Paper No. 1
Presentation Time: 8:00 AM

BIOGEOCHEMISTRY OF THE AL AZRAQ BASIN, JORDAN: DIFFERENTIATING BETWEEN TERRESTRIAL AND AQUATIC SOURCES OF ORGANIC CARBON


AHMED, Khaldoun I. and DAVIES, Caroline, Geosciences, University of Missouri Kansas City, 420 Flarsheim Hall, 5110 Rockhill Road, Kansas City, MO 64113, kiahf6@mail.umkc.edu

The Al-Azraq basin, a closed basin and the second largest on the Jordan Plateau, contains a long and detailed sediment record of paleoenvironment change. This study identifies organic matter (OM) sources and their environments of formation. Biogeochemistry, stable isotopes and mineralogy reveal biological processes that detail a lake history significantly different from present conditions. Analysis of two hundred and fifteen samples from 23 m of playa lake sediment identifies the presence and distribution of organic matter (OM). Changes in the proportion (%) of OM, C/N ratio, carbon isotopic composition and sediment characteristics are the basis for dividing the basin into five environmental zones. The distribution of OM (as Corg), increases with depth, ranging from 0.2% to 2.8% of the total sediment. The carbon isotopic composition values range from -26.8 to -15.00. These values indicate the abundance of C3 and CAM vegetation in the basin as a possible function of changing climates on the Jordan Plateau. C/N values differentiate terrestrial and lake OM sources. The changes in Corg %, source composition and OM origin establish a wide range of past environments that varied considerably from being both drier and wetter than the present conditions.