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    Cement fabrics and optical luminescence ages of beachrock, North Cyprus: Implications for Holocene sea-level changes
    (PERGAMON-ELSEVIER SCIENCE LTD, 2016) Ozturk, Muhammed Zeynel; Erginal, Ahmet Evren; Kiyak, Nafiye Gunec; Ozturk, Tugba
    CaCO3-cemented beachrocks are widely found along the northern coast of Cyprus. In this study, we aim to discuss the cementation history of beachrocks at ten particular sites within the context of Holocene sea-level changes. Cement fabrics, petrographic and geochemical characteristics, and optically-stimulated luminescence ages of buried quartz grains were studied. The seaward-inclined (similar to 5-10 degrees) parallel-stratified beds are composed mostly of sandstone alternating with conglomerate. Ooids, benthic and planktic foraminifera, bioclasts of red algae, echinoid spines and gastropods make up a significant proportion of the cemented beds. With CaCO3 content ranging between 37% and 65%, poorly-sorted grains are bonded by four distinct cements: circumgranular micritic coatings, sparry calcite infillings, pore fills, and meniscus bridges. This consecutive nature of cementation is typical of a marine phreatic and meteoric vadose environment when the sea level was lower than present but had a tendency to increase during middle to late Holocene. OSL ages ranging from 5.4 ka to 0.38 ka indicate that the deposition and ensuing cementation of the quartz grains occurred during two main stages; younger beds dated between 2.3 ka and 0.38 ka and older beds from 2.3 ka to 5.4 ka. A period devoid of beachrock formation was attested between 3.5 ka and 2.3 ka. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.
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    Records of repeated drought stages during the Holocene, Lake Iznik (Turkey) with reference to beachrock
    (PERGAMON-ELSEVIER SCIENCE LTD, 2016) Ozturk, Muhammed Zeynel; Erginal, Ahmet Evren; Kiyak, Nafiye Gunec; Demirci, Alper; Ekinci, Yunus Levent; Curebal, Isa; Ozturk, Tugba
    The cement fabrics, subsurface nature and optically stimulated luminescence age of beachrocks along the shores of Lake Iznik in NW Turkey were studied within the context of Holocene lake level changes. With a maximum thickness of 1.5 m, the low-angle (average 5-10 degrees) beds are composed of coarse grains and small gravels and extend up to 5 m offshore at their most lakeward extremities. Cement textures on and around the poorly-rounded grains are made up of micrite envelopes and meniscus bridges as well as acicular aragonite rims. Geoelectrical resistivity sections taken from a representative location along the beach where the beds have maximum thickness showed that the sand-buried beds are followed up to about 24 m landward. Based on the OSL ages of 33 samples, the cemented beds occurred at four drier periods of the following: Pre- and Early Holocene (dated to 15-9 ka), Holocene Climatic Optimum (7.9-5.6 ka), Middle Holocene (4.9 ka-2.8 ka) and Late Holocene (2.0 ka-0.9 ka). (C) 2015 Elsevier Ltd and INQUA. All rights reserved.