TY - JOUR
T1 - Hydrological isolation of the Paratethys in the late Middle-Late Miocene
T2 - Integrated stratigraphy, palaeoenvironments and biotic record of the Caspian Basin, Karagiye, Kazakhstan
AU - Lazarev, Sergei
AU - Mandic, Oleg
AU - Stoica, Marius
AU - Gol'din, Pavel
AU - Ćorić, Stjepan
AU - Harzhauser, Mathias
AU - Krijgsman, Wout
AU - Kadirbek, Dias
AU - Vasilyan, Davit
N1 - Publisher Copyright:
© 2025 The Authors
PY - 2025/3
Y1 - 2025/3
N2 - The hydrological connectivity of semi-isolated basins with the global ocean drives remarkable ecosystem turnover and regional climate shifts, making palaeoenvironmental and palaeohydrological studies of the epicontinental basins of high relevance. During the late Middle–Late Miocene, the Paratethys Sea, which occupied vast areas of the West Eurasian Interior, underwent a notable hydrological isolation from the global ocean. Between 12.65 and 7.65 Ma, the Paratethys experienced significant water level fluctuations and eventually near-total ecosystem collapse. The causes and timing of these hydrological and biotic changes remain unclear, especially in the understudied Caspian Sea region. Our study presents an integrated stratigraphic framework of the 136-m-thick Karagiye section on the east coast of the Caspian Sea (Mangystau region, Kazakhstan). The fauna-rich deposits document the pre- (Konkian), syn- (Volhynian, Bessarabian and Khersonian) and post-isolation (Maeotian) phases of Paratethys evolution at its eastern margin. We reconstruct the palaeoenvironmental history of the Caspian Basin by combining palaeomagnetic dating with biostratigraphic analyses of microfauna, molluscs, marine vertebrates and calcareous nannoplankton. Our key findings in the studied section include: 1. Konkian (incomplete): Open lagoonal environments with restricted connectivity to the global ocean in the early Konkian followed by a middle Konkian faunal influx and establishment of normal marine environments; 2. Volhynian (incomplete, 12.3–12.05 Ma): Onset of Paratethys hydrological isolation with marginal lagoonal environments, new endemic species, plus rare surviving Konkian taxa; 3. Bessarabian (12.05–9.9 Ma): Transgression and offshore setting at ∼12.05 Ma with maximum flooding at 11.6 Ma and Intra-Bessarabian Carbonate Surge at ∼10.7 Ma, followed by upper Bessarabian (10.7–9.9 Ma) carbonate platform interior settings; 4. Khersonian (9.9–7.65 Ma): Khersonian Ecological Crisis, carbonate platform to backshore environments with hiatus between 9.5 and ∼8.0 Ma representing an extreme lowstand. 5. Maeotian (incomplete 7.65–7.0 Ma): Transgression at 7.65 Ma, followed by a delayed invasion of Maeotian faunas at 7.5 Ma, linked to the reconnection of the Caspian Basin with the rest of the Eastern Paratethys. The well-dated biotic record of Karagiye enhances understanding of Paratethyan hydrological and ecological events in the Caspian Basin and provides a foundation for further palaeoclimatic and palaeobiogeographic studies across Eurasia.
AB - The hydrological connectivity of semi-isolated basins with the global ocean drives remarkable ecosystem turnover and regional climate shifts, making palaeoenvironmental and palaeohydrological studies of the epicontinental basins of high relevance. During the late Middle–Late Miocene, the Paratethys Sea, which occupied vast areas of the West Eurasian Interior, underwent a notable hydrological isolation from the global ocean. Between 12.65 and 7.65 Ma, the Paratethys experienced significant water level fluctuations and eventually near-total ecosystem collapse. The causes and timing of these hydrological and biotic changes remain unclear, especially in the understudied Caspian Sea region. Our study presents an integrated stratigraphic framework of the 136-m-thick Karagiye section on the east coast of the Caspian Sea (Mangystau region, Kazakhstan). The fauna-rich deposits document the pre- (Konkian), syn- (Volhynian, Bessarabian and Khersonian) and post-isolation (Maeotian) phases of Paratethys evolution at its eastern margin. We reconstruct the palaeoenvironmental history of the Caspian Basin by combining palaeomagnetic dating with biostratigraphic analyses of microfauna, molluscs, marine vertebrates and calcareous nannoplankton. Our key findings in the studied section include: 1. Konkian (incomplete): Open lagoonal environments with restricted connectivity to the global ocean in the early Konkian followed by a middle Konkian faunal influx and establishment of normal marine environments; 2. Volhynian (incomplete, 12.3–12.05 Ma): Onset of Paratethys hydrological isolation with marginal lagoonal environments, new endemic species, plus rare surviving Konkian taxa; 3. Bessarabian (12.05–9.9 Ma): Transgression and offshore setting at ∼12.05 Ma with maximum flooding at 11.6 Ma and Intra-Bessarabian Carbonate Surge at ∼10.7 Ma, followed by upper Bessarabian (10.7–9.9 Ma) carbonate platform interior settings; 4. Khersonian (9.9–7.65 Ma): Khersonian Ecological Crisis, carbonate platform to backshore environments with hiatus between 9.5 and ∼8.0 Ma representing an extreme lowstand. 5. Maeotian (incomplete 7.65–7.0 Ma): Transgression at 7.65 Ma, followed by a delayed invasion of Maeotian faunas at 7.5 Ma, linked to the reconnection of the Caspian Basin with the rest of the Eastern Paratethys. The well-dated biotic record of Karagiye enhances understanding of Paratethyan hydrological and ecological events in the Caspian Basin and provides a foundation for further palaeoclimatic and palaeobiogeographic studies across Eurasia.
KW - Biostratigraphy
KW - Caspian basin
KW - Eastern Paratethys
KW - Magnetostratigraphy
KW - Serravallian-Tortonian
KW - Vertebrate fauna
UR - http://www.scopus.com/inward/record.url?scp=85215546070&partnerID=8YFLogxK
U2 - 10.1016/j.marpetgeo.2025.107288
DO - 10.1016/j.marpetgeo.2025.107288
M3 - Article
AN - SCOPUS:85215546070
SN - 0264-8172
VL - 173
JO - Marine and Petroleum Geology
JF - Marine and Petroleum Geology
M1 - 107288
ER -