Late Devonian sedimentary record of the Paleotethys Ocean – The Mae Sariang section, northwestern Thailand

An 11 m thick condensed sequence of Late Devonian limestones in northwestern Thailand exhibits faunal associations and sedimentological-/microfacies data which are indicative of a pelagic facies setting. The entire long-ranging section is completely free from clastic input. Similar successions are known worldwide in a few sections only. The Mae Sariang section is characterised by low sedimentation rates as recognised by a number of hardgrounds, neptunian dikes and Fe/Mn crusts. The succession comprises a number of pelagic faunal elements e.g. conodonts, cephalopods and pelagic ostracodes. The fauna records rare macrofossils and the faunal diversity is low. The very condensed section ranges from the Late rhenana to praesulcata conodont biozones, but contains some global events as undoubtedly shown by biostratigraphical and carbon-isotope results (including major Kellwasser and Hangenberg biotic crises). In terms of plate tectonics this important succession most probably belongs to the Inthanon Zone comprising remnants of the Paleotethys Ocean.