Ionospheric total electron content and critical frequencies over Europe at solar minimum

The paper presents results obtained by analyzing high-resolution ionospheric vertical total electron content (vTEC) data set evaluated from a chain of European ground-based Global Positioning System (GPS) stations and its equivalent slab thickness, as well as the F2-layer critical frequency foF2 and propagation factor M(3000)F2 from nearby ionosonde stations over the period 2006–2007. The study covers data within an area between 36°N and 68°N geographic latitude, and 7°W and 21°E geographic longitude during these last two years of minimum solar activity in the 23rd solar cycle. It reveals 15 extraordinary events, all of which exhibited some form of large short-lived vTEC and foF2 enhancements of the duration of small-magnitude solar-terrestrial events. The results clearly show a well-defined vTEC and foF2 storm-like disturbance patterns developed under these conditions. They prove that there are still some open questions related to the large electron density variations during weak disturbances that require additional study for both their relevance to different Global Navigation Satellite Systems (GNSS) applications and their role in the formation and evolution of the daytime ionosphere at middle latitudes.     

Large-scale structure of the solar corona magnetic field

The configuration of the solar corona magnetic field has been studied. Data on the position of the K-corona emission polarization plane during the solar eclipses of September 21, 1941; February 25, 1952; and August 1, 2008, were used as an indicator of the magnetic field line orientation. Based on an analysis of these data, a conclusion has been made that the studied configuration has a large-scale organization in the form of a cellular structure with an alternating field reversal. The estimated cell size was 61° ± 6° (or 36° ± 2°) in longitude with a latitudinal extension of 40°?C50° in the range of visible distances 1.3?C2.0 R _Sun . A comparison of the detected cellular structure of the coronal magnetic field with synoptic {ie908-1} maps indicated that the structure latitudinal boundaries vary insignificantly within 1.1?C2.0 R _Sun . The possible causes of the formation of the magnetic field large-scale cellular configuration in the corona and the conditions for the transformation of this configuration into a two-sector structure are discussed.     

Height stratification and polar reversal of the Sun’s magnetic fields in cycles 21–23

Using calculations of the magnetic field in the solar atmosphere in the potential approximation, it is shown that, (1) as distance R from the Sun’s center grows, the area of the positive magnetic field (S _+field) in 10-deg latitude zones tends to 100% (0%) in the neighborhood of the solar minimum. At the distance R = 2.5R _⊙(R _⊙ is the solar radius), these values of the positive field are observed during ≈(12–55) Carrington rotations (CRs) for solar minima between neighboring cycles; (2) polar magnetic field reversals can occur repeatedly. Note that a polar reversal at large heights ends by 6–16 Carrington rotations earlier than on the Sun’s surface. On the Sun’s surface, a field polar reversal begins earlier at lower latitudes than at high ones; (3) for each longitude at different Rs and separately for each solar hemisphere the radial component of the field was averaged on synoptic maps in the 0°–40° latitude range. It is established that the T _R rotation periods of the boundaries between the sectors (areas of longitudes with the same sign of the averaged field) can be shorter than, longer than, and equal to Carrington solar rotation period T _CR. It turned out that boundaries with T _R < T _CR are observed at all heights, while boundaries with T _R > T _CR are observed at relatively small heights.     

Seasonal,longitudinal, and latitudinal differences in air temperatures in Russia in years of sunspot maxima and minima

Based on an analysis of a large array of meteorological data, we have shown that surface air temperatures differ significantly in years of sunspot maxima and minima for different months and latitudes and longitudes of observation points. This difference is the greatest at high latitudes of 60–83°; it is equal to +2.07 ± 0.28°C in February in the longitudinal range of 170 ± 190° and −1.41 ± 0.29°C in November in the longitude range of 150 ± 170°.     

Palaeomagnetism of the dyke swarms of the Gardar Igneous Province,south Greenland

