Bilal Gul, Leho Ainsaar, Tõnu Meidla

Baltoscandian Middle Ordovician brachiopod oxygen stable isotope trends: implications for palaeotemperature changes

Abstract Over the last two decades, there has been an intensive research effort focused on studying the climate fluctuations during the Ordovician period. In this study, we provide brachiopod and bulk carbonate rock stable isotopic data for oxygen (O) and carbon (C) from the Middle Ordovician succession from northern Estonia for evaluating the Middle Ordovician palaeotemperature and palaeoenvironmental history. We present δ¹⁸O curves from eight northern Estonian outcrops. This new data, together with the published results, enable compiling the first complete stable oxygen isotopic curve for Middle Ordovician to early Silurian for the eastern Baltoscandian Palaeobasin. Combining the published and new δ¹³C_brac and δ18Obrac data allows us to address chemostratigraphic correlation in the Middle Ordovician. The Baltoscandian δ¹⁸O data generally confirm a cooling trend from Early to Middle Ordovician documented by previous studies in different palaeobasins.

Doi https://doi.org/10.5200/baltica.2024.2.1

Keywords δ13C and δ18O chemostratigraphy; palaeotemperature; Ordovician; Baltoscandia

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