Elongated tufaceous stalagmites in the entrance of Batu Cave (Selangor, Malaysia)

Abstract

Research on the microbiology of cave environments and biologically mediated freshwater calcium carbonate deposits has been active in the past few decades. Among these deposits, tufaceous stalactites are common in tropical cave entrances and limestone cliffs. Their soft porous texture, irregular bulbous and generally positive phototropic morphologies reflect biological influences, principally those of cyanobacteria, algae and mosses. Despite the abundance of tufaceous stalactites, tufaceous stalagmites have rarely been documented and biologically mediated stalagmites have been reported only in a few locations worldwide. Four unusual elongated tufaceous stalagmites in the entrance passage of Temple Cave at Batu Caves (Selangor, Malaysia) are reported here. Their location, morphology and features indicate constructive and destructive biological influences. Some of their features resemble those of crayback stalagmites suggesting that similar processes played a role in their formation. Other features, such as prograding noses, macro-porosity, and internal stalactites, resemble those observed in non-spelean biologically mediated calcium carbonate deposits like tufa waterfalls. One of the stalagmites also has small scale erosive microrelief, including striations and rods. These are oriented parallel to incoming light from the cave entrance and are identified as photokarren, a particular and rare form of biokarst. This is the first published record of photokarren in a West Malaysian cave. The morphology of biologically influenced stalagmites is found to be more varied than previously thought and they are not particularly rare, but may have gone unrecognized in many tropical cave entrances. A conceptual model of asymmetrical stalagmite growth is presented with abiotic and biotic factors.