понедельник, 19 сентября 2016 г.
Palaeomagnetism in fold and thrust belts: use with caution
E. L. PUEYO, A. J. SUSSMAN, B. OLIVA-URCIA & F. CIFELLI
Abstract: The application of palaeomagnetism in fold and thrust belts is a unique way to obtain kinematic information regarding the evolution of these systems. However, since many potential problems can affect the reliability of palaeomagnetic datasets and their interpretations, such data should be used with caution. In this paper, we thoroughly review the sources of error from palaeomagnetism with a particular focus on deciphering vertical-axis rotations and the assumptions behind the method. Recent investigations have demonstrated that the age of the magnetization and syn-folding results from the fold test must also be carefully examined: factors such as internal deformation, deficient isolation of components (i.e. overlapping) or incorrect restoration procedures may produce apparent syn-folding results. In fact, the restoration procedure used to return the palaeomagnetic signal to the palaeogeographic coordinate system may itself inhibit accurate estimations of vertical-axis rotations when complex deformation histories induce different, noncoaxial, deformation axes. We recommend the auxiliary use of the inclination v. dip diagram as an efficient tool for identifying many errors. Finally, to determine accurate vertical axis rotations, the reference direction should honour standard reliability criteria and would ideally be measured within the undeformed foreland of the thrust system. In this paper, we review five decades of palaeomagnetic research in fold and thrust belts by concentrating on maximizing standard reliability criteria procedures to reduce uncertainty and increase confidence when applying palaeomagnetic data to unravel the tectonic evolution of fold and thrust belts.
From: Pueyo, E. L., Cifelli, F., Sussman, A. J. & Oliva-Urcia, B. (eds) 2016. Palaeomagnetism in Fold and Thrust Belts: New Perspectives. Geological Society, London, Special Publications, 425, 259–276. First published online July 7, 2016, http://doi.org/10.1144/SP425.14 # 2016 The Author(s). Published by The Geological Society of London. All rights reserved.
E. L. PUEYO, A. J. SUSSMAN, B. OLIVA-URCIA & F. CIFELLI
Abstract: The application of palaeomagnetism in fold and thrust belts is a unique way to obtain kinematic information regarding the evolution of these systems. However, since many potential problems can affect the reliability of palaeomagnetic datasets and their interpretations, such data should be used with caution. In this paper, we thoroughly review the sources of error from palaeomagnetism with a particular focus on deciphering vertical-axis rotations and the assumptions behind the method. Recent investigations have demonstrated that the age of the magnetization and syn-folding results from the fold test must also be carefully examined: factors such as internal deformation, deficient isolation of components (i.e. overlapping) or incorrect restoration procedures may produce apparent syn-folding results. In fact, the restoration procedure used to return the palaeomagnetic signal to the palaeogeographic coordinate system may itself inhibit accurate estimations of vertical-axis rotations when complex deformation histories induce different, noncoaxial, deformation axes. We recommend the auxiliary use of the inclination v. dip diagram as an efficient tool for identifying many errors. Finally, to determine accurate vertical axis rotations, the reference direction should honour standard reliability criteria and would ideally be measured within the undeformed foreland of the thrust system. In this paper, we review five decades of palaeomagnetic research in fold and thrust belts by concentrating on maximizing standard reliability criteria procedures to reduce uncertainty and increase confidence when applying palaeomagnetic data to unravel the tectonic evolution of fold and thrust belts.
From: Pueyo, E. L., Cifelli, F., Sussman, A. J. & Oliva-Urcia, B. (eds) 2016. Palaeomagnetism in Fold and Thrust Belts: New Perspectives. Geological Society, London, Special Publications, 425, 259–276. First published online July 7, 2016, http://doi.org/10.1144/SP425.14 # 2016 The Author(s). Published by The Geological Society of London. All rights reserved.
вторник, 14 июня 2016 г.
понедельник, 13 июня 2016 г.
воскресенье, 12 июня 2016 г.
geophysics.uni-tuebingen.de
Small-Circle Methods in Paleomagnetism
Small-circle methods provide some new ways to analyse palaeomagnetic remanences. They especially provide a geometrically alternative estimate of the palaeomagnetic field direction (cross-checking tilt correction and fold tests) and they are the key to the tectonic interpretation of synfolding remanences.
These pages provide manuals and software tools (Excel worksheets, scripts for Microstation and CorelDraw)
1. History: Who found what first?
2. Manuscripts and Comments: Some downloads
3. Techniques and Software:
Small-circle methods provide some new ways to analyse palaeomagnetic remanences. They especially provide a geometrically alternative estimate of the palaeomagnetic field direction (cross-checking tilt correction and fold tests) and they are the key to the tectonic interpretation of synfolding remanences.
These pages provide manuals and software tools (Excel worksheets, scripts for Microstation and CorelDraw)
1. History: Who found what first?
2. Manuscripts and Comments: Some downloads
3. Techniques and Software:
- Microstation CAD: handling palaeomagnetic and structural data together and in 3 dimensions.
- Create vectors and small circles directly in CorelDraw, using Corel script language or VBA-language
- Worksheets for small-circle calculations (SCI-estimates, small circle reconstruction, calculation of small circle intersections, numbers and ratios, etc.) and other common calculations (Fisher statistics, bedding correction, etc.).
- Microstation: handling directional data in 3 dimensions
- Microstation: creating dynamic reconstructions
- Drawing, remanences, small circles and their intersections: scripts and VBA-code for CorelDraw
- Worksheets for small circle calculations (intersections, SCI-estimates), Fisher statistics and other
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