Calibration of the in situ cosmogenic 14C production rate in New Zealand's Southern Alps

In situ cosmogenic ¹⁴C (in situ ¹⁴C) analysis from quartz‐bearing rocks is a novel isotopic tool useful for quantifying recent surface exposure histories (up to ～25 ka). It is particularly powerful when combined with longer‐lived cosmogenic isotopes such as ¹⁰Be. Recent advances in the extraction of in situ ¹⁴C from quartz now permit the routine application of this method. However, only a few experiments to calibrate the production rate of in situ ¹⁴C in quartz have been published to date. Here, we present a new in situ ¹⁴C production rate estimate derived from a well‐dated debris flow deposit in the Southern Alps, New Zealand, previously used to calibrate ¹⁰Be production rates. For example, based on a geomagnetic implementation of the Lal/Stone scaling scheme we derive a spallogenic production rate of 11.4 ± 0.9 atoms ¹⁴C (g quartz)^?1 a^?1 and a ¹⁴C/¹⁰Be spallogenic production rate ratio of 3.0 ± 0.2. The results are comparable with production rates from previous calibrations in the northern hemisphere. Copyright © 2012 John Wiley & Sons, Ltd.