Younger Dryas – early Holocene transition in the south‐eastern Iberian Peninsula: insights from land snail shell middens

Abstract

The land snail Sphincterochila candidissima from archeological records in Villena (SE Spain) was studied isotopically to estimate the Younger Dryas (YD)-early Holocene transition in the western Mediterranean. Live-collected individuals exhibited body (À21.8 AE 1.6%) and shell (À5.8 AE 1.4%) d 13 C values typical of a C 3 plant diet, probably combined with carbonate ingestion. Calculations of a carbon flux balance-mixing model suggest that living specimens experienced similar metabolic rates, with comparable ratio of input and output fluxes of bicarbonate from the snail hemolymph. All fossil shells showed comparable d 13 C values among each other, but values were $2% higher than living specimens. This may be explained by higher water stress at the YD-Holocene transition or by the Suess effect. Shell d 18 O values averaged þ1.3 AE 0.8% for living individuals, À0.5 AE 0.8% for Holocene (8.4-10.2 cal ka BP) specimens and þ0.4 AE 0.6% for YD (12.0-12.4 cal ka BP) snails. An oxygen flux balance-mixing model suggests that YD shells precipitated during relative humidity (RH) values of $79-82%, after which RH increased gradually reaching maximum values of $87-88% at $8.4-8.6 cal ka BP and, from there, RH eventually declined to present values of $82%. Comparisons with other snail data suggest that the xerophilous Sphincterochila records different environmental signatures fro other contemporaneous taxa.

Pedogenic carbonates: Forms and formation processes

“…mollusk shells) (Xu et al, 2010;Yanes et al, 2013)  Bone pieces (Berna et al, 2004;Krueger, 1991;Zazzo et al, 2009)  Eggshell particles (Janz et al, 2009;Kandel and Conard, 2005;Long et al, 1983;Vogel et al, 2001)  Tooth enamel and dentin (Feakins et al, 2013;Hedges et al, 1995;Hoppe et al, 2004)  Old wood ashes (Regev et al, 2011) and calcified fossil seeds Regev et al, 2011).…”

“…BC features are used to recognize the settlements or habitats, diet regimes and extinction periods of ancient humans, animals and plants (Hoppe et al, 2004;Janz et al, 2009;Kandel and Conard, 2005) as well as to reconstruct the environmental conditions during their lifetimes (Villagran and Poch, 2014;Xu et al, 2010;Yanes et al, 2013). PC formation and mixing with fossil BC will complicate the results of such paleo-reconstruction studies, e.g.…”

¿Es posible integrar las demandas de agua y el desarrollo sostenible en paisajes agrarios mediterráneos semiáridos? La huerta y la laguna de Villena (Alicante)

“…Este nos permite en base a la dominancia de las especies vegetales presentes en el registro identifi car las comunidades vegetales dominantes y un marco temporal de presencia (YLL et al 2003). YANES et al (2013) sugieren un patrón climático desde hace 12.400 años que presenta tres periodos árido -húmedo -árido. Las condiciones más áridas corresponden al periodo Younger Dryas (YD) hace entre 12.400 y 12.000 años (12.4-12.0 cal ka BP) con humedades relativas medias de 79 a 82%.…”

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“…Este nos permite en base a la dominancia de las especies vegetales presentes en el registro identificar las comunidades vegetales dominantes y un marco temporal de presencia (YLL et al 2003). YANES et al (2013) sugieren un patrón climático desde hace 12.400 años que presenta tres periodos árido -húmedoárido. Las condiciones más áridas corresponden al periodo Younger Dryas (YD) hace entre 12.400 y 12.000 años (12.4-12.0 cal ka BP) con humedades relativas medias de 79 a 82%.…”