Dolomite luminescence thermochronometry reconstructs the low-temperature exhumation history of carbonate rocks in the central Apennines, Italy.

Abstract

The lack of available thermochronological methods has so far hampered reconstructions of the cooling and exhumation histories in carbonate rock regions. Here we develop a new trapped charge thermochronometry tool based on the thermoluminescence signal of dolomite. It has a closure temperature range of 45-75 °C and is applicable to carbonate domains with cooling rates of 2-200 °C per million years. This new thermochronometric technique is tested in the central Apennines, where seismogenic, carbonate-hosted normal faulting controls regional neotectonics. Thermoluminescence dating is applied along the northeastern shoulder of the Late Pliocene-Quaternary L'Aquila Intermontane Basin, at the footwall of the extensional Monte Marine Fault. Dolomite samples from the bedrock have a mean thermoluminescence age of 4.60 ± 0.35 millions of years, whereas dolomite clasts within the fault damage zone have a mean thermoluminescence age of 2.53 ± 0.13 millions of years. These new thermoluminescence ages, corroborated by the existing stratigraphic constraints, (i) provide the first direct, low-temperature exhumation ages of the carbonate bedrocks in the central Apennines; (ii) constrain the activity of the basin boundary faults along the northeastern shoulder of the L'Aquila Intermontane Basin. Our study demonstrates the potential of dolomite luminescence thermochronometry in reconstructing the low-temperature cooling/exhumation history of carbonate bedrocks.