A ∼90° Late Silurian–Early Devonian apparent polar wander loop: The latest inertial interchange of planet earth?

Piper, J. D. A.

doi:10.1016/j.epsl.2006.08.001

Cited by 19 publications

(11 citation statements)

References 55 publications

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“…Precambrian v RMS was evidently much lower than these limiting values and never appears to have attained episodic speeds in excess of 18 cm/year proposed during the Palaeozoic by for example, Meert et al (1993), Van der Voo (1994) and Kirschvink et al (1997). Whilst resolution of the Precambrian data may be inadequate to detect such rapid movements, with possible exceptions of a Coronation Loop at w1870 Ma (Mitchell et al, 2010) and results from the Neoproterozoic Akademikerbreen Group of Svalbard (Maloof et al, 2006) which may also identify signals of TPW, there are as yet no indications in the present data for very rapid movements comparable to the w90 oscillatory motions recognised in the Ediacaran (Abrajevitch and Van der Voo, 2010) and SiluroeDevonian (Piper, 2006). Such rapid oscillatory APW movements have been attributed to Inertial Interchange True Polar Wander (IITPW) which could in principle, occur if interchange of the Earth's inertial axes occurs when the maximum principal inertia axis (I max ) falls below the intermediate axis (I int ) to cause the silicate outer shell to move over the liquid outer core and align the new I max with the spin axis (Goldreich and Toomre, 1969).…”

Section: Root Mean Square Velocity Analysiscontrasting

confidence: 54%

Continental velocity through Precambrian times: The link to magmatism, crustal accretion and episodes of global cooling

Piper

2013

Geoscience Frontiers

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a b s t r a c tQuasi-integrity of continental crust between Mid-Archaean and Ediacaran times is demonstrated by conformity of palaeomagnetic poles to near-static positions between w2.7e2.2 Ga, w1.5e1.2 Ga and w0.75e0.6 Ga. Intervening data accord to coherent APW loops turning at "hairpins" focused near a continental-centric location. Although peripheral adjustments occurred during Early Proterozoic (w2.2 Ga) and Grenville (w1.1 Ga) times, the crust retained a low order symmetrical crescent-shaped form constrained to a single global hemisphere until break-up in Ediacaran times. Conformity of palaeomagnetic data to specific Eulerian parameters enables definition of a master Precambrian APW path used to estimate the root mean square velocity (v RMS ) of continental crust between 2.8 and 0.6 Ga. A long interval of little polar movement between w2.7 and 2.2 Ga correlates with global magmatic shutdown between w2.45 and 2.2 Ga, whilst this interval and later slowdown at w0.75e0.6 Ga to velocities of <2 cm/year correlate with episodes of widespread glaciation implying that these prolonged climatic anomalies had an internal origin; the reduced input of volcanically-derived atmospheric greenhouse gases is inferred to have permitted freeze-over conditions with active ice sheets extending into equatorial latitudes as established by low magnetic inclinations in glaciogenic deposits. v RMS variations through Precambrian times correspond to the distribution of U-Pb ages in orogenic granitoids and detrital zircons and demonstrate that mobility of continental crust has been closely related to crustal tectonism and incrementation. Both periods of near-stillstand were followed by rapid v RMS recording massive heat release from beneath the continental lid at w2.2 and 0.6 Ga. The first coincided with the Lomagundi-Jatuli isotopic event and led to prolonged orogenesis accompanied by continental flooding and reconfiguration of the crust on the Earth's surface; the second led to continental break-up and instigated the comprehensive Plate Tectonics that has characterised Phanerozoic times. The Mesoproterozoic interval characterised by anorogenic magmatism correlates with low v RMS between w1.5 and 1.1 Ga. Insulation of the sub-continental mantle evidently permitted high temperature melting and weakening of the crustal lid to enable buoyant emplacement of large plutons at high crustal levels during this magmatic event unique to Mesoproterozoic and early Neoproterozoic times.Ó 2012, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.

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Section: Root Mean Square Velocity Analysiscontrasting

confidence: 54%

Continental velocity through Precambrian times: The link to magmatism, crustal accretion and episodes of global cooling

Piper

2013

Geoscience Frontiers

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“…This remanence is similar to magnetisations reported from late tectonic Early Devonian granites (ca. 400-390 Ma) in the Southern Uplands and the Lake District (Piper 2006). Radiometric dating and structural relationships show that these granites were intruded during the Acadian orogenic event (Thirlwall 1988;Soper and Woodcock 2003;Millward 2006;Woodcock and Soper 2006;Brown et al 2008) and, since the Dhoon granodiorite is apparently pre-Acadian in age, we interpret the single Dhoon remanence as an overprint superimposed during Acadian deformation and metamorphism.…”

