129939 20240116090136.0 doi 10.1111/sed.12440 sideral 107614 ART-2018-107614 eng Arenas, C. Universidad de Zaragoza (orcid)0000-0002-4212-0524 Seasonal temperatures from d18O in recent Spanish tufa stromatolites: Equilibrium redux! 2018 This study focuses on recent debate over the value of stable isotope-based environmental proxies recorded in riverine tufa stromatolites. A twelve-year record (1999 to 2012) of river-bed tufa stromatolites in the River Piedra (north-east Spain) was recovered in this study, along with a partly overlapping fifteen-year record (1994 to 2009) of accumulations in a drainage pipe: both deposits formed in water with near identical physico/chemical parameters. Measured water temperature data and near-constant d18Owater composition allowed selection of an ‘equilibrium’ palaeotemperature equation that best replicated actual temperatures. This study, as in some previous studies, found that just two published formulas for water temperature calculation from equilibrium calcite d18O compositions were appropriate for the River Piedra, where tufa deposition rates are high, with means between 5·6 mm and 10·8 mm in six months. The d18Ocalcite in both the river and the pipe deposits essentially records the full actual seasonal water temperature range. Only the coldest times (water temperature <10°C), when calcite precipitation mass decreased to minimum, are likely to be unrepresented, an effect most noticeable in the pipe where depositional masses are smaller and below sample resolution. While kinetic effects on d18Ocalcite-based calculated water temperature cannot be ruled out, the good fit between measured water temperature and d18Ocalcite-calculated water temperature indicates that temperature is the principal control. Textural and deposition rate variability between the river and pipe settings are caused by differences in flow velocity and illumination. In the river, calcification of growing cyanobacterial mat occurred throughout the year, producing composite dense and porous laminae, whereas in the pipe, discontinuous cyanobacterial growth in winter promoted more abiogenic calcification. High-resolution d18Ocalcite data from synchronous pipe and river laminae show that reversals in water temperature occur within laminae, not at lamina boundaries, a pattern consistent with progressive increase in calcite precipitation rate as cyanobacterial growth re-established in spring. Access copy available to the general public Unrestricted info:eu-repo/grantAgreement/ES/MICINN/CGL2013-42867 info:eu-repo/grantAgreement/ES/MINECO/CGL2009-09216-CLI info:eu-repo/semantics/openAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 3.244 2018 GEOLOGY 4 / 46 = 0.087 2018 Q1 T1 1.571 2018 Stratigraphy 2018 Q1 Geology 2018 Q1 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Osácar, M.C. Universidad de Zaragoza (orcid)0000-0002-5246-366X Auqué, L.F. Universidad de Zaragoza (orcid)0000-0003-1463-1682 Andrews, J.E. Pardo, G. (orcid)0000-0001-6082-5301 Marca, A. Martín-Bello, L. Universidad de Zaragoza (orcid)0000-0002-2141-2624 Pérez-Rivarés, F.J. (orcid)0000-0002-1802-2115 2000 685 Universidad de Zaragoza Dpto. Ciencias de la Tierra Área Petrología y Geoquímica 2000 280 Universidad de Zaragoza Dpto. Ciencias de la Tierra Área Estratigrafía 2000 120 Universidad de Zaragoza Dpto. Ciencias de la Tierra Área Cristalografía Mineralog. 65, 5 (2018), 1611-1630 Sedimentology SEDIMENTOLOGY 0037-0746 4697991 http://zaguan.unizar.es/record/129939/files/texto_completo.pdf Postprint 1289895 http://zaguan.unizar.es/record/129939/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:129939 articulos driver 2024-01-16-08:24:10 ARTICLE