Dating zircons from Francevillian Basin by laser-ablation inductively coupled plasma mass-spectrometry

Abstract

The aim of this bachelor’s thesis was to measure the U-Pb ages of the zircon samples from Francevillian Basin in Gabon using laser-ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS). Three samples were from tuff-like layers from an outcrop of Francevillian FB formation, and two samples were from K-bentonites from Francevillian FD formation intersected in Doume drillcore. As a result, zircon grains from FB formation yielded U-Pb ages over 2800 Ma suggesting that these zircons are inherited from the crystalline basement of the basin. Zircon grains from FD formation did not provide very reliable data. Only one signal was considered as reliable, and this signal yielded Pb-Pb age at 2082 ± 19 Ma.