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Age, provenance, and tectonic setting of Paleoproterozoic quartzite successions in the southwestern United States

James V. Jones, III^1,, James N. Connelly¹, Karl E. Karlstrom², Michael L. Williams³ and Michael F. Doe⁴

¹ Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas 78712, USA
² Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA
³ Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst, Massachusetts 01003, USA
⁴ Department of Geology and Geological Engineering, Colorado School of Mines, 1516 Illinois Street, Golden, Colorado 80401, USA

View larger version (74K): [in this window] [in a new window]   Figure 1. Paleoproterozoic quartzites of southwestern Laurentia. Inset shows possible western Rodinian continents and global Proterozoic quartzite occurrences (relative positions all uncertain; modified from Karlstrom et al., 2001; Sears and Price, 2000; Giles and Betts, 2000). Quartzite localities mentioned in text are labeled accordingly. Faults shown without thrust teeth are either inferred thrust faults or strike-slip faults. The outlines of possible depocenters are inferred and are discussed in the text.

View larger version (71K): [in this window] [in a new window]   Figure 2. Geology of the Blue Ridge area, Colorado. (A) Generalized geologic map of the Proterozoic metasedimentary succession exposed along Blue Ridge, Colorado (after Reuss, 1970, 1974). Locations of geochronology samples are indicated by stars. Paleocurrent data from lower quartzite unit are from Reuss (1974). (B) Schematic geologic cross section across Gooseberry Gulch syncline (from Reuss, 1970, 1974). (C) Field photograph of block of quartzite bedrock from north side of syncline near J01-BR1 sample locality. (D) Schematic diagram (not to scale) of interpreted crosscutting relationships and summary of new U-Pb igneous crystallization and detrital zircon ages.

View larger version (19K): [in this window] [in a new window]   Figure 3. U-Pb concordia diagrams for samples from Blue Ridge, Colorado. Ages were determined by linear regression through the data except where indicated, and probability of fit (%) is indicated in parentheses. For complete data set, see GSA Data Repository Table DR1 (see text footnote 1).

View larger version (66K): [in this window] [in a new window]   Figure 4. Relative probability diagrams for 207Pb/206Pb ages and U-Pb concordia diagrams for detrital zircon in Paleo-proterozoic quartzites and metaconglomerates exposed in southern Colorado and northern New Mexico. Plots represent all grains analyzed, and ages of significant peaks are indicated. See Table 1 for a summary of all ages, and see Figures 5–7 for plots of nearly concordant (3%) Paleoproterozoic grains only. For complete data set, see GSA Data Repository Table DR3 (see text footnote 1).

View larger version (36K): [in this window] [in a new window]   Figure 5. Lithostratigraphic section of quartzite and conglomerate (Q) and pelite (P) of the Uncompahgre Formation (after Harris and Eriksson, 1990). Paleocurrent data are summarized from Harris and Eriksson (1990) and are shown next to the corresponding stratigraphic interval. Open bars represent trough cross-beds, and filled bars represent tabular-planar to tangential cross strata. Detrital zircon 207Pb/206Pb ages (3% discordant, Proterozoic grains) and basement U-Pb crystallization ages for the Needle Mountains, Colorado, are also summarized. The Vallecito Conglomerate is interpreted to lie stratigraphically beneath the Uncompahgre Formation (Zinsser, 2006), but the thickness and detailed stratigraphy of this unit are not completely understood. Relative probability diagrams for: (A) Uncompahgre Formation upper Q4 quartzite; (B) Uncompahgre Formation lower Q4 quartzite; (C) Uncompahgre Formation basal conglomerate; (D) Fall Creek Formation of the Vallecito Conglomerate; and (E) basement U-Pb crystallization ages for exposures in the Needle Mountains (Gonzales and Van Schmus, 2007; Jones et al., 2005; Gonzales, 1997).

View larger version (17K): [in this window] [in a new window]   Figure 6. Summary of detrital zircon 207Pb/206Pb ages (3% discordant, Proterozoic grains) and basement U-Pb crystallization ages for the Gunnison area, Colorado, and northern New Mexico. Relative probability diagrams for: (A) quartzite exposed along Cebolla Creek, Colorado; (B) basement U-Pb crystallization ages in exposures in the Gunnison area, Colorado (Bickford et al., 1989b; Jessup et al., 2006); (C) Ortega quartzite exposed in the Tusas Mountains, New Mexico; and (D) basement U-Pb crystallization ages for exposures in northern New Mexico (Karlstrom et al., 2004, and references therein).

View larger version (15K): [in this window] [in a new window]   Figure 7. Summary of detrital zircon 207Pb/206Pb ages (3% discordant, Proterozoic grains) and basement U-Pb crystallization ages for the Salida and Cañon City area, Colorado. Relative probability diagrams for: (A) quartzite exposed along Phantom Canyon; (B) quartzite exposed at Blue Ridge; (C) basal conglomerate exposed at Blue Ridge; (D) quartzite exposed in the Sangre de Cristo Mountains; and (E) basement U-Pb crystallization ages for exposures in the Salida and Cañon City area, Colorado (Bickford et al., 1989a, 1989b; Jones and Connelly, 2006).

View larger version (19K): [in this window] [in a new window]   Figure 8. U-Pb concordia diagram for isotope dilution–thermal ionization mass spectrometry (ID-TIMS) analysis of youngest identified detrital zircon grains from quartzite exposed along Phantom Canyon, Colorado. The age was determined by linear regression through the three fractions, and probability of fit (%) is indicated in parentheses. Zircon fraction numbers refer to grain identification numbers reported in Jones (2005). For complete data set, see GSA Data Repository Table DR2 (see text footnote 1).

View larger version (25K): [in this window] [in a new window]   Figure 9. Cross sections of the Mazatzal thrust belt, Mazatzal Mountains, Arizona, showing the present (A) and restored (B) geometry of the Mazatzal Group. The Mazatzal Group consists of ~1.5 km of metarhyolite, quartzite, and schist that were deposited starting at 1701 ± 2 Ma (Cox et al., 2002b). The restored section indicates that the depositional basin was bounded by growth faults, which accommodated the influx of locally derived sediment. Basin inversion and development of the fold-and-thrust belt occurred during the Mazatzal orogeny and resulted in 35%–40% shortening (Doe and Karlstrom, 1991). This reinterpretation of the South Fork of Deadman Creek section (Doe and Karlstrom, 1991) used the original prerestored section and was updated by Doe through new mapping of digitized air photos, and it was restored using Midland Valley's 2DMove software.

View larger version (30K): [in this window] [in a new window]   Figure 10. Tectonic model for quartzite deposition and deformation in the Yavapai Province, southwestern United States. Basin development, quartzite sedimentation, and widespread rhyolitic volcanism (and contemporaneous granitic magmatism) are interpreted to have occurred in the upper plate of a north-dipping subduction zone during an interval of slab rollback following the ca. 1.70 Ga culmination of the Yavapai orogeny. Basin closure and quartzite burial and deformation occurred during the Mazatzal orogeny. CB—Cheyenne Belt. Figure was modified from Figure 3 of Giles et al. (2002) (also after Magnani et al., 2004; Selverstone et al., 1999; Karlstrom et al., 2005).