title: Cryogenic processes and fire activity in a high Atlantic mountain area in NW Iberia (Picos de Europa) during the Mid-Late Holocene.
abstract: Mid-Late Holocene environmental changes in the Cantabrian Mountains are a consequence of both climate variability and human activity. A 182cm-long sedimentary sequence was collected from Belbín depression, Western Massif of Picos de Europa (Cantabrian Mountains, NW Spain), in order to reconstruct Holocene environmental dynamics and the factors triggering landscape changes in the area. Using multi-proxy analysis of the uppermost 60cm of the sediments (texture, organic matter content, quartz grains microstructures, charcoal deposition) together with three14C AMS dates, a sequence of alternating warmer and colder phases has been inferred for the last ca. 6.7kycalBP. Warm stages are defined by low to moderate chemical weathering of the quartz grain particles with relative increases of the C/N ratio, while colder phases show a moderate to intense physical weathering of the quartz grains and lower C/N ratios. Warmer temperatures were recorded in Belbín area between: 6.7-5, 3.7-3, 2.6-1.1, 0.87-0.51 and since 0.01kycalBP. A colder regime occurred between 5-3.7, 3-2.6, 1.1-0.87 and 0.51 to 0.01kycalBP. The increasing organic matter content during the Late Holocene may be associated with increasing temperatures. The charcoal particles do not show a higher or lower concentration during prevailing colder or warmer conditions, and therefore may be linked to human-induced fire management of the landscape. The most intense period with fire activity occurred between 3.5 and 3kycalBP during the Bronze Age.
authors.affiliation: Department of Geography, University of Oviedo, Teniente Alfonso Martínez s/n, 33011 Oviedo, Spain. Electronic address: ruizjesus@uniovi.es.
authors.forename: Jesús
authors.initials: J
authors.lastname: Ruiz-Fernández
authors.affiliation: Centre for Geographical Studies - IGOT, Universidade de Lisboa, Rua Branca Edmée Marques, 1600-276 Lisboa, Portugal.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Nieuwendam
authors.affiliation: Centre for Geographical Studies - IGOT, Universidade de Lisboa, Rua Branca Edmée Marques, 1600-276 Lisboa, Portugal.
authors.forename: Marc
authors.initials: M
authors.lastname: Oliva
authors.affiliation: IDL, Faculty of Sciences, Universidade de Lisboa, Campo Grande, Edifício C6, 1749-016 Lisboa, Portugal.
authors.forename: Vera
authors.initials: V
authors.lastname: Lopes
authors.affiliation: IDL, Faculty of Sciences, Universidade de Lisboa, Campo Grande, Edifício C6, 1749-016 Lisboa, Portugal.
authors.forename: Anabela
authors.initials: A
authors.lastname: Cruces
authors.affiliation: IDL, Faculty of Sciences, Universidade de Lisboa, Campo Grande, Edifício C6, 1749-016 Lisboa, Portugal.
authors.forename: Maria Conceição
authors.initials: MC
authors.lastname: Freitas
authors.affiliation: IDL, Faculty of Sciences, Universidade de Lisboa, Campo Grande, Edifício C6, 1749-016 Lisboa, Portugal.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Janeiro
authors.affiliation: Institute of History, Center for Humanities and Social Sciences, CSIC, Albasanz 26-28, Madrid 28037, Spain.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: López-Sáez
keywords: Climate variability; Cryogenic processes; Fire activity; Holocene; Picos de Europa