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An animated tectonic reconstruction of southwestern North America since 36 Ma

¹ Division of Geological and Planetary Sciences, MS 100-23, California Institute of Technology, Pasadena, California 91125, USA

View larger version (13K): [in this window] [in a new window]   Figure 1. Schematic diagram illustrating the method of using regional structural constraints to limit possible displacement paths in tectonic reconstructions. See text for discussion and explanation of letters

View larger version (96K): [in this window] [in a new window]   Figure 2. Map of western North America showing the primary tectonic elements in the reconstruction. The gray shaded polygons represent the physiographic or geologic expression of mountain ranges, which in the Basin and Range are fault bounded and separated by alluvial valleys. Dashed boxes are the locations of Figures 3–5. The numbers refer to specific mountain ranges identified in Tables 1–6

View larger version (60K): [in this window] [in a new window]   Figure 3. Map of the northern Basin and Range showing the kinematic data incorporated into the model. Black numbers indicate horizontal displacement amount, red bold numbers indicate age range of motion. Arrows indicate approximate magnitude and direction of individual relative displacements between polygons. Data compiled from Allmendinger et al., 1986; Armstrong et al., 2004; Bartley and Wernicke, 1984; Coogan and DeCelles, 1996; DeCelles et al., 1995; Dilles and Gans, 1995; Faulds et al., 2003; Hardyman et al., 1984; Hintzi, 1973; Hudson and Oriel, 1979; Lee, 1999; Miller et al., 1999; Niemi, 2002; Niemi et al., 2004; Smith, 1992; Smith et al., 1990; Smith and Bruhn, 1984; Stockli, 2000, 2001; Surpless, 1999

View larger version (56K): [in this window] [in a new window]   Figure 4. Map of the central Basin and Range showing the kinematic data incorporated into the model. Motion of the Sierra Nevada with respect to the Colorado Plateau in this region is predominantly constrained by two distinctive sedimentary deposits (indicated as stars and hexagons) offset along extensive normal and strike-slip fault systems. Arrows indicate approximate magnitude and direction of individual relative displacements between polygons. Black numbers indicate horizontal displacement amount, bold red numbers indicate age range of displacement. Data from Axen et al., 1990; Brady et al., 2000; Burchfiel, 1968; Burchfiel et al., 1987; Cemen et al., 1985; Duebendorfer et al., 1998; Fitzgerald et al., 1991; Fowler and Calzia, 1999; Guth, 1989; Holm and Dokka, 1991, 1993; Hoisch and Simpson, 1993; Niemi et al., 2001; Snow and Lux, 1999; Snow and Wernicke, 1989, 2000; and Wernicke et al., 1988

View larger version (64K): [in this window] [in a new window]   Figure 5. Map of the Mojave and Southern Basin and Range region showing distribution of strike-slip faults (bold lines), vertical axis rotation data (curved arrows), and extensional offsets (straight arrows). For strike-slip faults, reported slip amounts (black numbers) are contrasted with model slip (bold blue numbers). For extension and rotation constraints, black numbers indicate horizontal displacement or amount of rotation, bold red numbers indicate age range of deformation. Red shaded area is the area of the model that undergoes 24–18 Ma core complex extension in the Mojave region. WRT indicates measured displacement is "with respect to" the Colorado Plateau. Data from Ballard, 1990; Bassett and Kupfer, 1964; Dokka, 1983, 1989; Foster et al., 1993; John and Foster, 1993; Hamilton, 1987; Howard and Miller, 1992; Miller, 1980; Miller and Morton, 1980; Powell, 1981; Richard et al., 1992; Richard, 1993; Richard and Dokka, 1992; Spencer and Reynolds, 1989; Spencer et al., 1995; Schermer et al., 1996; Walker et al., 1995

View larger version (84K): [in this window] [in a new window]   Figure 6. A: First-order constraints for displacement along the San Andreas fault and associated displacements to the west. Arrows indicate approximate magnitude and direction of individual relative displacements between polygons. Black numbers indicate horizontal displacement amount, bold red numbers indicate age range of displacement. Stippled areas labeled EPG show distribution of Eocene Poway Group and equivalents. Stippled area labeled SEPG marks the location of the source area for the Eocene Poway Group. Triangle pattern (Gulf of California), and stars (central California) show distribution of correlative volcanic units offset by the San Andreas–Gulf of California rift system. MTJ is modern location of the Mendocino triple junction. Data from Abbott and Smith, 1989; Bohannon and Geist, 1998; Crouch and Suppe, 1993; Dickinson and Wernicke, 1997; Dickinson, 1996; Graham et al., 1989; Hornafius et al., 1986; Luyendyk, 1991; Matthews, 1979; Oskin et al., 2001. B: Successive locations of the eastern edge of Pacific plate oceanic lithosphere relative to stable North America. The thick colored lines represent minimum extent of oceanic lithosphere at the times shown (from Atwater and Stock, 1998). These positions constrain the maximum westward extent of continental North America through time

View larger version (63K): [in this window] [in a new window]   Figure 7. Reconstructed paleogeographic maps (from 0–6 Ma) used in the reconstruction. The color scheme is the same as that for the animation, yellow polygons on a white background. Yellow polygons indicate areas where there are no data for how the region is deforming. Polygons (ranges) that have data associated with their motion are orange when associated faulting is inactive and red during fault activity. Panels represent different time slices: (a) 0 Ma, (b) 2 Ma, (c) 4 Ma, and (d) 6 Ma

View larger version (65K): [in this window] [in a new window]   Figure 8. Reconstructed paleogeographic maps (from 8 to 14 Ma) used in the reconstruction. The color scheme is the same as Figure 7. Panels represent different time slices: (a) 8 Ma, (b) 10 Ma, (c) 12 Ma, and (d) 14 Ma

View larger version (56K): [in this window] [in a new window]   Figure 9. Reconstructed paleogeographic maps (from 16 to 36 Ma) used in the reconstruction. The color scheme is the same as Figure 7. Panels represent different time slices: (a) 16 Ma, (b) 18 Ma, (c) 24 Ma, (d) 30 Ma, and (e) 36 Ma

View larger version (48K): [in this window] [in a new window]   Figure 9. (continued).

View larger version (76K): [in this window] [in a new window]   Figure 10. "Instantaneous" velocity fields based on 2 m.y. averages from 0 to 18 Ma, and 6 m.y. averages from 18 to 36 Ma. Arrows show displacement with respect to stable North America and were determined by connecting the centroids of specific ranges at one time with the centroid of the same range in a later time. Because the motion of individual ranges can be very slight at the eastern edge of the model, the line lengths representing each incremental offset were uniformly doubled. Map base is the palinspastic map from the youngest time in the 2 or 6 m.y. interval

View larger version (55K): [in this window] [in a new window]   Figure 10. (continued).

View larger version (69K): [in this window] [in a new window]   Figure 11. Map illustrating paths of various ranges from 0 to 36 Ma. Solid black circles indicate the positions of the ranges at 8 Ma, and open circles represent the positions of the ranges at 12 Ma. The westernmost point on each line represents the current location of each range. The easternmost point on the path represents the location of the range at 36 Ma. The blue arrows represent the motion of the Mendicino triple junction, with its position shown at 24, 15, 8, and 0 Ma (Atwater and Stock, 1998)