The NSS Bulletin - ISSN 1090-6924
Volume 52 Number 1: 70-86 - December 1990

A publication of the National Speleological Society

Extraordinary Subaqueous Speleothems in Lechuguila Cave, New Mexico
Donald G. Davis, Margaret V. Palmer, and Arthur N. Palmer

Abstract

Many helictites in Lechuguilla Cave, New Mexico, show conclusive evidence for a subaqueous origin. Some are apparently still growing, or remain in the environment in which they grew. Helictites have previously been interpreted as exclusively subaerial in origin. Growth of the subaqueous helictites is triggered by the common-ion effect, where calcite-saturated water comes in contact with gypsum blocks. Dissolution of gypsum rapidly drives the water to supersaturation with calcite forming helictites if the water enters a pool as discrete strands. Another previously undescribed speleothems type, tentatively named "pool fingers," is also subaqueous in origin. They are elongate growths of calcite that appear to coat organic filaments. Many are connected by curved bridges ("U-loops"). A third variety of speleothems, rarely described in the literature, consists of iron-oxide stalactites and columns lined with calcite. At least part of their origin was subaqueous. The iron oxide coats organic (bacterial?) filaments associated with oxidation reactions.

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