In the western part of the Gardar Igneous Province of southern Greenland, lamprophyre dykes intruded at ca. 1276-1254 m.y. RbSr biotite ages yield a palaeomagnetic pole at 206.5°E,3°N (nine sites, dψ = 5.1°, d_χ = 10.1°) Slightly younger dolerite dykes with RbSr biotite ages in the range 1278-1263 m.y. give a pole at 201.5°E,8.5°N (24 sites, dψ = 4.7°, d_χ = 9.4°), and the syeno-gabbro ring dyke of the Kûngnât complex (RbSr isochron age 1245 ± 17 m.y.) cutting both of these dykes swarms, gives a pole at 198.5°E, 3.5°N (four sites, dψ = 2.3°,d_χ = 4.4°). All these rock units have the same polarity and the poles are identical to those from Mackenzie and related igneous rocks of North America (1280-1220 m.y.) after closure of the Davis Strait; they confirm that this part of the Gardar Province is a lateral extension of the Mackenzie igneous episode within the Laurentian craton.In the Tugtutôq region of the eastern part of the Gardar Province 47 NNE-trending dykes of various petrologic types, and intruded between 1175 ± 9 and 1168 ± 37 m.y. (RbSr isochron ages) yield a palaeomagnetic pole at 223.9° E, 36.4°N (dψ = 4.1°, d_χ = 6.1°). Fifteen other dykes in this swarm were intruded during a transitional phase of the magnetic field which, however, does not appear to have achieved a complete reversal over a period of several millions of years. The majority of dykes studied are highly stable to AF and thermal demagnetisation and contain single high blocking temperature components with single Curie points in the range 380–560°C.Palaeomagnetic poles from the Gardar Province between ca. 1330 and 1160 m.y. in age define the earlier part of the Great Logan apparent polar-wander loop; they correlate closely with contemporaneous North American results and confirm the coherence of the Laurentian craton in Upper Proterozoic times.     

Spatial variations of precursory seismic quiescence observed in recent years in the eastern part of Turkey

A statistical analysis is made for the eastern part of Turkey in the beginning of 2009 by studying the phenomenon of seismic quiescence as a potential precursor of the main shocks. The results produced four areas having seismic quiescence in the beginning of 2009. These areas are observed to be centered at 39.96°N–40.69°E (around A?kale, Erzurum), 39.36°N–39.74°E (around Ovac?k, Tunceli), 39.02°N–40.52°E (including Elaz?? and Bingöl), and 38.45°N–42.94°E (Van Lake). Based on the recent results showing 5 ± 1.5 years quiescence before the occurrence of an earthquake in this region, the future earthquake would be expected between 2009.5 and 2010.5. The future earthquake occurrence may reach 2012 if we consider the standard deviation of average seismic quiescence as ±1.5 years. We have found that the M _W = 6.0 Elaz?? earthquake on 8 March 2010, followed a seismic quiescence starting about 5 years before the main shock. Thus, special interest should be given to the other regions where the seismic quiescence is observed.     

Anomalous night-time peaks in diurnal variations of NmF2 close to the geomagnetic equator: A statistical study

We present a study of anomalous night-time NmF2 peaks, ANNPs, observed by the La Paz, Natal, Djibouti, Kodaikanal, Madras, Manila, Talara, and Huancayo–Jicamarca ionosonde stations close to the geomagnetic equator. It is shown for the first time that the probabilities of occurrence of the first and second ANNPs depend on the geomagnetic longitude, and there is a longitude sector close to 110° geomagnetic longitude where the first and second ANNPs occur less frequently in comparison with the longitude regions located close to and below about 34° geomagnetic longitude and close to and above about 144° geomagnetic longitude. The found frequencies of occurrence of the ANNPs increase with increasing solar activity, except of the Djibouti and Kodaikanal ionosonde stations, where the probability of the first ANNP occurrence is found to decrease with increasing solar activity from low to moderate solar activity, and except of the Natal ionosonde station, where the frequencies of occurrence of the first and second ANNPs decrease with increasing solar activity from moderate to high solar activity. We found that the occurrence probabilities of ANNPs during geomagnetically disturbed conditions are greater than those during geomagnetically quiet conditions. The ANNP probabilities are largest in summer and are lowest in winter for the La-Paz, Talara, and Huancayo–Jicamarca sounders. These probabilities are lowest in summer for the Djibouti, Madras, and Manila ionosonde stations, and in spring for the Kodaikanal sounder. The maximums in the probabilities are found to be in autumn for the Djibouti, Madras, and Manila ionosonde stations, and in winter for the Kodaikanal sounder.     

