Revisiting the subalpine Mesolithic site Ullafelsen in the Fotsch Valley, Stubai Alps, Austria – new insights into pedogenesis and landscape evolution from leaf-wax-derived <i>n</i>-alkanes, black carbon and radiocarbon dating

Abstract. Archaeological research in high mountain regions has gotten a lot more attention since the discovery of copper age mummy called “Ötzi” Ötztaler Alps 1991. In Tyrolean Stubai Alps, Mesolithic site Ullafelsen at 1869 m a.s.l. (above sea level) close to recent upper timberline Fotsch Valley represents, on one hand, very important archaeological reference and offers, other intriguing questions related to, amongst others, pedogenesis. Given that no biomarkers stable isotopes have been hitherto investigated, we aimed contributing with respective analyses additional radiocarbon dating better understanding landscape evolution pedogenesis around Ullafelsen. Our results for modern vegetation suggest leaf-wax-derived n-alkanes allow us chemotaxonomically distinguish between subalpine deciduous trees (nC27 predominance) versus (sub)alpine grasses, herbs dwarf shrubs (nC29, nC31 and/or nC33 predominance). Except Juniperus, conifers produce or extremely low n-alkane contents. Although clear changes could be inferred from patterns investigated soil profiles, total content (TAC) was developed first time as an unambiguous proxy distinguishing buried (= fossil) topsoils (2Ahb horizons) humus-enriched subsoils such Bh horizons podzols. Based this leaf wax proxy, can rule out 2Ahb?/Bh? under question are suggested previously. Dating H2O2-pretreated samples yielded 14C ages podzol ranging 6.7 5.4 cal kyr BP. This is clearly younger than overlying living floor (LL) (10.9 9.5 BP) but pre-dates assumed intensification alpine pasturing Bronze Age onwards. Both LL directly OAh3 horizon black carbon maxima benzene polycarboxylic acid reflecting fire-induced human impact during Mesolithic. The discrepancy charcoal (ages ≥ obtained bulk 8.2 4.9 BP suggests non-alkane-producing predominated after occupation. Only anthropo-zoological lowering associated Neolithic especially n-alkane-producing cover (grasses, shrubs) started predominate.