NEW LITHOSTRATIGRAPHIC UNITS IN THE CROATIAN OFFSHORE AND THEIR DEFINITION IN THE «R» PROGRAMMING LANGUAGE

Abstract

New lithostratigraphic units in the Croatian offshore have been recently proposed, and are now used, especially in the Pleistocene and Holocene sediments. Two new formations in the Croatian part of Northern Adriatic have been previously named (Istra and Ivana), as well as recently three new lithostratigraphic members inside the Ivana Formation. In addition, name change of the Susak Formation has been proposed. Furthermore, in the Southern Dalmatia shallow offshore (i.e., palaeosediments of the Neretva River), the new Neretva Channel Formation has been recently named. It is divided into the Neretva Sands and the Mali Ston Bay Member. Due to the often descriptive task of the definition of the lithostratigraphic units, here the simplification of the task is made possible by the algorithm and the source code which are based on a sufficient number of measured porosity values in a vertical of a lithological unit or a depositional sequence. The algorithm directly defines the way of testing the hypothesis of the normal distribution of porosity values, and the code does it numerically and graphically. The normality test is performed with the Shapiro-Wilk test. Depending on the results of the hypothesis test (normal distribution of the measured values), it is simply evaluated if it is a homogeneous, permeable or non-permeable, or a heterogeneous lithostratigraphic unit, that always can be distinguished from top and base. Based on the result, and familiarity with the geographical location of the sample, the unit is easily named following the rules of lithostratigraphic nomenclature.