlier in Brechin Bum, a tributary of Esk River, northwestern Canterbury, New Zealand. Oligocene and Miocene strata are separated by an angular unconformity. The Oligocene rocks reflect high-energy marginal marine, shelf, and low-energy marine environments. The Miocene unit comprises marine to regressive fluviatile rocks. Both units are unconformity bounded sheets of sediment, representing discrete transgressive/regressive cycles.

Keywords:

• stratigraphy
• Canterbury
• Oligocene
• Miocene
• Esk Fault zone
• sedimentary cycles
• unconformities
• Esk Formation
• Brechin Formation