The relationship of strain and preferred orientation of phyllosilicate grains in rocks—a review

Oertel, Gerhard

doi:10.1016/0040-1951(83)90197-x

Cited by 150 publications

(58 citation statements)

References 195 publications

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“…Strain estimations using the March method are generally in good agreement with results of strain determinations using other methods (Tullis & Wood 1975;Wood & Oertel 1980;Oertel 1983). March (1932) showed that there is a relationship between preferred orientation and strain:…”

Section: Methodssupporting

confidence: 72%

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Structural contacts in subduction complexes and their tectonic significance: the Late Palaeozoic coastal accretionary wedge of central Chile

Richter

Ring

Willner

et al. 2007

JGS

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Understanding the contact between the very low-grade metagreywacke of the Eastern Series and high-pressure metamorphosed schist of the Western Series in the Late Palaeozoic accretionary wedge of central Chile is fundamental for the understanding of the evolution of ancient accretionary wedges. We show the progressive development of structures and finite strain from the least deformed rocks in the eastern part of the Eastern Series of the accretionary wedge to high-pressure schist of the Western Series at the Pacific coast. Upright chevron folds of sedimentary layering are associated with an axial-plane foliation, S 1 . As the F 1 folds became slightly overturned to the west, S 1 was folded about west-vergent open F 2 folds and an S 2 axial-plane foliation developed. Near the contact between the Western and Eastern Series S 2 represents a penetrative subhorizontal transposition foliation. Towards the structurally deepest units in the west the transposition foliation becomes progressively flattened. Finite-strain data as obtained by R f /ö analysis in metagreywacke and X-ray texture goniometry in phyllosilicate-rich rocks show a smooth and gradual increase in strain magnitude from east to west. Overturned folds and other shear-sense indicators show a uniform top-to-the-west shear sense in moderately deformed rocks, whereas the shear sense is alternating top-to-the-west and top-tothe-east in the strongly flattened high-pressure rocks of the Western Series near the Pacific coast. We interpret the progressive structural and strain evolution across the contact between the two series to reflect a continuous change in the mode of accretion in the subduction wedge. Initially, the rocks of the Eastern Series were frontally accreted to the pre-Andean margin before c. 300 Ma. Frontal accretion caused horizontal shortening, and upright folds and subvertical axial-plane foliations developed. At c. 300 Ma the mode of accretion changed and the rocks of the Western Series were underplated below the Andean margin. This basal accretion caused a major change in the flow field within the wedge and gave rise to vertical shortening and the development of the penetrative subhorizontal transposition foliation. Subsequent differential exhumation was resolved gradually over a wide region, implying that exhumation was not tectonically controlled.

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Section: Methodssupporting

confidence: 72%

“…(2) (Oertel 1983), where i net is the intensity in a certain measured sample position and i unif is the uniform intensity of all positions.…”

Section: Methodsmentioning

confidence: 99%

Structural contacts in subduction complexes and their tectonic significance: the Late Palaeozoic coastal accretionary wedge of central Chile

Richter

Ring

Willner

et al. 2007

JGS

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“…The orientation of the AMS ellipsoid is in most cases congruent with the strain ellipsoid. In finegrained rocks, such as the studied sediments, the preferred orientation of phyllosilicates depends on the strain caused by compaction and tectonic processes (Clark 1970;Moore & Geigle 1974;Oertel 1983;Peterson et al 1995), although depositional currents can also account for lineation. Several studies have shown the relationships between magnetic fabric and strain in compressional regimes (Kissel et al 1986;Lee et al 1990;Scheepers & Langereis 1994).…”

Section: Methods and Input Datamentioning

confidence: 99%

Subsidence, stress regime and rotation(s) of a tectonically active sedimentary basin within the western Alpine Orogen: the Tertiary Piedmont Basin (Alpine domain, NW Italy)

