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Paleoceanography of the Strait of Hormoz and its link to paleoclimate changes since the mid-Holocene

Abstract : This paper presents the paleocurrent evolution of the Persian Gulf deep water (PGDW) during the last 5000 years using faunal (foraminiferal assemblage) and non-faunal (magnetic susceptibility, sediment grain size, number of coarse relict particles and physicochemical characteristics) indicators from a 133 cm long core retrieved from the Strait of Hormoz (SH). Our results suggest that the precession-related insolation change and solar variability induced long-term and short-term sea surface temperature (SST) rise and fall resulted in variation of PGDW outflow strength. Two periods of decreasing SST (5000-4300 and 2000-1450 cal yr BP), accompanied by wetter conditions in the Middle East, are related to the reduction of the PGDW current velocity. A combination of high sedimentation rate (0.72 mm yr-1, due to high terrigenous input) with a relatively low bottom flow energy cause the settling of finer sediments providing a favourable environment for the expansion of benthic foraminifera (dominated by infaunal taxa). On the contrary, the PGDW current velocity strengthens in the periods of SST increase (4300-2000 and 1450 cal yr BP to present) with decreasing sedimentation rate (0.15-0.34 mm yr-1, due to low river discharge). During both periods of high-velocity bottom currents, the benthic foraminifera accumulation rate decreases. However, as the PGDW brings a relatively high amount of dissolved oxygen (3.25 mg/l in summer and 4.79 mg/l in winter) and phytodetritus particles, compared to the surrounding water, some particular foraminifera (especially robust suspension feeder epifaunal taxa) evolved. SST increase, intensified by anthropically caused global warming, may lead to PGDW intensification in the future.
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Submitted on : Tuesday, May 31, 2022 - 3:17:38 PM
Last modification on : Wednesday, June 1, 2022 - 3:39:00 AM

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Mohammad Ali Hamzeh, Maziar Khosravi, Xavier Carton, Dariush yarahmadi, Ezatollah Safarkhani. Paleoceanography of the Strait of Hormoz and its link to paleoclimate changes since the mid-Holocene. CONTINENTAL SHELF RESEARCH, 2021, 226, ⟨10.1016/j.csr.2021.104507⟩. ⟨insu-03683257⟩

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