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These plate tectonic maps are made from the datafiles used for the publication:
Hay, W.W., DeConto, R., Wold, C.N., Wilson, K.M., Voigt, S., Schulz, M., Wold-Rossby, A., Dullo, W.-C., Ronov, A.B., Balukhovsky, A.N. and E. Soeding (1999): ALTERNATIVE GLOBAL CRETACEOUS PALEOGEOGRAPHY, in Barrera, E. and Johnson, C. (eds.), The Evolution of Cretaceous Ocean/Climate Systems, Geological Society of America Special Paper 332, pp. 1-47.
The program calculating the rotations was programmed by Emanuel Soeding (GEOMAR), using the techniques described in Cox and Hart (1986, see reference below). Plotting the maps is done with GMT (Generic Mapping Tools) available from Soest/Hawaii. For more information about GMT, a free mapping software package, follow this link.
The selection of blocks and terranes used in these recontructions is that of Wilson (1989; most are also in Wilson et al., 1989a), with the addition of some oceanic plateaus. The 324 continental blocks, terranes, and plateaus for North America, South America, Africa, Australia, southeast Asia, Antarctica, Asia and the Indian and Pacific Oceans are shown in Figs. 2-8. Each block or terrane is indicated by a three letter abbreviation (or four letter abbreviation in the case of terranes with parts that are required to move separately). The key to abbreviations and list of names of fragments used in the reconstructions are given in Tables 1-11.
The Geologic Atlas of the World (Choubert and Faure-Muret, 1976) served as the basis for digitization of the continental blocks and terranes. Conversion of the digitized outlines to latitude-longitude coordinates requires a reverse transformation for each projection. The maps in the Geologic Atlas of the World are on several different projections. The maps of North and South America are on Miller's Bipolar Oblique Conic Conformal Projection. The forward and reverse transformations for this projection have been published by Sprinsky and Snyder (1986). The maps of the polar regions are on Polar Stereographic Projections; standard projections for which the reverse transformations can be found in a variety of sources, including Snyder (1982) and Pearson (1990). The maps of Africa, Europe, Asia, and Australia and the adjacent South Pacific are on Miller's Oblated Oblique Stereographic Projection. This projection has the advantage that the maps of this entire region can be shown as a single unit without great distortion anywhere, but its complexity is indicated by the sinuosity of the lines of latitude and longitude. The forward transformation for this projection has been published by Sprinsky and Snyder (1986). Unfortunately, because of its complexity, there can be no exact reverse transformation for Miller's Oblated Oblique Stereographic Projection. However, the functional equivalent of the reverse transformation was developed by one of us (Wold, in prep.), and used to convert the digitized data. The functional equivalent substitutes for the reverse transformation by using a series of iterations to calculate increasingly exact approximations of latitude-longitude coordinates that correspond to points digitized on the map sheets. Because of the differetn sources for data and the different projects there may be some places where the edges of two blocks slightly overlap or are slightly offset.
Oceanic plateaus and some continental margin areas were digitized from GEBCO sheets, which are on either Mercator or Polar Stereographic projections for which the reverse transformations are well known (Snyder, 1982; Pearson, 1990).
We attempted to restore passive margins to their shape before stretching. Where possible, we used the stretching of the margins indicated by seismic profiling to determine the original position of the edge of the continent (e.g see papers in Burke and Drake, 1970; Watkins and Drake, 1982). This frequently turned out to be the present position of the 200 m isobath (Wold et al., 1994), so this isobath was generally used as marking the original edge of the continental block where the stretching factor is otherwise unknown.
The rotation file for the fragments is available as textfile.
Whenever possible we used previously published suites of rotations. In the Tethys we devised rotations to follow the paths of blocks as indicated by Dercourt et al.
The first column of the table lists the fragment being moved, followed by the fragment to which its motion is referred (e.g. WNA-NAM = Western North America with respect to Central North America). The second column lists the age for the finite (or total) rotation, assuming the present position at age 0 (e.g. 40.0 means that the rotation given in the next three columns will place the block in the position it occupied at 40.0 Ma relative to the reference block). The MAS file will determine the position of the fragment at any age by interpolating between the total rotations that bracket it. Thus, if a block has four consecutive total rotations, for times 1, 2, 3, and 4, its position at time 3.5 will be midway between its position at times 3 and 4. The next three columns, LAT, LONG, and ROT, define the rotation. The pole is defined by its latitude and longitude relative to the reference block, and the rotation about the pole is counterclockwise if positive, clockwise if negative, following the "right-hand" rule. The last column, containing MAGNETIC ANOMALY, SOURCE, and COMMENTS, lists the magnetic anomaly on which the rotation is based, the author(s) and date of the publication, and comments.
Whenever possible the rotation of one block relative to another is based on superposing sea-floor magnetic anomalies. Except where noted, we assumed that the literature sources used the youngest side of the magnetic anomaly for matching. The ages assigned to magnetic anomalies have changed as more information becomes available, so that the ages given for rotations in the literature depend very much on when the paper was written. We have corrected all of the ages for the anomalies of the Cenozoic and Late Cretaceous to the time scale of Berggren et al. (1995).
