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The Chuska erg: Paleogeomorphic and paleoclimatic implications of an Oligocene sand sea on the Colorado Plateau

Steven M. Cather^,1, Sean D. Connell¹, Richard M. Chamberlin¹, William C. McIntosh¹, Glen E. Jones¹, Andre R. Potochnik², Spencer G. Lucas³ and Peggy S. Johnson⁴

¹ New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, New Mexico 87801, USA
² 18 E. Juniper Avenue, Flagstaff, Arizona 86001, USA
³ New Mexico Museum of Natural History, 1801 Mountain Road NW, Albuquerque, New Mexico 87104, USA
⁴ New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, New Mexico 87801, USA

View larger version (43K): [in this window] [in a new window]   Figure 1. Map showing Oligocene eolian sandstone localities and Oligocene volcanic fields and intrusions in relation to relict Laramide basins, uplifts, and the schematic Laramide paleodrainage net for the Colorado Plateau (after Potochnik, 2001b). Selected Laramide uplifts are: Du—Defiance uplift; Zu—Zuni uplift; Ku—Kaibab uplift; Mu—Monument uplift; SJu—San Juan uplift; Uu—Uinta uplift. Laramide basins are: Ub—Uinta Basin; GRb—greater Green River Basin; Pb—Piceance Basin; NPb—North Park-Middle Park Basin; Db—Denver Basin; Cb—Claron Basin; SPb—South Park Basin; Rb—Raton Basin; SJs—San Juan sag; Gb—Galisteo-El Rito Basin; CJb—Carthage-La Joya Basin; Sb—Sierra Blanca Basin.

View larger version (56K): [in this window] [in a new window]   Figure 2. (A) Digital elevation model for the Chuska Mountains area. Flat top of the southern Chuska Mountains is defined by silica-cemented zones within the Chuska Sandstone that formed during early, phreatic diagenesis (see text). Note the eastern boundary structure of the Laramide Defiance uplift (the Defiance monocline, DM) is buried by the Chuska Sandstone. Selected features of the Navajo volcanic field are Buell Park diatreme (BP), Narbona Pass maar (NP), sill at Beautiful Mountain (BM), and the Hidden Valley maar (HV). Volcanic necks at Roof Butte (RB) mark highest part of range (2980 m). (B) Simplified geologic map of the Chuska Mountains area, after Wright (1956).

View larger version (156K): [in this window] [in a new window]   Figure 3. Eolian crossbeds in Chuska Sandstone (Narbona Pass Member) at 2950 m elevation near Roof Butte, northern Chuska Mountains. Hammer for scale at center of photograph.

View larger version (199K): [in this window] [in a new window]   Figure 4. Thin section of eolian sandstone of Narbona Pass Member of the Chuska Sandstone showing isopachous rims of chalcedony cement, indicative of cementation in a phreatic environment. Width of field is 0.5 mm.

View larger version (43K): [in this window] [in a new window]   Figure 5. Chronostratigraphic correlation diagram for eolianites and associated rocks in the Chuska Mountains and the Mogollon-Datil volcanic field. (A) Chuska Mountains, showing members of Chuska Sandstone. (B) Western Mogollon-Datil field. (C) Northern Mogollon-Datil field. See text for sources of radioisotopic age data. Tmv—lava flows associated with maar at Narbona Pass; Tbp—Bishop Peak Tuff; Tcl—volcaniclastic unit of Cañon del Leon; Ttl—tuff of Luna; Tcb—Caballo Blanco Tuff; Tdc—Davis Canyon Tuff; Tvp—Vicks Peak Tuff; Tss—Squirrel Springs Canyon Andesite; Tsp—Shelly Peak Tuff; Tbg—Bloodgood Canyon Tuff; Tdw—Datil Well Tuff; Trh—Rock House Canyon Tuff; Tbc—Blue Canyon Tuff; Thm—Hells Mesa Tuff; Tcp—South Crosby Peak Formation; Tlj—La Jencia Tuff; Tlp—La Jara Peak Basaltic Andesite; Ths—basaltic andesite of Hidden Spring; Tsc—South Canyon Tuff; Tlm—Lion Mountain Andesite; Tcba—basaltic andesite of Crosby Mountains; Tts—tuff of Turkey Springs. Numbers in parentheses indicate radioisotopic age (Ma).

