Role of lichens in granite weathering in cold and arid environments of continental Antarctica
Mauro Guglielmin, Sergio E. Favero-Longo, Nicoletta Cannone, Rosanna Piervittori, Andrea Strini, 2011. "Role of lichens in granite weathering in cold and arid environments of continental Antarctica", Ice-Marginal and Periglacial Processes and Sediments, I. P. Martini, H. M. French, A. PéRez Alberti
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The mechanical and chemical effects of lichens on the outer and inner surfaces of tafoni features were investigated through a multidisciplinary approach at two locations (Oasi 74°42′S, 164°07′E, 40–250 m a.s.l.; Mount Keinath, 74°32′S; 163°58′E; 850 m a.s.l.) close to the Italian Antarctic station (Mario Zucchelli). Outer tafoni roof surfaces show low values of effective porosity coupled with pervasive hyphal penetration and an extensive reddish-brown weathering rind. Inner tafoni surfaces show higher values of effective porosity, which correspond with an almost absent weathering rind and low hyphal penetration. Our observations indicate that: (a) iron oxy-hydroxides, particularly concentrated where hyphal patches and bundles contact biotite, consist of hematite; (b) the microcosms of lichen hyphae and their precipitates fill voids to form case hardening on outer surfaces; and (c) on inner surfaces biological action is less active, most likely because of more intense thermal stress and salt action.