Assessing the potential of luminescence dating for fault slip rate studies on the Garlock fault, Mojave Desert, California, USA

Belinda J. Roder, Michael J. Lawson, Edward J. Rhodes, James F. Dolan, Lee J. McAuliffe, & Sally F. McGill

Published July 2012, SCEC Contribution #1518

Although there has been significant advancement of OSL (optically stimulated luminescence) dating of quartz over the past decade, the luminescence characteristics of quartz grains in many tectonically active areas are not suitable for accurate age determinations. At two sites along the central Garlock fault in the Mojave Desert, California, USA, samples collected for OSL dating have proven problematic. At the El Paso Peaks (EPP) trench site, a sequence of 24 OSL samples were collected from sandy units with a well-established radiocarbon record, providing the opportunity to assess different approaches and optimize our luminescence dating procedures. At Christmas Canyon West (CCW), where future Garlock fault slip rate studies will be conducted using luminescence dating, five sample were collected to assess the luminescence characteristics in this environment. At both site, signals from quartz and K-feldspar grains are systematically dim. However, the use of the synthetic super-aliquot approach may significantly enhance De determination by rejecting outlying high dose values and summing the signals from the remaining consistent values. K-feldspar IRSL measurements, made using a standard IRSL protocol measured at 50°C and using the post-IR IRSL protocol measured at 225°C, yield highly variable ages when compared to the radiocarbon control. Preliminary minimum isothermal thermoluminescence (ITL) signals of K-feldspar measured during preheating appear to be consistent with the radiocarbon age estimates, demonstrating good potential for accurate age determination in this kind of environment.

Citation
Roder, B. J., Lawson, M. J., Rhodes, E. J., Dolan, J. F., McAuliffe, L. J., & McGill, S. F. (2012). Assessing the potential of luminescence dating for fault slip rate studies on the Garlock fault, Mojave Desert, California, USA. Quaternary Geochronology, 10, 285-290. doi: 10.1016/j.quageo.2012.03.013.