Dewatering of a metamorphic pile

Norris, R. J.; Henley, Richard W.

doi:10.1130/0091-7613(1976)4<333:doamp>2.0.co;2

Cited by 118 publications

(40 citation statements)

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“…Significant fluid pressure ( or overpressure) would be dependent on high rock strength (Norris and Henley 1976), which is not obvious in the clastic rocks of the Marybank and Botanical Hill fc)rmations. With low or moderate rock strength a high degree of veining and fracturing would be expected, but these are rdatively rare.…”

Section: Discussionmentioning

confidence: 99%

Drumduan Group of East Nelson, New Zealand: Plant-bearing Jurassic arc rocks metamorphosed during terrane interaction

Johnston¹,

Raine

Watters

1987

Journal of the Royal Society of New Zealand

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The Drumduan Group, consisting of the Marybank and Botanical Hill formations, forms a fault-bounded block northeast of Nelson City, and comprises bedded pyroclastic and epiclastic (including sedimentary) debris of probable terrestrial deposition. Lawsonite is widespread, but not uniformly present. Plant macrofossils, including Mataia podocarpoides, Rissikia talbragarensis, Taenioptens thamsor/lana, T sp. cf. T crassinervis, Cladophlebis sp. and Podozamites sp., in the Marybank Formation indicate aJ urassic age. The group is separated from the Brook Street Volcanics (Permian) by the Delaware Fault Zone, along which arc slivers of Wakapuaka Phyllonite (pumpellyite-actinolite facies). In the west the group shows widespread hydrothermal alteration related to the adjacent Tasman Intrusives, but the Brook Street rocks arc not similarly altered and are not metamorphosed beyond prehnite-pumpellyite facies. We infer that during the Rangitata Orogeny the Drumduan Group, the Tasman Intrusives, and the underlying basement rocks, including the Pepin Group, were underthrust below the Brook Street Volcanics along the Delaware Fault Zone. The resulting depth of burial and confining nature of the overthrust plate on one side, and the Tasman Intrusives on the other, were responsible for the development of metamorphic rocks characterised by a relatively high PIT ratio and by the crystallisation oflawsonite, locally in abundance. Fluid pressures were probably nowhere greater than lithostatic pressure. The Delaware Fault Zone appears to form a major suture between the rocks of cast and west Nelson. The Drumduan Group, the Tasman Intrusives, and the Pepin Group arc assigned to the Tuhua Orogen.

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Section: Discussionmentioning

confidence: 99%

Drumduan Group of East Nelson, New Zealand: Plant-bearing Jurassic arc rocks metamorphosed during terrane interaction

Johnston¹,

Raine

Watters

1987

Journal of the Royal Society of New Zealand

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“…Norris & Henley (1976) pointed out that fluid movement must take place at least to the extent required to bleed off fluids released by devolatilization reactions, but we contend that the scale of the mass transport and fluid volumes inferred above demand a much more effective fluid mobility. In this section, we discuss the nature and magnitude of the major controls on fluid advection during metamorphism, before considering its broader implications.…”

Section: The Mobility Of the Metamorphic Fluidmentioning

confidence: 99%

“…These factors are: (1) at all but the lowest grades, the solid phases are not strong enough to support a pore with PI much less than PI, so irreversible pore collapse ensures Pf = P,; (2) continuous devolatilization reactions, both locally and deeper in the rock pile, are constantly increasing fluid volume, and thus P,; crystallizing magmas at all crustal levels also contribute to the fluid budget; (3) progressive burial in even a moderate thermal gradient leads to aqueous fluid expansion, which can substantially increase PI (Norris & Henley, 1976); and (4) there may be a significant input offluid from the mantle (Touret, 1971). Together, these factors will have the effect of maintaining P, at a threshold value limited only by the rock's hydraulic fracture strength.…”

Section: Gradientsmentioning

confidence: 99%

“…The ubiquitous presence of syn-metamorphic extension veins in low-grade rocks indicates that the fluid pressure (P,) exceeded the lithostatic rock pressure (P, -strictly the minimum principal compressive stress, us), at least periodically (Norris & Henley, 1976;Fyfe et al, 1978;Beach, 1977Beach, , 1979Etheridge et d., 1983).…”

Section: Low Metamorphic Grade ( < 400°c)mentioning

confidence: 99%

“…This paper explores the consequences of a high-pressure, mobile fluid for other aspects of the interaction between deformational and metamorphic processes. In this respect, it builds on the earlier work of Norris & Henley (1976), Price (1975) and Fyfe et al (1978), although none of these publications explored the implications of high P, in terms of the processes involved. We begin by reviewing the major metamorphic and microstructural characteristics of rocks of broadly felsic to pelitic composition at low, medium and high metamorphic grades.…”

Section: Introductionmentioning

confidence: 99%

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The role of the fluid phase during regional metamorphism and deformation

Etheridge

Wall

Vernon

1983

Journal Metamorphic Geology

507

218

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Abstract. Evidence from rock microstructures, mass transfer and isotopic exchange indicates that substantial quantities of aqueous fluids are involved in low-and medium-grade regional metamorphism. Similar conclusions are drawn from many retrograde environments, whereas high-grade metamorphic fluids may be melt dominated. The mobile fluids play essential roles in metamorphic reactions, mass transport and deformation processes. These processes are linked by the mechanical consequences of metamorphic fluid pressures (Pr) generally being greater than or equal to the minimum principal compressive stress. Under such conditions metamorphic porosity comprises grain boundary tubules and bubbles together with continuously generated (and healed) microfractures. Deformation results in significant interconnected porosity and hence enhanced permeability. Lithologically and structurally controlled permeability variations may cause effective fluid channelling.Simple Rayleigh-Darcy modelling of a uniformly permeable, crustal slab shows that convective instability of metamorphic fluid is expected at the permeabilities suggested for the high Pf metamorphic conditions. Complex, largescale convective cells operating in overpressured, but capped systems may provide a satisfactory explanation for the large fluid/rock ratios and extensive mass transport demonstrated for many low-and medium-grade metamorphic environments. Such large-scale fluid circulation may have important consequences for heat transfer in and the thermal evolution of metamorphic belts.

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