Net tectonic rotation, apparent tectonic rotation, and the structural tilt correction in paleomagnetic studies

MacDonald, W. D.

doi:10.1029/jb085ib07p03659

Cited by 236 publications

(73 citation statements)

References 34 publications

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“…And the primary directions were scattered by various modes of rotation around the vertical axis to bring highly scattered declinations. The convergence in inclination also excludes possibility of the net tectonic rotation that is suggested by MacDonald (1980). Only 6 sites yielded characteristic directions from the Tsugawa district.…”

Section: Tilt Correctionmentioning

confidence: 99%

Paleomagnetic evidence for Miocene transtensional deformations at the eastern margin of the Japan Sea

2014

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The opening of the Japan Sea backarc basin accompanied dextral, transtensional deformations in the NE Japan arc. To understand the intra-arc deformation we have studied paleomagnetism in the Uetsu area, NE Japan. Among the samples collected at 70 sites for paleomagnetic measurement reliable directions were obtained at 38 ones. About half of the sites yielded clockwise and the others show opposite declinations. Our data indicate that the northern Uetsu area rotated counterclockwise as a single block, whereas the southern Uetsu area was broken into a number of blocks that was rotated clockwise by the dextral transtension along the Nihonkoku-Miomote Line. Not only the Uetsu area but the entire eastern margin of the Japan Sea experienced such transtensional deformations in the Early to early Middle Miocene. The crust under NE Japan was broken into blocks but they rotated coherently with dextral transtension.

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Section: Tilt Correctionmentioning

confidence: 99%

Paleomagnetic evidence for Miocene transtensional deformations at the eastern margin of the Japan Sea

2014

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“…[24] Due to the potentially complex nature of deformation paths in orogenic belts, care is needed in restoring in situ paleomagnetic and deformation fabric directions, using successive rotations based on structural and timing relations [MacDonald, 1980]. For complex structural settings (e.g., plunging and conical folds), incorrect restoration paths may introduce spurious components of apparent vertical axis rotation [Pueyo et al, 2003].…”

Section: Evaluation Of Paleomagnetic and Deformation Fabric Datamentioning

confidence: 99%

Quantifying vertical axis rotation in curved orogens: Correlating multiple data sets with a refined weighted least squares strike test

Yonkee

Weil

2010

Tectonics

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[1] Map-scale curvature is a fundamental feature of most contractional orogenic belts and is central to understanding the kinematic and dynamic evolution of mountain systems. Paleomagnetic analysis, combined with detailed structural studies, is the most robust means of quantifying vertical axis rotations that produce curvature over a range of temporal and spatial scales. This paper explores how vertical axis rotations can best be evaluated for multiple data sets by applying a weighted least squares method to the classic strike test. This refined method provides measures of best fit slope, confidence interval, and goodness of fit between map-scale structural trend, paleomagnetic rotations, and deformation fabric orientations. Structural trend is estimated by averaging fold axial trace, formation contact, and bed strike data over kilometerscale areas. Paleomagnetic and deformation fabric site-mean orientations and measurement uncertainties are estimated using vector and bootstrap statistics. Weighting factors are estimated from combined measurement uncertainty, structural noise related to smallscale block rotation and stress/strain refraction, and variations in restoration paths. The number of sites needed to obtain a significant confidence interval in strike test slope is a function of combined uncertainty in paleomagnetic or deformation fabric directions and the total range in structural trend around a curved orogen. Improved estimates of strike test slope and rotation thus require systematic sampling with a wide distribution of sites, evaluation of appropriate weighting factors, and statistical analysis. A case study is presented that highlights application of this refined method to paleomagnetic and deformation fabric data sets from the Wyoming salient of the Sevier thrust belt. Paleomagnetic data yield a strike test slope of 0.76 ± 0.11, indicating that the Wyoming salient is a progressive arc, with ∼3/4 secondary curvature related to vertical axis rotation synchronous with large-scale thrusting and ∼1/4 initial curvature. Finite strain, anisotropy of magnetic susceptibility, and mesoscopic structural orientations, which are related to early layer-parallel shortening, all yield strike test slopes of ∼0.9 ± 0.1. Comparing these slopes with paleomagnetic results indicates that deformation fabrics had initial curvature and thus cannot be used alone to accurately estimate rotations. By integrating systematic paleomagnetic and structural data using statistical analysis, curvature models for the Wyoming salient are closely constrained. Citation: Yonkee, A., and A. B. Weil (2010), Quantifying vertical axis rotation in curved orogens: Correlating multiple data sets with a refined weighted least squares strike test, Tectonics, 29, TC3012,

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“…Judging from the vertical dip of the dike and the gentle attitude of the country rocks, it is unlikely that those rocks have been deformed locally by small-scale folds and/or faults which can produce significant shifts of remanent directions (MACDONALD, 1980). Therefore, possible interpretations for the anomalous sitemean declination are as follows: (1) regional rotation about a vertical axis after the emplacement of dike, and (2) an instantaneous record of the geomagnetic field swing such as a part of secular variation or polarity reversal.…”

Section: Results and Interpretationmentioning

confidence: 99%

Age Estimation of a High-Magnesian Andesite from the Kii Peninsula, Southwest Japan

Torii

Ishikawa

1986

J. geomagn. geoelec

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Net tectonic rotation, apparent tectonic rotation, and the structural tilt correction in paleomagnetic studies

Cited by 236 publications

References 34 publications

Paleomagnetic evidence for Miocene transtensional deformations at the eastern margin of the Japan Sea

Paleomagnetic evidence for Miocene transtensional deformations at the eastern margin of the Japan Sea

Quantifying vertical axis rotation in curved orogens: Correlating multiple data sets with a refined weighted least squares strike test

Age Estimation of a High-Magnesian Andesite from the Kii Peninsula, Southwest Japan

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