Temperature observations in Antarctic tafoni: implications for weathering, biological colonization, and tafoni formation

Abstract

Tafoni have long been recognized, measured and discussed within the Antarctic context. However, with respect to the formative processes tafoni still remain somewhat of an enigma. In terms of the weathering attributes of tafoni, one problem is the monitoring of environmental conditions without the transducers themselves altering that environment. The application of ultra-small thermocouples provides an avenue for monitoring of rock surface temperatures without influence on the tafoni environment. At an Antarctic site temperatures were measured both inside and outside of a tafone, with data at 20 second intervals. These data show a spatial variability that may help explain tafoni development, at least in terms of weathering. Humidity data indicate that moisture conditions are very low such that water-based weathering processes are temporally and spatially constrained. The presence of several episodes of extreme temperature variations indicates that thermal stress may be an important contributor to weathering here. It is argued that the absence of any endolithic communities (at this site) within the sandstone, in which the tafoni develop, is a reflection of weathering rates that exceed the ability of organisms to invade and colonize the rock. At the present time, weathering appears to be primarily in the form of granular disintegration and flaking.