engleski

Morphometric characteristics and origin of Palaeogene macroids from beach gravels in Stanići (vicinity of Omiš, Southern Croatia)

A collection comprising 322 samples of macroid pebbles was found at the beach at Stanići near Omiš (Dalmatia, southern Croatia), derived from the beach-rocks by the marine erosional processes. Macroids were measured by a digital caliper providing information on their size and shape.Thin sections microscopy pointed to the red algae as the dominant macroid builders, associated with acervulinid foraminifera and some other encrusters. Morphometric analyses of macroid shapes, together with micropaleontological analyses, enable the recognition of two macroid groups. Rhodolits and less complex macroids are dominantly spheroidal, exhibiting normal size distribution with good correlation. Multispecific macroids (composed of red algae, acervulinid foraminifera and other encrusters) exhibit a variety of shapes, mostly discoidal or elongate, with poor correlation. Rhodolits were derived from the Eocene bioclastic rocks rich in nummulitids and other benthic biota, informally known as "Nummulitic breccias". Blocks of these rocks, scattered along the beaches in the vicinity of Omiš, are a part of rockfall and avalanche deposits developed as megabeds during the collapse of Dinaride shelf margins.

Macroids ; measurements ; fossil bioconstructors ; Eocene ; Croatia

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