Factors controlling the morphological evolution of the Çanakkale Strait (Dardanelles, Turkey)

Seismic profiling, bathymetric and physical oceanographic data collected from the Çanakkale Strait revealed that the morphological evolution of the strait has been controlled by tectonic activity, and sediment erosion and deposition. Sediments in the strait have been sourced mostly by rivers draining the Biga Peninsula during lowstand periods. In highstand periods, by contrast, deposits in the strait were reworked by currents. The seafloor morphology of the Çanakkale Strait is also controlled by a sequence of factors ranging from tectonics to current erosion and deposition. Channel deposits overlying the basement are being eroded at the narrower, meandering central section of the strait (the Nara Passage) due to high current velocities. The eroded sediments are deposited in the relatively linear and wider, northern and southern sectors of the strait exposed to low current velocities. As a result, the high-energy areas are more deeply incised due to the erosion, whereas deposition elevates the seafloor in the areas exposed to lower current energy. Three strike-slip faults, which possibly relate to the activity of the North Anatolian Fault Zone, are responsible for the irregular shape of the strait and this, in turn, controls the current velocity along the strait. The high-energy conditions probably commenced with the latest invasion of Mediterranean waters some 12 ka b.p., and have continued as a two-layered current system to the present day.     

Late Quaternary evolution of the Çanakkale Strait region (Dardanelles, NW Turkey): implications of a major erosional event for the postglacial Mediterranean-Marmara Sea connection

Seismic and bathymetric data from the Çanakkale Strait and its extensions onto the shelves of the Marmara and Aegean seas indicate that the strait was formed mainly by an erosional event. Four seismic units are observed on seismic profiles. The lower two of these (units 4 and 3) constitute the basement of a regionally widespread erosional unconformity (ravinement), which developed during marine isotope stage 2 (MIS 2). The two upper units (units 2 and 1), which overlie the ravinement surface, form a higher-order sequence. Sequence stratigraphic analysis indicates that units 2 and 1 deposited as lowstand and highstand systems tracts respectively, since the end of MIS 2. The transgressive systems tract is represented by a major erosional event which occurred throughout the Çanakkale sill area when the Mediterranean-Marmara Sea connection and, hence, the Çanakkale Strait was formed. The existence of the erosive ?arköy Canyon along the shelf edge of the southern Marmara Sea demonstrates that the flow direction causing the erosion was from south to north, thus proving that it was produced by Mediterranean water flowing over the sill into the Marmara Sea basin.     

Petrogenesis and geodynamics of plagiogranites from Central Turkey (Ekecikdağ/Aksaray): new geochemical and isotopic data for generation in an arc basin system within the northern branch of Neotethys

International Journal of Earth Sciences - In the Late Cretaceous, throughout the closure of the Neotethys Ocean, ophiolitic rocks from the İzmir–Ankara–Erzincan ocean branch were...     

A literature review of Algerian salt lakes: values,threats and implications

Chotts are salt lakes located in the arid regions of Northern Africa. These unique wetlands are recognized for their role in the migration and breeding of waterbirds and economic values generated from mineral extraction, agriculture and tourist activities. Despite their importance for flora and fauna biodiversity, they continue to face important threats due to human activities. This article consolidates a literature review of Algerian chotts from global to local importance. An in-depth view demonstrates the changes in land use of two large chotts in the southeastern region of Algeria: Chotts Merouane and Melghir. Land use images highlight a net expansion of agricultural lands, a decrease in grazing area around the lakes and a decrease of salt lake surface area. The local focus highlights the threats and changes of Algerian and Northern African chotts and proposes some perspectives for the future.     

