Recycling of foliations during folding

Ham, A.P.; Bell, T. H.

doi:10.1016/j.jsg.2004.04.003

Cited by 50 publications

(20 citation statements)

References 30 publications

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“…Our results show that foliation at any orientation lowers residual rock strength. Therefore we suggest that this weakness may contribute to the reactivation of crenulation fabrics, often over multiple episodes of deformation, which is observed in field analyses (Bell, 1986;Davis and Forde, 1994;Ham and Bell, 2004).…”

Section: Foliated Rock Deformation In Naturementioning

confidence: 71%

Experimental investigation of incipient shear failure in foliated rock

Ikari

Niemeijer

Marone

2015

Journal of Structural Geology

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Section: Foliated Rock Deformation In Naturementioning

confidence: 71%

Experimental investigation of incipient shear failure in foliated rock

Ikari

Niemeijer

Marone

2015

Journal of Structural Geology

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“…Schoneveld, 1977). Furthermore, many structural geologists routinely publish papers using the shear sense derived from the asymmetry of crenulated cleavages into zones of differentiation to interpret structural development Johnson, 1989, 1992;Hayward, 1992;Davis, 1993Davis, , 1995Davis and Forde, 1994;Aerden, 1994Aerden, , 1998Ham and Bell, 2004;Rich, 2006). This state of ambivalence on whether or not shear occurs along a foliation increased with the recognition of S and C planes in some mylonites (Berthé et al 1979) and "extensional" crenulation cleavages in others ( Fig.3; Platt and Vissers, 1980) where all structural geologists agreed that shear occurred along the C plane or crenulation long limb respectively.…”

Section: Genesis Of the Shear On Foliation Problemmentioning

confidence: 99%

“…The curvature of the inclusion trails in the porphyroblast rims preserves the shear sense that operated on the foliation that was developing when it grew (e.g. Bell et al 2003Bell et al , 2005Ham and Bell, 2004).…”

Section: Foliation Re-use and Shear Sensementioning

confidence: 99%

Foliations and shear sense: A modern approach to an old problem

Bell

Hobbs

2010

J Geol Soc India

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Argument about shear on foliations began in the mid 19 th century and continues to the present day. It results from varying interpretations of what takes place during the development of different types of foliations ranging from slaty cleavages through differentiated crenulation cleavages, schistosity and gneissosity to mylonites. Computer modelling, quantitative microstructural work and monazite dating have provided a unique solution through access to the history of foliation development preserved by porphyroblasts. All foliations involve shear in their development and most can be used to derive a shear sense. The shear sense obtained is consistent between foliation types and accords with recent computer modelling of these structures preserved within porphyroblasts relative to those in the matrix. The asymmetry of curving foliation into a locally developing new one allows determination of the shear sense along the latter foliation in most rocks. The problem of shear on fold limbs and parallelism of foliation and the flattening plane of the strain ellipse is resolved through the partitioning of shearing and shortening components of deformation into zones that anastomose around ellipsoidal domains lying parallel to the XY plane. Conflicts in shear sense occur if multiple reuse or reactivation of foliations is not recognized and allowed for but are readily resolved if taken into account.

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“…In multiply deformed and metamorphosed rocks, foliations in the matrix, especially schistosity parallel to compositional layering, have generally undergone long and complex histories (e.g., Ham and Bell 2004). Different relics of this history can be left in strain shadows or portions where later deformation partitioning was less pervasive and if not decoded carefully will lead to erroneous or ambiguous results (e.g., Spiess and Bell 1996).…”

Section: Introductionmentioning

confidence: 99%

“…These are generally isolated from the matrix phases and act as robust candidates for studying deformation and metamorphic processes. Such quantitative research has greatly increased our understanding of complex inclusion trail relationships, which otherwise could not be interpreted or were misleading (e.g., Ham and Bell 2004).…”

Section: Introductionmentioning

confidence: 99%

Ninety million years of orogenesis, 250 million years of quiescence and further orogenesis with no change in PT: Significance for the role of deformation in porphyroblast growth

Shah

Bell

2012

J Earth Syst Sci

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In situ dating of monazite grains preserved as inclusions within foliations defining FIAs (foliation inflection/intersection axes preserved within porphyroblasts) contained within garnet, staurolite, andalusite and cordierite porphyroblasts provides a chronology of ages that matches the FIA succession for the Big Thompson region of the northern Colorado Rocky Mountains. FIA sets 1, 2 and 3 trending NE-SW, E-W and SE-NW were formed at 1760.5 ± 9.7, 1719.7 ± 6.4 and 1674 ± 11 Ma, respectively. For three samples where garnet first grew during just one of each of these FIAs, the intersection of Ca, Mg, and Fe isopleths in their cores indicate that these rocks never got above 4 kbars throughout the Colorado Orogeny. Furthermore, they remained around approximately the same depth for ∼250 million years to the onset of the younger Berthoud Orogeny at 1415 ± 16 Ma when the pressure decreased slightly as porphyroblasts formed with inclusion trails preserving FIA set 4 trending NNE-SSW. No porphyroblast growth occurred during the intervening ∼250 million years of quiescence, even though the PT did not change over this period. This confirms microstructural evidence gathered over the past 25 years that crenulation deformation at the scale of a porphyroblast is required for reactions to re-initiate and enable further growth.

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Recycling of foliations during folding

Cited by 50 publications

References 30 publications

Experimental investigation of incipient shear failure in foliated rock

Experimental investigation of incipient shear failure in foliated rock

Foliations and shear sense: A modern approach to an old problem

Ninety million years of orogenesis, 250 million years of quiescence and further orogenesis with no change in PT: Significance for the role of deformation in porphyroblast growth

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