Diurnal and Longitudinal Variations of the Structure of an Equatorial Anomaly During Equinoxes According to Intercosmos-19 Satellite Data

Longitudinal and local time variations in the structure of the equatorial anomaly under high solar activity in the equinox are considered according to the Intercosmos-19 topside sounding data. It is shown that the anomaly begins to form at 0800 LT, when the southern crest is formed. The development of the equatorial anomaly is associated with well-known variations in the equatorial ionosphere: a change in the direction of the electric field from the west to the east, which causes vertical plasma drift W (directed upward) and the fountain effect. At 1000 LT, both anomaly crests appear, but they become completely symmetrical only by 1400 LT. The average position of the crests increases from I = 20° at 1000 LT to I = 28° at 1400 LT. The position of the crests is quite strong, sometimes up to 15°, varies with longitude. The foF2 value above the equator and the equatorial anomaly intensity (EAI) at 1200–1400 LT vary with the longitude according to changes in the vertical plasma drift velocity W. At this time, four harmonics are observed in the longitudinal variations of W, foF2, and EAI. The equatorial anomaly intensity increases to the maximum 1.5–2 h after the evening burst in the vertical plasma drift velocity. Longitudinal variations of foF2 for 2000–2200 LT are also associated with corresponding variations in the vertical plasma drift velocity. The equatorial anomaly intensity decreases after the maximum at 2000 LT and the crests decrease in size and shift towards the equator, but the anomaly is well developed at midnight. On the contrary, after midnight, foF2 maxima in the region of the anomaly crests are farther from the equator, but this is obviously associated with the action of the neutral wind. At 0200 LT, in contrast to the morning hours, only the northern crest of the anomaly is clearly pronounced. Thus, in the case of high solar activity during the equinoxes, a well-defined equatorial anomaly is observed from 1000 to 2400 LT. It reaches the maximum at 2000 LT.     

Anomalous Variations of Ionosphere Associated with the Strong Earthquake at Pakistan-Iran Border at a Low Latitude Station Agra,India

In this paper, we analyze the TEC data for April 2013 observed at Agra station, India (geogr. lat. 27.2° N, long. 78° E) to examine the effect of earthquake of magnitude M = 7.8 which occurred on 16 April 2013 at Pakistan–Iran border region. We process the TEC data using the s statistical criterion to find out anomalous variation in TEC data. We also study the VLF propagation signal from NPM, Hawaii (21.42° N, 158° W), which is monitored at the same station (Agra station) in the light of this earthquake as well as solar flares. The nighttime fluctuation method is used to analyze the VLF data for the period of ±5 days from the day of earthquake (11–21 April 2013). The anomalous enhancements and depletions are found in TEC data on 1–9 days before the occurrence of event.     

Indication of a geomagnetic low-inclination excursion in supposed Middle Weichselian interstadial marine clay at Rubjerg,Denmark

Palaeomagnetic measurements have been made on specimens from Late Pleistocene sediments of a piston boring at Rubjerg in Vendsyssel, northern Jutland. The stratigraphy of the deposits is based on content of foraminifera. A total of 70 relatively oriented specimens were investigated palaeomagnetically. Normal steep inclinations close to that of the axial dipole field were found in the Upper Saxicava Sand and in the Younger Yoldia Clay (radiocarbon dated at 14,650 ± 190?12,650 ± 180 B.P.), and a secular variation with an amplitude of 10–12° in the inclincation and a “period” roughly estimated at about 350–400 years was found in the Younger Yoldia Clay.Seventeen relatively oriented specimens from undisturbed older marine deposits revealed a stable low inclination of 11° with α₉₅ = 3°. The age of this apparent geomagnetic excursion falls somewhere between 23,000 and 40,000 B.P. (Older Yoldia Clay). Among other known geomagnetic excursions and events within this interval are Laschamp in France, Mono Lake in California and Lake Mungo in Australia. Until more definite ages have been obtained, the excursion is provisionally named the “Rubjerg Excursion”.     

Forcing of the ionosphere from above and below during the Arctic winter of 2005/2006

The present paper focuses on planetary wave type responses of the thermosphere/ionosphere system to forcing from above and below during the Arctic winter of 2005/2006. The forcing from above is described by the sunspot numbers, the solar wind speed, the B_z-component of the IMF and the geomagnetic Kp-index, while the forcing from below, i.e. by upward propagating atmospheric waves, is represented by the SABER/TIMED temperatures. The observed global ionospheric zonally symmetric oscillations with periods of ～9, ～14 and ～24–27 days were approved to be of solar origin. The most persistent ～9-day oscillation is linked to a triad of solar coronal holes distributed roughly 120° apart in solar longitude. The ～18-day westward propagating wave with zonal wavenumber 1, observed in the ionospheric currents (detected by magnetometer data), and in the F-region plasma (foF2 and TEC) could be allocated to a simultaneous 18-day westward propagating planetary wave observed in the stratosphere/mesosphere/lower thermosphere region with large (～70 km) vertical wavelength.     

