Transport properties of pyroclastic rocks from Montagne Pelée volcano (Martinique, Lesser Antilles)

Abstract

[1] The hydraulic and electrical properties of pyroclastic rocks have been investigated in laboratory on a representative sampling of Montagne Pelée (Martinique, France) deposits with renewed interest in geophysical applications. This sampling covers all the lithologic units of this volcano: lava dome and lava flows, pumices from ash-andpumice fall and flow deposits, lava blocks from block-and-ash flow and Peléean ''nuées ardentes'' deposits, scoriae from scoria flow deposits. The connected porosity varies over a wide range from 3 to 62%. The unconnected porosity is important only on pumices where it can reach 15%. The permeability covers more than 5 orders of magnitude, ranging from 10 À16 to 35 Â 10 À12 m 2 . The higher values are obtained on lava blocks and the scoriae, even if these rocks are less porous than the pumices. The formation factor ranges from 7 to 1139. The transport properties of these rocks are slightly correlated with porosity. This indicates that these properties are not only controlled by the connected porosity. To connect the transport properties to the textural characteristics of the pore network of pyroclastic rocks, different models, based on geometrical considerations or percolation theory, were tested. The pore access radius distribution and the tortuosity control the transport properties of pyroclastic rocks. Consequently, the models (electric and hydraulic) based on the concept of percolation (e.g., the models of Katz and Thompson), apply better than the equivalent channel model of Kozeny-Carman. In addition, the difference in transport properties observed on lava blocks and pumices confirms that the mechanisms of degassing and vesiculation are different for these two types of rock.

Physical property relationships of the Rotokawa Andesite, a significant geothermal reservoir rock in the Taupo Volcanic Zone, New Zealand

“…We do however need to consider those data points that have a very similar value of permeability (approximately 3.2 × 10 −17 m 2 , Table 4), with a porosity range of 7.6 to 10.3 vol% that indicate that there is variability of the samples with respect to permeability that may be reflected in the tortuosity of the porous network. This is consistent with the findings of Bernard et al (2007) and Heap et al (2014) such that the permeability in volcanic rocks is highly dependent upon connectivity of the microstructure. With respect to microstructure, we have shown that the porosity is very closely linked to crack surface area ( Figure 8D) and, thus, that increasing crack density corresponds to a sample with a higher permeability.…”

“…Forms of the KozenyCarman relation have previously been used in the study of volcanic rocks (e.g., Saar and Manga 1999;Costa 2006;Bernard et al 2007;Heap et al 2014), while others have used a heavily simplified version (e.g., Rust et al 2003;Mueller et al 2005;Lavallée et al 2013). The Kozeny-Carman relation is of the form:…”

Effect of temperature on the permeability of lava dome rocks from the 2004–2008 eruption of Mount St. Helens

“…By contrast, numerous room temperature permeability measurements have been reported for extrusive volcanic rocks such as lava blocks from Mt. Pelee, Colima, and Unzen (e.g., Bernard et al 2007;Heap et al 2015;Kendrick et al 2013;Mueller et al 2005). Additionally, a handful of studies have assessed the temporal changes in the permeability of hydrothermal systems at constant temperatures (Moore et al 1994;Morrow et al 2001) or under combined high pressure and temperature conditions (30 to 150 MPa and up to 600°C) (Zharikov et al 2003).…”

Controls on magma permeability in the volcanic conduit during the climactic phase of the Kos Plateau Tuff eruption (Aegean Arc)

“…Manga 1999; Polacci et al 2003;Rust et al 2003;Rosi et al 2004;Mueller et al 2005;Gualda and Rivers 2006;Wright et al 2006;Bernard et al 2007; Bouvet de Maisonneuve et al 2008).…”