TYPES AND DISTRIBUTION OF QUATERNARY DEPOSITS ORIGINATING FROM CARBONATE ROCK SLOPES IN THE VINODOL VALLEY, CROATIA – NEW INSIGHT USING AIRBORNE LIDAR DATA

Abstract

The Vinodol Valley, situated in the north-western Adriatic in Croatia, is characterized by complex geological and morphological conditions. Palaeogene flysch deposits form the inner parts of the valley, while the steep valley flanks are composed of Cretaceous and Palaeogene carbonate rocks. Flysch bedrock is mostly covered by diverse Quaternary deposits, among which deposits originating from carbonate rock slopes are abundant. During previous investigations, based on conventional field geological mapping and mostly conducted in the north-western and central parts of the Vinodol Valley, such Quaternary deposits were addressed to the tectonic evolution of the study area and rockfalls, respectively. Therefore, they were generally named as Quaternary rockfall breccias, or Quaternary rockfall deposits. This study presents six types of the Quaternary deposits originating from carbonate rock slopes and their spatial distribution in the whole Vinodol Valley (64.57 km2 ), which are identified and mapped based on the visual interpretation of 1-m airborne LiDAR (Light Detection and Ranging) Digital Terrain Model (DTM). Lithological materials are classified according to engineering geological principles, and represent engineering formations. New insight into the types, shapes, geometric characteristics and hypsometrical positions of the identified sedimentary bodies indicate that some other gravitational mass movements, and not just rockfalls, played an important role in the formation of the Quaternary deposits originating from the carbonate rock slopes in the Vinodol Valley. This study also presents the potential of the visual interpretation of high-resolution LiDAR DTM for identification and mapping of superficial deposits in study areas characterized by complex geological and morphological conditions.