Rudarsko-geološko-naftni Zbornik (Dec 1997)
INFLUENCE OF SEDIMENTARY ENVIRONMENT ON THE TECHNICAL PROPERTIES OF THE LOWER CRETACEOUS LIMESTONES FROM THE LAKOVIĆI QUARRY IN ISTRIA (CROATIA)
Abstract
The Lower Cretaceous limestones from the Lakovići quarry belong to the basal part of the Aptian limestones. These limestones are the beginning of the second transgressive-regrcssive megasequence in Istria which followed a general Upper Aptian emersion event. Within the approximately 50 m thick limestone sequence that is quarried, four facies units were defined according to their petrographic and sedimen-tological features. The following facies units were devided: A- Micritic limestones, which were deposited as shallowing-upward cycles and which begin with breccias containing clay matrix or terminate with dark-gray clays sporadically accompanied by deposition and redeposi-lion of black terrestrial and swamp clays, as well as sediments from bogs and pools that were developed in isolated bays and/or laggons; B -Grain supported limestone deposited as fine-grained to coarse-grained carbonate sands in a predominantly high-energy shallows, bars and sandy beaches; C - Micritic limestones deposited in restricted low-energy shallow subtidal environments; D - Drain supported limestones deposited as fine grained carbonate sands in high-energy shallows and bars. The results of petrological, sedimentological and technological investigations show that the limestones from each individual facies unit have different technical properties, notably porosity, bulk density and water absorption, i.e. the wide range of technical quality of the limestones quarried is a direct consequence of their facies characteristics. The outlined facies units enable separation of rock mass in the quarry not only by their petrological characteristics but also according to the technical quality of the rock.