Trapped solar wind He,Ne, and Ar and energetic He in Surveyor 3

The Apollo 12 mission brought back sections of the Surveyor 3 vehicle suitable for mass spectrometric studies of implanted solar wind and solar cosmic rays. Using this method, we have determined an average solar wind ⁴He flux of 6.1 × 10⁶ ions/cm² sec for the 31 months of exposure. We have also measured ⁴He/³He= 2700 ± 50;⁴He/²⁰Ne= 410 ± 30;²⁰Ne/²²Ne= 13.5 ± 0.2;²⁰Ne/³⁶Ar= 24.5 ± 2.5; and ³⁶Ar/³⁸Ar= 5.41 ± 0.20. These measurements provide solar wind values averaged over considerably longer periods of time than the Apollo Solar Wind Composition experiments and suggest that the short term SWC measurements during a period of high solar activity may not be a reliable measure of average solar wind composition.     

Cosmogenic radioisotopes in the Dhajala chondrite: implications to variations of cosmic ray fluxes in the interplanetary space

Activities of a suite of radioisotopes ranging in half-life from 5.6 days (⁵²Mn) to 3.7 m.y. (⁵³Mn) have been measured in the Dhajala chondrite. The results show that all the radioactivities are close to the expected levels except⁵⁴Mn and ²²Na. Their activities are higher than those based on the interplanetary fluxes at 1 A.U. near the ecliptic, expected immediately before the fall of Dhajala, corresponding to the time of solar minimum. Furthermore, activity ratios of ⁵⁴Mn/⁵³Mn and ²²Na/²⁶Al are higher by 30–50% than expected. The departure from the expected values is discussed in terms of spatial variations of cosmic rays based on the computed orbital parameters of the meteoroid. If the galactic cosmic ray fluxes in the equatorial region (±15°) are assumed to be the same as in the ecliptic plane then these results suggest higher fluxes by 33 ± 7% at heliographic latitudes 15–40°S, during solar minimum.     

High-pressure phases of Co2GeO4, Ni2GeO4, Mn2GeO4 and MnGeO3: implications for the germanate-silicate modeling scheme and the Earth's mantle

In a diamond-anvil press coupled with YAG laser heating, the spinels of Co₂GeO₄ and Ni₂GeO₄ have been found to disproportionate into their isochemical oxide mixtures at about 250 kbar and 1400–1800°C in the same manner as their silicate analogues. At about the same P-T conditions MnGeO₃ transforms to the orthorhombic perovskite structure (space group Pbnm); the lattice parameters at room temperature and 1 bar are a₀ = 5.084 ± 0.002, b₀ = 5.214 ± 0.002, and c₀ = 7.323 ± 0.003Å with Z = 4 for the perovskite phase. The zero-pressure volume change associated with the ilmenite-perovskite phase transition in MnGeO₃ is ?6.6%. Mn₂GeO₄ disproportionates into a mixture of the perovskite phase of MnGeO₃ plus the rocksalt phase of MnO at P = 250kbar and T = 1400–1800°C. The concept of utilizing germanates as high-pressure models for silicates is valid in general. The results of this study support the previous conclusion that the lower mantle comprises predominantly the orthorhombic perovskite phase of ferromagnesian silicate.     

Palaeomagnetism and K-Ar ages of triassic igneous rocks from the Ischigualasto-Ischichuca Basin and Puesto Viejo Formation,Argentina

The palaeomagnetism of Middle Triassic (224 ± 5 m.y.) igneous rocks from the Ischigualasto-Ischichuca Basin (67°40′W, 30°20′S) was investigated through 86 oriented hand samples from 11 sites. At least one reversal of the geomagnetic field has been found in these rocks. Nine sites yield a palaeomagnetic pole at 239°E, 79°S (α₉₅ = 15°, k = 13).The K-Ar age determinations of five igneous units of the Puesto Viejo Formation give a mean age of 232 ± 4 m.y. (Early Triassic). The palaeomagnetism of six igneous units of the Puesto Viejo Formation (68°W, 35°S) was investigated through 60 oriented samples. These units, two reversed relative to the present magnetic field of the Earth and four normal, yield a pole at 236°E, 76°S (α₉₅ = 18°, k = 14).Data from the Puesto Viejo Formation indicate, for the first time on the basis of palaeomagnetic and radiometric data, that the Illawarra Zone, which defines the end of the Kiaman Magnetic Interval, extends at least down to 232 ± 4 m.y. within the Early Triassic. The palaeomagnetic poles for the igneous rocks of the Ischigualasto-Ischichuca Basin and Puesto Viejo Formation form an “age group” with the South American Triassic palaeomagnetic poles (mean pole position: 239°E, 77°S; α₉₅ = 6.6°, k = 190). The Middle and Upper Permian, Triassic and Middle Jurassic palaeomagnetic poles for South America would define a “time group” reflecting a quasi-static interval (mean pole position: 232°E, 81°S; α₉₅ = 4°, k = 131).     

