Ahmet Evren Erginal

Investigation of Beachrock Using Microanalyses and OSL Dating: A Case Study from Bozcaada Island, Turkey

Abstract We investigated the origin and absolute age of beachrock samples on Bozcaada Island, located on the northern Aegean Sea coast of Turkey, using energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) analyses and optically stimulated luminescence (OSL) dating. Various types of cements were identified, such as micritic, meniscus, and biologic cements, revealing that the beachrock could have occurred as a result of the combined effects of marine-phreatic and supratidal cementation conditions. Optical dating results showed that the formation of beachrock ranged in age from 5.41 ± 0.58 ka BP to 0.33 ± 0.05 ka BP. However, much of the beachrock body (about 3 m in thickness) is drowned or submerged today, suggesting that submerged beachrocks extending to −5 m date to earlier times than the start of the cementation period discussed herein.

Characterization of a Landslide using Seismic Refraction, Electrical Resistivity and Hydrometer Methods, Adatepe – Çanakkale, NW Turkey

Seismic refraction and electrical resistivity surveys were carried out to characterize a landslide that occurred near the Canakkale-Lapseki-Bursa highway, in northwest Turkey. Hydrometer analyses were also performed to highlight the composition of the slip surface material. The combined interpretation of the methods yielded the mass of the landslide body and the possible subsurface nature of a basal slip plane. Sediment-size fraction maps show that the slip surface material contained an excessive amount of clay. The clay-rich slipping layer was observed to a maximum depth of 4–5 m marked by a low (2–4 ohm‐m) resistivity zone, contrasting with the underlying sand-rich beds with relatively higher resistivities (<6 ohm‐m) . A velocity variation ranging between ∼1,250–1,500 m∕s also characterized this water-saturated slipping zone. Results indicated a buried failure surface under the studied shallow slide mass, which appeared to be a prolongation of the long upward-concave slip surface of the old landslide ar...

GEOMORPHOLOGICAL INVESTIGATION OF THE EXCAVATION-INDUCED DÜNDAR LANDSLIDE, BURSA — TURKEY

Abstract. This paper discusses the occurrence and development of the excavation‐induce deep‐seated landslide, which took place near Dündar village, located west of Orhaneli town in northwestern Turkey. The event occurred in the Bursa‐Orhaneli lignite field, which has been actively operating since 1979. Due to undermining of a gently inclined slope (10°) to extract a coal seam, primary tension cracks, which were precursors of the movement, were first observed in the northern head area in mid‐ to late October 2003. This movement happened simultaneously with precipitation that was significantly above long‐term average measured at a nearby climatology station (Keles). This precipitation amount is characterized statistically by a significant standardized anomaly of 1.6. The majority of the monthly precipitation total in October 2003, which mainly consisted of rain showers and thunderstorms, occurred in the last week of the month. By April 2004, rotational failure continued intermittently. After a relatively wet (rainy and snowy) period from January 2004 to April 2004, the main rotational slump occurred in late April 2004, causing the entire destruction of Dündar villages cemetery. Daily climatic and synoptic meteorological data have proved that heavy showers in late April may had triggered the last slump by producing rain showers of 19.3 mm and 19.9 mm daily total on 27 and 28 April 2004, respectively. Field observations carried out along the main head scarp have shown that the slope failure was facilitated by a pre‐existing normal fault with an east‐ west direction and 80° dip. Grain‐size analysis showed that the failure occurred on clayey silt, which forms 55% of the slip surface material. Based on the evidence from X‐ray fluorescence and energy dispersive X‐ray spectroscopy results, smectite‐type clay ‐ a product of the chemical weathering of tuff ‐ was the main constituent of the slip surface material. The landslide occurred over an area of 600 m × 650 m with a total volume of 8775 000 m3. Approximately 28 hectares of farm land were entirely destroyed and the excavated coal seam was buried. The mining operation was moved to 100 m north of the landslide area near Gümüşpınar village. From morphological evidence, it is concluded that excavation activities caused the failure to extend in more than one direction as an enlarging sliding mechanism; this produced a high landslide risk for Gümüşpınar village, where the most significant normal fault with a 75 m vertical displacement in a coal‐bearing sequence is found in the lignite field.

Optical Stimulated Luminescence Dating Study of Eolianite on the Island of Bozcaada, Turkey: Preliminary Results

Abstract In the present paper, eolianite exposed on the south coast of the semiarid island of Bozcaada, Turkey, was investigated on the basis of geomorphologic and petrographic data, and optically stimulated luminescence (OSL) dating results. The eolianite is lithic arenite in composition and contains abundant quartz, calcite, and various lithoclasts amalgamated with micritic calcite, sparitic calcite, and meniscus cements. Within the youngest layers standing at 1–2 m above sea level, the rock contains rhizoliths with or without carbonaceous fills. The OSL ages obtained ranged between 24.21 ± 1.53 ka and 16.18 ± 1.70 ka, suggesting that eolianite constitutes an example of low stand deposits coinciding with oxygen isotope stage 2 (OIS-2).

Distribution and environmental risk evaluation of heavy metal in core sediments from Lake Çıldır (NE Turkey).