Carrapa

Bertotti

Krijgsman

2003

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The Oligocene to Miocene Tertiary Piedmont Basin (TPB) is located in the NW part of Italy at the junction between the Apennine and the Alpine thrust belts. The position of the TPB on top of the Alpine/Apennine Orogen poses fundamental questions as to the tectonics of the basin subsidence. Having undergone little deformation, the TPB sediments provide an insight into the stress regime and rotations in the kinematically very complex area surrounding the basin itself. In this study we integrate subsidence and structural analysis with measurements of magnetic susceptibility anisotropy (AMS) and natural remanent magnetization (NRM) in order to better constrain the tectonic kinematics of the basin evolution. A major important period of subsidence occurred in the Middle Miocene involving the whole basin. During this period the TPB experienced NE-SW-directed compression and limited shortening. Some NW-SE-directed compressional features have been identified and they were probably active during post Tortonian times. Structures associated with north-south tension are quite common, but the amount of strain that they accommodate is minor. In addition this research provides new preliminary data suggesting counterclockwise rotation in the TPB by c. 20° which has taken place during Middle Miocene time.

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“…Preferred-orientation data were measured in transmission mode, which is recommended for XRD peaks with low diffraction angles (20) such as for the relatively intense (001) peaks of phyllosilicates (e.g., Oertel, 1985;Wenk, 1985). In transmission mode, Xrays pass through the sample and the detector is positioned at a pre-set 20 angle to receive X-rays diffracted by a specific set of planes of a specific phase.…”

Section: Preparationmentioning

confidence: 99%

Preferred Orientation of Phyllosilicates in Gulf Coast Mudstones and Relation to the Smectite-Illite Transition

Peacor

Pluijm

1999

Clays and clay miner.

103

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Abstract--Development of preferred orientations of illite-smectite (I-S) has been studied using X-ray diffraction (XRD) texture goniometry to produce pole figures for clay minerals of a suite of 16 mudstone samples from a core from the Gulf Coast. Samples represent a compaction-loading environment in which the smectite-to-illite (S-I) transition occurs. In five shallow, pre-transition samples, there is no significant preferred orientation for smectite rich I-S. Development of preferred orientation of I-S, although weak, was first detected at depths slightly less than that of the S-I transition. The degree of preferred orientation, which is always bedding-parallel, increases rather abruptly, but continuously, over a narrow interval corresponding to the onset of the S-I transition, then continues to strengthen only slightly with increasing depth. The degree of post-transition preferred orientation is also dependent on lithology, where the preferred orientation is less well-defined for quartz-rich samples.Previously obtained transmission electron microscope (TEM) data define textures consistent with the change in orientation over many crystallites. The smectite in pre-transition rocks consists largely of anastomosing, "wavy" layers with variable orientation and whose mean orientation is parallel to bedding, but which deviate continuously from that orientation. This results in broad, poorly defined peaks in pole figures. Post-transition illite, by contrast, consists of thin, straight packets, with most individual crystallites being parallel or nearly parallel to bedding. This results in pole figures with sharply defined maxima. By analogy with development of slaty cleavage in response to tectonic stress during metamorphism, the S-I transition is marked by dissolution of smectite and neocrystallization of illite or I-S locally within the continuous "megacrystals" of smectite. The transition is inferred to have some component of mechanical rotation of coherent illite crystals within a pliant matrix of smectite. The data suggest that change in orientation and coalescence of clay packets plays an important role in the formation of the hydraulic seal required for over-pressure generation.

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The relationship of strain and preferred orientation of phyllosilicate grains in rocks—a review

Cited by 150 publications

References 195 publications

Structural contacts in subduction complexes and their tectonic significance: the Late Palaeozoic coastal accretionary wedge of central Chile

Structural contacts in subduction complexes and their tectonic significance: the Late Palaeozoic coastal accretionary wedge of central Chile

Subsidence, stress regime and rotation(s) of a tectonically active sedimentary basin within the western Alpine Orogen: the Tertiary Piedmont Basin (Alpine domain, NW Italy)

Preferred Orientation of Phyllosilicates in Gulf Coast Mudstones and Relation to the Smectite-Illite Transition

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