Documentation

This page serves as a documentation of the database. Attributes marked with an asterisk (*) are optional choices in the query form. Note that some properties (e.g. inclination) are stored directly in the database, whereas others, such as paleolatitude, have been calculated using the database entry and a server-side PHP script. Javascript is used in the shortcuts of the query form.

Res

The unique reference number of the entry in the database. Reference numbers have been generated as follows:

  1. If the entry originates from the latest version of Global Paleomagnetic Database (GPMDB) [Pisarevsky, 2005] (http://www.ngu.no/geodynamics/gpmdb/), it has a reference number accordingly. However, if the PALEOMAGIA team has split the GPMDB entry into two polarity groups, these have separate reference numbers, generated using the GPMDB number with an additional "1" or "2" in the end for normal and reversed polarities, respectively. For example, the GPMDB entry 1633 (Akaicho River Formation -C) is accompanied by entries 16331 (Akaicho River Formation -N) and 16332 (Akaicho River Formation -R). However, if the GPMDB number has just three digits, its respective N and R polarity entries have numbers constructed using the GPMDB number and "01" or "02" in the end. The Phalaborwa igneous complex (entries 834, 83401 and 83402) sets a good example of this.
  2. Numbers originating from David A.D. Evans's unpublished paleomagnetic data catalogue. These have six digits, with "100" in the beginning. However, in cases where N and R polarities have been later added, "1" or "2" has been added to the end of the result number. Entries of Småland intrusives (100369, 1003691 and 1003692) are a typical case.
  3. Entries with numbers generated by the PALEOMAGIA team. These have five digits, starting from 10000. Numbers ending with "0", "1" and "2" have been reserved for combined, normal and reversed polarities in dual polarity cases, and numbers ending with other digits refer to single-polarity entries, respectively.

T

This shows the type of rock (igneous, sedimentary or metamorphic) (i, s or m). The definition is in some cases uncertain, e.g. the Kurgan volcanosedimentary rocks of Kazakhstan [Levashova et al., 2011] include red sandstones, siltstones, pyroclastic flows and ash tuffs. There are also sedimentary rocks, which have later been baked by an intrusion and have a magnetization of that age, and should therefore be listed paleomagnetically as igneous rocks. For example, the results of Satakunta sandstone by Neuvonen [1973] are significantly dissimilar to those of Klein et al. [2012] and are actually considered an overprint by Post-Jotnian diabases.

Rock unit

This shows the rock from where the samples were gathered, e.g. Sipoo diabase dykes of southern Finland [Mertanen and Pesonen, 1995]. Abbreviations have been used sparingly. If the article has a digital object identifier (doi), its abstract, or depending on the user's subscription status, the entire article can be accessed via clicking the name of the rock unit.

C

This shows the present-day country where the data were obtained according to the following codes.

AL: AlgeriaAN: AntarcticaAO: AngolaAR: ArgentinaAU: AustraliaBF: Burkina FasoBI: BurundiBL: BelarusBR: BrazilBW: Botswana
CA: CanadaCF: Central African RepublicCI: Ivory CoastCN: ChinaCO: CameroonCZ: Czech RepublicDE: GermanyDK: Denmark (including Greenland)EG: Equatorial GuineaFI: Finland
FR: FranceGA: GabonGE: GeorgiaGF: French GuyanaGH: GhanaIN: IndiaIR: IranIS: IsraelKE: KenyaKZ: Kazakhstan
LR: LiberiaMA: MaliMG: MadagascarMN: MongoliaMO: MoroccoMR: MauritaniaMX: MexicoNA: NamibiaNO: NorwayOM: Oman
RU: RussiaSB: Saudi ArabiaSD: SudanSE: SwedenSR: SurinameSY: SeychellesSZ: SwazilandTZ: TanzaniaUA: UkraineUK: United Kingdom
UR: UruguayUS: United States of AmericaVE: VenezuelaZA: South AfricaZM: ZambiaZW: Zimbabwe

Comp

This shows the paleomagnetic component, whenever a multicomponent analysis has been made or there is another reason to distinguish between components.

