Development of a fracture network in crystalline rocks during weathering: Study of Bishop Creek chronosequence using X-ray computed tomography and<sup>14</sup>C-PMMA impregnation method

Mazurier, Arnaud; Sardini, Paul; Rossi, Ann Marie; Graham, Robert C.; Hellmuth, Karl-Heinz; Parneix, Jean-Claude; Siitari-Kauppi, Marja; Voutilainen, Mikko; Caner, Laurent

doi:10.1130/b31336.1

“…Thus, most differentiate micro porosity as water filled pore space at field capacity, with diameters less the 30 μm (typically inter‐grain pores in soil), and macro porosity as air‐filled pore space at field capacity, with diameters greater than 30 μm (typically inter aggregate voids in soil). Because weathered bedrock, saprock, and saprolite have no identifiable aggregates, but can have large voids based on mineral grain size and fractures, as well as microcrack and macrocrack structures (Mazurier et al, ), we have defined pore size distribution here as micro pores: less than 30 μm; meso pores: 30–75 μm; and macro pores: >75 μm. Examples of mechanisms that form these different size classes of porosity are: tectonically formed joint fractures and microfractures; microfractures formed and expanded by weathering (e.g., stress fracturing induced by biotite expansion); and pores generated by chemical dissolution and resulting material loss (Mazurier et al, ; Rossi & Graham, ).…”

Section: Process Controls On Plant‐accessible Watermentioning

confidence: 99%

Subsurface plant‐accessible water in mountain ecosystems with a Mediterranean climate

Klos

¹

,

Goulden²,

Riebe³

et al. 2018

View full text Add to dashboard Cite

Enhanced understanding of subsurface water storage will improve prediction of future impacts of climate change, including drought, forest mortality, wildland fire, and strained water security. Previous research has examined the importance of plant‐accessible water in soil, but in upland landscapes within Mediterranean climates, soil often accounts for only a fraction of subsurface water storage. We draw insights from previous research and a case study of the Southern Sierra Critical Zone Observatory to define attributes of subsurface storage; review observed patterns in their distribution; highlight nested methods for estimating them across scales; and showcase the fundamental processes controlling their formation. We review observations that highlight how forest ecosystems subsist on lasting plant‐accessible stores of subsurface water during the summer dry period and during multiyear droughts. The data suggest that trees in these forest ecosystems are rooted deeply in the weathered, highly porous saprolite or saprock, which reaches up to 10–20 m beneath the surface. This review confirms that the system harbors large volumes of subsurface water and shows that they are vital to supporting the ecosystem through the summer dry season and extended droughts. This research enhances understanding of deep subsurface water storage across landscapes and identifies key remaining challenges in predicting and managing response to climate and land use change in mountain ecosystems of the Sierra Nevada and in other Mediterranean climates worldwide. This article is categorized under: Science of Water > Hydrological Processes Science of Water > Water Extremes Water and Life > Nature of Freshwater Ecosystems

show abstract

“…On the contrary, further mechanical disintegration by fault wear processes produces fine-grained gouge and therefore low threshold size and connectivity impeding permeability (Géraud et al, 1995(Géraud et al, , 2006Bense et al, 2013). Fracturing may be accompanied or succeeded by fracture wall dissolution or precipitation due to chemically active fluids within the fracture network (Boyce et al, 2003;Ferry, 1979;Mazurier et al, 2016;Nishimoto and Yoshida, 2010), which may either increase or decrease the porosity and threshold size (Géraud et al, 2010;Katsube and Kamineni, 1983;Yoshida et al, 2009). Also, volumetric expansion related to alteration of primary sheeted silicates such as biotite may induce local stress variations producing fractures (Lachassagne et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Also, volumetric expansion related to alteration of primary sheeted silicates such as biotite may induce local stress variations producing fractures (Lachassagne et al, 2011). Conceptual models of porosity and permeability distribution in complex fracture or fault zones have been drawn to account for a variety of conductive and sealing structures (Bense et al, 2013;Caine et al, 1996;Evans et al, 1997;Faulkner et al, 2010Faulkner et al, , 2011Mitchell and Faulkner, 2009;Wilson et al, 2003). Porosity-permeability relations of these structures are not straightforward since permeability depends on the pore-throat arrangement and scales linearly with the porosity and by power law with the characteristic threshold size (Bernabé et al, 2003;David et al, 1994;Katz and Thompson, 1987;Wardlaw et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

Granite microporosity changes due to fracturing and alteration: secondary mineral phases as proxies for porosity and permeability estimation

