LA-ICP-MS-based apatite fission track dating of the Todos Santos Formation sandstones from the Sierra de Chiapas (SE Mexico) and its tectonic significance

This study reports the first LA-ICP-MS-based apatite fission track age data from the Toarcian–Oxfordian Todos Santos Formation sandstones exposed in the Sierra de Chiapas (SCH), SE Mexico. Single-grain fission track ages obtained from four rock samples vary between 232 ± 31 (1σ) and 40 ± 3 (1σ) Ma, indicating partial resetting of detrital apatite populations by post-depositional heating during diagenesis. Decomposed data were interpreted as follows: (a) cooling of the sediment source area at 203 ± 7 (1σ) and 163 ± 3 (1σ) Ma, which are respectively coincident with the late Permian–Triassic thermo-tectonic event and Early–Middle Jurassic arc volcanism that affected the Chiapas Massif Complex; and (b) a post-burial cooling period (with variable cooling rates of <3°C Ma–1) in the range of ~83–51 Ma controlled by a Late Cretaceous–early Eocene tectonic activity, which can be correlated with the Laramide orogeny that occurred along central and northern Mexico during the same period of time (i.e. from 85–80 to 50–40 Ma). The results obtained in the present study, as well as previously published data, indicate that the SCH has experienced a multi-episodic thermo-tectonic evolution with at least four main stages.