Dated oxygen and carbon isotopic profiles from a Holocene stalagmite (11.9-1.1 ka) from the Jeita cave, Lebanon, are compared to variations in crystallographic habit, stalagmite diameter and growth rate. The profiles show generally high δ18O and δ13C values during the late-glacial period, low values during the early Holocene, and again high values after 5.8 ka. On the basis of the good correlation between the morphological and crystallographic aspect of the stalagmite and its isotopic records, as well as the isotopic response of speleothems from central and northern Israel, we relate high δ18O and δ13C values to drier conditions. Between 6.5 and 5.8 ka an increase in isotopic values, a decrease in growth rate and stalagmite diameter suggest a transition from wet conditions in the early Holocene towards drier conditions in the mid-Holocene. The transition occurred in two steps, first a progressive change to drier conditions started at 6.5 ka but was interrupted by a short (∼ 100 years) return to wetter conditions, followed by an equally rapid (< 200 years) change to drier conditions.
Bibliographical noteFunding Information:
This research was primarily funded by the Lebanese National Council for Scientific Research (LNCSR). We thank Dr. Nabil Haddad, director of MAPAS (operator of Jeita Grotto showcave) for his continuous support and generous hospitality, B. Idriss (AUB) helped with field and lab-work, M. Ijreiss (AUB) with technical support, and A. Koumaiha and W. Nasr Jad with graphic support. Members of the Spéléo-Club du Liban also helped during the fieldwork inside the cave and providing maps and data. We thank Sami Karkabi for fruitful discussion and guidance. The authors are grateful to the comments and suggestions of S. Robinson, an anonymous referee and editor E. Steig, who have improved this contribution.
- Oxygen isotopes