racing exhumation and orogenic wedge dynamics in the European Alps with detrital thermochronology: COMMENT
Abstract
n a recent paper, Carrapa (2009) used low-temperature thermochronologic data of detrital grains from the pro- and retro-side foreland basins of the European Alps to determine when the two oppositely vergent wedges of the Alps were in subcritical or supercritical taper states. She used the lag time concept, where lag time is defined as the difference between the apparent fission-track (apatite, zircon) or 40Ar-39Ar (white mica) cooling age of a detrital grain and the depositional age of the grain in a foreland basin, to interpret the change of the taper states of the Alpine orogenic wedges through time. Carrapa found that shortening in lag time, and therefore an increase in the exhumation rate, supposedly represents a subcritical wedge, whereas an increase in lag time, or decrease in exhumation rate, represents a supercritical wedge.