Application of the (U‐Th)/He Thermochronometry to the Tectono‐Thermal Evolution of Sedimentary Basin—A Case History of Well KQ1 in the Tarim Basin

Abstract

AbstractThe (U‐Th)/He thermochronometry of apatite and zircon has been used as a new technique to study the tectonic uplift and thermal history of sedimentary basins in recent years. Based on the tested apatite and zircon helium ages data from well samples, an evolution model of apatite He ages with depth and/or temperature is built, which illustrates that the apatite helium closure temperature is about 85°C in the Tarim basin. However, the zircon He ages reveal that these samples hadn't undergone its higher closure temperature. The thermal history since Ordovician in Well KQ1 has been modeled by using the He ages, AFT and Ro data. The modeling result shows that the thermal gradient was about 35.5°C/km in the end of Ordovician, and 33.3~34.5°C/km during the period of Silurian to Devonian, and it decreased to 27.6°C/km in the end of Cretaceous. Therefore, the (U‐Th)/He ages may provide a new tool to rebuilt the thermal history of sedimentary basins, especially for the Low Paleozoic carbonate stratum in Tarim basin which lacks normal thermal indicators.