Journal of Cave and Karst Studies - ISSN 1090-6924
Volume 67 Number 1: 69-87 - April 2005

A publication of the National Speleological Society

Carbonate precipitation along a microclimatic gradient in a Thailand cave - Continuum of calcareous tufa and speleothems
Danko Taboroši, Kazuomi Hirakawa, and Takanobu Swagaki

Abstract

Variations in the local microclimate can profoundly affect vadose carbonate precipitation. This may be negligible deep inside caves, but is intense in climatically less stable environments, such as cave entrances and twilight zones. In such settings, microclimate can exert primary control on the characteristics of actively forming stalactites, far outweighing the other factors, notably dripwater properties.

Based on temperature, humidity, and light intensity monitoring of a cave in southern Thailand and analyses of associated cave deposits, we have seen that microclimatic (and ensuing biologic) gradients that exist between the cave entrance and cave interior are closely reflected by the morphology and petrology of actively forming stalactites. Spanning the cave’s microclimatically most variable and most stable parts, these stalactites comprise uninterrupted morphologic and petrologic series, ranging from extremely porous and largely biogenic stalactitic accretions of calcareous tufa growing around the dripline (and even outside the cave) to the dense coarsely crystalline stalactites (speleothems) in cave interior. This rarely observed continuum between tufas and speleothems indicates that the boundary between the two is hardly distinct (or justified) and any observed differences can be simply a result of different microclimatic regimes of their depositional settings.

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