PerspectiveGeology

The Rodinia Jigsaw Puzzle

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Science  30 May 2003:
Vol. 300, Issue 5624, pp. 1379-1381
DOI: 10.1126/science.1083469

Earth's surface is divided into a dozen tectonic plates [HN1] that either drift apart, creating new oceanic crust, or collide, generating mountain belts such as the Himalayas. In the past, continents have coalesced into single supercontinents [HN2], which had dramatic effects on both surface and deep Earth processes. But while much is known about Pangaea (the most recent supercontinent on Earth), the earlier Rodinia supercontinent remains shrouded in mystery.

Pangaea [HN3] started to form ∼330 million years ago and reached its maximum extent in the Late Permian [HN4] (250 million years ago) (see the first figure). Not all continents coalesced simultaneously; some were added along Pangaea's margins just as others rifted off. The supercontinent changed the distribution of land and sea areas and brought about unusual climatic and biological conditions. Increased mantle temperatures and continental bulging in the interior of Pangaea may also have occurred as a result of long-term shielding of large parts of the underlying mantle (1). The ultimate breakup of Pangaea ∼175 million years ago was preceded by and associated with widespread magmatic activity.

The Pangaea supercontinent in the Late Permian.

At the time of its maximum extent, Pangaea did not contain North and South China, and new oceanic crust was formed along the eastern margin. Precambrian terranes or continents often discussed in Rodinia reconstructions (but at different locations; see the second figure) are shown in yellow. Gondwana, in the Southern Hemisphere, was formed ∼550 million years ago. In the Northern Hemisphere, the earlier terranes of Laurentia, Avalonia, and Baltica combined in the Early Devonian (418 to 400 million years ago) to form Laurussia. Gondwana and Laurussia later collided to form Pangaea.

There is some evidence that supercontinents have formed periodically during Earth's history. The existence of a supercontinent in the Precambrian [HN5] (before 544 million years ago) was proposed in the 1970s, when many geologists noted a large number of mountain belts with similar ages (1300 to 1000 million years old) that are today located on different continents (2). In the early 1990s, the name Rodinia [HN6] was adopted for this supercontinent (35).

Most Rodinia models have sought to match the 1300- to 1000-million-year-old mountain belts. In these models, Laurentia forms the core of the supercontinent, with Australia-East Antarctica situated along its present-day western margin and Baltica-Amazonia along the eastern margin (see the left panel, second figure).

Rodinia old and new.

(Left) Classic Rodinia reconstruction at 750 million years ago. (Right) Alternative reconstruction of Rodinia at 750 million years ago. The positions of Australia-East Antarctica (10) and Congo have been revised (12). The Amazonia-West Africa reconstruction follows Hoffman (5), and North China is tentatively placed north of Baltica. Continental fragments and magmatic arcs (Avalonian, Cadomian, and Timanian) along the southeastern margin of Rodinia were welded onto West Africa, Amazonia, Baltica, and Siberia in the Late Precambrian.

CREDIT: LEFT PANEL ADAPTED FROM (7, 14)

The models assumed that the geometry of the supercontinent, after its formation, remained static until it broke up around 700 million years ago, when Australia-East Antarctica rifted off the western margin of Laurentia. Many other continents such as Baltica and Amazonia rifted off Laurentia later (600 to 550 million years ago), opening the Iapetus Ocean [HN7] between them.

Paleomagnetism [HN8]—the study of the permanent magnetism in rocks, which provides the latitude and rotation for a continent—has been used to reconstruct the timing of the growth and dispersal of Rodinia. Early paleomagnetic studies were broadly supportive of the existence of a Rodinia supercontinent (68). But the quality of the data was insufficient for rigorous tests, in part because many of these early paleomagnetic studies were not tied to a precise radiometric age [HN9]. Newer studies combining paleomagnetic and isotopic age data from 750-million-year-old rocks from the Seychelles islands and India (9) also generally support classic Rodinia configurations.

However, these data have been contradicted by recent paleomagnetic data from Australia (10) [HN10], which radically change our notion of Rodinia at 750 million years ago (see the right panel, second figure). The revised latitude for Australia displaces Australia-East Antarctica (considered as a coherent landmass) 1400 kilometers southward. In such a configuration, India could not have been connected to East Antarctica as portrayed in the left panel. Therefore, East Antarctica-India fits used in traditional Rodinia models only appear valid after India collided with East Antarctica around 550 to 500 million years ago during the growth of Gondwana [HN11] (which ultimately became part of Pangaea; see the first figure).

