Incomplete blueschist re-crystallization in high-grade metamorphics from the Sesia-Lanzo Unit (Vasario-Sparone Subunit, Western Alps); a case history of metastability

Saved in:
Online Access: Get full text
doi: 10.1016/0024-4937(88)90016-3
Authors:Pognante, U.; Talarico, F.; Benna, P.
Author Affiliations:Primary:
Univ. Torino, Dip. Sci. Terra, Turin 10125, Italy
Volume Title:Lithos (Oslo)
Source:Lithos (Oslo), 21(2), p.129-142. Publisher: Elsevier, Amsterdam, International. ISSN: 0024-4937
Publication Date:1988
Note:In English. 2 p. refs.; illus. incl. 2 tables, geol. sketch map
Summary:The Vasario-Sparone subunit represents a thin and discontinuous slice of pre-Alpine deep continental crust. Metastable relics and a sequence of incomplete transformations are preserved. The rocks record a pre-Alpine high grade of metamorphism (780 ± 50°C, ∼6 kbar) which is comparable to the metamorphism dated ∼500 m.y. in the Ivrea Zone. During the Alpine evolution the rocks sustained an early blueschist stage (300-400°C, ≥ 8-10 kbar) of probable Cretaceous age and a later low-T, low-P stage of Tertiary age. The blueschist transformations are governed by slow reaction kinetics, by the heterogeneous distribution of pervasive deformations and by syn-metamorphic fluid phase. In particular, transient kyanite formed in the early stages of the blueschist re-crystallization in response to a process controlled by fluid-deficient conditions and by internal buffering of aH2O at low values. [G.R.]
Subjects:Alpine Orogeny; Blueschist; Cenozoic; Continental crust; Cretaceous; Crust; Eclogite; High pressure; High temperature; High-grade metamorphism; Low pressure; Mesozoic; Metamorphic rocks; Metamorphism; Petrology; Polymetamorphism; Pressure; Schists; Temperature; Tertiary; Alps; Europe; Italy; Piedmont Alps; Piemonte Italy; Sesia-Lanzo Zone; Southern Europe; Western Alps; Vasario-Sparone
Abstract Numbers:89M/1299
Record ID:1990073850
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
Tags: Add Tag
No Tags, Be the first to tag this record!
Be the first to leave a comment!
You must be logged in first