Terrane

This gives the terrane inside the continent. Terrane is here used as an umbrella term which includes cratons, cratonic boundaries, geologic provinces, orogens and mountain belts alike. Since the configuration of terranes has been subject to change, rocks presently lying close to one another may have belonged to different terranes in the past, e.g. Slave and Superior cratons prior to 1.78 Ga. Prior to the unification of Laurentia, these cratons are referred to as just Slave and Superior, but for data of the same geographic area and a younger age, notations of Laurentia-Slave and Laurentia-Superior have been used. For a list of terranes, see this page.

Slat, Slon

These show the latitude (°N) and longitude (°E) of the sampling site in decimal degrees. In cases where these are absent in the original source of data, approximate values have been estimated from the map or calculated inversely from the paleomagnetic direction and pole.

LMA*, HMA*

These are the estimated plausible lower and upper limits of the age of the magnetization, i.e. age interval, as determined using the isotopic results or geological information in the way explained in Column P. Like all ages in the catalogue, LMA and HMA are denoted in million years (Ma). If the age is considered well defined, i.e. it has been obtained e.g. using U-Pb or other reliable method (e.g. 39Ar/40Ar), the difference between LMA and HMA is similar to the error limits of the results of the dating. For instance, the Nemegosenda alkaline complex [Costanzo-Alvarez et al., 1993] has an U-Pb age of 1105.4 ± 2.6 Ma and therefore its LMA is 1103 Ma and HMA 1108 Ma. In cases where two plausible isotopic ages exist, LMA and HMA are set accordingly. For example, in the case of normal-polarity Arizona diabases [Donadini et al., 2009], age constraints are 1085 ± 5.2 and 1088 ± 11 Ma, thus giving 1080 Ma for LMA and 1100 Ma for HMA. For some results the age is based on geologic and paleomagnetic information only (APWP dating), and in these cases, LMA and HMA may be somewhat arbitrary.

Isoage*, Met*

This shows the isotopic age, if measured. In some cases various ages have been given, but U-Pb ages have been preferred, if available. The real age of the magnetization may be remarkably different from the isotopic age, especially for slowly cooled large intrusions, plutonic rocks and in particular for metamorphic rocks, where the U-Pb isotopic age tells nothing about the age of the metamorphism and presumably of magnetization. The determination method of the isotopic age is shown in another column, with following coding: a = geological (APWP), b = fission track, c = 39Ar-40Ar, d = K-Ar, e = Rb-Sr (mineral isochron), f = Rb-Sr (whole rock), g = U-Pb, h = Sm-Nd, i = Pb-Th, j = Pb-Pb, k = Lu-Hf, l = Re-Os, s = stratigraphic, corr. = correlation, foss. = based on fossils, detr. zr. = based on detrital zircons). Whenever no other age information has been available, geological (APWP) or stratigraphic age estimates have been used.

Age references

This shows the reference from where the age data has been obtained. It may be e.g. a peer-reviewed article, Global Paleomagnetic Database, conference proceedings or personal communication with a renowned paleomagnesist. The age may be an estimate based on more than one reference. The complete list of PALEOMAGIA age references is available here as a dynamically generated table. In the database, age references are directly stored in a short form, e.g. Salminen et al. (2014a) or Bogdanova and Bibikova (2003). This form should be used when searching entries using the age reference as a filtering criterion.

Age

The ages of Precambrian rocks are in many cases uncertain. For upper level crustal igneous bodies, such as dykes, sills and lavas, isotopic age data have been preferred. For volumetrically small igneous units, such as dolerite dykes, lamprophyres, kimberlites, small mafic or alkaline plugs, lava flows, etc., the magnetic age has been adjusted to equal the paleomagnetic block-in age. However, in larger plutons, e.g. Korosten [Elming et al., 2001] and Bushveld [Letts et al., 2009], the slow cooling of the ca. 2-10 km body caused the block-in time to be delayed [Pechersky et al., 2004; Elming et al., 2009] and this results in ca. 10-30 Ma delay in the magnetization when compared to the isotopic blocking. There is no way to apply corrections for this problem due to the lack of knowledge of the dimensions of the pluton, depth of the occurrence and parameters of the physical state of the host rock. Here a 10 Ma reduction from the isotopic U-Pb age has been used for simplicity. If the rock has also been dated using the 39Ar-40Ar method, this allows another way to adjust the magnetization age, roughly by following biotite-pyroxenite cooling ages. Whenever the age has been adjusted, the value of the column is generally the same as the mean of LMA and HMA, with certain ages obtained from isochrones as an exception. For instance, the U-Pb age of 1235 +7/-3 Ma for Sudbury dykes gives the 1235 Ma for AGE, 1232 Ma for LMA and 1242 Ma for HMA [Palmer et al., 1977]. Non-isotopic ages have been obtained using the geological history of the source area, the APWP of the craton and in some cases correlation or stratigraphy.

