http://www.cnr.it/ontology/cnr/individuo/prodotto/ID29061

Pressure fluctuation during uplift of the Northern Apennines (Italy): a fluid inclusions study (Articolo in rivista)

Type

Articolo in rivista (Classe)
Prodotto della ricerca (Classe)

Label

Pressure fluctuation during uplift of the Northern Apennines (Italy): a fluid inclusions study (Articolo in rivista) (literal)

Anno

2001-01-01T00:00:00+01:00 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi

10.1016/S0040-1951(01)00197-4 (literal)

Alternative label

Montomoli C. (1), Ruggieri G. (2), Boiron M.C. (3), Cathelineau M. (4) (2001)
Pressure fluctuation during uplift of the Northern Apennines (Italy): a fluid inclusions study
in Tectonophysics (Amst. Online)
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

Montomoli C. (1), Ruggieri G. (2), Boiron M.C. (3), Cathelineau M. (4) (literal)

Pagina inizio

121 (literal)

Pagina fine

139 (literal)

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This work demonstrates that fluid inclusions are very sensitive to pressure fluctuations and can record substantially lower pressure than the pressure derived from mineralogical data. They are, therefore, a potentially effective tool for investigating and testing models of pressure variations in the upper crust.Tectonophysics is a well known international journal for the publication of significant original research studies and comprehensive reviews in the fields of geotectonics, and geology and physics of the earth's crust and interior. The Editorial Board, composed of prominent scientists from around the world, is representative of the many disciplines covered by the journal. (literal)

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http://www.sciencedirect.com/science/article/pii/S0040195101001974 (literal)

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341 (literal)

Rivista

Tectonophysics (Rivista)

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Impact Factor 1,473 (literal)

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The present study represents an attempt at constraining fluid migration and P- T conditions existing after the main syn-collision tectonic phase in the western part of the chain in the Tuscan Nappe, e.g. in the La Spezia area. It is based on a detailed microstructural, petrographic and fluid inclusion study of quartz of typical D2 syn-tectonic veins developed in the Tertiary flysch at the top of the Tuscan Nappe. In addition, to better distinguish the different growing steps of the quartz crystals in relation to the trapping of the different types of fluid inclusions, SEM-cathodoluminescence analyses have been performed on syn-tectonic quartz fibres.The main objectives of our study were to document: (i) the P-T-X fluid evolution through fluid inclusion study and especially the relation between pressure fluctuation during vein formation and quartz crystallization and/or deformation; (ii) the compatibility of the determined P-T conditions with the general evolution of the chain during uplift. (literal)

Note

ISI Web of Science (WOS) (literal)

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(1) Dipartimento di Scienze della Terra, Università, via S. Maria 53,Pisa, Italia; (2) CNR-Istituto Internazionale per le Ricerche Geotermiche, Via G. Moruzzi, 1, 56124 Pisa, Italy; (3) UMR G2R-7655 and CREGU, BP 23, 54501 Vandoeuvre les Nancy Cedex, France. (literal)

Titolo

Pressure fluctuation during uplift of the Northern Apennines (Italy): a fluid inclusions study (literal)

Abstract

P-T conditions existing after the main syn-collision tectonic phase in the western part of the Northern Apenninic chain (Italy), e.g. in the Tuscan Nappe outcropping in the La Spezia area, were estimated on the basis of a detailed microstructural, structural, petrographic and fluid inclusion study of quartz of syn-tectonic (D2) veins developed in the Tertiary flysch at the top of the Tuscan Nappe (Macigno formation). Three main fluid events have been distinguished as follows. During retrograde metamorphism (D1 to D2 phase), fluids in equilibrium with turbidites from the Tuscan Nappe were H2O-CH4 mixtures issued from water-organic matter interactions in temperatures conditions that may have reached at least 260 °C or more (280 °C) depending on the considered depth estimates and maximum pressures around 210-250 MPa. Evidence of strong fluid pressure fluctuation between lithostatic and hydrostatic within the metamorphic formations (up to 100-150 MPa), possibly linked to fault-valve activity at the beginning of the uplift, triggered phase separation of the water-methane fluids and production of methane-rich and water-rich fluids; fluctuations in pressure during these events played a crucial role in quartz crystallization especially in extensional fissures formed perpendicular to the D2 folds axial foliation. Changes in the fluid regime and sources with time are evidenced by the input of brines, which mix to distinct degrees and are trapped in healing microfissures during retrograde fluid evolution. Such mixing processes are an indication of the connection between separate fluid reservoirs with different temperature conditions. Consequently, mass and heat transfer have to be taken into account, as the downward percolation of cooler fluids probably accelerated the rate of cooling of the exhumed formations. These processes are certainly common to most orogenic terrains and can be quantitatively studied through P-V-T-X reconstruction using fluid inclusion data on the drainage zones where the mixing processes occurred. This work confirms that fluid inclusion studies can provide accurate quantitative estimates of fluid pressure variations during the evolution of orogenic terrains and could, therefore, constitute a useful tool in tectonic interpretations at the light of the models developed for pressure variations in the upper crust. (literal)

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