LA-ICP-MS APATITE FISSION-TRACK DATING OF THE SIBERIAN TRAPS INTRUSIONS: METHOD, FIRST RESULTS AND THEIR INTERPRETATION

Abstract

In this paper we present the results on apatite fission-track dating, which was first performed at the Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, using the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS, Dobretsov Geological Institute, Siberian Branch of the Russian Academy of Sciences) for two intrusions of the Siberian Permian-Triassic large igneous province: Magan alkaline-ultramafic pluton (two samples) and Kontay intrusion (one sample). The obtained AFT ages are 217.6±18.6 and 238.8±35.8 Ma (95% confidence) for the Magan intrusion and 150.0±23.0 Ma for the Kontay intrusion and mark the time since they have been cooled below 120 °C. The distributions of track lengths in apatite grains from the studied samples indicate their rapid cooling to near-surface temperatures. We provide a detailed description of the method used, and also demonstrate that the results of fissiontrack analysis performed on the "sample-to-sample" principle by the classical external detector method (EDM) and the LA-ICP-MS method in the modification of the zeta calibration coincide within the age uncertainty.

Keywords

• apatite fission-track analysis
• apatite fission-track dating
• apatite
• la-icp-ms
• thermochronology
• geochronology
• siberian traps