First results of simultaneous recording of VLF emissions at two closely located points at auroral latitudes

For the first time, simultaneous observations of very low frequency (VLF) emissions at auroral latitudes (L = 5.3) are carried out at two points located at close geomagnetic latitudes and spaced in longitude by 400 km: the Finnish Kannuslehto station (Φ = 64.2°) and the Russian Lovozero observatory (Φ = 64.1°). A recording equipment with similar frequency responses was used. The first results of a comparison of simultaneous observations showed that, in the overwhelming majority of cases, bursts of VLF emission appeared at both points synchronously with an identical (more often right-handed) polarization of the magnetic field of VLF waves, which can be evidence in favor of large dimensions of the ionosphere exit region of VLF waves. A simultaneous burst of quasi-periodic VLF emissions that occurred on February 02, 2013, during a substorm at 23–24 UT is discussed in detail. Additionally, VLF bursts were recorded which were observed only at one point, e.g., the appearance of left-hand polarized periodic emissions (PEs) in band 2.5–4.0 kHz with a repetition period of 3–4 s.     

Palaeomagnetism of the Early Carboniferous Deer Lake Group,western Newfoundland: no evidence for mid-Carboniferous displacement of “Acadia”

Early Carboniferous (Viséan to possibly earliest Namurian) sedimentary rocks of the Deer Lake Group of western Newfoundland rest unconformably on Grenvillian basement rocks of the Canadian Shield which form the western border of the Early Palaeozoic Appalachian orogen. In addition to magnetically soft magnetizations directed along the present field, three families of magnetization directions are found. Two of them (referred to as N (north) and S (south)) are antiparallel and prefolding, and were probably acquired during the depositional process. N and S are roughly of equal frequency. They have a mean direction irrespective of sign of 0.7°, ?35.2°, k = 40, α₉₅ = 8.9°, and a palaeopole 21.5°N, 121.8°E (10.3°, 6.0°) corresponding to a palaeolatitude of 20 ± 6°S. This agrees with the palaeolatitude (17 ± 5°S) determined from the somewhat older Early Carboniferous (Tournaisian) Terenceville Formation of the Avalon Platform on the eastern side of the Appalachian orogen in Newfoundland. The third magnetization, referred to as H (roughly horizontal), has a mean direction 156.8°, ?13.3°, k = 37, α₉₅ = 10.1°, and a palaeopole 45.4°N, 140.3°E (10.3°, 5.3°) corresponding to a palaeolatitude of 7 ± 4°N; we interpret this to be an early Kiaman (latest Carboniferous to early Permian) overprint probably acquired chemically. The palaeolatitude determined from the H overprint agrees with that determined from Early Carboniferous rocks of cratonic North America west of the Appalachians. Therefore, we argue, Early Carboniferous palaeofield determinations for cratonic North America have been strongly biased by unremoved Kiaman overprints. Because of this, and because of the good agreement between Early Carboniferous palaeolatitudes obtained from opposite margins of the Appalachian orogen, we suggest that there is, at present, no palaeomagnetic evidence for the previously proposed 1500 km displacement from the south of an eastern portion of the Appalachians (“Acadia”) relative to cratonic North America during the Carboniferous.     

