A 13000-year, high-resolution multi-proxy record of climate variability with episodes of enhanced atmospheric dust in Western Asia: Evidence from Neor peat complex in NW Iran


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A 13000-year, high-resolution multi-proxy record of climate variability with episodes of enhanced atmospheric dust in Western Asia: Evidence from Neor peat complex in NW Iran
  A 13000-year, high-resolution multi-proxy record of climate variability withepisodes of enhanced atmospheric dust in Western Asia: Evidence from Neorpeat complex in NW Iran Orash Sharifi  1 ; A. Pourmand  1 , E.A. Canuel  2  and L.C. Peterson  1   1. Division of Marine Geology and Geophysics, University of Miami, Rosenstiel Schoolof Marine and Atmospheric Science, Miami, FL, USA.2- Virginia Institute of Marine Science, College of William & Mary, P.O. Box 1346,Gloucester Point, VA, USA.The regional climate over West Asia, extending between Iran and the Arabian Peninsulato the eastern Mediterranean Sea, is governed by interactions between three majorsynoptic systems; mid-latitude Westerlies, the Siberian Anticyclone and the IndianOcean Summer Monsoon. In recent years, a number of paleoclimate studies havedrawn potential links between episodes of abrupt climate change during the Holocene,and the rise and fall of human civilizations across the “Fertile Crescent” of West Asia.High-resolution archives of climate variability from this region, however, are scarce, andat times contradicting. For example, while pollen and planktonic data from lakes inTurkey and Iran suggest that dry, continental conditions prevailed during the early-middle Holocene, oxygen isotope records indicate that relatively wet conditionsdominated during this interval over West Asia. We present interannual to decadal multi-proxy records of climate variability from a peat complex in NW Iran to reconstructchanges in moisture and atmospheric dust content during the last 13000 years.Radiocarbon dating on 20 samples from a 775-cm peat core show a nearly constantrate of accumulation (1.7 mm yr -1 , R 2 =0.99) since 13356 ± 116 cal yr B.P. Down-core X-ray fluorescence measurements of conservative lithogenic elements ( e.g., Al, Zr, Ti) aswell as redox-sensitive elements ( e.g., Fe, K, Rb, Zn, Cu, and Co) at 2 mm intervalsreveal several periods of elevated dust input to this region since the early Holocene.Down-core variations of total organic carbon and total nitrogen co-vary closely and areinversely correlated with conservative lithogenic elements (Al, Si, Ti), indicating apotential link between climate change and accumulation of organic carbon in the Neorpeat mire. Major episodes of enhanced dust deposition (13000-12000, 11700-11200,9200-8800, 7000-6000, 4200-3200, 2800-2200 and 1500-600 cal yr B.P) are in goodagreement with other proxy records that document more arid climate in Asia andeastern Mediterranean Sea during these intervals. The relationship between periods ofelevated dust input and the response of civilizations in the region, such as the Akkadianand Persian Empires, can also be inferred from variation of conservative lithogenicelements since 4200 cal yr B.P. Intensive dust deposition during 4200-3200 cal yr BP,for example, coincides with similar dry conditions documented by oxygen isotope andgeochemical data from Lake Van and Tecer of Turkey, the geochemical data from theGulf of Oman and oxygen isotope records from Soreq Cave in Israel. Several significantperiodicities ( e.g. 750, 900, 1550 and 3000 yr) observed from wavelet analysis ofrefractory elements correspond with the timing of internal climate feedbacks and/orsolar variability as potential modulating mechanisms for abrupt climate change in WestAsia during the Holocene.
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