The upper Albian Amadeus Segment, which falls within Oceanic Anoxic Event 1c, exhibits cyclical alternations of marls/black shales and carbonate-rich beds that record evidence of orbital climate and sedimentary dynamics. A combined micropalaeontological (planktic and benthic foraminifera, and palynomorphs) and geochemical (stable isotopes, clay mineralogy, and major element distribution) investigation allowed recognition of a remarkable influence of continental material within the black shales. Moreover, the palaeoproductivity record is characterised by a nonlinear response to the orbital forcing. The micropalaeontological and geochemical record suggests that upper Albian bedded cycles in the Marne a Fucoidi Formation resulted from interplay of changes in atmospheric and hydrological parameters of the western Tethys and its drainage basin. In particular, deposition of the black shales occurred during precession minima, in times of increased precipitation, enhanced continental runoff and stratification of the upper water column. In this respect, the black shales of the Amadeus Segment share similarities with the Neogene Eastern Mediterranean sapropels. (C) 2002 Elsevier Science B.V. All rights reserved.
Orbitally modulated black shale deposition in the upper Albian Amadeus Segment (central Italy): a multi-proxy reconstruction
Sprovieri M;
2003
Abstract
The upper Albian Amadeus Segment, which falls within Oceanic Anoxic Event 1c, exhibits cyclical alternations of marls/black shales and carbonate-rich beds that record evidence of orbital climate and sedimentary dynamics. A combined micropalaeontological (planktic and benthic foraminifera, and palynomorphs) and geochemical (stable isotopes, clay mineralogy, and major element distribution) investigation allowed recognition of a remarkable influence of continental material within the black shales. Moreover, the palaeoproductivity record is characterised by a nonlinear response to the orbital forcing. The micropalaeontological and geochemical record suggests that upper Albian bedded cycles in the Marne a Fucoidi Formation resulted from interplay of changes in atmospheric and hydrological parameters of the western Tethys and its drainage basin. In particular, deposition of the black shales occurred during precession minima, in times of increased precipitation, enhanced continental runoff and stratification of the upper water column. In this respect, the black shales of the Amadeus Segment share similarities with the Neogene Eastern Mediterranean sapropels. (C) 2002 Elsevier Science B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
