Reference frame, angular momentum, and porphyroblast rotation

Jiang, Dazhi; Williams, Peter

doi:10.1016/j.jsg.2004.06.012

Cited by 31 publications

(10 citation statements)

References 28 publications

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“…One group of workers (Bell 1985;Bell and Johnson 1989;Bell et al 1992aBell et al , 1992bHickey and Bell 1999) have strongly argued that porphyroblasts do not rotate with respect to an external frame of reference and that even 'snow-ball' type spiral inclusion trails can be reinterpreted as a product of repeated overprinting deformation and transposition of the matrix foliation around a growing and non-rotating porphyroblast. The other group supports the existing and 'traditional' view of rotation of porphyroblasts in non-coaxial flow to explain strongly folded and rotated inclusion trails in porphyroblasts (Schoneveld 1979;Vernon 1988;Busa and Grey 1992;Visser and Mancktelow 1992;Passchier et al 1992;Williams and Jiang 1999;Jiang and Williams 2004). However, there is an inherent ambiguity in the interpretation of spiral inclusions by either rotation and non-rotation models (Johnson 1993a, b).…”

Section: Introductionmentioning

confidence: 71%

Polyphase deformation and garnet growth in pelitic schists of Sausar Group in Ramtek area, Maharashtra, India: A study of porphyroblast-matrix relationship

Chattopadhyay

Ghosh

2007

J Earth Syst Sci

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Polyphase deformation and metamorphism of pelitic schists of Chorbaoli Formation of Sausar Group in and around Ramtek area, Nagpur district, Maharashtra, India has led to the development of garnet and staurolite porphyroblasts in a predominantly quartz-mica matrix. Microstructural study of oriented thin sections of these rocks shows that garnet and staurolite have different growth histories and these porphyroblasts share a complex relationship with the matrix. Garnet shows at least two phases of growth -first intertectonic between D 1 and D 2 (pre-D 2 phase) and then syn-tectonic to post-tectonic with respect to D 2 deformation. Growth of later phase of garnet on the earlier (pre-D 2 ) garnet grains has led to the discordance of quartz inclusion trails between core and rim portion of the same garnet grain. Staurolite develops only syn-D 2 and shows close association with garnet of the later phase. The peak metamorphic temperature thus coincided with D 2 deformation, which developed the dominant crenulation schistosity (S 2 ), regionally persistent in the terrain. The metamorphic grade reached up to middle amphibolite facies in the study area, which is higher than the adjoining southern parts of Sausar Fold Belt.

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Section: Introductionmentioning

confidence: 71%

Polyphase deformation and garnet growth in pelitic schists of Sausar Group in Ramtek area, Maharashtra, India: A study of porphyroblast-matrix relationship

Chattopadhyay

Ghosh

2007

J Earth Syst Sci

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“…However, it led to a model that suggested that spiral and staircase inclusion trails also formed without rotation of the porphyroblasts and this led to 2 further decades of debate (e.g. Passchier et al 1992;Jiang and Williams, 2004). Although a large data bank on the orientation of foliation intersection axes preserved in porphyroblasts (FIAs) strongly suggests that porphyroblasts do not rotate during ductile deformation, no one had succeeded in providing an explanation of this process using continuum mechanics, analogue or computer modelling.…”

Section: Inclusion Trails Defined By a Differentiated Crenulation Clementioning

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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“…Conflicting kinematic models have been postulated for the development of 'millipede' and 'rotational' microstructures preserved in porphyroblasts involving porphyroblast rotation (e.g. Jiang and Williams, 2004;Jessell and others, 2009), non-rotation (e.g. Aerden and Sayab, 2008;Bell and Hobbs, 2010) or little relative rotation (e.g.…”

Section: Lower-crustal Flow Beneath the Tibetan Plateau: Evidence Fromentioning

confidence: 99%