Burial history and thermal maturity of Mesozoic rocks of the Dolomites, Northern Italy

Abstract

Thermal maturity analyses provide a valid basis to reconstruct the burial and temperature history of sedimentary rocks. In combination with computer based modeling it is possible to quantify former overburden and erosional thickness. This study was carried out to analyze thermal maturity and elaborate the burial history of Permo-Mesozoic sediments of the Western Dolomites, Northern Italy. Based on their location in the non-metamorphosed Southern Alps of the Alpine realm, the Dolomites are well suited to study thermal maturation in a complex orogenic setting. Determination of maturity was carried out by vitrinite reflectance and solid bitumen reflectance measurements on a large number of samples as well as by Rock–Eval pyrolysis. Vitrinite reflectance commonly ranges between 0.5 % VRr for Triassic and 0.76 % VRr for Permian sediments allowing an analysis of the lateral and vertical maturation patterns. Several 1D basin models were developed and calibrated by maturity measurements. Results show that deepest burial probably occurred at the end of Cretaceous times, followed by erosion of about 1800 ± 200 m. The estimated heat flows were moderate with 75 mW/m2 for Jurassic rifting, 46 mW/m2 for times of deepest burial and 41 mW/m2 for present day.