B, N

These columns show the number of sites (B) and the total number of samples (N), if known. In most cases the number of sites has been used to calculate the statistical parameters. However, whenever sample means have been used, it is denoted with a dot (*) after the number of samples. Generally sample means are preferred only in cases where the number of sites is small or unknown, or in continuous measurement sequences, most prominently sedimentary strata.

Pol

This shows the paleomagnetic polarity (N = normal, R = reversed, C = combined mean). C has been calculated in cases where the rock unit shows both polarity groups with a same age and an asymmetry of less than 20°. The concept of M = mixed polarity has been used if separation into discrete N and R populations has turned out to be impossible, a problem common in sedimentary data but also occurring e.g. when the data for one polarity group is insufficient for calculating Fisher means. In these cases, the fit to the APWP path of the craton is often poor. Although absolute polarities are unknown for the Precambrian, distinct polarity patterns are visible.

D, I

These give the declination and inclination of the characteristic component (ChRM) of the natural remanent magnetization (NRM) in degrees and decimals. These have been obtained most often from tables, but in some cases even from digitized figures if otherwise unavailable. The Ilimaussaq intrusion [Piper et al., 1999] sets an example of this.

α95

This gives Fisherian 95 % confidence circle for the mean direction. Left out if B or N is two or less.

k

This gives the precision parameter [Fisher, 1953] for the mean direction. Left out if B, N or n is two or less.

s*

This gives the angular standard deviation of the mean directions, as calculated by s = 81/√k.

S*

This gives the angular standard deviation of the paleomagnetic poles, used most prominently in the paleosecular variation (PSV) analysis [e.g. Smirnov et al., 2011]. No within-site correction has been made for values in this column. This value of S has been calculated using the inclination and k value of the mean paleomagnetic pole instead of applying angular distances from individual VGPs directly.

|λ|*, Θ*

These give the absolute values of paleolatitude and paleocolatitude, assuming the Geocentric Axial Dipole (GAD) hypothesis to hold true.

Plat, Plon

These show the latitude (°N) and longitude (°E) of the mean paleomagnetic pole calculated assuming the GAD field. The polarity option, which most closely fits the APWP of the terrane, has been chosen here.

dp*, dm*

These show the semi-axes of the 95 % confidence ovals (inclination error dp and declination error dm) of the pole in degrees and decimals.

A95

This shows the 95 % confidence circle of the pole in degrees and decimals in cases where site mean poles have been used to obtain the mean pole. If directions have been used to calculate the mean pole, A95 has been estimated using the equation A95 = √(dp×dm).

1...6*

These columns show classes in the quality grading [Van der Voo, 1990], which has been modified to be more suitable for dealing with Precambrian data. Each class has a dichotomy: 1 means that the criterion is met, 0 means the opposite.

  1. Well-determined rock age and a presumption that magnetization is the same age
  2. Sufficient number of samples (N > 24, k ≥ 10 and α95 ≤ 16.0°)
  3. Adequate demagnetization that demonstrably includes vector subtraction
  4. Field tests that constrain the age of magnetization
  5. Structural coherence, and tectonic coherence with craton or block involved
  6. The presence of reversals
  7. No resemblance to paleopoles of younger age

The seventh class has been omitted in this database, because there is strong evidence that Precambrian poles of different ages occupy same geographic positions. For example, the 1.88 Ga Stark Formation of Canada [Bingham and Evans, 1976] has a pole very similar to those of 1.47...1.40 Ga old Belt-Purcell Supergroup poles of Wyoming, USA [Elston et al., 2002].

AV

This shows the modified Van der Voo quality grading as calculated using the sum of 1...6 columns. The minimum requirement for a reliable pole is AV ≥ 3.

