engleski

The Middle/Upper Lutatian foraminiferal paleocommunities from central Istrian Basin.

The Middle/Upper Lutetian carbonate sediments of Central Istrian Basin are characterized by three distinctive foraminiferal paleocommunities, which reflect adaptation to progressive deepening from inner-middle neritic, to outer neritic and upper bathyal. The faunal and sedimentological characteristics of neritic and platform (euphotic) carbonates comprise relatively high diversified and low dominance upper photic larger benthic foraminiferal paleocommunity (composed of alveolinids, orbitolitids, nummulitids, assilinids, miliolids, operculinids), which by depth became oligotypic and strongly dominated by only a few orthophragminid species or morphotypes. The oligotypic cornmunity is characteristic for lower photic environment (outer neritic), as indicated by associated planktonics and smaller benthics. The upper bathyal paleocommunity is characterized by absence of larger benthic foraminifers, and abrupt diversification and proliferation of planktonic foraminifers and opportunistic smaller, deep and shallow-water benthic foraminifers. These are followed by moderate diversification due to immigration of new taxa and/or selective adaptation on local substrate conditions (biconvex lenticulinids and oridorsalidids being gradually replaced by cylindrical uvigeriniids invading the ecosystem).

foraminifers; assemblages;

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