Micro-karstification in a stalagmite, Küpeli Cave, southern Turkey

Abstract

This article deals with micro-karstification forming abundant dissolution features in a stalagmite from Küpeli Cave in southern Turkey. Dissolution occurs when cave water enriched with CO₂ from the soil and epikarst, and in certain conditions also from the cave atmosphere, seeps into the stalagmite. Here, we hypothesise that water is transmitted from the former surface of the stalagmite to the interior by the roughly vertical or diagonal notch-shaped pores formed by the enlargement of intercrystalline pores by dissolution. These slightly elongated pores randomly developed in the stalagmite under repeated conditions at different stages of the stalagmite formation, affecting the last few macroscopic growth layers (lamina set under the microscope) from its former surface, finally its upper end was covered by a newly forming growth layer. Later, when this water reaches the relatively more permeable growth layer surfaces, it flows along these surfaces, and diffuse dissolution features form. The dissolution features include micro-scale pitted and etched surface structures, rounded and enlarged crystal boundaries and intercrystalline pores, and the breakdown of relatively large crystals (≥ 4 μm) into nm sized smaller crystal aggregates. In the dissolution pores, calcite re-precipitation occurs as rim and pore-filling cements when the percolation water is sufficiently saturated with calcium carbonate in the stalagmite. Under the repeated conditions, the dissolution was followed by calcite re-precipitation in the stalagmite, probably due to seasonal variation in CO₂ and CaCO₃ contents of the water in the epikarst zone as well as within the stalagmite.