Authors, Title*, Journal, Year, Vol, Pages

These columns show the complete reference of the entry, including author, title, journal or book, volume and pages. In cases with entries calculated from more than one article, the key reference is given. Most results in the database have been derived from the peer-reviewed journals and monographs. Other articles, conference proceedings, monographs, catalogues as well as some national and regional geological survey reports have not undergone peer-review.

The following abbreviations of journals are used throughout the database, including the age reference list.

Acta G. SinicaActa Geologica Sinica
Acta P. SinicaActa Petrologica Sinica
Adv. in Phys.Advances in Physics
Am. J. Sci.American Journal of Science
Ann. Geophys.Annales Geophysicae
Aust. J. Earth Sci.Australian Journal of Earth Sciences
Bull. Geol. Soc. DenmarkBulletin of the Geological Society of Denmark
Bull. Geol. Soc. Fin.Bulletin of the Geological Society of Finland
Bull. Geol. Surv. Fin.Bulletin of the Geological Survey of Finland
Bull. NGRIBulletin of the National Geophysical Research Institute
C.R. GeoscienceComptus Rendus Geoscience
C.R. Soc. Geol. FinlandeComptus Rendus de la Société Géologique de Finlande
Can. J. Earth Sci.Canadian Journal of Earth Sciences
Chin. J. Geophys.Chinese Journal of Geophysics
Chin. Sci. Bull.Chinese Science Bulletin
Current Sci.Current Science
Dokl. Earth Sci.Doklady Earth Sciences
Earth Evol. Sci.Earth Evolution Sciences
Earth Plan. Sci. Lett.Earth and Planetary Science Letters
Earth Sci. Rev.Earth Science Reviews
Econ. Geol.Economic Geology
Expl. Geophys.Exploration Geophysics
Geochem. Geophys. Geosyst.Geochemistry Geophysics Geosystems
Geodyn. Ser.Geodynamics Series
Geofyz. SborníkGeofyzikální Sborník
Geol. Assoc. Can. Sp. Paper Geological Association of Canada Special Paper
Geol. Fören. Stockholm FörhandlingarGeologiska Föreningens i Stockholm Förhandlingar
Geol. J.Geological Journal
Geol. Mag.Geological Magazine
Geol. Soc. Am. Bull.Geological Society of America Bulletin
Geol. Soc. Am. MemoirGeological Society of America Memoir
Geol. Soc. Am. Sp. PaperGeological Society of America Special Paper
Geol. Soc. Lon. Sp. Pub.Geological Society of London Special Publication
Geol. Surv. Can. Bull.Geological Survey of Canada Bulletin
Geol. Surv. Can. PaperGeological Survey of Canada Paper
Geol. Surv. Fin. Bull.Geological Survey of Finland Bulletin
Geol. Surv. Fin. Sp. PaperGeological Survey of Finland Paper
Geol. Surv. India Sp. Pub.Geological Survey of India Special Publication
Geol. Surv. Nor. Sp. Pub.Geological Survey of Norway Special Publication
Geophys. J.Geophysical Journal
Geophys. J. Int.Geophysical Journal International
Geophys. JRASGeophysical Journal of the Royal Astronomical Society
