Thermochronology and stratigraphy of the Thomson Orogen, north-eastern Australia

The Thomson Orogen comprises basement rocks of a large part of north-eastern Australia. Much of the Thomson Orogen is made up of metasediments, but the depositional environments of these rocks remain largely undescribed. Most previous studies of the northern Thomson Orogen have focused on relatively large exposures in the Anakie Inlier and Charters Towers Province, leaving some smaller exposures overlooked. One of these relatively small exposures is at Mount McLaren in east-central Queensland, where >2,000 m of previously undescribed strata of the northern Thomson Orogen are exposed. These metasediments are herein named the Mount McLaren beds. Based on lithological and geochronological similarities, we suggest that the Mount McLaren beds correlate with the Les Jumelles beds and the Puddler Creek Fm. We propose that the late CambrianEarly Ordovician relatively shallow-marine environment of the Mount McLaren beds was a precursor to the Ordovician deep marine environment of much of the Lachlan and southern Thomson Orogens. 2.