Abstract
Abstract. In the last few decades, multidisciplinary research on calcareous tufas as palaeoenvironmental and palaeoclimatic records has intensively grown, which has provided an increasing number of well-documented sites. Consequently, inter-site comparisons and regional- to continental-scale reviews have developed, discussing the link between tufa distribution and climate or providing diachronic comparisons of climatic and environmental conditions prevailing during Quaternary interglacials (and interstadials). This paper proposes such a review for the southeastern Mediterranean area, including new dating and isotopic data from Aït Said ou Idder (northern Morocco) to be compared with available regional data, in order to discuss the intensity of some humid periods of the last 125 kyr. According to several radiocarbon and U–Th dates, three chronological phases are indeed identified at Aït Said ou Idder: the Holocene, the Dansgaard–Oeschger (D–O) interstadial 8 and the Marine Isotopic Stage (MIS) 5e. Similarly, other tufa deposits from both Morocco and southern Spain (mostly Andalusia) appear to have preferentially developed during interglacial or interstadial periods, marked by maximal developments of the Mediterranean forest as reported in the palynological records from regional marine cores. Furthermore, isotopic data (δ18O and δ13C) from Aït Said ou Idder (and from other southeastern Mediterranean tufa deposits where available) suggest no significant difference in terms of temperature or air mass circulation between the Holocene, D–O 8 and MIS 5e. In terms of humidity conditions, no evidence of strong aridity is recorded even if D–O 8 appears drier than both interglacials. Conditions seems slightly wetter during the Holocene than during MIS 5e, but δ13C values at Aït Said ou Idder could also reflect strong differences in the seasonality of these interglacials. We demonstrate that calcareous tufa deposits have promising potential for discussing, in both space and time, the climate variability in the southeastern Mediterranean area, but new investigations, including dating and stable isotopes, are required to accurately feed such discussions.
Highlights
This paper proposes to review the climatic significance of tufa deposits in the southeastern Mediterranean area based on their chronological distribution and isotopic signal
At Aït Said ou Idder and more generally in both Morocco and southern Spain, phases of maximal tufa deposition appear contemporaneously with periods of maximal development of the Mediterranean forest
Aït Said ou Idder (ASI) δ13C values show no evidence of evaporation processes that may result from strong aridity, which is observed in tufa deposits from Andalusia
Summary
In the last few decades, multidisciplinary research on calcareous tufas has intensively grown regarding their potential for palaeoenvironmental and palaeoclimatic studies: they are one of the few continental archives to simultaneously provide records of past environments (including fauna and flora) and independent proxies for climatic variations (from calcite stable isotopes) which can be precisely and objectively dated (Andrews, 2006; Capezzuoli et al, 2014; Dabkowski, 2014). In Morocco, reviews on the ages of tufa deposits have been initiated on the basis of U–Th dating (Falguères et al, 2016; Rousseau et al, 2017; Weisrock et al, 2008), but they concerned indurated, well-crystallised deposits (socalled “travertines”), from which palaeoenvironmental and palaeoclimatic data are more difficult to retrieve (Capezzuoli et al, 2014; Dabkowski, 2014). The tufa sequence of Aït Said ou Idder in the Middle Atlas is the first to have recently provided palaeoenvironmental reconstructions based on malacological data (Wackenheim et al, 2020)
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