This study examined the vertical distribution of heavy metals in core sediments taken from Lake Çıldır, Turkey, and their potential ecological risks together with organic carbon content and chlorophyll degradation products. Samples were collected from six sampling stations determined along two main transections aligned in north–south and east–west directions. The enrichment (EF) and contamination factor (CF), potential ecological risk (PER) index, and pollution load index (PLI) were calculated from the obtained results. For the elements Pb, As, and Cd, a moderate level of contamination was detected, whereas a moderate-to-high concentration level was obtained for Mn. The highest contamination level was found for Hg. A pollutant accumulation exists particularly in the surface sediments. Cd and Hg are the only two metals considered to be a potential risk factor in the lake.

Depositional Characteristics of Carbonate-Cemented Fossil Eolian Sand Dunes: Bozcaada Island, Turkey

ABSTRACT Erginal, A.E.; Ekinci, Y.L.; Demirci, A.; Avcıoğlu, M.; Öztürk, M.Z.; Türkeş, M., and Yiğitbaş, E., 2013. Depositional characteristics of carbonate-cemented fossil eolian sand dunes: Bozcaada Island, Turkey. Coastal eolianite on the south coast of Bozcaada Island, Turkey, was investigated by field observations, petrographic and climatological examinations, and electrical resistivity tomography data. The 4- to 7-m-thick eolianite, including rhizolith morphotypes characterized by root tubules and bifurcated root casts, demonstrates dune-sand accumulation during the Upper Pleistocene. Our results showed that paleowind drift and recent windblown sand drift on the island are similar. The dune sands exhibit various cement types formed of calcite and aragonite, such as micrite encrustations, meniscus and gravitational cements, and in particular, void fills. Dune-sand accumulation took place on the truncated surface of Miocene deposits. Geophysical data showed the existence of large weathered cavities within the eolianite and a high-angle normal fault, which displaces the eolianite, together with the underlying Miocene unit.

Physico-Chemical Characteristics of Coastal Dunes on the Saros Gulf, Turkey

Abstract In the present paper, several physico-chemical characteristics of dune sands in a rapidly prograding delta environment on the east coast of the Saros Gulf, northwest Turkey, are presented. For accurate characterization and classification of coastal dunes 4 km long and maximum 500 m wide, the pH, CaCO3 content, electrical conductivity, organic matter content, and x-ray fluorescence spectroscopy data were assessed. In terms of dune classification, our results showed the presence of three distinctive coastal dune types: (1) foredune, (2) semistable gray dune, and (3) stationary dark dune. Field observations combining with aerial photo and satellite image interpretations for the period between 1962 and 2007 also revealed dune loss and migration in the dunefield as a consequence of bidirectional effects of south-westerly and northwesterly winds and wind-force rise of lagoon waters.

Beachrock as evidence of sea-level lowstand during the classical period, Parion antique city, Marmara Sea, Turkey

Results obtained from beachrock lying on the north coast of the antique city of Parion in Çanakkale province, NW Turkey, are presented based on field data, petrographic analyses, cement fabrics, and radiocarbon dating. Extending to 20 m offshore at a depth of −2 m, the studied 50-cm thick beachrock is poorly sorted lithic sandstone. Both exposed and submerged parts are characterized by sequentially precipitated marine phreatic and vadose cements composed of micrite encrustations with micro-organism borings, pseudopeloidal aggregates of high-Mg calcites with scalenohedral habits and meniscus bridges. Radiocarbon ages point to a deposition during the classical period when the sea level was below (between −1 and −1.5 m) that of the present. The beachrock witnesses a granule- and pebble-dominated wide beach prior to cementation, suggesting that Parion’s fortification walls were behind the coastline during this lowstand and raises questions concerning the existence of a harbor north of the city.

A Preliminary Note on Depositional Characteristics and Optical Luminescence Age of a Marine Terrace, Strait of ¸ Canakkale, Turkey

ABSTRACT Avcıoğlu, M.; Erginal, A.E.; Kiyak, N.G.; Kapan-Yeşilyurt, S., and Yiğitbaş. 2013. A preliminary note on depositional characteristics and optical luminescence age of a marine terrace, Strait of Çanakkale, Turkey This preliminary study investigated the depositional features and optical luminescence age of marine terrace sediments located on the east coast of the Strait of Çanakkale, Turkey. With regard to depositional setting, the studied sequence is formed mostly of shallow marine deposits rich in quartz and oysters as well as other accessory minerals and various fossil sea shells. In vertical section, the sequence is characterized by two different stratigraphic units, i.e. a 1.50-m-thick sandy to gravely bottom unit (unit A) and an overlying 2.5-m-thick fossiliferous zone (unit B). On the basis of optically stimulated luminescence (OSL) age estimations obtained from six sampling levels from bottom to top, we determined superimposed cycles of deposition during interglacials from 246.47 ± 25.32 ka (unit A) at MIS 7 to 127.48 ± 8.91 ka (unit B) at MIS 5.

First note on marine-like cementation of Late Holocene beachrock, Iznik Lake (Turkey)

Micro-fabric characteristics and optically stimulated luminescence (OSL) dating results are presented to discuss the controlling agents and timing of beachrock cementation on the fresh-water Iznik Lake shoreline. The beachrocks are made up of grain-supported polygenic conglomerate containing 20.42% carbonate with encrusted grains, basically as micrite coatings, isopachous aragonite rims, cryptocrystalline void fills and meniscus bridges. The optical ages of twelve samples yielded ages that range from 4.226±0.569 ka on the lowermost beds to 0.706±0.081 on the uppermost. This is the first report of precipitation of marine-like cements in Iznik Lake. The abundant aragonite-dominated cement is likely indicative of precipitation-prone dry evaporative conditions from the climatic optimum to the last millennia.