Scientific Article
previous document  unige:41224  next document
add to browser collection
Title

Magnetic fabric, welding texture and strain fabric in the Nuraxi Tuff, Sardinia, Italy

Authors
Lanza, R.
Ort, M.
Rosi, M.
Published in Bulletin of Volcanology. 2008, vol. 70, no. 9, p. 1123-1137
Abstract Anisotropy of magnetic susceptibility (AMS) has been used to interpret flow directions in ignimbrites, but no study has demonstrated that the AMS fabric corresponds to the flow fabric. In this paper, we show that the AMS and strain fabric coincide in a high-grade ignimbrite, the Nuraxi Tuff, a Miocene rhyolitic ignimbrite displaying a wide variability of rheomorphic features and a well-defined magnetic fabric. Natural remanent magnetization (NRM) data indicate that the magnetization of the tuff is homogeneous and was acquired at high temperatures by Ti-magnetite crystals. Comparison between the magnetic fabric and the deformation features along a representative section shows that AMS and anisotropy of isothermal remanent magnetization (AIRM) fabric are coaxial with and reproduce the shape of the strain ellipsoid. Magnetic tests and scanning electron microscopy observations indicate that the fabric is due to trails of micrometer-size, pseudo-single domain, magnetically interacting magnetite crystals. Microlites formed along discontinuities such as shard rims and vesicle walls mimicking the petrofabric of the tuff. The fabric was thus acquired after deposition, before late rheomorphic processes, and accurately mimics homogeneous deformation features of the shards during welding processes and mass flow.
Identifiers
Full text
Article (Published version) (986 Kb) - document accessible for UNIGE members only Limited access to UNIGE
Other version: http://link.springer.com/10.1007/s00445-008-0194-1
Citation
(ISO format)
PIOLI, Laura et al. Magnetic fabric, welding texture and strain fabric in the Nuraxi Tuff, Sardinia, Italy. In: Bulletin of Volcanology, 2008, vol. 70, n° 9, p. 1123-1137. https://archive-ouverte.unige.ch/unige:41224

159 hits

0 download

Update

Deposited on : 2014-10-28

Export document
Format :
Citation style :