Cool glacial temperatures and changes in moisture source recorded in Oman groundwaters

Concentrations of atmospheric noble gases (neon, argon, krypton, and xenon) dissolved in groundwaters from northern Oman indicate that the average gro und temperature during the Late Pleistocene (15,000 to 24,000 years before present) was 6.5 degrees +/- 0.6 degrees C Lower than that of today. Stable oxygen and hydrogen isotopic groundwater data show that the origin of atmo spheric water vapor changed from a primarily southern, Indian Ocean source during the Late Pleistocene to a dominantly northern, Mediterranean source today. The reduced northern water vapor source is consistent with a drier L ast Glacial Maximum through much of northern Africa and Arabia.