The Occurrence and Origin of Remagnetization in the Sedimentary Rocks of North America

Elmore, R. Douglas; McCabe, Chad

doi:10.1002/rog.1991.29.s1.377

Cited by 36 publications

(14 citation statements)

References 86 publications

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“…2) is also interpreted to be magnetite and/or maghemite. The secondary B component is a Kiaman age overprint that has been observed throughout the Maritime Provinces (Roy & Park 1969; Kent 1982; Irving & Strong 1984; DiVenere & Opdyke 1990, 1991) and in other parts of North America and the world (Creer 1968; Irving & Pullaiah 1976; Kent & Opdyke 1979; Roy & Morris 1983, McCabe & Elmore 1989; Elmore & McCabe 1991).…”

Section: Discussionmentioning

confidence: 99%

Palaeomagnetism and magnetic anisotropy of Carboniferous red beds from the Maritime Provinces of Canada: evidence for shallow palaeomagnetic inclinations and implications for North American apparent polar wander

Bilardello

Kodama

2010

Geophysical Journal International

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S U M M A R YA palaeomagnetic and magnetic anisotropy study was conducted on the lower-middle Carboniferous Maringouin and Shepody red bed formations of the Maritime Provinces of Canada to detect and correct inclination shallowing. Because of the shallow inclinations commonly observed in red beds and the strong dependence of North America's Palaeo-Mesozoic apparent polar wander (APW) on red beds, inclination shallowing may substantially affect large portions of North America's APW path.Hematite is the primary magnetic mineral carrier in these red beds, accompanied by secondary magnetite, maghemite, goethite and pigmentary hematite.Thermal and chemical demagnetization of the Shepody Fm. successfully isolated characteristic remanence directions of D = 177 • , I = 20.4 • , α 95 = 6.5 • , N = 19 and D = 177.8 • I = 17.7 • , α 95 = 6.9 • , N = 16, respectively. Thermal demagnetization of the Maringouin Fm. isolated a characteristic remanence direction of D = 178.7 • , I = 24.9 • , α 95 = 14.5 • , N = 9.High field anisotropy of isothermal remanence followed by alternating field and thermal cleaning on leached samples was used to isolate the fabric of hematite. Individual particle anisotropy was measured directly from magnetic separates using a new technique. Hematite's magnetic fabric and particle anisotropy were used to apply an inclination correction.Our inclination corrections indicate up to 10 • of inclination shallowing, corresponding to corrected palaeopole positions of 27.2 • N, 118.3 • E, A 95 = 6.2 • and 27.4 • N, 117.2 • E, A 95 = 13.1 • for the Shepody and Maringouin formations, respectively. This correction corresponds to a ∼ 6 • increase in colatitude for Carboniferous North America, which translates into approximately a 650 km change in North America's palaeogeographic position. The proposed position of North America supports a Pangea B-type reconstruction.

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Section: Discussionmentioning

confidence: 99%

Palaeomagnetism and magnetic anisotropy of Carboniferous red beds from the Maritime Provinces of Canada: evidence for shallow palaeomagnetic inclinations and implications for North American apparent polar wander

Bilardello

Kodama

2010

Geophysical Journal International

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“…Secondary magnetizations are common in sedimentary rocks and several mechanisms have been invoked to explain these as a CRM (Elmore & McCabe 1991; Elmore et al . 1993; Katz et al .…”

Section: Introductionmentioning

confidence: 99%

Detailed analysis of successive pTRMs carried by pyrrhotite in Himalayan metacarbonates: an example from Hidden Valley, Central Nepal

