The drawbacks of sectioning rocks relative to fabric orientations in the matrix: A case study from the Robertson River Metamorphics (Northern Queensland, Australia)

Cihan, M.

doi:10.1016/j.jsg.2004.07.001

Cited by 20 publications

(15 citation statements)

References 39 publications

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“…SSITs appear so obviously a product of rotation of the porphyroblast within a foliation as progressive shearing occurred that no one considered the possibility that this might not be the case until the 1980s. However, a technique for quantitatively measuring the axes of SSITs was developed (Hayward, 1990;Bell, Forde & Wang, 1995) and a large amount of data has now been published on the orientation of spiral axes around folds (Bell & Hickey, 1997;Hickey & Bell, 2001;Bell & Chen, 2002;Timms, 2004), around oroclines (Bell & Mares, 1999;Yeh & Bell, 2004) and along and across orogens (Bell & Bruce, 2006;Bell, Hickey & Upton, 1998;Bell, Ham & Hickey, 2003, Bell, Ham & Kim, 2004Bell et al 2005;Cihan, 2004;Cihan & Parsons, 2005). He also generated a non-coaxial strain field diagram that mimicked asymmetric crenulation cleavages and straight to slightly sigmoidal inclusion trails that are common in so many porphyroblasts.…”

Section: E Alpine Top-to-the-s Shearing During Main Menderes Metammentioning

confidence: 99%

Extensional v. contractional origin for the southern Menderes shear zone, SW Turkey: tectonic and metamorphic implications

Bozkurt

2006

Geol. Mag.

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The southern Menderes Massif in southwest Turkey consists mainly of orthogneisses and overlying Palaeozoic-Middle Paleocene schists and marbles. The contact between the two distinct rock types is almost everywhere structural, herein named the southern Menderes shear zone: a S-facing, high-angle ductile shear zone that separates metamorphic rocks of differing grade. Although there is a consensus that the shear zone was associated with top-to-the-S-SSW shearing and is of Tertiary age, its origin and nature have been highly debated over the last decade. Some claim the contact is a thrust fault, while others have argued for an extensional shear zone. Integration of field and microstructural data (the identification of different fabrics, associated kinematics and overprinting relationships) with fissiontrack thermochronology and the P-T paths of the rocks above and below the shear zone, supports the conclusion that the southern Menderes shear zone is an extensional shear zone and not a thrust. The data are consistent with a model that the exhumation and cooling of the southern Menderes Massif occurred after a period of extensional deformation. Pervasive top-to-the-N-NNE high-temperature-mediumpressure ductile shear structures (D 2 deformation) overprint an early HP event (D 1 deformation). The subsequent top-to-the-S-SSW greenschist shear band foliation (D 3 deformation) developed mostly around the orthogniess-schist contact and forms the most characteristic features of the massif. The topto-the-N-NNE structures are attributed to the main Alpine constructional deformation that developed during back-thrusting of the Lycian nappes during the latest Palaeogene collision between the Sakarya continent and the Anatolide-Tauride platform across the Neotethyan Ocean. The top-to-the-S-SSW structures are interpreted to be the result of the exhumation of the massif during the activity of the southern Menderes shear zone. The presence of these two distinct fabrics with differing kinematics suggests that the southern Menderes shear zone operated as a top-to-the-N-NNE thrust fault during early Alpine contractional deformation but was later reactivated with an opposite sense of movement (top-to-the-S-SSW) during subsequent Oligocene-Miocene extensional collapse.

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Section: E Alpine Top-to-the-s Shearing During Main Menderes Metammentioning

confidence: 99%

Extensional v. contractional origin for the southern Menderes shear zone, SW Turkey: tectonic and metamorphic implications

Bozkurt

2006

Geol. Mag.

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“…30 m for standard petrographic thin sections, 100-300 m for fluid-inclusion study thick sections). To highlight multiple episodes of crystal growth, some studies are based on sequences of vertical thin sections with different strikes on oriented samples in order to fully illustrate the trend of inclusions (Cihan, 2004). Inclusion-trail studies in garnet have also been carried out using X-ray tomography (Huddlestone-Holmes and Ketcham, 2005).…”

Section: Garnet In Earth Sciencesmentioning

confidence: 99%

External and internal features of garnet revealed by the multifocus imaging technique

Thiéry

2013

Micron

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“…However, when thin sections dipping at 90° are cut with different strikes around the compass, truncational relationships between the matrix and the inclusion trails in the porphyroblasts are revealed (Fig.8c; e.g. Cihan, 2004). Therefore, one cannot use the inclusion trail asymmetry preserved within a porphyroblast to determine shear on an adjacent matrix foliation using just one or two orthogonal thin sections.…”

Section: Ages From Fia Successionsmentioning

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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The drawbacks of sectioning rocks relative to fabric orientations in the matrix: A case study from the Robertson River Metamorphics (Northern Queensland, Australia)

Cited by 20 publications

References 39 publications

Extensional v. contractional origin for the southern Menderes shear zone, SW Turkey: tectonic and metamorphic implications

Extensional v. contractional origin for the southern Menderes shear zone, SW Turkey: tectonic and metamorphic implications

External and internal features of garnet revealed by the multifocus imaging technique

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

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