Beyhan Öztürk

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.

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.

Thermal indices in Western part of Turkey

In this study are used heat index, effective temperature, wet bulb globe temperature, and apparent temperature indices. Air vapor pressure, temperature, relative humidity, and wind speed data are very effective meteorological parameters over the sensitive temperature. Daily mean temperature (°C), relative humidity (%), wind speed (m/s), and vapor pressure (hPa) data are used in this study. Using the thermal indices is calculated to long-term data from 49 stations distributed over the western part of Turkey. The Mann-Kendall test is applied to identify statistically significant trends at each series of thermal indices. The results of this study have shown that there are marked spatiotemporal variations in the thermal indices in the western part of Turkey. Increasing trends are stronger in summer compare with other season. Analysis are displayed that the increasing trends have shown warm-hot and discomfort days, especially during the summer season. High values of these indices are mainly connected to Azor high-pressure system and Monsoonal circulation and weakly etesian winds in summer.

Batı Burnu kumul sahasında (Bozcaada) rüzgâr etkinliği ve kum taşınım ilişkileri

Bu calismada Bozcaada’nin bati kesimindeki, boyuna kumul sirtlari, bu sirtlar arasindaki tabani nemli oluklar ve parabolik ve fincan sekilli deflasyon cukurlarindan olusan kiyi kumullari, tane boyu parametreleri, elektron mikroskobu analizleri ve hava fotografi/uydu goruntusu yorumlarina dayali olarak tartisilmaktadir. Granulometrik analizler icin kumul sirtlarini dikine kesen 4 hat boyunca 33 ayri noktada yuzey kumlari toplanmis, istatistiksel olarak analiz edilmis ve deflasyon ile ruzgâr ve nemlilik kosullariyla olan iliskisi degerlendirilmistir. Elde edilen sonuclara gore, nemin minimuma indigi ve kuzey yonlu kuvvetli ruzgârlarin kurutucu etkisinin arttigi maksimum deflasyon devresi olan yaz aylari basta olmak uzere, yil boyunca kuzey sektorlu ruzgârlar egemendir. Kumul sirtlari ve depresyonlarinin dogrultulari hakim ruzgâr yonlerine uyumludur. Ayrica ortalama tane boyu ve boylanma katsayilari degerleri de KD-GB dogrultusunda bir dagilim gosterir. Hava fotografi ve uygu goruntusu analizlerine gore 1962-2008 yillari arasinda kumul sahasinin dogu-kuzeydogu kesiminde ruzgâr erozyonu daha etkili olmus, guney ve guney bati kesiminde ise bitki kapaliligi artmis ve deflasyon etkisi azalmistir. Anahtar Sozcukler: Kiyi kumulu, granulometrik analiz, deflasyon devresi, Bati Burnu, Bozcaada