Timing of Atmospheric Precipitation in the Zagros Mountains Inferred from a Multi-Proxy Record from Lake Mirabad, Iran

Abstract

A sediment core 7.2 m long from Lake Mirabad, Iran, was examined for loss-on-ignition, mineralogy, oxygen-isotopic composition of authigenic calcite, and trace-element composition of ostracodes to complement earlier pollen and ostracode-assemblage studies. Pollen, ostracode-inferred lake level, and high Sr/Ca ratios indicate that the early Holocene (10000 to 6500 cal yr BP) was drier than the late Holocene. Low δ18O values during this interval are interpreted as resulting from winter-dominated precipitation, characteristic of a Mediterranean climate. Increasing δ18O values after 6500 cal yr BP signal a gradual increase in spring rains, which are present today. A severe 600-yr drought occurred at ca. 5500 cal yr BP, shortly after the transition from pistachio-almond to oak forest. During the late Holocene, two milder droughts occurred at about 1500 and 500 cal yr BP. Within the resolution of the record, no drought is evident during the collapse of the Akkadian empire (4200–3900 cal yr BP). Rather, a decrease in δ18O values to early-Holocene levels may indicate the return to a Mediterranean precipitation regime.

Holocene Climate and Cultural Evolution in Late Prehistoric–Early Historic West Asia

“…Pollen records of the region corroborate this interpretation (Rossignol-Strick, 1999). While winter/ spring rain over the central and eastern Mediterranean decreased across the mid-Holocene (Bar-Matthews et al, 1997;, Frisia et al, 2006, and probably around the Aegean Sea (Rohling et al, 2002), it increased over Iran , Griffiths et al, 2001Stevens et al, 2006;Wasylikowa et al, 2006). Over northern parts of South Asia, the early and midHolocene appears to have been wetter than the late Holocene and the present day (Swain et al, 1983;Enzel et al, 1999;Bush, 2004, Staubwasser, 2006Prasad and Enzel, 2006).…”

“…Several records from the Thar desert show an event at that time, but see the detailed discussion by Prasad and Enzel (2006). In western Iran, multiple records exist that indicate the 4.2 ka event, but different proxies conflict regarding the nature of change (Stevens et al, 2006). Several African and central to East Asian records indicate climate change around 4200 cal yr BP, but some apparently of opposite sign.…”

Middle East coastal ecosystem response to middle-to-late Holocene abrupt climate changes

“…(3). Lower precipitation amounts in the southern Levant (1), brine sediments from the northern Red Sea (26), ␦ 13 C and ␦ 18 O data from Göbekli Tepe (27) and Lake Zeribar (28), all point toward a shift to more arid conditions in western Asia during the time period ca. 2250 to 2050 B.C.…”

Hydrological variability in the Northern Levant: a 250 ka multi-proxy record from the Yammoûneh (Lebanon) sedimentary sequence

“…During interglacial peaks, maximum tree pollen percentages reflect warm conditions and higher precipitation from the mid-latitude westerly system. Changes in seasonality were proposed by several authors to explain Holocene climate in the region (Stevens et al, 2001(Stevens et al, , 2006Magny, 2007;Tzedakis, 2007;Peyron et al, 2010;Djamali et al, 2010). At Yammoûneh, sharp δ c increases in phase with arboreal pollen peaks, attributed to enhanced seasonal thermal and hydrological contrasts, suggest that the hypothesis of seasonal changes is valid for older interglacial stages (e.g., MIS 5.5 and MIS 5.1).…”

“…1; Eastwood et al, 2007), or changes in precipitation seasonality (at Lakes Zeribar and Mirabad, NW Iran, Fig. 1; Stevens et al, 2001Stevens et al, , 2006). As discussed above from both pollen and isotope data, we favour the hypothesis of seasonal increased hydrological and thermal contrasts with wet cool winters, possibly a longer rainy season, and very dry warm summers generating strong evaporative effects in both the drainage area and the waterbody.…”