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New stable carbon isotope data (δ13Ccarb and δ18Ocarb) from the Lower–Middle Ordovician is presented from petroleum exploration well Olympic 1 in the Canning Basin, Western Australia. Olympic 1 continuously cored 319.53 m of sedimentary strata, from the basal part of the Willara Formation through the majority of the Nambeet Formation. This cored section comprises carbonate and siliciclastic deposits that constitute the primary fill sequence of the Canning Basin. Previous studies report CA-IDTIMS dates between 479.37 ± 0.16 Ma and 470.18 ± 0.13 Ma from bentonite beds within the Nambeet Formation and lower Willara Formation in Olympic 1. Four conodont biozones ranging from the Paroistodus proteus conodont Biozone (upper Tremadocian) to the Jumudontus gananda Biozone (upper Floian to lower Dapingian) have been identified from the same interval. The new carbon isotope data from the Olympic 1 core are superimposed on this robust framework to provide context for Tremadocian to Dapingian stable isotope trends for Australia. Three positive δ13Ccarb excursions are identified in the Olympic 1 δ13Ccarb isotope curve, which are correlated to the global generalized δ13C curve. The highest of these occurs in the basal Willara Formation, immediately above a CA-IDTIMS radioisotopic date of 470.18 ± 0.13 Ma within the upper Floian to lower Dapingian J. gananda conodont Biozone. The second falls in the upper Nambeet Formation, immediately above a middle Floian CA-IDTIMS radioisotopic date of 472.82 ± 0.13 Ma, and within the Oepikodus communis conodont Biozone. The oldest positive excursion occurs in the lower Nambeet Formation, immediately above a CA-IDTIMS radioisotopic date of 479.37 ± 0.16 Ma, and within the upper Tremadocian P. proteus conodont Biozone. Correlation of the Olympic 1 δ13Ccarb curve to Lower-Middle Ordovician δ13Ccarb curves from the Great Basin USA, Argentine Precordillera, Western Newfoundland and South China confirms the global distribution of dissolved inorganic carbon preserved in the geological record. This integrated record may be a useful reference for constraining the timing of major oceanographic events, and a key to establishing better links between the sedimentary successions of Western Australia and the larger Ordovician world.

New and published stratigraphic data are integrated herein to resolve the age and depositional setting of Middle Devonian strata in the Gobi-Altai Terrane of south-central Mongolia (Bayanhongar Province). The Tsagaankhaalga Formation (Emsian?–Eifelian) is composed primarily of tabular sandy carbonates; it is sharply overlain by dark, fine-grained volcanoclastic marine sedimentary rock of the Govialtai Formation (Givetian), which is comparatively unfossiliferous, except for sporadic, fossiliferous carbonate interbeds. The latter unit contains abundant tentaculites as well as a newly recovered collection of conodonts assigned to the lower Givetian varcus Zone ( timorensis , rhenana , or ansatus ). A positive shift in bulk magnetic susceptibility coincides with the Tsagaankhaalga/Govialtai contact, and elevated values within the Govialtai correspond to tuffaceous and rhyolitic strata. The transition from carbonate facies of the Tsagaankhaalga Formation to the volcanoclastic shales of the Govialtai Formation is interpreted as the result of local tectonic activity. This may be qualitatively described as a transition from a shallow marine carbonate shoal with an epibenthic fauna (Tsagaankhaalga), to a deeper, clastic dominated environment with a nektic fauna (Govialtai). The pulse of tectonism must predate the lower Givetian, and it echoes the “Tsakhir Event”, which is recorded by the transition from Ordovician–Silurian carbonates to Lochkovian conglomerate. These findings provide useful biostratigraphic control and insight into the complex tectonic evolution of the Gobi-Altai Terrane and adjacent blocks on the Eurasian Craton.