Section: Dhoon Granodioritementioning

confidence: 94%

“…Reconstruction of palaeofield directions for the British Isles through the Silurian and Devonian (Piper 2006) has highlighted a rapid southerly excursion in the local apparent polar wander path during the Late Silurian and Early Devonian (Figure 9). The steep rate of change in declination and inclination immediately prior to and during the Acadian orogenic event provides a framework to test the temporal significance of palaeomagnetic directions recovered from the Isle of Man.…”

Section: Post-iapetus Palaeomagnetic Evolutionmentioning

confidence: 99%

“…A potentially closer correlation is provided by the Pragian to Emsian Abdon Group and Woodbank Group of the Welsh Borders (Figure 10). Both the Peel Sandstone Group and the Abdon and Woodbank groups are characterised by southerly-directed palaeocurrent vectors, 'heavy' mineral suites rich in garnet, and the occurrence of gravelly facies containing volcanic and fossiliferous (Wenlock/Ludlow) limestone clasts (Allen and Crowley 1983 (Piper 2006). Silurian and Devonian time-scales are taken from Gradstein et al (2004) and Kaufmann (2006) respectively.…”

Section: Correlation and Linkage With The Anglo-welsh Basinmentioning

confidence: 99%

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Age of the peel sandstone group, isle of man

et al. 2008

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An Early Devonian age for the continental, red‐bed succession of the Peel Sandstone Group can be defined on the basis of: (1) a derived marine fauna of late Wenlock (Homerian) age, (2) a Scoyenia ichnofacies assemblage (including Beaconites and Diplichnites) characteristic of latest Silurian to Early Devonian (Lower Old Red Sandstone magnafacies) sediments in the British Isles, (3) a microflora of late Lochkovian to Pragian age, (4) a detrital palaeomagnetic remanence that pre‐dates local, Acadian palaeomagnetic directions and coincides with a prominent, southerly, Late Silurian to Early Devonian excursion in the local apparent polar wander path, and (5) a mid‐Devonian palaeomagnetic remanence that overprints (?)Acadian, thrust‐related folding. Data presented in this study confirm previous suggestions (Allen and Crowley 1983) that the Peel Sandstone Group represents a rare example of Early Devonian sedimentation preserved on the northern margin of the former Eastern Avalonia microcontinent. Potential correlations and linkages with other Lower Old Red Sandstone successions exposed in the Anglo‐Welsh Basin are developed and discussed. Copyright © 2008 John Wiley & Sons, Ltd.

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“…If C, B, and A represent these principal moments in descending order at some epoch and if C À B changes sign at some point in time, then it will become energetically favorable for Earth to reorient through 90°. Such inertial interchange events, here denoted as IITPW, have been hypothesized as major events in Earth history [Kirschvink et al, 1997;Evans, 1998;Piper, 2006;Maloof et al, 2006].…”

Section: Introductionmentioning

confidence: 99%

Theoretical constraints on true polar wander

Tsai¹,

Stevenson²

2007

J. Geophys. Res.

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[1] For the present geologic epoch, true polar wander (TPW) is relatively small, but simple theoretical considerations suggest that it could have been larger in other epochs. In this work, we use scaling arguments to assess the qualitative behavior of TPW and a simple Maxwell model to analytically describe how changes in mass anomalies translate into TPW. Unlike previous work, we derive simple analytical estimates of TPW based on the characteristic amplitudes and timescales for changes in the moment of inertia. We find estimates for both the amplitude and speed of TPW as a function of Earth properties. The following four main factors influence how large the maximum TPW can be: the (geological) timescale over which the desired TPW occurs t TPW , the viscosity structure of the mantle which yields a weighted average viscosity h, the characteristic amplitude of the nonhydrostatic changes in the moment of inertia dC, and the added moment of inertia due to the equatorial bulge (C À A). For the nominal values h = 3 Â 10 22 Pa s and dC/(C À A) = 0.003, the maximum TPW is 61°over 100 Myr and 8°over 10 Myr. The maximum TPW speed is only sensitive to h, dC, and (C À A), and is 2.4°Myr -1 for the nominal values. TPW is shown to act as a low-pass filter; rapid changes in moment of inertia produce smaller and delayed TPW. A consequence of this is that inertial interchange TPW does not have a different character than TPW. TPW can have an important contribution to plate motions over relatively long timescales but not over shorter timescales. Our simple approach allows us to assess whether multiple TPW events are possible but the major uncertainty continues to be the mantle viscosity structure.

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A ∼90° Late Silurian–Early Devonian apparent polar wander loop: The latest inertial interchange of planet earth?

Cited by 19 publications

References 55 publications

Continental velocity through Precambrian times: The link to magmatism, crustal accretion and episodes of global cooling

Continental velocity through Precambrian times: The link to magmatism, crustal accretion and episodes of global cooling

Age of the peel sandstone group, isle of man

Theoretical constraints on true polar wander

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