Defining denudation rate of carbonate rocks using cosmogenic 36Cl in the Taurus Mountain, S-SW Turkey

Denudation of carbonate terrains occurs by the contribution of both chemical and mechanical weathering. In-situ cosmogenic ³⁶Cl is a robust proxy to quantify the long-term total denudation rate of carbonate rocks. In this study, we defined the steady-state denudation rate of carbonate bedrock using ³⁶Cl for 10⁵-10⁶ years under the temperate Mediterranean to semi-arid climate in and around the Taurus Mountain Range, S-SW Turkey. We collected 13 samples from different lithological units; Jurassic-Cretaceous neritic limestone in the temperate western Taurus, Miocene neritic limestone in the semi-arid Central Taurus, and Mesozoic marbles in the continental part of Central Taurus. The calculated denudation rates range from 28.9 ± 1.4 mm/ka in the Mediterranean coastal range to 1.6 ± 0.1 mm/ka towards northern continental/rain shadow. We compared the denudation rates with a range of parameters such as topographic, climatic, lithologic and mechanical properties of rocks. For almost all samples denudation rate increases with elevation, with two exceptions with the highest rates despite their lower elevations. This high denudation rates could be due to their proximity to the sea. Our results showed that denudation rates decrease with increasing distance from the coast. All denudation rates showed a positive correlation with mean annual precipitation (MAP ~ 400-760 mm) as suggested by other studies worldwide. Annual temperatures (MAT ~ 6-16 °C), however, has a negative correlation with the denudation rates, i.e. the highest denudations occur in the low temperatures (MAT ~ 6-8 °C). The mechanical strength of the rocks was measured with a Schmidt hammer in the field. The high rebound values of Schmidt hammer, indicating the high mechanical strength, correlate with low denudation rates. Nevertheless, the mechanical strength of the carbonate bedrock is not as effective as precipitation or available moisture on denudation rates. This could be shown by two samples close to the Mediterranean which both have high mechanical strength nonetheless show the highest denudation rates. In conclusion, our study suggests that carbonate bedrock denudation in Taurus Mountain correlates with high elevation (~ 1900-2250 m), high precipitation (~ 700-800 mm), low temperatures (~ 6-8 °C) and short distances from the Mediterranean coast.