Terrestrial laser scanning and electrical resistivity tomography as combined tools for the geoarchaeological study of the Kritsa-Latô dolines (Mirambello, Crete, Greece)

Abstract

A complex of enclosed karst depressions near Kritsa-Lato (Dikti Mountains, Eastern Crete) was analysed with regard to its surface and subsurface topography using a new multi-method approach. Based on a combination of terrestrial laser scanning, electrical resistivity tomography and geographic information systems, crucial geophysical and morphometrical parametres were derived and correlated with sedimentological results in order to provide first-time insights into the formation, size and archive function of dolines. High-resolution digital elevation models (0.25 m, 2 m) allowed conducting topographical analyses with special respect to micro-relief attributes and traces of former land use, as well as placing all findings into a 3D context for enhanced interpretation. As shown by the results, both limestone dissolution and local tectonics led to the development of an extensive sediment trap, whose subsurface is characterised by a distinct three-part segmentation. Above the bedrock, a highly fractured epikarst zone exhibits features typical of buried karst systems, such as subterraneous sinkholes and pinnacles. In contrast, the near-surface section completely consists of fine-grained, loamy substrates. Despite thicknesses of up to 25 m, the loose infilling entirely lacks stratification and therefore indicates permanent low energetic colluviation processes under rather stable geomorphodynamic conditions during the Quaternary. In respect to the local human impact, several geophysical anomalies suggest the existence of an ancient water harvesting system, which quite likely dates back to Minoan or Dorian times. As water supply must be considered essential for agricultural purposes in the karstified mountains of Crete, the Kritsa dolines must have served as favourable locations for settlement and land use purposes. With the the help of the multi-technique approach, both the geomorphological and the geoarchaeological characteristics of the study area could be captured. The findings help improve the understanding of the landscape evolution and the associated man-environment interactions in Eastern Crete. Combining terrestrial laser scanning and tomographical mapping proves to be particularly suitable for integral surface and subsurface prospecting and therefore promises substantial potential for future studies.