Current paleomagnetic data usually only allow testing of Rodinia paleogeographic relationships between two or three continents at discrete time intervals (11). However, for 750 million years ago, data exist from at least seven continents or microcontinents. Recent Rodinia models show a more dynamic planet at 750 million years ago than previously realized. If Rodinia formed 1100 to 1000 million years ago, the demise of the supercontinent probably occurred before 750 million years ago. Disruption likely began with the opening of an ocean between western Laurentia and Australia-East Antarctica (right panel). The East Gondwana landmass could not have been a coherent block 750 million years ago (9, 12), and India-Madagascar-Seychelles must have been located west of Australia. Recent maps (13) also show Baltica geographically inverted relative to Laurentia (right panel).

Large uncertainties concern the position of Siberia. Early Rodinia reconstructions show Siberia north of Laurentia (5, 9, 14), whereas others place Siberia along the western margin of Laurentia. Yet another extreme shows Siberia west of Baltica (right panel). The positions of Amazonia-Rio Plata and Congo-Kalahari also differ substantially between the old and new models (see the second figure), demonstrating the fluid and controversial nature of Rodinia reconstructions. Before 750 million years ago, the Congo and Kalahari cratons [HN12] were probably in very different locations in Rodinia (12). For Amazonia, paleomagnetic data now suggest early collision (∼1200 million years ago) with Laurentia near Texas (15), followed by a later move along the Laurentian margin to its position at 750 million years ago (see the right panel).

The current data indicate that the internal geometry of Rodinia changed considerably during its few hundred million years of existence. Geologic and paleomagnetic data suggest that the supercontinent consolidated at 1100 to 1000 million years ago and most likely disintegrated between 850 and 800 million years ago. However, elucidation of its amalgamation, continental makeup, and fragmentation is hampered by the fact that at any given time, the latitudes for only a few continents are known.

To overcome these problems, we must tie paleomagnetic information to geologic matching of rock units with the same age between various continents. Doing so requires more precise dating of mobile belts [HN13] and rift sequences associated with Rodinia's breakup. New paleomagnetic studies conducted in close conjunction with radiometric age studies are urgently needed to shed new light on the supercontinent's evolution. Until then, our efforts resemble a jigsaw puzzle where we must contend with missing and faulty pieces and have misplaced the picture on the box.

HyperNotes Related Resources on the World Wide Web

General Hypernotes

Dictionaries and Glossaries

The xrefer Web site makes available a searchable collection of scientific dictionaries and other reference works.

A geology glossary is provided by Houghton-Mifflin's GeologyLink Web site.

A geologic glossary is provided by the Geology in the Parks Web site of the U.S. Geological Survey (USGS).

Web Collections, References, and Resource Lists

The Yahoo Directory provides links to Internet resources on geology and geophysics.

Academic Info provides links to geology resources.

Sci-Info from the University of Arizona Library provides a guide to Internet geoscience resources.

Resources for Earth Science and Geography Instruction are maintained by M. Francek, Department of Geography, Central Michigan University.

Links for Mineralogists provides an annotation selection of geology Internet resources.

Geo-Guide, a collection of links to Internet geology resources, is provided by the Göttingen State and University Library, Germany.

Online Texts and Lecture Notes

The University of California Museum of Paleontology (UCMP) offers presentations on geologic time and plate tectonics. A glossary of geological terms is also provided.

The Dynamic Earth Web site, provided as a teaching resource by the School of Earth Sciences, University of Leeds, UK, offers presentations with Internet links on the dynamic Earth and tectonics.

The Palaeos Web site includes a section on paleogeography.

Paleogeography Through Geologic Time is a collection of maps and globes presented by R. Blakey, Department of Geology. Northern Arizona University.

The University of Chicago's Paleogeographic Atlas Project has as its objective to apply the plate tectonics paradigm to the reconstruction of the geological past in all its aspects.

C. Scotese's PALEOMAP Project has as its goal to illustrate the plate tectonic development of the ocean basins and continents, as well as the changing distribution of land and sea during the past 1100 million years.

J. Rial, Department of Geological Sciences, University of North Carolina, provides a tutorial on the principles of global dynamics.

Planet Earth and the New Geosciences is an online textbook by V. Schmidt and W. Harbert, Department of Geology and Planetary Sciences, University of Pittsburgh.