Magnetic anomalies provide no guidance for motions during the Cretaceous Quiet Interval, from 83.5 to 120.4 Ma. Magnetic anomalies are also often indistinct along rifted margins and may not define a fit. In any case, fits of major blocks using the new digitized outlines will always be different from those previously published. Except in the western and northern Pacific, sea-floor magnetic anomalies are of little use in defining terrane motions because the critical lineations have been subducted. Paleomagnetic data from a terrane may provide useful information about its latitude at a given time, but not about its longitude. Plate tectonics assumes that blocks, terranes, and oceanic plateaus are attached to rigid plates. However, the motions of terranes described in the regional literature are often ad-hoc solutions based on paleomagnetic data. From these rotations alone one could come to the conclusion that each terrane moves on its own plate. We have attempted to determine groups of terrane motions that can be accommodated by a single rotation; these are listed as terranes "FIXED TO" other terranes or blocks in Tables 1-10.
The rotation of each fragment is given with reference to some other fragment previously listed in the table. For example, the position of South America relative to North America is not known directly because there are no intervening magnetic anomalies. However, the position of Africa relative to North America is known from the North Atlantic anomalies, and the position of central South America (our Parana Block) with respect to Africa is known from the South Atlantic anomalies. The rotations for fragments are chained together, ultimately coming back to the reference frame rotations at the beginning of the file. Some of the chains of rotations are quite long and complex. The abbreviated version A&O file is shown in Table 11. It is divided into segments for ease of discussion.
We use the paleomagnetic reference frame for North America of Harrison and Lindh (1982) as the standard. This paleomagnetic reference frame was originally considered best because at the time it was published the largest number of reliable paleomagnetic pole positions were from North America. Another paleomagentic reference frame, van der Voo (1990), and two hotspot reference frames, Cox and Hart (1986) and Mueller et al., (1993), are available. The other reference frames can be applied to the map by selecting them in the appropriate box.
No shorelines are indicated. These can be sketched onto the plate tectonic base maps using sources, such as Ronov et al. (1989) and Smith et al. (1995).
The DSDP and ODP sites appear on the map if the oldest strata drilled are equal to or younger than the age of the map. Strata of the age of the map may not be present or may not have been cored at these sites. Where the age at the bottom of the hole is vague (e.g. Early Cretaceous?) the age for the base of the Early Cretaceous assigned to the hole may result in its being rotated too far. Some old sites with uncertain ages rotate back onto continental blocks, obviously an error.
The major differences between these and other reconstruction can be summarized as follows:
Most plate tectonic reconstructions for the Cretaceous have assumed that five major continental blocks: Eurasia, North America-Greenland, South America, Africa, India-Madagascar, and Australia-Antarctica had either completely or partially separated from one another and were surrounded by deep ocean passages. There were deep connections between the Pacific, Tethyan, Atlantic, and Indian Ocean basins. North America, Eurasia, and Africa were crossed by shallow meridional seaways. This classic view of Cretaceous paleogeography apples only to the latest Late Cretaceous.
During the Early Cretaceous there were three large continental blocks: North America-Eurasia, South America-Antarctica-India-Madagascar-Australia, and Africa, a large open Pacific Basin, a wide eastern Tethys, and a circum-African Seaway extending from the western Tethys ("Mediterranean") region through the North and South Atlantic into the juvenile Indian Ocean between Madagascar-India and Africa. There were no deep water passages to the Arctic.
The Iberian and Grand Banks margins separated about 130 Ma. This motion was followed by the opening of Rockall Trough, which was synchronous with stretching in the North Sea and formation of basins in northern Germany.
The Labrador Sea started to open during the Cretaceous Magnetic Quiet Interval and had finished by 33 Ma. The opening of the Labrador Sea slowed during the Early Cenozoic and sea -floor spreading shifted to the transform motion between North America-Greenland and Eurasia that has been opening both the Norwegian-Greenland Sea and the Eurasian Basin of the Arctic since 57 Ma.
The original Early Cretaceous "home" of the Caribbean Plate is suggested to be along the western margin of northern South America. The earliest time it can pass between northern Central America and South America is about 100 Ma. Its advance into the Atlantic was stopped by collision with South Florida and the Bahama Platforms at the end of the Cretaceous resulting in a major reorganization of Atlantic Plate motions. During much of the Cretaceous the deep water passage from the Central Atlantic to the Pacific was blocked by the Caribbean plate.
The opening of the South Atlantic began with "unwrapping" of the San Jorge, Colorado, Salada, and Parana basins of South America from Africa. As these motions occurred, the Falkland Plateau carried Madagascar-India-Antarctica-Australia with it in an arc. Subsequently, South America and Africa separated along a transform fault between the northeastern margin of Brazil and the Guinea Coast of Africa. Antarctica then moved south, but the Antarctic Peninsula remained in contact with the southern Andes, forming a continuous mountain chain that was not interrupted until the Oligocene.
