Precambrian database PALEOMAGIA
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The unique reference number of the entry in the database. Reference numbers have been generated as follows:
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  are significantly dissimilar to those of Klein et al.  and are actually considered an overprint by Post-Jotnian diabases.
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.
This shows the present-day country where the data were obtained according to the following codes.
|AL: Algeria||AN: Antarctica||AO: Angola||AR: Argentina||AU: Australia||BF: Burkina Faso||BI: Burundi||BL: Belarus||BR: Brazil||BW: Botswana|
|CA: Canada||CF: Central African Republic||CI: Ivory Coast||CN: China||CO: Cameroon||CZ: Czech Republic||DE: Germany||DK: Denmark (including Greenland)||EG: Equatorial Guinea||FI: Finland|
|FR: France||GA: Gabon||GE: Georgia||GF: French Guyana||GH: Ghana||IN: India||IR: Iran||IS: Israel||KE: Kenya||KZ: Kazakhstan|
|LR: Liberia||MA: Mali||MG: Madagascar||MN: Mongolia||MO: Morocco||MR: Mauritania||MX: Mexico||NA: Namibia||NO: Norway||OM: Oman|
|RU: Russia||SB: Saudi Arabia||SD: Sudan||SE: Sweden||SR: Suriname||SY: Seychelles||SZ: Swaziland||TZ: Tanzania||UA: Ukraine||UK: United Kingdom|
|UR: Uruguay||US: United States of America||VE: Venezuela||ZA: South Africa||ZM: Zambia||ZW: Zimbabwe|
This shows the paleomagnetic component, whenever a multicomponent analysis has been made or there is another reason to distinguish between components.
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.
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.
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.
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.
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.
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.
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.
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.
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.
This gives Fisherian 95 % confidence circle for the mean direction. Left out if B or N is two or less.
This gives the precision parameter [Fisher, 1953] for the mean direction. Left out if B, N or n is two or less.
This gives the angular standard deviation of the mean directions, as calculated by s = 81/√k.
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.
These give the absolute values of paleolatitude and paleocolatitude, assuming the Geocentric Axial Dipole (GAD) hypothesis to hold true.
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.
These show the semi-axes of the 95 % confidence ovals (inclination error dp and declination error dm) of the pole in degrees and decimals.
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).
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.
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].
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. Sinica||Acta Geologica Sinica|
|Acta P. Sinica||Acta 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. Denmark||Bulletin 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. NGRI||Bulletin of the National Geophysical Research Institute|
|C.R. Geoscience||Comptus Rendus Geoscience|
|C.R. Soc. Geol. Finlande||Comptus 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. Sborník||Geofyzikální Sborník|
|Geol. Assoc. Can. Sp. Paper||Geological Association of Canada Special Paper|
|Geol. Fören. Stockholm Förhandlingar||Geologiska Föreningens i Stockholm Förhandlingar|
|Geol. J.||Geological Journal|
|Geol. Mag.||Geological Magazine|
|Geol. Soc. Am. Bull.||Geological Society of America Bulletin|
|Geol. Soc. Am. Memoir||Geological Society of America Memoir|
|Geol. Soc. Am. Sp. Paper||Geological 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. Paper||Geological Survey of Canada Paper|
|Geol. Surv. Fin. Bull.||Geological Survey of Finland Bulletin|
|Geol. Surv. Fin. Sp. Paper||Geological 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. JRAS||Geophysical 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 Review||International Geology Review|
|Int. J. Earth Sci.||International Journal of Earth Science|
|Int. J. Geomag. Aeronomy||International Journal of Geomagnetism and Aeronomy|
|Izvestiya, Phys. Solid Earth||Izvestiya, 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. Paper||Ontario Geological Survey Miscellaneous Paper|
|Palaeogeog. Palaeoclim. Palaeoecol.||Palaeogeography, Palaeoclimatology, Palaeoecology|
|Phil. Mag.||Philosophical Magazine|
|Phil. Trans. Roy. Soc. Lon. Ser. A||Philosophical Transactions of the Royal Society, London, Series A|
|Phys. Chem. Earth (Part A)||Physics and Chemistry of the Earth, Part A|
|Phys. Chem. Upper Mantle||Physics 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|
|Terra Nova||Terra 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|
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.
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.
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.
|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).|