Mid-Holocene changes in the geochemical and biotic conditions of an aquatic ecosystem, in Eastern Mediterranean

Annales de Limnologie: International journal of limnology

article

Michael Styllas¹  Elias Dimitriou¹  Kostas Gritzalis²  Maria Koutsodimou²  Ioannis Karaouzas²  Nikolaos Skoulikidis²  Alexandra Gogou² 

[1] Geoservice ltd;Hellenic Centre for Marine Research

关键词: Mediterranean Temporary Ponds;    sediment biogeochemistry;    mid-Holocene drought;    Omalos;    Crete;   

DOI  :  10.1051/limn/2018013

学科分类：地球科学(综合)

来源: EDP Sciences

【 摘 要 】

Mediterranean Temporary Ponds (MTPs) are unique and sensitive aquatic ecosystems that due to their hydrological characteristics constitute an ideal setting for the study of past environmental dynamics. A 176 cm core was retrieved from the littoral zone of Omalos MTP in Lefka Ori massif, to provide a general view of the processes that drove its Lateglacial and Holocene evolution. The sedimentary sequence is partitioned in two major units: (i) Unit II (∼17–4.7 ka BP), characterized by the catchment-derived transport, allogenic deposition of fine, Al2O3-rich, sediments and endogenic deposition of clays, under overall anoxic and dry climatic conditions, and (ii) Unit I (∼4.7 ka to present), characterized by increasing wetness, establishment of watershed, aquatic and herbaceous vegetation and by SiO2 dominated sedimentation under overall oxic conditions. The enrichment of SiO2 in the littoral sediments since the mid-Holocene, can be of clastic, aeolian and biogenic origin, but the undertaken analyses did not permit such distinction. The overall dryness of Unit II was interrupted between ∼14.7 and 13 ka BP by wet conditions, evidenced by the establishment of littoral vegetation. The transition to the mid-Holocene system reorganization, was expressed by peak values of Al2O3, Fe2O3, K2O, MgO and Cr2O3 and by the deposition of calcite under warm and dry conditions. The mid-Holocene (∼4.7 ka BP) period of Omalos MTP ecosystem disturbance, likely corresponds to the “4.2 ka mega drought event” widespread in the eastern Mediterranean region. The potential of MTP's sedimentary sequences in reconstructing past environmental conditions is emphasized.

【 授权许可】

CC BY