ORIGIN OF SOME ATYPICAL SPELEOTHEMS (STALAGMITIC PIPES) AND THE ROLE OF CONCOMITANT DEDOLOMITIZATION IN THEIR FORMATION

We apply the term stalagmitic pipes to morphologically atypical speleo thems that consist of pipes that are a few centimeters to 3 m long and with walls 1-2 cm thick. They are developed from and in cataclastic s and, made up exclusively of dolomite, present in certain sectors of th e cave known as Cueva del Agua (Iznalloz, southern Spain). The catacla stic character of the dolomite sand, with its high porosity and permea bility, leads to the development of this unusual morphology as a resul t of the dispersing mechanical effect of water dripping from the roof of the cave. The high Ca2+/Mg2+ ratio of the water is responsible for the cementing of the dolomitic sand grains forming the speleothems. Th is chemistry is also responsible for dedolomitization of the dolomite sand grains. Scalenohedral calcite cement is found in some pores and c overs the inner surfaces of the speleothems.