Staněk

¹

,

Géraud

²

2019

View full text Add to dashboard Cite

Abstract. Several alteration facies of fractured Lipnice granite are studied in detail on borehole samples by means of mercury intrusion porosimetry, polarized and fluorescent light microscopy, and microprobe chemical analyses. The goal is to describe the granite void space geometry in the vicinity of fractures with alteration halos and to link specific geometries with simply detectable parameters to facilitate quick estimation of porosity and permeability based on, for example, drill cuttings. The core of the study is the results of porosity and throat size distribution analyses on 21 specimens representing unique combinations of fracture-related structures within six different alteration facies basically differing in secondary phyllosilicate chemistry and porosity structure. Based on a simple model to calculate permeability from the measured porosities and throat size distributions, the difference in permeability between the fresh granite and the most fractured and altered granite is 5 orders of magnitude. Our observations suggest that the porosity, the size of connections and the proportion of crack porosity increase with fracture density, while precipitation of iron-rich infills as well as of fine-grained secondary phyllosilicates acts in the opposite way. Different styles and intensities of such end-member agents shape the final void space geometry and imply various combinations of storage, transport and retardation capacity for specific structures. This study also shows the possibility to use standard mercury intrusion porosimetry with advanced experimental settings and data treatment to distinguish important differences in void space geometry within a span of a few percent of porosity.

show abstract

“…On the contrary, further mechanical disintegration by fault wear processes produces fine-grained gouge and therefore low threshold size and connectivity impeding permeability (Géraud et al, 1995(Géraud et al, , 2006Bense et al, 2013). Fracturing may be accompanied or succeeded by fracture wall dissolution or precipitation due to chemically active fluids within the fracture network (Boyce et al, 2003;Ferry, 1979;Mazurier et al, 2016;Nishimoto and Yoshida, 2010), which may either increase or decrease the porosity and threshold size (Géraud et al, 2010;Katsube and Kamineni, 1983;Yoshida et al, 2009). Also, volumetric expansion related to alteration of primary sheeted silicates such as biotite may induce local stress variations producing fractures (Lachassagne et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Also, volumetric expansion related to alteration of primary sheeted silicates such as biotite may induce local stress variations producing fractures (Lachassagne et al, 2011). Conceptual models of porosity and permeability distribution in complex fracture or fault zones have been drawn to account for a variety of conductive and sealing structures (Bense et al, 2013;Caine et al, 1996;Evans et al, 1997;Faulkner et al, 2010Faulkner et al, , 2011Mitchell and Faulkner, 2009;Wilson et al, 2003). Porosity-permeability relations of these structures are not straightforward since permeability depends on the pore-throat arrangement and scales linearly with the porosity and by power law with the characteristic threshold size (Bernabé et al, 2003;David et al, 1994;Katz and Thompson, 1987;Wardlaw et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

Reviewer comments

Marti¹

2018

Preprint

0

View full text Add to dashboard Cite

Several alteration facies of fractured Lipnice granite are studied in detail on borehole samples by means of mercury intrusion porosimetry, polarized and fluorescent light microscopy, and microprobe chemical analyses. The goal is to describe the granite void space geometry in the vicinity of fractures with alteration halos and to link specific geometries with simply detectable parameters to facilitate quick estimation of porosity and permeability based on, for example, drill cuttings. The core of the study is the results of porosity and throat size distribution analyses on 21 specimens representing unique combinations of fracture-related structures within six different alteration facies basically differing in secondary phyllosilicate chemistry and porosity structure. Based on a simple model to calculate permeability from the measured porosities and throat size distributions, the difference in permeability between the fresh granite and the most fractured and altered granite is 5 orders of magnitude. Our observations suggest that the porosity, the size of connections and the proportion of crack porosity increase with fracture density, while precipitation of iron-rich infills as well as of finegrained secondary phyllosilicates acts in the opposite way. Different styles and intensities of such end-member agents shape the final void space geometry and imply various combinations of storage, transport and retardation capacity for specific structures. This study also shows the possibility to use standard mercury intrusion porosimetry with advanced experimental settings and data treatment to distinguish important differences in void space geometry within a span of a few percent of porosity.

show abstract

Development of a fracture network in crystalline rocks during weathering: Study of Bishop Creek chronosequence using X-ray computed tomography and¹⁴C-PMMA impregnation method

Cited by 23 publications

References 73 publications

Subsurface plant‐accessible water in mountain ecosystems with a Mediterranean climate

Subsurface plant‐accessible water in mountain ecosystems with a Mediterranean climate

Granite microporosity changes due to fracturing and alteration: secondary mineral phases as proxies for porosity and permeability estimation

Reviewer comments

Contact Info

Product

Resources

About

Development of a fracture network in crystalline rocks during weathering: Study of Bishop Creek chronosequence using X-ray computed tomography and14C-PMMA impregnation method

Cited by 23 publications

References 73 publications

Subsurface plant‐accessible water in mountain ecosystems with a Mediterranean climate

Subsurface plant‐accessible water in mountain ecosystems with a Mediterranean climate

Granite microporosity changes due to fracturing and alteration: secondary mineral phases as proxies for porosity and permeability estimation

Reviewer comments

Contact Info

Product

Resources

About

Development of a fracture network in crystalline rocks during weathering: Study of Bishop Creek chronosequence using X-ray computed tomography and¹⁴C-PMMA impregnation method