titoli, abstracts, parole chiave >>>
Messinian palaeoclimate and palaeo-environment in the western Mediterranean realm: insights from the geochemistry of continental deposits of NW Sardinia (Italy)

Mongelli, Giovanni and Mameli, Paola and Oggiano, Giacomo and Sinisi, Rosa (2012) Messinian palaeoclimate and palaeo-environment in the western Mediterranean realm: insights from the geochemistry of continental deposits of NW Sardinia (Italy). International Geology Review, Vol. 54 (8), p. 971-990. eISSN 1938-2839. Article.

Full text not available from this repository.

DOI: 10.1080/00206814.2011.588823

Abstract

To evaluate the palaeo-environmental parameters of a portion of the Sardinia–Corsica microplate during the Messinian drop in sea level, we examined the chemistry and mineralogy of upper Tortonian–lower Messinian (late Miocene) clayey continental deposits from NW Sardinia. Differences exist between the uppermost part of the succession, which is devoid of carbonate phases, and the lower part, reflecting changes in provenance and climate. The carbonate-free samples were probably derived from quartzite of the metamorphic basement and were deposited under a climate characterized by alternating dry and relatively wet periods. The other samples were derived from basement phyllite and were deposited under a warm, dry climate that promoted the capillary rise of Ca2+ and bicarbonate from a shallow water table, and therefore, the precipitation of carbonate. This part of the succession contains both calcite and dolomite. The presence of barite indicates an important concentration of SO4 2− in the solution from which the CaMg(CO3)2 precipitated. The formation of dolomite under hypersaline conditions may be explained by bacterial degradation of organic matter, which produced CO2 and ammonia, thereby increasing the solution alkalinity. The succession formed in an oxic environment, except for a calcite-rich level that formed under relatively reducing conditions. For this level, the large amount of calcite and the lack of dolomite indicate an alkaline environment and a very low Mg2+/Ca2+ ratio in the soil solution. These observations, coupled with the reducing conditions, indicate the availability of large amounts of degraded organic matter, probably related to a period typified by a wetter climate.

Item Type:Article
ID Code:7382
Status:Published
Refereed:Yes
Uncontrolled Keywords:Geochemistry, late Miocene, dolomite, palaeo-environment, NW Sardinia
Subjects:Area 04 - Scienze della terra > GEO/09 Georisorse minerarie e applicazioni mineralogico- petrografiche per l'ambiente ed i beni culturali
Area 04 - Scienze della terra > GEO/03 Geologia strutturale
Divisions:001 Università di Sassari > 01-a Nuovi Dipartimenti dal 2012 > Scienze della Natura e del Territorio
Publisher:Taylor & Francis
eISSN:1938-2839
Deposited On:16 Apr 2012 09:04

I documenti depositati in UnissResearch sono protetti dalle leggi che regolano il diritto d'autore

Repository Staff Only: item control page