The Present Is the Key to the Past is an online historical geology textbook provided by H. Rance's Geowords Web site.

S. Nelson, Department of Geology, Tulane University, provides lecture notes for a physical geology course.

V. DiVenere, Department of Earth and Environmental Science, Long Island University, C. W. Post campus, offers lecture notes for a course on continental drift and plate tectonics.

H. Maher, Department of Geography and Geology, University of Nebraska, provides lecture notes for a course on plate tectonics.

S. Stein, Department of Geological Sciences, Northwestern University, provides lecture notes for a course on plate tectonics.

R. D. Müller, Division of Geology and Geophysics, University of Sydney, Australia, provides lecture notes in PDF format for a course on deep Earth structure and global tectonics. Also available are plate tectonics animations.

General Reports and Articles

This Dynamic Earth: The Story of Plate Tectonics by W. J. Kious and R. Tilling is made available on the Web by the USGS.

“When the Earth moves: Seafloor spreading and plate tectonics” is a Beyond Discovery presentation from the National Academy of Sciences.

Paleomagnetism: Magnetic Domains to Geologic Terranes is a 1992 book that the author, R. F. Butler, Department of Geosciences, University of Arizona, makes available in PDF format.

The Deutsche Geophysikalische Gesellschaft (DGG) makes available in PDF format a paper by J. Tait titled “Paleomagnetism: Implications to paleogeography and plate tectonics” that was presented at the 2000 DDG colloquium “Die Magnetik in der Geophysik.”

The Physics of Geological Processes Web site at the University of Oslo makes available (in PDF format) the March 2002 Geology article by E. H. Hartz and T. H. Torsvik titled “Baltica upside down: A new plate tectonic model for Rodinia and the Iapetus Ocean.”

Numbered Hypernotes

1. Plate tectonics. The Plate Tectonics Web site provides an overview of plate tectonics. An Introduction to Plate Tectonics is provided by the Hartebeesthoek Radio Astronomy Observatory, Krugersdorp, South Africa. S. Dutch, Department of Natural and Applied Sciences, University of Wisconsin, Green Bay, provides lecture notes on plate tectonics for a physical geology course; a presentation on the history of global plate motions is also provided. J. Revenaugh, Department of Earth Sciences, University of California, Santa Cruz, offers lecture notes on plate tectonics for a course on geologic principles. The PLATES Project at the Institute for Geophysics, University of Texas, is a program of research into plate tectonic and geologic reconstructions.

2. Supercontinents. H. Maher provides a presentation on Pangaea, Gondwana, Rodinia, and the supercontinent hypothesis for a course on plate tectonics. J. Sprinkle, Department of Geological Sciences, University of Texas, provides a diagrammatic history of major continents for a course on plate tectonics and Earth history. As part of a plate tectonic primer, L. Fichter, Department of Geology and Environmental Science, James Madison University, provides a synopsis of plate tectonic theory, the supercontinent cycle, and its implications for Earth history. D. Evans, Department of Geology and Geophysics, Yale University, offers an introduction to his research on the reconstruction of supercontinents. M. Gurnis, Seismological Laboratory, California Institute of Technology, provides an animation of supercontinent aggregation and dispersal. K. Condie, Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, makes available in PDF format a 2002 article (from the Journal of African Earth Sciences, vol. 35, no. 2) titled “The supercontinent cycle: Are there two patterns of cyclicity?”

3. Pangaea. The Palaeos Web site provides an introduction to Pangaea. H. Rance's Present Is the Key to the Past has chapters on Pangaea and Pangaea reconstructed. W. Chaisson, Department of Earth and Environmental Sciences, University of Rochester, offers lecture notes on assembling Pangaea for a course on Earth evolution. C. Scotese's PALEOMAP Project offers an introduction to Pangaea as well as animations of the assembly and breakup of Pangaea; also available is an animation illustrating seafloor spreading during the Pangaea breakup. The Discover Our Earth Web site from the Institute for the Study of the Continents, Cornell University, offers a Pangaea tectonics puzzle.

4. An introduction to the Permian is provided by UCMP. P. Gore, Science Department, Georgia Perimeter College, offers lecture notes on the Permian for a for a historical geology course. The Paleogeographic Atlas Project offers a presentation on Permian geography, vegetation and climates.

5. Precambrian. UCMP provides a presentation on the Precambrian. C. Scotese's PALEOMAP Project offers an introduction to the Late Precambrian. P. Gore provides lecture notes on the Precambrian for a historical geology course.