Crouzet¹,

Stang²,

Appel³

et al. 2001

Geophysical Journal International

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Summary Low‐grade metacarbonates from the Tethyan Himalaya were sampled for palaeomagnetic studies in Hidden Valley (Central Nepal). The remanence is carried by pyrrhotite, evidenced by thermomagnetic runs of susceptibility (Hopkinson peak at ∼300 °C), alternating field demagnetization, isothermal remanent magnetization acquisition and subsequent thermal demagnetization. The palaeomagnetic directions reflect a Tertiary overprint after the main folding event, probably synchronous with the metamorphism. Normal and reverse remanence directions were separated and vary with altitude. It is also possible to retrieve several antiparallel components versus temperature during thermal demagnetization of a single sample. At higher altitudes (4920–5500 m), the first component recorded is reverse (R1). At a lower temperature a normal component can be extracted (N1). For sites sampled at lower altitudes (4700–4900 m), the high‐temperature reverse component disappears but a medium‐temperature reverse component (R2) demagnetized in a narrow temperature range can be identified in between two normal components (N1 at high temperature and N2 at low temperature). At the lowest altitudes (4450–4700 m), only a normal component (N2) appears. The occurrence of successive normal and reverse polarities in one sample is interpreted as the record of successive reversals of the geomagnetic field during the post‐metamorphic Tertiary cooling of the studied area. The polarity versus altitude function is a powerful argument for a thermomagnetic origin of the magnetization. No obvious rotations around a vertical axis with respect to the stable Indian plate are evidenced for the Tertiary. However, the inclination is not consistent with the expected inclination. Main Central Thrust ramping can be invoked to explain our observations. R1, N1 and N2 inclinations are slightly different and their tendency is consistent with tilting towards the north during magnetization acquisition. The minimum total amount of such tilting is around 25°. Accurate geochronological data from the Tethyan Himalaya would be of a great help for better resolution.

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“…There are several possible mechanisms proposed for remagnetization. Chemical remanent magnetization (CRM) acquired by the formation of authigenic magnetic minerals in association with the lateral migration of orogenic or basinal fluids, introduction of meteoric fluids, as well as migration of hydrocarbons has been proposed as the mechanism of remagnetization (McCabe et al, 1983;Oliver, 1986;Elmore and McCabe, 1991). Prolonged exposure to elevated temperature below the Curie temperature affecting the ability of rocks to retain a primary NRM has been suggested responsible for the acquisition of thermoviscous magnetization (TVRM, e.g., Kent, 1985).…”

Section: Remagnetization Of the Chopyeong Formationmentioning

confidence: 99%

Paleomagnetic and rock magnetic studies of Cretaceous rocks in the Eumsung basin, Korea

Doh

Suk

Kim³

2014

Earth Planet Sp

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Paleomagnetic results are obtained from 41 sites from the Chopyeong Formation within the Eumsung basin, located along the northern boundary of the Ogcheon Belt, Korea. The Chopyeong Formation, deposited in early Cretaceous, yields the mean direction of D/I = 347.8• /57.3• ) before tilt correction, and D/I = 0.7• /61.7• ) after tilt correction. The parameter estimating fold test and the stepwise unfolding test of the red bed and greenish mudstone of the Chopyeong Formation yield the maximum value of k at 21.9% and at 20% untilting, respectively, indicating that the remanence whose mean direction of D/I = 350.8• /57.9• (k = 177.9, α 95 = 1.8• ) at 20% untilting was acquired during or after tilting of the strata. The comparison of the paleomagnetic pole from the Chopyeong Formation with those from the Youngdong basin and the Euiseong area in the Gyeongsang basin indicates that the remanence was acquired during late Cretaceous to early Tertiary. Electron microscope observations and rock magnetic experiments show that secondary hematite and magnetite grains of single domain to pseudo-single domain size were authigenically formed under the influence of fluids presumably triggered by the igneous activities, thus confirm the chemical remagnetization.It is revealed that the age of the granite in the east is Jurassic because the mean direction of the east granite (D/I = 347.0• /47.7• ) is similar to the Jurassic direction of Korea Peninsula. The age of the granite in the west, however, is left undetermined whether it is Cretaceous or Jurassic because of the weak intensity and instability of the remanence of the granite during demagnetization treatments.

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The Occurrence and Origin of Remagnetization in the Sedimentary Rocks of North America

Cited by 36 publications

References 86 publications

Palaeomagnetism and magnetic anisotropy of Carboniferous red beds from the Maritime Provinces of Canada: evidence for shallow palaeomagnetic inclinations and implications for North American apparent polar wander

Palaeomagnetism and magnetic anisotropy of Carboniferous red beds from the Maritime Provinces of Canada: evidence for shallow palaeomagnetic inclinations and implications for North American apparent polar wander

Detailed analysis of successive pTRMs carried by pyrrhotite in Himalayan metacarbonates: an example from Hidden Valley, Central Nepal

Paleomagnetic and rock magnetic studies of Cretaceous rocks in the Eumsung basin, Korea

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