EGU22-3147
https://doi.org/10.5194/egusphere-egu22-3147
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

NAO control on the hydrology of Laguna Grande de Archidona (southern Spain) during the Iberian Roman Humid Period recorded by stable isotopes (δ18O and δD) of gypsum hydration water 

Fernando Gázquez1,2, Aurora Castillo-Baquera3, Antonio García-Alix3, Gonzalo Jiménez-Moreno3, Francisco Jiménez-Espejo4, Lucia Martegani1,2, and Miguel Rodríguez-Rodríguez5
Fernando Gázquez et al.
  • 1Department of Biology and Geology. University of Almería, Almería, Spain
  • 2Andalusian Centre for the Monitoring and Assessment of Global Change, University of Almería, Spain
  • 3Department of Stratigraphy and Paleontology, University of Granada, Granada, Spain
  • 4Instituto Andaluz de Ciencias de la Tierra (CSIC-IACT), Granada, Spain
  • 5Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, Seville, Spain

The North Atlantic Oscillation (NAO) has a major effect on the modern precipitation patterns in the southern Iberian Peninsula and also controlled the hydroclimate of this region in the past [1,2]. The oxygen and hydrogen stable isotopes (δ18O and δD) of lake waters are sensitive to long-term changes in hydrological conditions (e.g. relative humidity, evaporation/outflow ratio, etc.). Here we reconstruct the δ18O and δD values of Laguna Grande de Archidona Lake (Málaga Province, southern Spain) from the stable isotopes of hydration water of gypsum (CaSO4·2H2O) [3] that precipitated and deposited in the lake from 2.7 to 1.4 ka BP.

The maximum δ18O and δD of values of the lake water (7.8‰ and 23.9‰, respectively) were recorded at 2.7 ka BP (~700 BCE), suggesting that relatively dry conditions prevailed during the Early Iron Age in southern Iberia. Subsequently, the δ18O and δD of the lake decreased to minimum values (3.0 and -2.2‰, respectively) at 2.4 ka BP, during the early stages of the Iberian Roman Humid Period (~600 BCE to ~400 CE). A relatively arid phase was also recorded at 2.2 ka BP, which preceded a wetter stage at 2.0 ka BP. A longer drier phase occurred later on, from 1.6 ka to 1.4 ka BP, coinciding with the decline of the Western Roman Empire (395-476 CE).

The comparison of our paleo-humidity proxy with long-term NAO index [4] shows that the lake water was isotopically enriched during periods of persistent NAO+ mode, suggesting drier and more evaporative conditions and probably lake level lowstands. In contrast, lower δ18O and δD of values of the lake water occurred during periods of NAO- configuration, resulting in wetter and less evaporative conditions and lake level highstands. In summary, our results indicate that the hydrologic balance of Laguna Grande de Archidona during the Iberian Roman Humid Period was controlled by the strength of the long-term NAO and that stable isotopes of gypsum hydration water are a powerful tool for paleo-hydrologic reconstructions.

 

 

[1] Toney et al. (2020), Quat. Sci. Rev. 106395; [2] Martín-Puertas et al. (2009), Quat. Res. 71, 108–120; [3] Gázquez et al. (2018), Earth Plan. Sci. Lett. 48, 177–188; [4] Faust et al., (2016), Earth Plan. Sci. Lett. 435, 84-93.

Acknowledgement

This study was supported by projects PY18-871 and Retos P20_00059 of the Junta de Andalucía, the project CGL2017-85415-R of the Ministerio de Economía y Competitividad of Spain and Fondo Europeo de Desarrollo Regional FEDER and the project B-RNM-144-UGR18. Dr. Antonio García-Alix acknowledges the Ramón y Cajal fellowship, RYC-2015-18966. Dr. Fernando Gázquez acknowledges the Ramón y Cajal fellowship, RYC2020-029811-I.

How to cite: Gázquez, F., Castillo-Baquera, A., García-Alix, A., Jiménez-Moreno, G., Jiménez-Espejo, F., Martegani, L., and Rodríguez-Rodríguez, M.: NAO control on the hydrology of Laguna Grande de Archidona (southern Spain) during the Iberian Roman Humid Period recorded by stable isotopes (δ18O and δD) of gypsum hydration water , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3147, https://doi.org/10.5194/egusphere-egu22-3147, 2022.