Geophys. Norveg.Geophysica Norvegica
Geophys. Res. Bull.Geophysical Research Bulletin
Geophys. Res. Lett.Geophysical Research Letters
Geophys. Surv.Geophysical Surveys
Gond. Res.Gondwana Research
Int. Geology ReviewInternational Geology Review
Int. J. Earth Sci.International Journal of Earth Science
Int. J. Geomag. AeronomyInternational Journal of Geomagnetism and Aeronomy
Izvestiya, Phys. Solid EarthIzvestiya, Physics of the Solid Earth
J. Afr. Earth Sci.Journal of African Earth Sciences
J. Asian Earth Sci.Journal of Asian Earth Sciences
J. Earth Syst. Sci.Journal of Earth System Science
J. Geochem. Expl.Journal of Geochemical Exploration
J. Geodyn.Journal of Geodynamics
J. Geol.Journal of Geology
J. Geol. Soc. Austr.Journal of the Geological Society of Australia
J. Geol. Soc. Ind.Journal of the Geological Society of India
J. Geol. Soc. Lon.Journal of the Geological Society of London
J. Geomag. Geoelectr.Journal of Geomagnetism and Geoelectricity
J. Geophys.Journal of Geophysics
J. Geophys. Res.Journal of Geophysical Research
J. Ind. Geoph. Un.Journal of the Indian Geophysical Union
J. S. Am. Earth Sci.Journal of South American Earth Sciences
J. Struct. Geol.Journal of Structural Geology
Meteoritics & Planet. Sci.Meteoritics & Planetary Science
Mon. Not. Roy. Astr. Soc. Geophys. Suppl.Monthly Notices of the Royal Astronomical Society, Geophysical Supplement
Mosc. Univ. Geol. Bull.Moscow University Geological Bulletin
Ontario Geol. Surv. Misc. PaperOntario Geological Survey Miscellaneous Paper
Palaeogeog. Palaeoclim. Palaeoecol.Palaeogeography, Palaeoclimatology, Palaeoecology
Phil. Mag.Philosophical Magazine
Phil. Trans. Roy. Soc. Lon. Ser. APhilosophical Transactions of the Royal Society, London, Series A
Phys. Chem. Earth (Part A)Physics and Chemistry of the Earth, Part A
Phys. Chem. Upper MantlePhysics and Chemistry of the Upper Mantle
Phys. Earth Plan. Int.Physics of the Earth and Planetary Interiors
Polar Geosci.Polar Geoscience
Prec. Res.Precambrian Research
Pure Appl. Geophys.Pure and Applied Geophysics
Rev. Econ. Geol.Reviews in Economic Geology
Russ. Geol. Geophy.Russian Geology and Geophysics
Russ. J. Earth Sci.Russian Journal of Earth Sciences
Russ. J. Pac. Geol.Russian Journal of Pacific Geology
S. Afr. J. Geol.South African Journal of Geology
Scott. J. Geol.Scottish Journal of Geology
Stud. Geophys. Geod.Studia Geophysica et Geodaetica
TectonicsTectonics
Tectonophys.Tectonophysics
Terra NovaTerra Nova
Texas J. Sci.Texas Journal of Science
Trans. Geol. Soc. S. Afr.Transactions of the Geological Society of South Africa
Trans. Inst. Min. Metal.Transactions, Section B: Applied Earth Science, Institution of Mining and Metallurgy
Trans. Roy. Soc. S. Aust.Transactions of the Royal Society of South Australia
Zeits. Geophys.Zeitschrift für Geophysik

