Mn-rich crusts interbedded within glacially-related Hirnantian deposits of Sardinia result from starved sedimentation in isolated sub-basins. These latter result from low glacio-eustatic sea-levels on the North-Gondwanian platform. During very low sea-levels, large supplies of fresh water are responsible for oxidizing conditions allowing Mn-oxides concretions to form. During relatively higher sea-levels, sea water inflows result in water stratification, reducing conditions and Mn-carbonate concretions. A hydrothermal origin associated with a rifting event is suggested for the manganese. (C) 2000 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.

Caractérisation des horizons manganésifères de l’Ordovicien supérieur de Sardaigne : relation avec la glaciation fini-ordovicienne / Ghienne JF; Bartier D; Leone F; Loi A. - 331:4(2000), pp. 257-264.

Caractérisation des horizons manganésifères de l’Ordovicien supérieur de Sardaigne : relation avec la glaciation fini-ordovicienne

LOI, ALFREDO
2000

Abstract

Mn-rich crusts interbedded within glacially-related Hirnantian deposits of Sardinia result from starved sedimentation in isolated sub-basins. These latter result from low glacio-eustatic sea-levels on the North-Gondwanian platform. During very low sea-levels, large supplies of fresh water are responsible for oxidizing conditions allowing Mn-oxides concretions to form. During relatively higher sea-levels, sea water inflows result in water stratification, reducing conditions and Mn-carbonate concretions. A hydrothermal origin associated with a rifting event is suggested for the manganese. (C) 2000 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.
Sardinia / Mn-carbonates / Mn-oxides / glaciation / eustasy; Sardaigne / Mn-carbonates / Mn-oxydes / glaciation / eustatisme
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11584/31701
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