Paleomagnetism of certain constituents of the Bay St. George sub-basin,western Newfoundland

Paleomagnetic studies have been made of certain constituents of the Bay St. George sub-basin. Specifically, results are reported from the Spout Falls Formation (Tournaisian), the Jeffreys Village Member of the Robinsons River Formation (Visean), and the Searston Formation (Namurian-Westphalian). The following magnetizations have been isolated: Spout Falls A (Tournaisian) with D = 343.5°, I = ?22.7°, k = 61.2, α₉₅ = 7.1° and the corresponding pole at 28.6°N, 139.5°E (4.5°, 8.5°); Spout Falls B (Kiaman) with D = 166.7°, I = 12.2°, k = 51.7, α₉₅ = 10.7° and the corresponding pole at 34.5°S, 42.7°W (5.5°, 10.9°); Jeffreys Village A (Visean) with D = 351.2°, I = ?27.3°, k = 54.0, α₉₅ = 7.6° and the corresponding pole at 26.5°N, 130.7°E (4.5°, 8.3°); Searston A (Namurian) with D = 161.7°, I = 11.7°, k = 107, α₉₅ = 7.4° and the corresponding pole at 33.9°S, 37.2°W (3.8°, 7.5°); and Searston C with D = 111.6°, I = ?13.8°, k = 28.8, α₉₅ = 14.5° and the corresponding pole at 19.6°S, 19.0°E (7.6°, 14.8°). After comparison with paleopoles of similar ages derived from eastern and western Newfoundland rocks, from constituents of the east coast basin and for interior North America, it is concluded that: (1) it is unlikely that any large scale relative motion took place since the Early Carboniferous between eastern and western Newfoundland; (2) it is unlikely that any north-south relative motion took place between the east coast basin and the Bay St. George sub-basin; and (3) the Bay St. George sub-basin results do not support the earlier proposed displaced terrane hypothesis of the northern Appalachians in as much as the motions during the Carboniferous are not supported. There is evidence of the northward motion of the Appalachians and North America as a whole during the Carboniferous. The magnetostratigraphic horizon marker in the Carboniferous separating a dominant normal and reversed magnetization on the older side and an entirely reversed (Kiaman) magnetization on the younger side may be placed in the Bay St. George sub-basin at the base of the Searston Formation.     

Disproportionation of Ni2SiO4 to stishovite plus bunsenite at high pressures and temperatures

Samples of Ni₂SiO₄ in both olivine and spinel phases have been compressed to pressures above 140 kbar in a diamond-anvil cell and heated to temperatures of 1400–1800°C using a continuous YAG laser. After quenching and releasing pressure, X-ray diffraction examination indicates that the samples disproportionate to a mixture of stishovite (SiO₂) and bunsenite (NiO) at pressures between 140 and 190 kbar. The exact disproportionation pressure is not certain due to transient increases in pressure during the local and rapid heating. However, thermodynamic calculations suggest that the transition pressure is about 192 ± 4 kbar at 1545°C and that the equation of the spinel-mixed oxides phase boundary isP(kbar) = 121 + (0.046 ± 0.020) T (°C).     

Palaeomagnetism of porphyritic stocks and rhyolite sills,Avalon Zone of eastern Newfoundland

The eastern segment of the Appalachian orogen is largely underlain by late Precambrian (Hadrynian) rocks affected by the Avalonian, Acadian and possibly Alleghenian orogenies. The provenance of the Avalon Zone of Newfoundland is uncertain. The region investigated in this segment consists of porphyrite stocks and sills (laccoliths) intrusive into the sedimentary, tuffaceous and volcanic rocks of the Harbour Main Group and rhyolite sills intrusive into the porphyrites. Some 55 oriented samples (148 specimens) collected at 11 sites were thermally (20–650°C) and AF (0.05–100 mT) demagnetized. Three components of magnetization were isolated: C (311°, +48°, α₉₅ = 11°, k = 21, 10 sites), A (13°, +37°, α₉₅ = 14°, k = 22, 6 sites), and B (67°, +45°, α₉₅ = 15°, k = 27,5 sites). Based on coercivity spectra, unblocking temperatures, frequency distribution and precision parameters of the respective components, it is suggested that component C is older than component A which is turn is older than component B. The palaeopoles of components C, A and B are: 211°E, 48°N (d_p = 9.8°, d_m = 14.7°); 101°E, 61°N (d_p = 9.6°, d_m = 16.4°); 33°E, 34°N (d_p = 12°, d_m = 19°), respectively. Component C is most probably primary. Component A is secondary and its pole is near that of Carboniferous and Early Permian North America poles, indicating that the porphyrites and the rhyolites were remagnetized in the late Palaeozoic. Component B remains unexplained; it is possible that it is an unresolved pseudo-component but it is more likely an overprint. There are few palaeomagnetic results for the late Precambrian period in Avalon terrane(s). The preliminary results of this study suggest the presence of a separate plate from North American at that time. These results will prove useful for the palaeoreconstruction of the continents (North Africa, northeast Europe) in the late Precambrian period.