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    Grain size and heavy mineral distribution as related to hinterland and environmental conditions for modern beach sediments from the Gulfs of Antalya and Finike, eastern Mediterranean
    (ELSEVIER SCIENCE BV, 2007) Ergin, Mustafa; Keskin, Seref; Dogan, A. Umran; Kadioglu, Yusuf Kaan; Karakas, Zehra
    Backshore sediment samples from 22 beaches along the Antalya and Finike Gulfs have been studied for their grain size, chemical and heavy mineral composition. Data presented here suggest that well- to moderately-sorted (0.41 Phi-0.92 Phi) medium sand (1 Phi-2 Phi) represents dominant mean grain size in most beaches. In contrast, some beaches from the western part of the Gulf of Antalya (Goynuk, Kemer-Kiris and Beldibi) are composed of pebble- to boulder-size grained beaches which are located close to mouths of short and steep-gradient ephemeral rivers entering the sea from the Western Taurus Mountains. The heavy mineral assemblages are dominated by detrital opaque minerals (14-58% magnetite, chromite, and hematite), pyroxene (8-65% augite), amphibole (3-15% tremolite and actinolite), epidote (3-25%), garnet (2-9% pyrope and almandine) and micas (3-20 biotite, muscovite and chlorite). The very high concentrations of heavy minerals (up to 86% of bulk sediment) together with the significant concentrations of some elements found in beach sediments from the Gulf of Finike and western Gulf of Antalya (Fe: 18.40%; Cr: 10.00%; and Ti: 1.32%) are indicative of ultramafic origin, mainly derived from the ophiolitic rocks of the Antalya-Tekirova nappe on coastal hinterland. (c) 2007 Elsevier B.V. All rights reserved.
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    Late Quaternary climate and sea-level changes recorded in sediment composition off the Buyuk Menderes River delta (eastern Aegean Sea, Turkey)
    (PERGAMON-ELSEVIER SCIENCE LTD, 2007) Ergin, Mustafa; Kadir, Selahattin; Keskin, Seref; Turhan-Akyuz, Nilufer; Yasar, Dogan
    Influences of Holocene climatic and sea level changes on sedimentation on the continental shelf off the Buyuk Menderes River delta, SW Turkey were investigated using grain size and X-ray clay mineralogical data on surficial and 14C-dated core sediments collected at 19-81 m water depths. Modern, fine-grained, siliciclastic sediments cover most of the seafloor of inner to mid-shelf areas. A narrow, relict belt extends from northwest to south (at 66-81 m water depths), where sediments are characterized by abundant sand and gravel (27-52%) and biogenic carbonate (16-44%) contents, and microscopic examination suggests an older origin. The radiocarbon ages of mid and lower sections in cores (3670-10,380 yr BP) reflect sedimentation under depositional conditions from early to late Holocene in the study area. Additionally, downcore changes of grain size toward coarser-grained sediments most probably record global climatic effects with sea level changes, specifically the transition from lowstand in early Holocene to highstand at mid-late Holocene. The presence of this relict belt in offshore waters can be attributed largely to active uplift tectonics. The coarser-grained relict belt, compared with available seismic profiles, corresponds to an lowstand unconformity of bottomset beds of the prograding Buyuk Menderes Delta. Reconstruction from nautical charts clearly showed the presence of an E-W-trending submarine canyon ("Paleo-Buyuk Menderes River valley") in the course of Buyuk Menderes Graben. This is interpreted as product of combination of sea-level lowstands and subsidence tectonics throughout the late Quaternary. Smectite (35-62 %), illite (28-51 %) and kaolinite (12-19 %) constitute the dominant clay minerals in the < 2 mu m fraction of the surface sediments. The patterns of clay mineral distribution suggest sediment transport from the Buyuk Menderes River and dispersal from the river to the outer continental shelf by the prevailing current regime. Downcore changes in the clay mineral assemblages (downward-decreasing smectite/iilite ratios) reflect changes in weathering conditions of the terrigenous source, from a colder climate during early Holocene to relatively warmer periods toward the present. Widely occurring partly metamorphosed volcanic rocks characterize the major geological sources of clay minerals on the adjacent hinterland. (c) 2007 Elsevier Ltd and INQUA. All rights reserved.
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    Provenance discrimination among foreshore, backshore, and dune environments in the black sand beaches along the Samandag/Hatay coasts, SE Turkey (E Mediterranean)
    (SPRINGER HEIDELBERG, 2018) Ergin, Mustafa; Karakas, Zehra S.; Tekin, Erdogan; Eser, Basak; Sozeri, Koray; Copuroglu, Ibrahim; Simsek, Barbaros
    The occurrence of beach placers, the chromite-rich black sand, and the factors controlling their distribution along the Samandag coasts, SE Turkey, was investigated. One hundred fifty-two surficial (upper 2 to 5 cm) samples of beach sediments from foreshore, backshore, and dune subenvironments; 24 river sediments; 25 samples from ophiolitic source rocks; and ore samples from 4 chromitite mines were collected between the years 2012 and 2015. In addition to hydrogeographic and geomorphological field observations, grain size analysis and total heavy mineral separation and conventional petrographic microscopy studies were carried out. Bimodal, well to moderately well sorted, fine to medium sands were predominant, and on the basis of grain size distribution, at least six sectors could be distinguished by their alongshore fining or coarsening tendencies. Obviously, spatial variations in drainage pattern of fluvial input, wave and current motions, and beach morphology played a crucial role in changing sediment texture. The total heavy mineral (THM) concentrations ranged from 1 to 92 wt% (avg. 40 wt%) in beach sediments and from 3 to 50 wt% in fluvial sediments whereby the bed load of the major and perennial Asi River contained lower THM (9-25 wt%) than its ephemeral tributaries (14-50 wt%) which are in much closer proximity to the source areas. Overall, the THM concentrations in foreshore, backshore, and dune subenvironments tend to decrease in southward direction, except for THM enrichment close to the Asi River mouth. This would reflect rather higher inputs from northerly ephemeral rivers draining the ophiolitic rocks with additionally net longshore sediment transport towards south. The coastal physical processes favoring heavy mineral enrichment such as spatial and temporal variations in swashzone wave dynamics with uprush, backwash, and infiltration effects on the beaches were also observed in the field. The opaque heavy mineral fractions are mostly found in grain size less than 0.25 mm and composed of chromite, magnetite, and ilmenite species with intergrowth textures. Non-opaque heavy mineral fractions were dominated by various species of pyroxenes and amphiboles with lesser amounts of serpentinized olivine. Formation of chromite-rich black sand placers along the Samandag beaches (SE Turkey) and also in river/stream beds resulted from the weathering of mafic-ultramafic rock complexes ("Hatay or Kizildag Ophiolites") and chromite-rich ores of the Amanos Mountains to define the provenance of placers and no considerable input was detected from the Asi River downstream from the Bassaer ophiolites of Syria.