Earth-prints repository, logo   DSpace

About DSpace Software
|earth-prints home page | roma library | bologna library | catania library | milano library | napoli library | palermo library
Please use this identifier to cite or link to this item:

Authors: Mollo, S.*
Heap, M. J.*
Dingwell, D. B.*
Hess, K-U.*
Iezzi, G.*
Masotta, M.*
Scarlato, P.*
Vinciguerra, S.*
Title: Decarbonation and thermal microcracking under magmatic P-T-fCO2 conditions: the role of skarn substrata in promoting volcanic instability
Title of journal: Geophysical Journal International
Series/Report no.: /195(2013)
Publisher: Wiley-Blackwell
Issue Date: 2013
DOI: 10.1093/gji/ggt265
Keywords: Volcanic hazards and risks
Abstract: We present a systematic study on the influence of pressure (0.1–600 MPa), temperature (750– 1200 ◦C), carbon dioxide fugacity (logfCO2 = −4.41 to 3.60) and time (2–12 hr) on the chemical and physical properties of carbonate rock. Our experiments aim to reproduce the conditions at the periphery of magma chamber where carbonate host rock is influenced by, but not readily assimilated by, magma. This permits the investigation of the natural conditions at which circulating fluids/gases promote infiltration reactions typical of metasomatic skarns that can involve large volumes of subvolcanic carbonate basements. Results show that, providing that carbon dioxide is retained in the pore space, decarbonation does not proceed at any magmatic pressure and temperature. However, when the carbon dioxide is free to escape, decarbonation can occur rapidly and is not hindered by a low initial porosity or permeability. Together with carbon dioxide and lime, portlandite, a mineral commonly found in voluminous metasomatic skarns, readily forms during carbonate decomposition. Post-experimental analyses highlight that thermal microcracking, a result of the highly anisotropic thermal expansion of calcite, exerts a greater influence on rock physical properties (porosity, ultrasonic wave velocities and elastic moduli) than decarbonation. Our data suggest that this will be especially true at the margins of dykes or magma bodies, where temperatures can reach up to 1200 ◦C. However, rock compressive strength is significantly reduced by both thermal cracking and decarbonation, explained by the relative weakness of lime + portlandite compared to calcite, and an increase in grain size with increasing temperature. Metasomatic skarns, whose petrogenetic reactions may involve a few tens of cubic kilometres, could therefore represent an important source of volcanic instability.
Appears in Collections:04.08.08. Volcanic risk
Papers Published / Papers in press

Files in This Item:

File SizeFormatVisibility
07_Mollo et al._2013_GJI_195_369-380.pdf1.94 MBAdobe PDFonly authorized users View/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Share this record




Stumble it!



Valid XHTML 1.0! ICT Support, development & maintenance are provided by CINECA. Powered on DSpace Software. CINECA