Upper Jurassic–Lower Cretaceous carbonate successions are widely exposed throughout the Sakarya Zone, Northern Turkey. The carbonates are considered as invaluable archives of palaeoceanographic and palaeoclimatic conditions of Tethys Ocean. We, here, present new micropaleontological, microfacies, and stable isotope data (δ¹⁸O and δ¹³C) of Lower Cretaceous carbonate succession of the eastern part of Sakarya Zone, NE Turkey. The studied Lower Cretaceous carbonates are characterized by, from bottom to top, microfacies associations within Unit 1 and Unit 2 that were deposited in the Barremian–Albian. Unit 1 (Barremian–Aptian) is represented by the predominance of benthic foraminiferal associations and shallow marine organisms. Unit 1 shows alternations of different microfacies, including non-laminated mudstone (MF-1), autochthonous bioclastic-foraminiferal grainstone and packstone (MF-2) and intraclastic grainstone/packstone (MF-3). An abrupt palaeoenvironment change is represented by Unit 2 with deeper water microfacies associations consisting of dark grey limestones with chert nodules, mud-rich texture, reworked skeletal fragments, sponge spiculitics and a presence of the planktonic organism. Unit 2 (Albian) displays two different microfacies: reworked bioclastic packstone/wackestone microfacies (MF-4) and gradually overlying sponge spiculitic wackestone–mudstone (MF-5). The integration of microfacies and micropaleontological data implies that the Barremian–Albian interval represents the inner platform to the slope palaeoceanographic conditions revealing an overall transgressive trend, which is consistent with a significant rise in the sea level throughout Tethys margin during the Albian. The Albian sea-level rise is likely triggered by the sedimentary evolution of the basin due to the extensional tectonic regime in NE Turkey. Besides, the palaeo-temperatures are measured by the δ¹⁸O data that were obtained from well-preserved belemnite samples in Unit 2. Palaeotemperature analysis presents a range of 18.30–26.77 °C with an average of 23.13 °C during the Albian. Our palaeo-temperature data are conformable with the warm Cretaceous climatic conditions, which are recorded in the different parts of the Tethys margin. Therefore, this contribution provides the first insight into the palaeoclimatic conditions of the Tethys ocean for the eastern part of the Sakarya, NE Turkey.

上侏罗统 - 下白垩统碳酸盐岩层序广泛暴露于土耳其北部萨卡里亚地区。碳酸盐被认为是特提斯洋古海洋和古气候条件的宝贵档案。我们在这里展示了新的微古生物学、微相和稳定同位素数据（δ ¹⁸ O 和 δ ¹³C) 土耳其东北部萨卡里亚带东部下白垩统碳酸盐岩层序。所研究的下白垩统碳酸盐岩的特征是，从下到上，单元 1 和单元 2 内的微相组合是沉积在 Barremian-Albian 中的。单元 1（Barremian-Aptian）以底栖有孔虫协会和浅海生物的优势为代表。单元 1 显示了不同微相的交替，包括非层状泥岩（MF-1）、原地生物碎屑-有孔虫颗粒岩和堆积岩（MF-2）和内部碎屑颗粒岩/堆积岩（MF-3）。单元 2 代表了突然的古环境变化，深水微相组合由深灰色石灰岩和燧石结核、富含泥浆的质地、重新加工的骨骼碎片、海绵骨刺和浮游生物的存在。单元 2 (Albian) 显示了两种不同的微相：再加工的生物碎屑泥灰岩/泥灰岩微相 (MF-4) 和逐渐上覆的海绵片状硅灰岩-泥岩 (MF-5)。微相和微古生物学数据的整合表明，Barremian-Albian 层段代表了斜坡古海洋条件的内部平台，揭示了整体海进趋势，这与 Albian 期间整个特提斯边缘海平面的显着上升一致。由于土耳其东北部的伸展构造体制，阿尔比海平面上升可能是由盆地的沉积演化引发的。此外，古温度由 δ 重新加工的生物碎屑颗粒岩/泥灰岩微相（MF-4）和逐渐上覆的海绵粒状泥灰岩-泥岩（MF-5）。微相和微古生物学数据的整合表明，Barremian-Albian 层段代表了斜坡古海洋条件的内部平台，揭示了整体海进趋势，这与 Albian 期间整个特提斯边缘海平面的显着上升一致。由于土耳其东北部的伸展构造体制，阿尔比海平面上升可能是由盆地的沉积演化引发的。此外，古温度由 δ 重新加工的生物碎屑颗粒岩/泥灰岩微相（MF-4）和逐渐上覆的海绵粒状泥灰岩-泥岩（MF-5）。微相和微古生物学数据的整合表明，Barremian-Albian 层段代表了斜坡古海洋条件的内部平台，揭示了整体海进趋势，这与 Albian 期间整个特提斯边缘海平面的显着上升一致。由于土耳其东北部的伸展构造体制，阿尔比海平面上升可能是由盆地的沉积演化引发的。此外，古温度由 δ 微相和微古生物学数据的整合表明，Barremian-Albian 层段代表了斜坡古海洋条件的内部平台，揭示了整体海进趋势，这与 Albian 期间整个特提斯边缘海平面的显着上升一致。由于土耳其东北部的伸展构造体制，阿尔比海平面上升可能是由盆地的沉积演化引发的。此外，古温度由 δ 微相和微古生物学数据的整合表明，Barremian-Albian 层段代表了斜坡古海洋条件的内部平台，揭示了整体海进趋势，这与 Albian 期间整个特提斯边缘海平面的显着上升一致。由于土耳其东北部的伸展构造体制，阿尔比海平面上升可能是由盆地的沉积演化引发的。此外，古温度由 δ 由于土耳其东北部的伸展构造体制，阿尔比海平面上升可能是由盆地的沉积演化引发的。此外，古温度由 δ 由于土耳其东北部的伸展构造体制，阿尔比海平面上升可能是由盆地的沉积演化引发的。此外，古温度由 δ¹⁸ O 数据来自 2 号单元保存完好的锰铝石样品。古温度分析显示阿尔比纪期间的平均温度为 18.30-26.77°C，平均为 23.13°C。我们的古温度数据符合温暖的白垩纪气候条件，这些条件记录在特提斯边缘的不同部分。因此，这项贡献提供了对土耳其东北部萨卡里亚东部特提斯海洋古气候条件的第一次洞察。