Calcite U–Pb age of the Cretaceous vertebrate‐bearing Bayn Shire Formation in the Eastern Gobi Desert of Mongolia: Usefulness of caliche for age determination
Yuto Kurumada, Shogo Aoki, Kazumasa Aoki, Daichi Kato, Mototaka Saneyoshi, Khishigjav Tsogtbaatar, Brian F. Windley, Shinobu Ishigaki
Abstract
Abstract To verify the usefulness of calcite U–Pb measurement for vertebrate‐bearing strata in the Eastern Gobi, Mongolia, we performed laser ablation‐inductively coupled plasma‐mass spectrometry calcite U–Pb and trace element analyses of three caliche (calcrete) of the Bayn Shire Formation. The trace element analysis demonstrates high concentration of U in the calcites. Two meaningful calcite U–Pb ages were obtained; 95.9 ± 6.0 and 89.6 ± 4.0 Ma, which are consistent with published ages from the Bayn Shire Formation. Our results demonstrate that the calcite U–Pb method can be powerful tool for age determination of vertebrate‐bearing strata in the Gobi that do not contain index fossils or beds, but do contain caliches. This would make it possible for a comparison of biostratigraphy between the Gobi and other areas yielding abundant vertebrate fossils in Asia, North America and Europe, based on chronological data.