| 1. |
- Gennari, Giordana, et al.
(författare)
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Faunal evidence of a Holocene pluvial phase in Southern Arabia with remarks on the morphological variability of Helenina anderseni
- 2011
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Ingår i: Journal of Foraminiferal Research. - 0096-1191 .- 1943-264X. ; 41, s. 248-259
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Tidskriftsartikel (refereegranskat)abstract
- Although foraminifera have been found living in inlandsaline lakes isolated from the sea, this phenomenon has rarelybeen recognized in the fossil record. This study documents theoccurrence of benthic foraminifera in Holocene lake sedimentslocated nearly 500 km inland from the Red Sea, in theAl-Mundafan region of southern Saudi Arabia. The lakeformed during a regional pluvial period, 10,500–6000 yr BP.The presence of foraminifera and brackish charophytes in thestudied section represent an interval when the lake wasslightly brackish due to high evaporation. The studiedsediments yielded a bispecific benthic foraminiferal faunacomprised of Helenina anderseni and Trichohyalus aguayoi,as well as the brackish charophyte genus Lamprothamnium.The benthic foraminifera are species characteristic ofmangrove swamps, salt marshes, and lagoons, which areenvironments currently widespread along the Red Sea coasts.Because the Al Mundafan area was never connected to the seaduring the Quaternary, wading birds must have been thevector that transported the foraminifera to the paleolake
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| 2. |
- Rosenberg, Thomas M., et al.
(författare)
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Middle and Late Pleistocene humid periods recorded in palaeolake deposits of the Nafud desert, Saudi Arabia
- 2013
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 70, s. 109-123
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Tidskriftsartikel (refereegranskat)abstract
- Present climate in the Nafud desert of northern Saudi Arabia is hyper-arid and moisture brought by north-westerly winds scarcely reaches the region. The existence of abundant palaeolake sediments provides evidence for a considerably wetter climate in the past. However, the existing chronological framework of these deposits is solely based on radiocarbon dating of questionable reliability, due to potential post-depositional contamination with younger C-14. By using luminescence dating, we show that the lake deposits were not formed between 40 and 20 ka as suggested previously, but approximately ca 410 ka, 320 ka, 200 ka, 125 ka, and 100 ka ago. All of these humid phases are in good agreement with those recorded in lake sediments and speleothems from southern Arabia. Surprisingly, no Holocene lake deposits were identified. Geological characteristics of the deposits and diatom analysis suggest that a single, perennial lake covered the entire south-western Nafud ca 320 ka ago. In contrast, lakes of the 200 ka, 125 ka, and 100 ka humid intervals were smaller and restricted to interdune depressions of a preexisting dune relief. The concurrent occurrence of humid phases in the Nafud, southern Arabia and the eastern Mediterranean suggests that moisture in northern Arabia originated either from the Mediterranean due to more frequent frontal depression systems or from stronger Indian monsoon circulation, respectively. However, based on previously published climate model simulations and palaecolimate evidence from central Arabia and the Negev desert, we argue that humid climate conditions in the Nafud were probably caused by a stronger African monsoon and a distinct change in zonal atmospheric circulation.
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