Assessment of variations in water quality using statistical techniques: a case study of Işıklı Lake, Çivril/Denizli,Turkey

A study of the hydrochemical evaluation of waters in the I??kl? Lake and surrounding area was carried out with the objective of identifying the geochemical processes and their relation with water quality in the region. The multivariate statistical techniques were used in the hydrochemical evaluation of waters. Statistical analysis of water quality parameters was made to seeing the interrelationship between different variables in order to explain the water quality and pollution status of study area. For this purpose, water samples were taken from lake, river, stream, and springs which are represented by investigated area and water qualities were evaluated. Generally, Ca²⁺, Mg²⁺, and Cl^?, HCO₃ ^? ions are dominant within surface water and water sources. Arsenic concentration increase is determined in I??kl? spring and Kufi stream water samples. Also, aluminum concentration is high level in the Kufi stream water samples. This increase was related to igneous rocks as geogenic origin. Also, geogenic contamination was identified in R-mode factor and cluster analyses. There is high correlation between electrical conductivity and major ions of waters.     

Subsurface geophysics applied to archaeological investigation of Thabudeos Roman fortress (Biskra,Algeria)

Tahouda, former Roman Thabudeos, is situated 400 km south of Algiers (Algeria). It is one of the fortresses belonging to Roman south defense line in North Africa. This region is archaeologically very poorly known except for surface remains. The geophysical survey formed part of a wider research project designed to record and assess the landscape context of the longest Roman defense line in North Africa. We present the geophysical mapping and imaging using electric resistivity tomography and electromagnetics to help in investigating the subsurface properties of the region. Data were obtained using: (1) Saris resistance meter with up to 25 electrodes spaced at 2 m intervals and lines up to 50 m long. A total of 11 lines was obtained. (2) Geonics EM31, in two dipole configuration modes with 16 lines up to 100 m sampled every meter. These methods prove to be very powerful tools to give insight and locate the anthropologic remains from the surface to a depth of 6 m and outline their geometry. The results obtained by the two methods are consistent above the main remains like walls and rooms.     

Hydrogeological and mixing process of waters in deep aquifers in arid regions: south east Tunisia

This study addresses the hydrogeochemistry of thermal and cold waters from south east Tunisia. Temperature intervals are 38.5–68 °C and 22–27.8 °C for thermal water and cold water, respectively. Three distinct hydrogeological systems supply water either for irrigation or for drinking; they are: (1) the Continental Intercalaire geothermal aquifer (CI), (2) the Turonian aquifer and (3) the Senonian aquifer. A synthetic study including hydrochemical, hydrogeological and geothermal approaches have been applied in order to evaluate the inter-aquifers water transfer in south east of Tunisia. By using silica geothermometers and saturation indices for different solid phases, estimated thermal reservoir temperature varies between 52 and 87 °C and between 75 and 110 °C, respectively. Based on chemical and thermal data, mixing, which occurs between the ascending deep geothermal water and shallow cold water, is about 57 % cold water.     

Atmospheric concentrations of PAHs, their possible sources and gas-to-particle partitioning at a residential site of Bursa, Turkey

Atmospheric PAH concentrations were determined in Gulbahce district of Bursa, Turkey between August 2004 and April 2005. Measured PAH concentrations were classified as heating and non-heating season samples. The concentrations of total PAHs in heating season were almost ten times higher than those in non-heating season. Diagnostic ratios and factor analysis results show that in the heating season traffic along with residential heating emissions heavily influence PAH concentrations. The plot of logK_p versus logP_L⁰ for all the data set of heating and non-heating season samples gave significantly different slopes. The slope for the heating season samples (− 0.92) was steeper than the one for the non-heating season samples (− 0.78). The partitioning results for individual samples further indicated that slope values varied depending on air parcel trajectories. Air parcels traveled over water (either over the Black Sea or Aegean Sea) prior to arriving at the sampling site had less steep slopes. Partitioning of PAHs was also investigated by comparing experimentally determined K_p values with the results obtained both from octanol-based model (K_p(Oct.)) and soot and octanol-based model (K_p (Soot + Oct.)). Both models were useful in predicting the experimental K_p values. However, they did not explain the observed variability in the experimental K_p values.