Preliminary results on the origin of dissolution pipes in coastal eolianites of ？ile (？stanbul)

The origin of cylindrical and cone-shaped dissolution pipes commonly observed on coastal eolianites at tropical and Mediterranean coasts is still under debate. Such unusual paleokarstic landforms have been first recognized on Turkey’s coasts at Do？anc？l？ village to the west of ？ile, ？stanbul. Main aim of this study is explain physical properties and development model of these forms. Pipes are carved into cross-bedded laminae of 5 m-thick oolitic eolianites and forms are seen along cliff surface located northern part of the eolianite. Depth and perimeter of 45 pipes which are good condition are measured via ruler. Based on measurements of 45 dissolution pipes along sea-faced cliffs where they are preserved, pipes have the maximum upper diameter of 60 cm and depth of 460 cm. The depth of some pipes reaches the boundary with the underlying paleosol. The vertical shape of these holes are not apparently controlled by the cross bedded laminae. Variability in dimension of forms might represent differences in generation of pipe formation. Composite forms formed by combination of closely-spaced pipes verged into the sharp-edged blocks, i.e. pinnacle, as result of the removal of side walls. These weathered holes in eolianite dated to late MIS6 and early MIS5 might have formed during more humid conditions succeeding hotter and drier conditions, favoring the deposition and cementation of eolianite sands. The lack of calcarete within the dissolution pipes reveals nonoccurrence of arid stages during their formation. Consequently, dissolution pipes are likely the result of covered fossil (covered) karst caused by infiltrated waters having more acidity due to soil CO2. The vertical dissolution taking place on macro pores were possibly caused by the effects of infiltrated waters, passing from plant roots to preferred flow paths in vadose zone