Sea–land oxygen isotopic relationships from planktonic foraminifera and speleothems in the Eastern Mediterranean region and their implication for paleorainfall during interglacial intervals

Queen's Chamber, King's Palace, Carlsbad Caverns National Park, USA. NPS Photo Sea–land oxygen isotopic relationships from planktonic foraminifera and speleothems in the Eastern Mediterranean region and their implication for paleorainfall during interglacial intervals
Geochimica et Cosmochimica Acta
Volume 67, Issue 17, Pages 3181-3199, 1 September 2003.

Miryam Bar-Matthews 1,2, Avner Ayalon1, Mabs Gilmour2, Alan Matthews3, and Chris J. Hawkesworth2,4
1Geological Survey of Israel, 30 Malchei Israel Street, Jerusalem 95501, Israel
2Department of Earth Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom
3Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem91904, Israel
4Department of Earth Sciences, University of Bristol, Bristol, United Kingdom

ABSTRACT:
The oxygen and carbon stable isotope compositions of cave speleothems provide a powerful method for understanding continental climate change. Here, we examine the question of the regionality of this isotopic record and its linkage with the marine isotopic record in the Eastern Mediterranean (EM) region. The study presents a new, accurately dated 250-kyr d18O and d13C record determined from speleothems of the Peqiin Cave, Northern Israel. Its comparison with the continuous 185-kyr isotopic record of the Soreq Cave speleothems from Central Israel reveals striking similarities. Thus, a strong regional climatic signal, brought about by variations in temperature and rainfall amount, is reflected in both cave records. Low d18O minima in the Peqiin profile for the last 250- to 185-kyr period (interglacial marine isotopic stage 7) match the timing of sapropels 9 to 7 and are indicative of high rainfall in the EM region at these times. The combined Soreq and Peqiin d18O record for the last 250 kyr excellently matches the published Globigerinoides ruber (G. ruber) marine d18O record for the EM Sea, with the isotopic compositional difference DG.ruber-speleothems remaining relatively constant at -5.6 ± 0.7 per mil, thus establishing for the first time a robust, exploitable link between the land and the marine isotopic records. The correspondence of low d18O speleothem values and high cave water stands with low G. ruber d18O values during interglacial sapropel events indicates that these periods were characterized by enhanced rainfall in the EM land and sea regions. By use of sea surface temperatures derived from alkenone data as a proxy for land temperatures at the Soreq Cave, we calculate the paleorainfall d18O values and its amounts. Maximum rainfall and lowest temperature conditions occurred at the beginning of the sapropel events and were followed by decrease in rainfall and increase in temperatures, leading to arid conditions. The record for the last 7000 yr shows a trend toward increasing aridity and agrees well with climatic and archeological data from North Africa and the Middle East.

DATA:
Download the data from this study:
Speleothem d18O data from Soreq and Peqiin Caves, Israel.

To read or view the full study, please visit the Science Direct website.
It was published in Geochimica et Cosmochimica Acta
Volume 67, Issue 17, Pages 3181-3199, 1 September 2003.


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3 September 2003