Orbitally induced cycles in benthonic foraminiferal morphogroups and trophic structure distribution patterns from the Late Albian “Amadeus Segment” (Central Italy)

Abstract. A detailed analysis was made of benthonic foraminiferal distribution patterns and morphogroups in the late Albian “Amadeus Segment” of the Aptian-Albian organic-rich Scisti a Fucoidi Formation outcropping over a widespread area of the Umbria-Marche region, Central Italy. Rhythmic changes in the trophic structures and composition of benthonic foraminiferal assemblages suggest cyclical fluctuations of the sea floor environment which appear to be orbitally induced. Benthonic foraminiferal assemblages varied significantly through the section and appear to contain a strong paleoecological signal. Fluctuations in both bottom water oxygenation and the surface primary productivity as a result of the orbital forcing are interpreted to have been the primary controls on benthonic foraminiferal distribution patterns.