Abstract. We present a new method for the assessment of the most recent cooling and denudation rates using paramagnetic centers in quartz measured by electron spin resonance (ESR) spectroscopy. These centers have a relatively low thermal stability. For cooling rates of 40 ø and 1000øC Myr -•, effective closure temperatures vary between 55 ø and 82øC (Ti center) and 49 ø and 64 øC (A1 center), respectively. Samples were collected from two cores that were drilled into the Eldzhurtinskiy Granite, which has an emplacement age of ~2 Ma as measured by U/Pb analyses of zircons. One 1500 rn core was taken from a drill hole into the dome of the granite, a second core of 4000 rn from a drill hole at the base of the Baksan However, the ESR denudation rates underestimate the erosion rate of the Baksan Valley because the geothermal gradient is not equilibrated between the surface and the depth of the annihilation temperatures, 950 and 1800 rn for the A1 and Ti centers, respectively. We conclude that ESR measurements of paramagnetic centers in quartz will allow the reconstruction of landscape dynamics for the past 10-1000 kyr and that in conjunction with U/Pb, fission track, and Ar/Ar analyses it will be possible to develop dynamic models for Quaternary tectonic movements.
Aim and Scope of This Study
IntroductionThe aim of this study was to demonstrate that electron spin resonance (ESR) measurements of paramagnetic centers can be used for the estimation of denudation and cooling rates, to assess the potential of this method, and to identify the weaknesses on which future research has to be focussed. The cores of the Eldzhurtinskiy Granite were ideally suited for this study: samples could be collected from a very long core to study the thermal stabilities of all centers involved; the present day uplift rate is known (N6-8 mm a -• as measured by a nearby Global Positioning System (GPS) station using a Trimble 4000 SSE system); and it is a very young intrusion, suggesting that the paramagnetic centers would not be saturated.• Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia.