Sensitivity of the hypsometric integral (HI) and its connections with lithology and neotectonics in the Rodna Mountains, Romanian Carpathians

Abstract

This study investigates the sensitivity of the hypsometric integral (HI) and its connections with lithology and neotectonics from northern Romanian Carpathians, Rodna Mountains. Two types of DEM was used in analysis (a 30m DEM resolution with specific grid size and a non-gridded 30m DEM resolution). Several methods have been applied in order to calculate HI as: the CalHypso GIS extension was used to automatically extract multiple hypsometric curves from digital elevation model (DEM) and to calculate the main statistics related to the HI by applying polynomial fits; local indices of spatial autocorrelation were applied using Anselin Local Moran’s I and Getis-Ord Gi* in order to see if HI distribution has spatial patterns values and selection of valid squares (500m² grid using 30m DEM using ArcMap 10.1) for the lithological analysis. The values of the hypsometric kurtosis density, kurtosis, skew and density skew are increasing eastwards. Values of hypsometric skewness for the northern slope are in range between 0.290 – 0.816 and sowthern part between 0.414 – 0.507. The results show that HI values are higher than 0.5 in the areas with recent tectonic influences especially in northern part near Dragoş Vodă fault system. The formations with a Oligocene, Miocene, Pleistocene and Holocene age have low values (<0.5) wile the other ones from Precambrian, Cambrian, Silurian, Eocene, Miocene and Pliocene age have higher values (>0.5). Comparing HI values from these two analysis (500m grid size DEM and the DEM without grid size) of the DEM we find some slightly differences in HI values specially in the northern part of the range on Repedea, Negoiescu Mare, Fântâna and Lala basins