| 1. |
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Ancient Supercontinents and the Paleogeography of Earth
- 2021
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- Ancient Supercontinents and the Paleogeography of Earth offers a systematic examination of Precambrian cratons and supercontinents. Through detailed maps of drift histories and paleogeography of each continent, this book examines topics related to Earth’s tectonic evolution prior to Pangea, including plate kinematics, orogenic development, and paleoenvironments. Additionally, this book discusses the methodologies used, principally paleomagnetism and tectonostratigraphy, and addresses geophysical topics of mantle dynamics and geodynamo evolution over billions of years. Structured clearly with consistent coverage for Precambrian cratons, this book combines state-of-the-art paleomagnetic and geochronologic data to reconstruct the paleogeography of the Earth in the context of major climatic events such as global glaciations. It is an ideal, up-to>date reference for geoscientists and geographers looking for answers to questions surrounding the tectonic evolution of Earth.
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| 2. |
- Elming, Sten-Åke, et al.
(författare)
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Paleo-Mesoproterozoic Nuna supercycle
- 2021
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Ingår i: Ancient Supercontinents and the Paleogeography of Earth. - : Elsevier. ; , s. 499-548
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Bokkapitel (refereegranskat)abstract
- We review models of the Precambrian supercontinent Nuna (c.1.80–1.20 Ga) and present a new model of the Nuna life-cycle. We explore the option where Amazonia−West Africa and Congo−São Francisco cratons were not a part of Nuna but form a cluster of cratons named Atlantica. Nuna was finally assembled at c.1.65 Ga, encompassing Laurentia, Baltica, Siberia, proto-Australia, North China, and India. The break up of Nuna is here suggested to have started at c.1.3 Ga with Australian cratons moving away from Laurentia. Varying drift rates and length between coeval poles from separate cratons support the operation of modern style plate tectonics during the Nuna supercycle. Moreover, if there was no link between Nuna and the Atlantica cratons, the size of Nuna might not meet the criteria for a supercontinent, but should be regarded as a huge landmass.
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| 3. |
- Evans, David A.D., et al.
(författare)
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An expanding list of reliable paleomagnetic poles for Precambrian tectonic reconstructions
- 2021
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Ingår i: Ancient Supercontinents and the Paleogeography of Earth. - : Elsevier. ; , s. 605-639
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Bokkapitel (refereegranskat)abstract
- We present a compilation of reliable Precambrian paleomagnetic poles from three successive international workshops (in years 2009, 2014, 2017), comprising paleomagnetists specializing in Precambrian tectonic reconstructions. The working groups compiled lists of two global classes of poles, published through the end of 2017. “Grade-A” results are judged to provide essential constraints on tectonic reconstructions; “Grade-B” poles are judged to be suggestive of high-quality, but not yet demonstrated to be primary, or perhaps lacking precise geochronologic or other constraints. Our catalog documents a resurgence of high-quality data acquisition in recent years, and highlights specific cratons and time intervals that are most lacking in the data needed to reconstruct those blocks through supercontinental cycles.
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| 4. |
- Luoto, T., et al.
(författare)
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New palaeoproterozoic palaeomagnetic data from Central and Northern Finland indicate a long-lived stable position for Fennoscandia
- 2023
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Ingår i: Geophysical Journal International. - : Oxford Univ Press. - 0956-540X .- 1365-246X. ; 235:2, s. 1810-1831
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Tidskriftsartikel (refereegranskat)abstract
- The Svecofennian gabbro intrusions coincide temporally with the global 2100-1800 Ma orogens related to the amalgamation of the Mesoproterozoic supercontinent Nuna. We provide a new reliable 1891-1875 Ma palaeomagnetic pole for Fennoscandia based on rock magnetic and palaeomagnetic studies on the Svecofennian intrusions in central Finland to fill gaps in the Palaeoproterozoic palaeomagnetic record. By using the new pole together with other global high-quality data, we propose a new palaeogeographic reconstruction at 1885 Ma. This, together with previous data, supports a long-lived relatively stable position of Fennoscandia at low to moderate latitudes at 1890-1790 Ma. Similar stable pole positions have also been obtained for Kalahari at 1880-1830 Ma, Siberia at 1880-1850 Ma, and possibly India at 1980-1775 Ma. A new reconstruction at the beginning of this period indicates the convergence of several cratons at 1885 Ma in the initial stages of the amalgamation of the Nuna supercontinent at low to moderate latitudes. The close proximity of cratons at low to moderate latitudes is further supported by global and regional palaeoclimatic indicators. Stable position of several cratons could indicate a global period of minimal apparent drift at ca. 1880-1830 Ma. Before this period, the global palaeomagnetic record indicates large back-and-forth swings, most prominently seen in the high-resolution 2020-1870 Ma Coronation loops of the Slave craton. These large back-and-forth movements have been explained as resulting from an unstable geomagnetic field or basin- or local-scale vertical-axis rotations. However, the most likely explanation is inertial interchange true polar wander (IITPW) events, which is in line with the suggestion of large amplitude true polar wander events during the formation of the supercontinent.
