Speleothem-based stable isotope records are valuable in sub-humid and semi-arid settings where
ma... more Speleothem-based stable isotope records are valuable in sub-humid and semi-arid settings where many other terrestrial climate proxies are fragmentary. The Eastern Mediterranean is one such region. Here we present an 80-kyr-long precisely-dated (by U-series) and high-resolution oxygen (δ18O) and carbon (δ13C) records from Dim Cave (~36°N) in SW Turkey. The glacial-interglacial δ18O variations in the Dim Cave speleothem are best explained in terms of changes in the trajectories of winter westerly air masses. These are along a northerly (European) track (isotopically less depleted) during the early last glaciation but are gradually depressed southward closer to the modern westerly track along the North African coast (more depleted) after c.50 kyr and remain in the southern track through the Last Glacial Maximum. The southward displacement of the westerly track reflects growth of the Fennoscandian ice sheet and its impact on westerly wind fields. Changes in δ13C are interpreted as reflecting soil organic matter composition and/or thickness. δ13C values are significantly more negative in interglacials reflecting active carbonic acid production in the soil and less negative in glacial times reflecting carbonate rock values. Several Heinrich events are recorded in the Dim record indicating intensification of westerly flow across this part of the EM.
Speleothem-based stable isotope records are valuable in sub-humid and semi-arid settings where
ma... more Speleothem-based stable isotope records are valuable in sub-humid and semi-arid settings where many other terrestrial climate proxies are fragmentary. The Eastern Mediterranean is one such region. Here we present an 80-kyr-long precisely-dated (by U-series) and high-resolution oxygen (δ18O) and carbon (δ13C) records from Dim Cave (~36°N) in SW Turkey. The glacial-interglacial δ18O variations in the Dim Cave speleothem are best explained in terms of changes in the trajectories of winter westerly air masses. These are along a northerly (European) track (isotopically less depleted) during the early last glaciation but are gradually depressed southward closer to the modern westerly track along the North African coast (more depleted) after c.50 kyr and remain in the southern track through the Last Glacial Maximum. The southward displacement of the westerly track reflects growth of the Fennoscandian ice sheet and its impact on westerly wind fields. Changes in δ13C are interpreted as reflecting soil organic matter composition and/or thickness. δ13C values are significantly more negative in interglacials reflecting active carbonic acid production in the soil and less negative in glacial times reflecting carbonate rock values. Several Heinrich events are recorded in the Dim record indicating intensification of westerly flow across this part of the EM.
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many other terrestrial climate proxies are fragmentary. The Eastern Mediterranean is one such
region. Here we present an 80-kyr-long precisely-dated (by U-series) and high-resolution oxygen
(δ18O) and carbon (δ13C) records from Dim Cave (~36°N) in SW Turkey. The glacial-interglacial δ18O
variations in the Dim Cave speleothem are best explained in terms of changes in the trajectories of
winter westerly air masses. These are along a northerly (European) track (isotopically less depleted)
during the early last glaciation but are gradually depressed southward closer to the modern westerly
track along the North African coast (more depleted) after c.50 kyr and remain in the southern track
through the Last Glacial Maximum. The southward displacement of the westerly track reflects growth
of the Fennoscandian ice sheet and its impact on westerly wind fields. Changes in δ13C are interpreted
as reflecting soil organic matter composition and/or thickness. δ13C values are significantly more
negative in interglacials reflecting active carbonic acid production in the soil and less negative in
glacial times reflecting carbonate rock values. Several Heinrich events are recorded in the Dim record
indicating intensification of westerly flow across this part of the EM.
many other terrestrial climate proxies are fragmentary. The Eastern Mediterranean is one such
region. Here we present an 80-kyr-long precisely-dated (by U-series) and high-resolution oxygen
(δ18O) and carbon (δ13C) records from Dim Cave (~36°N) in SW Turkey. The glacial-interglacial δ18O
variations in the Dim Cave speleothem are best explained in terms of changes in the trajectories of
winter westerly air masses. These are along a northerly (European) track (isotopically less depleted)
during the early last glaciation but are gradually depressed southward closer to the modern westerly
track along the North African coast (more depleted) after c.50 kyr and remain in the southern track
through the Last Glacial Maximum. The southward displacement of the westerly track reflects growth
of the Fennoscandian ice sheet and its impact on westerly wind fields. Changes in δ13C are interpreted
as reflecting soil organic matter composition and/or thickness. δ13C values are significantly more
negative in interglacials reflecting active carbonic acid production in the soil and less negative in
glacial times reflecting carbonate rock values. Several Heinrich events are recorded in the Dim record
indicating intensification of westerly flow across this part of the EM.