Some guidelines for the practical application of Fry's method of strain analysis

Crespi, Jean

doi:10.1016/0191-8141(86)90026-x

Cited by 37 publications

(10 citation statements)

References 9 publications

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“…Under this assumption we measured finite strains in 12 oriented samples using the Fry [1979] method. Following Crespi [1986], we digitized a minimum of 200 grain centers, sample size permitting, on each of three perpendicular rock slabs; visually estimated a strain ellipse for each section; and combined the data to calculate a best ellipsoid using the method of Owens [ 1984].…”

Section: This Retrogression Of Biotite To Chlorite + Prehnite Is Wimentioning

confidence: 99%

“…The figure illustrates a general scatter in the data as well as the wide range of strains from virtually undeformed rocks to moderately deformed rocks. The scatter in the data is probably in part due to imprecise strain measurements in these weakly deformed rocks as well as inherent problems in measuring strain in igneous rocks (see Crespi [1986] for a discussion). Moreover, some of the scatter may result from superposition of an igneous flow fabric and later solid-state flow, e.g., cases of flattening versus conslrictional strains.…”

Section: This Retrogression Of Biotite To Chlorite + Prehnite Is Wimentioning

confidence: 99%

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Early Cretaceous near‐trench plutonism in southern Alaska: Atonalite‐Trondhjemite Intrusive Complex injected during ductile thrusting along the Border Ranges Fault System

Pavlis¹,

Monteverde²,

Bowman³

et al. 1988

Tectonics

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A group of leucotonalite to trondhjemite plutons in the western Chugach Mountains, Alaska, record a period of Early Cretaceous near-trench plutonism along the paleo-Alaskan/Aleutian subduction zone. The plutons were emplaced along the tectonic join between an older (Jurassic) arc massif and a younger (Cretaceous) melange terrane that was accreted by subduction beneath the crystalline massif. The plutonic rocks were injected during a major thrusting event that placed upper mantle(?) ultramafic masses atop the Cretaceous subduction assemblages. Deformation during this thrusting event apparently progressed from ductile to brittle conditions, and plutonic rocks were injected during both phases. Evidence for plutonism synchronous with ductile deformation includes boudinage or folding of leucotonalite dikes as well as a characteristic weak fabric within larger plutons. The latter is commonly associated with secondary mineral growth as well as deformation-induced microstructures that suggest deformation under temperatures that decreased from lower amphibolite to subgreenschist facies conditions, conditions which are equivalent to the structural/metamorphic progression in adjacent schists. Paradoxically, however, the plutons locally crosscut low-grade melange fabrics in the footwall as well as brittle fault networks within structurally higher parts of the crystalline hanging wall. The paradoxical field relationships are partially due to shuffling by early Tertiary(?) dextral strike-slip faulting but are also indicative of plutonic emplacement over a period of time. The absolute age span of plutonism, however, need not have been long considering the syntectonic emplacement history. In particular, the deformation locally may have been meltdominated such that after initial injection of melts, the deformation was concentrated in the igneous masses. Lithologically, the plutons follow a low-K series from diorite to muscovite-garnet trondhjemite, a trend that is unusual in Phanerozoic terranes and is typically associated with Archean terranes. Moreover, the compositional trends are unlike the calc-alkaline trend of near-trench plutons studied by Hill et al. (1981). The tectonic mechanism for the near-trench plutonic event is elusive, but shallow melting of amphibolite or metagreywacke along a young subduction zone provides the most reasonable explanations for the observations. However, an alternative model relating magmatic activity to a ridgetrench encounter is also allowable. Nonetheless, in either model the genesis of the igneous rocks within a hightemperature ductile thrust zone is atypical of modern subduction zones. Thus structural setting and lithologic association have many similarities to Archean systems, and the rocks may represent a young analog that ultimately may provide key petrogenetic constraints for the Archean system. General Geology, Western Chugach MountainsLate Mesozoic "near-trench" plutonic rocks have been recognized at three localities along the Border Ranges fault: in the western Chugach Mountains north...

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Section: This Retrogression Of Biotite To Chlorite + Prehnite Is Wimentioning

confidence: 99%

Section: This Retrogression Of Biotite To Chlorite + Prehnite Is Wimentioning

confidence: 99%

Early Cretaceous near‐trench plutonism in southern Alaska: Atonalite‐Trondhjemite Intrusive Complex injected during ductile thrusting along the Border Ranges Fault System

Pavlis¹,

Monteverde²,

Bowman³

et al. 1988

Tectonics

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“…Despite the wide usage of the Fry method, there are many objections to the technique and particularly to the method of ellipse fitting to the vacant hole. The central hole gets often vaguely defined owing to cut effects (Bhattacharyya et al 1986;Crespi, 1986;Srivastava, 1995). They may be far from elliptical and may contain maverick points.…”

Section: Introductionmentioning

confidence: 99%

A computer program for the determination of finite strain using fry method

Roday¹,

Purohit

Prajapati

2010

J Geol Soc India

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Fry method enables rapid estimate of finite strain from deformed aggregates such as clastic grains, fossil colonies, oolitic or pisolitic aggregates, prophyroblastic minerals or phenocrysts. It has an advantage over the other methods of finite strain analysis in its very quality of enabling rapid estimation with a reasonable degree of accuracy. Details of the software to prepare a plot using Fry method are outlined. This program has an advantage over other computer based programs on the world wide web in its aesthetic getup, small size, user friendliness and a help file.The program is a freeware and can be downloaded by following the links on a software website http://www.alstructural-geology-software.com.FryPlotSetup.zip or http://www.al-structural-geology-software.com/FryProg/ FryPlotProgSetup.exe

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“…These strengths, as well as the fact that deformed objects exposed at outcrop and/or under the microscope are generally not good strain markers on account of their unknown shapes in the pre-deformed state, make the Fry method applicable as a simple and powerful tool to quantify homogeneous deformation recorded by the distribution of points in rocks of variable kinds (e.g., Hanna and Fry, 1979;González-Casado et al, 1983;Crespi, 1986;Onasch, 1986;Ghaleb and Fry, 1995;Genier and Epard, 2007), and even the spatial distribution of mineralization (Vearncombe and Vearncombe, 1999).…”

Section: Introductionmentioning

confidence: 99%