Abstract
Abstract. The extent to which climate, eustasy and tectonics interact to shape the late Quaternary landscape is poorly known. Alluvial fans often provide useful indexes that allow the decoding of information recorded on complex coastal landscapes, such as those of the eastern Mediterranean. In this paper we analyse and date (using infrared stimulated luminescence (IRSL) dating) a double alluvial fan system on southwest Crete, an island straddling the forearc of the Hellenic subduction margin, in order to constrain the timing and magnitude of its vertical deformation and discuss the factors contributing to its landscape evolution. The studied alluvial system is exceptional because each of its two juxtaposed fans records individual phases of alluvial and marine incision, thus providing unprecedented resolution in the formation and evolution of its landscape. Specifically, our analysis shows that the fan sequence at Domata developed during Marine Isotope Stage (MIS) 3 due to five distinct stages of marine transgressions and regressions and associated river incision, in response to sea-level fluctuations and tectonic uplift at averaged rates of ∼ 2.2 mm yr−1. Interestingly, comparison of our results with published tectonic uplift rates from western Crete shows that uplift during 20–50 kyr BP was minimal (or even negative). Thus, most of the uplift recorded at Domata must have occurred in the last 20 kyr. This implies that eustasy and tectonism impacted the landscape at Domata over mainly distinct time intervals (e.g. sequentially and not synchronously), with eustasy forming and tectonism preserving the coastal landforms.
Highlights
Sea-level fluctuations relative to the modern sea level are well constrained for the last 0.5 Myr (e.g. Imbrie et al, 1984; Martinson et al, 1987; Bassinot et al, 1994; Chappell et al, 1996; Dickinson, 2001; Siddall et al, 2003; Rabineau et al, 2005; Lambeck and Purcell, 2005; Lisiecki and Raymo, 2005; Antonioli et al, 2007). When these fluctuations are used in conjunction with dating techniques, they provide a powerful tool for interpreting coastal geomorphology and assessing vertical deformation from marine and marginal marine deposits through the middle and late Quaternary (e.g. Pirazzoli et al, 1996; Rabineau et al, 2005; Antonioli et al, 2007; Mouslopoulou et al, 2015a)
Using luminescence dating together with the Siddall et al (2003) sea-level curve, we find that the alluvial fan system at Domata was consecutively affected by (1) sea-level fluctuations, triggering building of the fans and subsequent river and marine incision between ∼ 45 and 20 kyr BP, during a period of minimal tectonic activity, and (2) intense tectonic uplift between ∼ 20 ka and present, at rates that exceeded those of the rising sea level, resulting in the preservation of the entire fan sequence
The Sfakia fan is somewhat different from the Domata fan in catchment size, fan size (5.3 km2 compared with 0.1 km2), the presence of more than one feeder channel at Sfakia, and in the nature of deposits
Summary
Sea-level fluctuations relative to the modern sea level are well constrained for the last 0.5 Myr (e.g. Imbrie et al, 1984; Martinson et al, 1987; Bassinot et al, 1994; Chappell et al, 1996; Dickinson, 2001; Siddall et al, 2003; Rabineau et al, 2005; Lambeck and Purcell, 2005; Lisiecki and Raymo, 2005; Antonioli et al, 2007). Imbrie et al, 1984; Martinson et al, 1987; Bassinot et al, 1994; Chappell et al, 1996; Dickinson, 2001; Siddall et al, 2003; Rabineau et al, 2005; Lambeck and Purcell, 2005; Lisiecki and Raymo, 2005; Antonioli et al, 2007) When these fluctuations are used in conjunction with dating techniques, they provide a powerful tool for interpreting coastal geomorphology and assessing vertical deformation from marine and marginal marine deposits through the middle and late Quaternary
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