Factors controlling growth of modern tufa: results of a field experiment

Abstract

AbstractA field experiment was performed at four sites in Slovakia and Poland in order to identify factors that influence the growth rate and textures of modern tufas. Two pairs of tablets were placed at each study point, every pair consisting of a limestone tablet and a copper tablet. One pair at each site was changed every three or four months, while the second pair was left for approximately 14 months. Each tablet was weighed before placing and after removal to find the amount of the tufa growth.Tufa growth rate was found to depend on SIcalc. of parent water, though deposition of tufa on limestone tablets was substantially faster than on copper tablets. This result indicates that micro-organisms are essential for more efficient growth of tufa. Tufa growth rate was higher in fast-flowing water than in nearby sluggish flow settings.Fast-growing tufa has crystalline texture or consists of highly encrusted algal filaments. The latter texture is due to faster growth of micro-organisms, forced by rapid crystallization of calcite on their cells. The slow-growing tufa exhibits mainly micritic textures. Clotted micrite with numerous diatoms forms mostly in winter, while encrusted algal filaments are typical for spring and summer growth.