Resumen de Partial resetting of fission tracks in detritai zircon
J.I. Garver, B.C.D. Riley, G. Wang
Partial resetting o f mixed suites ofzircon is most conspicuous when sedimentary zircons with a wide range of radiation damage are brought to elevated temperatures (c. 200°C), and then allowed to cool. In many instances, only the most radiation-damaged grains become thermally reset and other grains with lower radiation damage can be virtually unaffected. In these cases, the young component population corresponds to the cooling following the thermal event. We review three cases where sedimentary zircons with in excess o f ¡00 Myr o f radiation damage (c. 5 x 10's a events/mg for a grain with 150 ppm U) have been brought to temperatures approaching 200°C. We highlight the young population and relate those to the thermal event, with examples from the Hudson Valley (NY, USA), the Huachuca Mountains, (AZ, USA), and the Kunlun Mountains (NE Tibet, China). In general, reset grains are those with highest uranium concentrations. Older component populations need to be interpreted with care because o f possible age reduction.