Comments*

This column gives additional comments, which may be necessary for understanding the result, or give more clarity to it. For example, the age information may be more thoroughly explained here. Also, in this column a note is added is the authors of this database have made recalculations of some values in the entry in cases where the values have not been tabulated (e.g. α95 has been solved with the existing value of k using the appropriate equation. Generally, standard paleomagnetic equations [e.g. Tauxe, 1998] have been used.

Recalculations*

In this column, it is shown if any of the main quantities to obtain a paleomagnetic pole (Slat, Slon, D, I, Plat or Plon) differs from that published in the original source due to any recalculation. Typical reasons for a recalculation include new age or geochemical information, which has required the PALEOMAGIA team to omit some directional data, which was used in the original publication.

MagIC

This column gives links from PALEOMAGIA entries to the corresponding entries in the Magnetics Information Consortium (MagIC) database. The general syntax of MagIC links is based on Digital Object Identifiers (doi) of the respective publication, e.g. http://earthref.org/doi/10.1111/j.1365-246X.2008.03859.x points to the pole of Salmi basalts in Russian Karelia.


References for this page

Bingham, D., Evans, M., 1976. Paleomagnetism of the Great Slave Supergroup, Northwest Territories, Canada: the Stark Formation. Canadian Journal of Earth Sciences 13, 563-578 (link).
Costanzo-Alvarez, V., Dunlop, D., Pesonen, L., 1993. Paleomagnetism of alkaline complexes and remagnetization in the Kapuskasing Structural Zone, Ontario, Canada. Journal of Geophysical Research 98, 4063-4079 (link).
Donadini, F., Pesonen, L., Korhonen, K., Deutsch, A., Harlan, S., 2009. Paleomagnetism and Paleointensity of the 1.1 Ga Old Diabase Sheets from Central Arizona. Geophysica 47, 3-30 (link).
Elming, S.-Å., Mikhailova, N., Kravchenko, S., 2001. Palaeomagnetism of Proterozoic rocks from the Ukrainian Shield: new tectonic reconstructions of the Ukrainian and Fennoscandian shields. Tectonophysics 339, 19-38 (link).
Elming, S.-Å., Moakhar, M., Layer, P., Donadini, F., 2009. Uplift deduced from remanent magnetization of a proterozoic basic dyke and the baked country rock in the Hoting area, Central Sweden: a palaeomagnetic and 40Ar/39Ar study. Geophysical Journal International 179, 59-78 (link).
Elston, D., Enkin, R., Baker, J., Kisilevsky, D., 2002. Tightening the Belt: Paleomagnetic-stratigraphic constraints on deposition, correlation, and deformation of the Middle Proterozoic (ca. 1.4 Ga) Belt-Purcell Supergroup, United States and Canada. Geological Society of America Bulletin 114, 619-638 (link).
Fisher, R., 1953. Dispersion on a sphere. Proceedings of the Royal Society of London A217, 295-305 (link).
Klein, R., Pesonen, L., Mertanen, S., 2012. Paleomagnetic study of Satakunta sandstone. SW-Finland: Implications for Baltica during the Proterozoic, in: Supercontinent Symposium 2012. Programme and Abstracts, edited by S. Mertanen, L.J. Pesonen and P. Sangchan, pp. 68-69, Geological Survey of Finland, Espoo, Finland (link).
Letts, S., Torsvik, T., Webb, S., Ashwal, L., 2009. Palaeomagnetism of the 2054 Ma Bushveld Complex (South Africa): implications for emplacement and cooling. Geophysical Journal International 179, 850-872 (link).
Levashova, N., Meert, J., Gibsher, A., Grice, W., Bazhenov, M., 2011. The origin of microcontinents in the Central Asian Orogenic Belt: Constraints from paleomagnetism and geochronology. Precambrian Research 185, 37-54 (link).
Mertanen, S., Pesonen, L., 1995. Paleomagnetic and rock magnetic investigations of the Sipoo Subjotnian quartz porphyry and diabase dykes, southern Fennoscandia. Physics of the Earth and Planetary Interiors 88, 145-175 (link).
Neuvonen, K., 1973. Remanent magnetization of the Jotnian Sandstone in Satakunta, SW-Finland. Bulletin of the Geological Society of Finland 45, 23-27.
Palmer, H., Merz, B., Hayatsu, A., 1977. The Sudbury dikes of the Grenville Front region: paleomagnetism, petrochemistry, and K-Ar age studies. Canadian Journal of Earth Science 14, 1867-1887 (link).
Pechersky, D., Burakov, K., Zakharov, V., Sharkov, E., 2004. Variations in the Geomagnetic Field Direction during Cooling of the Monchegorsk Pluton. Izvestiya, Physics of the Solid Earth 38, 236-257.
Pesonen, L.J., Bylund, G., Torsvik, T., Elming, S.-Å., Mertanen, S., 1991. Catalogue of paleomagnetic directions and poles from Fennoscandia: Archean to Tertiary. Tectonophysics 195, 151-207 (link).
Piper, J.D.A., Thomas, D.N., Share, S., Zhang, Q.R., 1999. The palaeomagnetism of (Mesoproterozoic) Eriksfjord Group red beds, South Greenland: multiphase remagnetization during the Gardar and Grenville episodes. Geophys. J. Int. 136, 739-756 (link).
Pisarevsky, S., 2005. New edition of the Global Paleomagnetic Database. EOS Transactions, AGU 86(17), 170 (link).
Smirnov, A., Tarduno, J., Evans, D., 2011. Evolving core conditions ca. 2 billion years ago detected by paleosecular variation. Physics of the Earth and Planetary Interiors 187, 225-231 (link).
Tauxe, L., 1998. Paleomagnetic principles and practice. Springer, 299pp.
Van der Voo, R., 1990. The reliability of paleomagnetic data. Tectonophysics 184, 1-9 (link).