6. Rodinia. Palaeos provides an introduction to Rodinia. Dance of the Continents is a presentation about Rodinia (and Pangaea) by the University of Washington's Burke Museum of Natural History and Culture. C. Scotese's PALEOMAP Project includes a presentation on Rodinia and the breakup of Rodinia. D. Fox, Department of Geology and Geophysics, University of Minnesota, provides lecture notes on Rodinia and Snowball Earth for an Earth history course. The 7 June 1991 issue of Science had a report by P. Hoffman titled “Did the breakout of Laurentia turn Gondwanaland inside-out?” (5) (AAASMember.org offers access to the JSTOR Science archive). The Tectonics Special Research Centre, University of Western Australia, provides an introduction to its Rodinia project. J. Meert, Department of Geological Sciences, University of Florida, makes available in PDF format a preprint of an article by J. G. Meert and T. H. Torsvik titled “The making and unmaking of a supercontinent: Rodinia revisited.”

7. Iapetus Ocean is defined in xrefer's Dictionary of Earth Sciences and in S. Baum's Glossary of Physical Oceanography and Related Disciplines.

8. Paleomagnetism. An entry on paleomagnetism is included in the Columbia Encyclopedia. The University of Leeds Dynamic Earth Web site offers a tutorial on paleomagnetism and moving continents. J. Meert's Paleomagnetism Home Page includes a FAQ about paleomagnetism and other resources. H. Rance's Present Is the Key to the Past includes a presentation on paleomagnetic poles. A section on magnetic reversals and moving continents is included in D. Stern's The Great Magnet, the Earth. J. B. Bennington, Department of Geology, Hofstra University, offers lecture notes on paleomagnetism for a historical geology course. L. Tauxe, Paleomagnetic Laboratory, Scripps Institution of Oceanography, provides lecture notes on paleomagnetism and continental drift for a global tectonics course. The Global Paleomagnetic Database is provided by the DRAGON Project at the Geological Survey of Norway. The AGU Geomagnetism and Paleomagnetism Section provides links to Internet resources.

9. Radiometric dating. The USGS publication Geologic Time by W. Newman includes a section on radiometric dating. An introduction to radiometric dating is provided by the USGS Geology in the Parks Program in its presentation on geologic time. A student Web project on radiometric dating was prepared for W. Chaisson's course on the evolution of Earth. The University of Michigan's Global Change Curriculum offers lecture notes by B. van der Pluijm titled “Clocks in rocks: Isotopes and age of Earth.” J. B. Bennington offers lecture notes on radiometric dating for a historical geology course. R. Cas, Department of Earth Sciences, Monash University, Australia, provides lecture notes on radiometric dating for an Earth sciences course. W. White, Department of Earth and Atmospheric Sciences, Cornell University, offers lecture notes (in PDF format) for a course on isotope geochemistry.

10. Recent data from Australia. The Tectonics Special Research Centre, University of Western Australia, makes available (in PDF format) annual reports of its project on Rodinia assembly and breakup; the 2002 report mentions the recent paleomagnetic data, as reported in an article in the March 2000 issue of Precambrian Research titled “Age and palaeomagnetism of the Mundine Well dyke swarm, Western Australia: Implications for an Australia-Laurentia connection at 755 Ma” by M. Wingate and J. Giddings (10).

11. Gondwana. Palaeos provides an introduction to Gondwana. C. Scotese's PALEOMAP Project offers an animation of the breakup of Gondwana. The International Institute for Geo-Information Science and Earth Observation offers Gondwana animations. The British Antarctic Survey offers a presentation about Gondwana and its breakup. J. Meert makes available in PDF format his article titled “A synopsis of events related to the assembly of eastern Gondwana” that appeared in the 6 February 2003 issue of Tectonophysics.

12. Craton is defined in xrefer's Dictionary of Geography and in the USGS glossary. L. Fichter's plate tectonic primer provides an introduction to cratons. H. Rance's Present Is the Key to the Past has a section on cratons.

13. Mobile belts. Mobile belt is defined in xrefer's Dictionary of Earth Sciences. A discussion of mobile belts is included in a section of H. Rance's Present Is the Key to the Past. S. Dutch discusses orogenic belts in lecture notes on subduction zones and orogeny for a physical geology course.

14. T. H. Torsvik is in the VISTA Project, Norwegian Academy of Science and Statoil, and at the Geodynamic Center, Geological Survey of Norway, Trondheim.

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