The Calcare di Base (CdB), a carbonate unit deposited at the base of the evaporitic succession, is a key to understanding the paleoenvironmental conditions before the Messinian Salinity Crisis. The concentration of rare earth elements and yttrium (REE+ Y) in the CdB, cropping out in the Rossano Basin, were measured with inductively coupled mass spectrometry (ICP-MS). The CdB shows coherent and reliable REE+Y patterns with typical characteristics of microbial carbonates: (1) enrichment in heavy REE (NdSN/YbSN = 0.52, SD = 0.09), (2) negative Ce and positive La anomalies, (3) marine Y/Ho ratios (57.08, SD = 3.07), (4) slightly positive Gd anomalies, and (5) tetrad effect especially in the La–Ce–Pr–Nd, and [Pm]–Sm–Eu–Gd tetrads. These features suggest that the CdB incorporated REEs in equilibrium with oxygenated seawater. They also corroborate the depositional model of Guido et al. in Palaeogeogr Palaeoclimatol Palaeoecol 255:265–283, (2007) that maintains carbonatogenesis occurred via heterotrophic microbial activity. The REE+Y signatures of the CdB support the interpretation that these sediments were deposited in normal marine condition and cannot belong to the evaporite succession.

Rare earth element signatures in the Messinian pre-evaporitic Calcare di Base formation (Northern Calabria, Italy): evidence of normal seawater deposition.

MASTANDREA, Adelaide;BARCA, Donatella;GUIDO A;
2010-01-01

Abstract

The Calcare di Base (CdB), a carbonate unit deposited at the base of the evaporitic succession, is a key to understanding the paleoenvironmental conditions before the Messinian Salinity Crisis. The concentration of rare earth elements and yttrium (REE+ Y) in the CdB, cropping out in the Rossano Basin, were measured with inductively coupled mass spectrometry (ICP-MS). The CdB shows coherent and reliable REE+Y patterns with typical characteristics of microbial carbonates: (1) enrichment in heavy REE (NdSN/YbSN = 0.52, SD = 0.09), (2) negative Ce and positive La anomalies, (3) marine Y/Ho ratios (57.08, SD = 3.07), (4) slightly positive Gd anomalies, and (5) tetrad effect especially in the La–Ce–Pr–Nd, and [Pm]–Sm–Eu–Gd tetrads. These features suggest that the CdB incorporated REEs in equilibrium with oxygenated seawater. They also corroborate the depositional model of Guido et al. in Palaeogeogr Palaeoclimatol Palaeoecol 255:265–283, (2007) that maintains carbonatogenesis occurred via heterotrophic microbial activity. The REE+Y signatures of the CdB support the interpretation that these sediments were deposited in normal marine condition and cannot belong to the evaporite succession.
Rare earth elements - Carbonates; Microbialites - Calcare di Base ; Messinian - Calabria - Italy
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/124235
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