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Did the Variscan relief influence the Permian climate of Mesoeurope? Insights from geochemical and mineralogical proxies from Sardinia (Italy)

Sinisi, Rosa and Mongelli, Giovanni and Mameli, Paola and Oggiano, Giacomo (2014) Did the Variscan relief influence the Permian climate of Mesoeurope? Insights from geochemical and mineralogical proxies from Sardinia (Italy). Paleogeography, Palaeoclimatology, Palaeoecology, Vol. 396 , p. 132-154. ISSN 0031-0182. eISSN 1872-616X. Article.

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DOI: 10.1016/j.palaeo.2013.12.030

Abstract

Red beds deposits of Permian–Triassic basins of Sardinia (western Italy), where a wide segment of the Variscan orogen is exposed, were studied. The basins were selected according to their position within the structural zones of Variscan orogen, i.e. from the external to the inner sectors of the chain. Detailed mineralogical, petrographical, and chemical analyses were performed on shale and calcrete layers laying along the sedimentary sequences, to examine their compositional features and stratigraphic variation. In this regard, enrichment factors (F(e)) for major and trace elements (relative to the PAAS composition) were calculated and discussed. Several geochemical proxies were also calculated and used to assess the palaeoclimate conditions during the red beds deposition. The weathering indices (CIA and CIW) accounted for more humid conditions in the basins of the axial zone relative to the basins those of the foreland, which instead were characterised by an arid climate. However, the presence of carbonates, albeit discontinuous, and the values of calcification, salinity, and hydrolysis indices suggest that, in the axial zone, dry and hot periods also occurred. Compositional data of the sedimentary records were correlated to the Sardinia geological setting and significant information were obtained on the palaeoenvironment characterizing the south-western Mesoeurope during Permian and Triassic. Al2O3–TiO2–Zr ternary plot and Zr/Sc vs. Th/Sc diagram show that both sorting and sedimentary recycling affected the studied basins. Precisely, our data lead us to suppose that a wide regional subsidence caused both the recycling of uplifted Variscan rocks and the diagenetic K-metasomatism of Permian sediments revealed by the A–CN–K diagram. Finally, a supply from upper continental source has been suggested by the provenance proxies (such as (Gd/Yb)N and Eu/Eu*) and the La-Th-Sc plot that also reflect the paucity of mafic rocks in feeding areas.

Item Type:Article
ID Code:9869
Status:Published
Refereed:Yes
Uncontrolled Keywords:Permian–Triassic red beds, Variscan relief, palaeoclimate proxies, sedimentary recycling, diagenetic K-metasomatism
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:Elsevier
ISSN:0031-0182
eISSN:1872-616X
Copyright Holders:© 2013 Elsevier B.V. All rights reserved
Deposited On:11 Jun 2014 12:05

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