Climate, palaeohydrology and land use change in the Central Iberian Range over the last 1.6 kyr: The La Parra Lake record

Abstract

A multiproxy study of a 7 m long sedimentary sequence from Lake La Parra (39º 50.948', 1º 52', 1014 m a.s.l) supported by 11 14 C AMS and 210 Pb/ 137 Cs dates provides a robust, high-resolution hydrological and environmental variability record for the last 1600 years of the Las Torcas sinkhole Complex in the Central Iberian Range. The succession of depositional environments in Lake La Parra sinkhole is controlled by both changes in the regional water table and by the balance between sedimentary input through ephemeral creeks and in-lake production of carbonates and organic matter. Although synergetic links with climate are likely, phases of increased sediment delivery to the lake at ca 500-700 AD, ca 1000 AD, 1450-1500 AD, 1550-650 AD and since 1700 till recent times are driven primarily by human impact in the watershed. Prior to ca 300 AD the sinkhole was dry, then became a lake at the end of the Roman Period (350 AD) when the doline was flooded, and it has not dried out during the last 1600 years. Moderate lake levels with deposition of coarser clastic facies dominated up to the 12 th century (400-1200 AD), and relatively higher levels with deposition of laminated facies during the 13 th -15 th centuries (1200-1600 AD).The pattern of paleohydrological evolution at a centennial scale is roughly coherent with most Iberian lacustrine records, however, the 'La Parra' sequence indicates that increased humidity during Iberian-Roman times was restricted to southern Spain, and the humid phases of the LIA starting and ending earlier in the central Iberian Range compared to the Pyrenean Domain and southern Spain. This new sequence highlights the heterogeneity through space and time of the main dry and wet climatic periods at shorter scales, emphasizing the impact of latitudinal climate gradients on the Iberian Peninsula climate variability.

Erosion in Mediterranean mountain landscapes during the last millennium: a quantitative approach based on lake sediment sequences (Iberian Range, Spain)

“…The sedimentary sequences and geochemical data for Lake La Parra, El Tobar and Taravilla have already been published (Barreiro-Lostres et al, 2014Moreno et al, 2008;Valero-Garcés et al, 2008). Work in El Tejo sequence is in progress and here we summarize some of the main results (see supplementary material).…”

“…In mountainous lakes, biogenic sediment production is limited and can often be neglected in relation to the rapid input of terrigenous material (Einsele and Hinderer, 1998). As sedimentological analyses have shown in these lakes, most sediments are delivered from the watershed ( Barreiro-Lostres et al, 2014Moreno et al, 2008). Thus, terrigenous carbonate and siliciclastic are the dominant mineral fraction in the sediment.…”

“…Exo-and endo-karstic processes are responsible for the formation of numerous lake basins in different settings: behind travertine dams as in the Lake Taravilla , due to collapse and dissolution karstic processes as in El Tobar Lake (Barreiro-Lostres et al, 2015), sinkhole formation as in the seven karstic lakes of the Cañada del Hoyo complex, which includes El Tejo and La Parra lakes (Barreiro-Lostres et al, 2014;Julià et al, 1998). …”

“…They present very similar facies, mainly massive to banded clastic carbonate-rich silts and muds in fining-upward sequences, occasionally interbedded with intervals with endogenic calcite laminations (Barreiro-Lostres et al, 2014). The El Tobar Lake sequence spans the last 1000 years and is mainly composed by alternation of laminated to banded, fine to medium carbonate-rich silts.…”

Sediment delivery and lake dynamics in a Mediterranean mountain watershed: Human-climate interactions during the last millennium (El Tobar Lake record, Iberian Range, Spain)

“…Human impact in Iberian landscapes has been particularly intense during the last two millennia (Barreiro-Lostres et al, 2014;Corella et al, 2013;García-Ruíz et al, 2013;García-Ruiz, 2010;Pèlachs et al, 2009;Roberts et al, 2004). The Iberian Range, located between the Castille Plateau, the Ebro Basin and the Mediterranean coast, provides an excellent case-study for the complex interactions of human activities and climate change in Mediterranean mountain areas at a larger time scales than recent global changes.…”