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| 5. |
- Meert, Joseph G., et al.
(författare)
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The magnificent seven : A proposal for modest revision of the Van der Voo (1990) quality index
- 2020
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Ingår i: Tectonophysics. - : Elsevier. - 0040-1951 .- 1879-3266. ; 790
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Tidskriftsartikel (refereegranskat)abstract
- Thirty years ago, Rob Van der Voo proposed an elegant and simple system for evaluating the quality of paleomagnetic data. As a second-year Ph.D. student, the lead author remembers Rob waxing philosophical about the need to have an appropriate, but not overly rigid evaluation system. The end result was a 7-point system that assigned a (1) or (0) for any paleomagnetic result based on objective criteria. The goal was never to reject or blindly accept any particular result, but merely to indicate the degree of quality for any paleomagnetic pole. At the time, the global paleomagnetic database was burgeoning and it was deemed useful to rank older paleomagnetic results with the newer data being developed in modern laboratories. Van der Voo's, 1990 paper launched a silent revolution in paleomagnetism. Researchers began to evaluate their data against those seven criteria with the anticipation that reviewers would be similarly critical.Today, paleomagnetism is a mature science. Our methods, analyses, and results are more sophisticated than they were 30 years ago. Therefore, we feel it is appropriate to revisit the Van der Voo (1990) criteria in light of those developments. We hope to honor the intention of the original paper by keeping the criteria simple and easy to evaluate while also acknowledging the advances in science. This paper aims to update the criteria and modernize the process. We base our changes on advances in paleomagnetism and geochronology with a faithful adherence to the simplicity of the original publication. We offer the “Reliability” or “R” index as the next generation of the Van der Voo “Quality” or “Q” index. The new R-criteria evaluate seven different information items for each paleomagnetic pole including age, statistical requirements, identification of magnetic carriers, field tests, structural integrity, presence of reversals and an evaluation for possible remagnetization.
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| 6. |
- Pesonen, Lauri J., et al.
(författare)
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Precambrian supercontinents and supercycles—an overview
- 2021
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Ingår i: Ancient Supercontinents and the Paleogeography of Earth. - : Elsevier. ; , s. 1-50
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Bokkapitel (refereegranskat)abstract
- There is ample evidence that supercontinent cycles on Earth have been operating since the Late Paleoproterozoic. Evidence for the supercontinent cyclicity arises from multidisciplinary observations from geology, geochronology, geophysics (e.g., paleomagnetism, seismology, heat flow), isotope geology, and geochemistry. This overview summarizes current views of Precambrian supercontinent episodicity or cyclicity. In addition, paleogeographic reconstructions based on global key paleomagnetic poles and kinematic models of Paleo-Mesoproterozoic Nuna supercycle, Meso-Neoproterozoic Rodinia supercycle, and the Phanerozoic Gondwana/Pangea supercycle are explored. The lifecycle of supercontinents is tested by geological, geophysical, and geochemical data coupled with secular evolution trends of Earth. Results suggest that (1) supercontinent cyclicity has a characteristic (quasi-) period of ~700–500 million years, supported by planetary secular evolutionary trends, but other periods are also present; (2) supercontinents Nuna, Rodinia, and Gondwana/Pangea have different configurations and secular evolutionary trends possibly due to different tectonic styles of assembly; (3) globally averaged plate velocity during the Precambrian reveals a wave-like pattern with peaks and lows corresponding with features in several secular evolution indices including the distribution of U−Pb ages, passive margins, metamorphic events, tectonic proxies, and magmatic activity; (4) the data suggest three tectonomagmatic lulls during the Proterozoic, but the proposed Mesoproterozoic quiescent period, coined as “boring billion” years of Earth history (1.8–0.8 Ga) appears to be seen mainly by atmospheric and biospheric data rather than tectonomagmatic activity; and (5) tectonic processes driving supercontinent cyclicity are interactive, with feedbacks from all six spheres of the Earth—the geosphere, cryosphere, hydrosphere, biosphere, atmosphere, and magnetosphere.
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| 7. |
- Pesonen, Lauri J., et al.
(författare)
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Preface
- 2021
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Ingår i: Ancient Supercontinents and the Paleogeography of Earth. - : Elsevier. ; , s. xv-xvi
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Salminen, Johanna, et al.