In the Indian Ocean region, India first moved south with Antarctica and Madagascar. Beginning in the Early Cretaceous, India began to rotate away from Antarctica, moving along a transform and sliding past Madagascar. However, it remained connected to Antarctica by a land bridge formed by Kerguelen Plateau, Sri Lanka, and possibly also by Ninetyeast Ridge until final separation occurred in the Late Cretaceous. In the Late Cretaceous, India separated from Madagascar.
Deep water passages between the Tethys, the Atlantic, the Pacific, and the developing Indian Ocean formed during the Late Cretaceous. There were many isolated land areas in the Late Cretaceous, but they were mostly separated by epicontinental seas.
This facility was developed with support from the Deutsche Forschungsgemeinschaft. The plate tectonic reconstructions were developed with support from the Deutsche Forschungs-gemeinschaft, from the Donors of The Petroleum Research Fund administered by the American Chemical Society, and through grants EAR 9320136 and EAR 9405737 from the Earth Sciences Section of the U.S. National Science Foundation.
REFERENCES
Berggren, W. A., Kent, D. V., Aubry, M. P., and Hardenbol, J., Eds., 1995, Geochronology, Time Scales and Global Stratigraphic Correlations: A Unified Temporal Framework for an Historical Geology, SEPM Special Publication No. 54, Berggren, W. A., Kent, D. V., and Hardenbol, J., eds.: Tulsa, Oklahoma, SEPM - Society for Sedimentary Geology, p. 392.
Burke, C. A., and Drake, C. L., Eds., 1970, Geology of Continental Margins: Berlin, Springer Verlag.
Choubert, G., and Faure-Muret, A., 1976, Geological World Atlas: Paris, UNESCO, p. 22 sheets with explanations.
Cox, A., and Hart, R. B., 1986, Plate Tectonics: How It Works: Oxford, UK, Blackwell Scientific Publications.
Dercourt, J., Ricou, L. E., and Vrielynck, B., Eds., 1992, Atlas Tethys Paleoenvironmental Maps: Paris, Gauthier-Villars, p. 307.
Harrison, C. G. A., and Lindh, T., 1982, A polar wandering curve for North America during the Mesozoic and Cenozoic: Journal of Geophysical Research, v. 87, p. 1903-1920.
Mueller, R. D., Royer, J.-Y., and Lawver L. A., 1993, Revised plate motions relative to the hotspots from combined Atlantic and Indian Ocean hotspot tracks: Geology, v. 21, p. 275-278.
Pearson II, F., 1990, Map Projections: Theory and Applications: Boca Raton, FL, CRC Press, Inc.
Ronov, A. B., Khain, V. E., and Balukhovsky, A. N., 1989, Atlas of Lithological-Paleogeographical Maps of the World: Mesozoic and Cenozoic of Continents and Oceans, Barsukov, V. L., and Laviorov, N. P., eds.: Moscow, Editorial Publishing Group VNIIZarubezh-geologia, p. 79.
Smith, A. G., Smith, D. G., and Funnell, B. M., 1994, Atlas of Mesozoic and Cenozoic Coastlines: Cambridge, Cambridge University Press, p. 99.
Snyder, J. P., 1982, Map projections used by the U.S. Geological Survey: U.S. Geological Survey Bulletin 1532, Washington, D. C., U. S. Government Printing Office, p. 1-313.
Sprinsky, W. H., and Snyder, J. P., 1986, The Miller Oblated Stereographic Projection for Africa, Europe, Asia, and Australia: The American Cartographer, v. 13, p. 253-261.
van der Voo, R., 1990, Phanerozoic paleomagnetic poles for Europe ad North America and comparison with continental reconstructions: Reviews of Geophysics, v. 28, p. 167-206.
Watkins, J. S., and Drake, C. L., Eds., 1982, Studies in Continental Margin Geology: American Associationof Petroleum Geologists Memoir 34, Tulsa, Oklahoma, American Association of Petroleum Geologists.
Wilson, K. ., 1989, Mesozoic Suspect Terranes and Global Tectonics, Ph. D. Thesis: Boulder, Colorado, University of Colorado, p. 372.
Wilson, K. M., Rosol, M. J., and Hay, W. W., 1989a, Global Mesozoic reconstructions using revised contiental data and terrane histories: a progress report, in Hillhouse, J. W., ed., Deep Sructure and Past Kinematics of Accreted Terranes, American Geophysical Union/IUGG Monograph 50/5: Wahington, D. C., American Geophysical Union, p. 1-40.
Wold, C. N., Hay, W. W., and Wilson, K. M., 1994, Eine verbesserte Anpassung von Südamerika an Afrika: Die Geowissenschaften, v. 12, no. 2, p. 48-54.
Reference Frames
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