Paleotemperature reconstruction using environmental isotopes and noble gases in groundwater in Morocco | Reconstruction des paléotempératures à l’aide des isotopes environnementaux et des gaz nobles dans les eaux souterraines du Maroc Reconstrucción de la paleotemperatura utilizando isótopos ambientales y gases nobles en las aguas subterráneas de Marruecos 基于地下水中环境同位素和惰性气体的摩洛哥古温度重建 Reconstrução da paleotemperatura usando isótopos ambientais e gases nobres em águas subterrâneas no Marrocos
2020
Túri, Marianna | Saadi, Radouan | Marah, Hamid | Temovski, Marjan | Molnár, Mihály | Palcsu, László
A Turonian limestone-dolomite aquifer from the Tadla basin of Morocco was analysed using a multi-tracer approach (δ¹⁸O, δ²H, δ¹³C, ³H, ¹⁴C and noble gases) to reconstruct the paleotemperature evolution from the late Pleistocene to the Holocene. The Turonian aquifer was found to be suitable for a groundwater-based paleoclimate reconstruction, representing the Holocene–late Pleistocene epochs. After correction for young water contribution, mean residence times (MRTs) of groundwater were calculated using the Pearson radiocarbon model. Additionally, terrigenic helium content was used as an age indicator. Noble gas temperature (NGT) results from wells with groundwater ages corresponding to glacial periods showed an average of 17.2 ± 1.7°C. In contrast, samples of recent recharge water gave a mean NGT of 25.2 ± 1.3°C. This reveals a temperature difference of 8.0 ± 2.1 °C between the Holocene and late Pleistocene. This significant Pleistocene–Holocene temperature difference observed in Africa has considerable significance and can be extended to address an important topic relating to the nature of the wet epochs during which the fossil aquifers of North Africa were recharged. It is evident that this aquifer was recharged during both interglacial (warm) and glacial (cool) wet periods.
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