(författare)
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Paleomagnetic studies of rapakivi complexes in the Fennoscandian shield – Implications to the origin of Proterozoic massif-type anorthosite magmatism
- 2021
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Ingår i: Precambrian Research. - : Elsevier. - 0301-9268 .- 1872-7433. ; 365
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Tidskriftsartikel (refereegranskat)abstract
- Paleomagnetic studies have been performed on five rapakivi related complexes in Sweden and Finland. Poles of varying quality have been defined and the majority of the similar to 1640-1497 Ma poles are clustering on low latitudinal positions. By combining data from similar to 1500 Ma intrusions a new high-quality pole (Plat: 13 degrees N; Plon: 190 degrees E; A(95): 11 degrees, K: 14) for Baltica has been defined. Tectonic reconstructions, on the basis of the new data and previously published high-quality data, indicate that Baltica experienced stable low latitude to equatorial positions during 1640-1470 Ma, temporally coinciding with globally pronounced rapakivi-anorthosite magmatism. Our study argues against single hotspot source for similar to 1640-1620 Ma, similar to 1590-1520 Ma, and 1470-1410 Ma rapakivianorthosites, but supports a model of large-scale superswell under a stationary low-latitude position of supercontinent Nuna for the origin of rapakivi-anorthosite magmatism. However, a possibility for convergent tectonism as the origin cannot be ruled out.
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| 9. |
- Salminen, Johanna, et al.
(författare)
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The Precambrian drift history and paleogeography of Baltica
- 2021
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Ingår i: Ancient Supercontinents and the Paleogeography of Earth. - : Elsevier. ; , s. 155-205
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Bokkapitel (refereegranskat)abstract
- We review paleomagnetic data and paleoclimatological indicators of Baltica and its subcratons. Between Neoarchean and middle Mesoproterozoic Karelia and Kola, and later the united Baltica were located mostly at the latitudes between 35°N and 35°S. Location of Baltica oscillated between high latitudes and the equator at late Mesoproterozic–Neoproterozoic. Drift velocities of the separate cratons between Neoarchean and middle Proterozoic are lower than the velocities of the united Baltica at late Paleoproterozoic–middle Mesoproterozoic. At Late Mesoproterozoic–Neoproterozoic Baltica shows high velocity peaks, which correlate temporarily with the ones obtained for Laurentia and can be ascribed to true polar wander. Increase in drift rates correlate temporarily with orogenies related to the formation of the supercontinents Nuna and Rodinia and in smaller scale to the crustal growth of Baltica. Based on the results, we review possible nearest neighbors for the Kola and Karelia in the Superia supercraton and for Baltica in the Nuna and Rodinia supercontinents.
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| 10. |
- Salminen, J., et al.
(författare)
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Timing the break-up of the Baltica and Laurentia connection in Nuna – Rapid plate motion oscillation and plate tectonics in the Mesoproterozoic
- 2023
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Ingår i: Precambrian Research. - : Elsevier B.V.. - 0301-9268 .- 1872-7433. ; 384
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Tidskriftsartikel (refereegranskat)abstract
- Meso– to Neoproterozoic geological and paleomagnetic data support a direct connection between Baltica and Laurentia in both Nuna and Rodinia supercontinents, however in different relative configurations. Previous paleomagnetic data limit the time of break-up of Nuna core configuration and ca. 90° rotation of Baltica relative to Laurentia between 1.27 Ga and 0.99 Ga. Despite the well documented relative motion of continents, the tectonic mode during the Meso– to Neoproterozoic has been questioned and the operation of single lid tectonics at 1.6–1.0 Ga during the Nuna-Rodinia supercontinent cycles has been proposed.In this study, new paleomagnetic and whole rock 40Ar-39Ar geochronological data from a basic dyke in Stugun central Sweden are combined with coeval data to produce a 1.22 Ga (1.244–1.200 Ga) moderate-quality paleomagnetic pole. This is done to better estimate the break-up time of the core of Nuna and explore the plate tectonics at the Mesoproterozoic. The new pole fills part of the 1.247–1.140 Ga gap in the paleomagnetic record of Baltica. By comparing apparent polar wander paths (APWPs) and calculated drift velocities, a break-up of Baltica and Laurentia at 1.12–1.04 Ga is suggested. Plate velocities calculated for Laurentia, Baltica and Siberia for the time of the Nuna supercycle are similar and low to moderately high corresponding with the present-day tectonic speeds. Furthermore, the obtained velocity peaks may be related with onset of the break-up of the Nuna supercontinent, the break-up of the direct Baltica–Laurentia connection in Nuna and nascent Rodinia. We suggest that the velocity peaks and large oscillating shifts in late Mesoproterozoic pole positions for Laurentia and Baltica result from a combination of relative plate motion and inertial interchange true polar wander (IITPW) events. Both IITPW events and relative plate motions argue for an operation of plate tectonics in the Meso– to Neoproterozoic.
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