Paleoclimatic significance of Early Holocene faunal assemblages in wet interdune deposits of the Wahiba Sand Sea, Sultanate of Oman

Invertebrate and trace fossil assemblages in wet interdune deposits of the Wahiba Sand Sea record environmental changes associated with the Indian Ocean Monsoon system during the Early Holocene wet period. This period is dated locally by infrared stimulated luminescence (IRSL) from ca. 9300 to 5500 years ago. Lacustrine deposits from interdune areas of the central sand sea developed during peak precipitation 9300 years (IRSL) ago. The deposits represent short-lived but permanent lakes characterized by salinity tolerant freshwater snails and ostracodes. Diverse trace fossils exposed on the present-day surface show that the dried out lake sediments became substrates for the dwelling, feeding, and reproductive activities of insects. This period of continued moist conditions with pronounced vegetation cover is recorded in post-lacustrine, wet interdune deposits from the coastal Wahiba Sand Sea. A 4-m thick succession of interdune deposits was dated to ca. 8500-5500 years (IRSL). This interdune succession shows intense bioturbation by rhizocretions and insect burrows and nests. Both sites of wet interdune deposits show that changes of moist conditions during the Early Holocene wet period can be monitored by a variety of biological indicators. The ecological information of in situ animal species and trace fossil assemblages adds to the understanding how climatic changes are expressed in continental environments.