View larger version (34K): [in this window] [in a new window]   Figure 6. Simplified geologic map of the northern Mogollon-Datil volcanic field showing thickness distribution of Oligocene eolian sandstone. Thickness data from Wrucke (1961), Chamberlin and Harris (1994), Harrison (1980), Bornhorst (1976), Lopez (1975), Cather (1986), Coffin (1981), Ferguson (1986), Ratté (1980, 1981, 1989), and Lawrence and Richter (1986). Circled numerals correspond to wells: (1) Belcher 1/State; (2) Alpine 1/Federal. Hfs—Hickman fault system; RLfs—Red Lake fault system; Ab—Albuquerque Basin; Sab—San Agustin Basin; Rg—Reserve graben; Bg—Blue graben; Dm—Datil Mountains; Gm—Gallinas Mountains.

View larger version (151K): [in this window] [in a new window]   Figure 7. Lenticular, nonwelded ignimbrite (Tvp—Vicks Peak Tuff; 28.8 Ma) inter-bedded with eolian sandstone near Mangas, New Mexico. Note only minor erosion of the avalanche face of dune beneath ignimbrite.

View larger version (61K): [in this window] [in a new window]   Figure 8. Digital elevation model for the Albuquerque Basin area, showing basin boundaries (dashed lines) and cross-section line (Fig. 10). Wells are: (1) Tamara #1-Y; (2) West Mesa Federal #1; (3) Shell Isleta #2; (4) TransOcean Isleta #1.

View larger version (18K): [in this window] [in a new window]   Figure 9. Gamma-ray and conductivity logs for Tamara #1-Y well. The unit of Isleta #2 is interpreted to be largely eolian in this well. amsl—above mean sea level; mmhos—millimhos (= 10–3 siemens).

View larger version (18K): [in this window] [in a new window]   Figure 10. Cross-section A–A' of Cenozoic rocks in the northern and central Albuquerque Basin, showing interpreted relationships between Oligocene eolian and non-eolian strata. Cross-section line is shown in Figure 8. Modified from Connell et al. (2001).

View larger version (109K): [in this window] [in a new window]   Figure 11. Topography of selected modern ergs. Contour interval is 100 m; elevations are relative to mean sea level. Dotted white lines delimit areas of relatively complete eolian sand cover. (A) Grand Erg Oriental, Algeria and Tunisia; (B) Great Sand Sea, Egypt and Libya; (C) Grand Erg Occidental, Algeria; (D) Aoukâr, Makteïr, and Ouarane ergs, Mauritania; (E) northwestern Simpson Desert, Australia; (F) Peski Kyzyl-Kum and Peski Kara-Kum, Uzbekistan and Turkmenistan; (G) Erg Bilma-Tènèrè, Niger; (H) Takla Makan, People's Republic of China; (I) Rub'al Khali, Saudi Arabia. Slope data for ergs are presented in Table 4.

View larger version (12K): [in this window] [in a new window]   Figure 12. Hydrologic model to predict the lateral extent of a convex-up dune field necessary to support a phreatic groundwater system 300 m thick. See text for discussion.

View larger version (40K): [in this window] [in a new window]   Figure 13. Map showing interpreted early Oligocene paleogeography in the Colorado Plateau-Rocky Mountain area in relation to relict Laramide uplifts and selected Miocene sedimentary deposits. A–E is line of section for Figure 14. Selected Laramide uplifts are: Du—Defiance uplift; Zu—Zuni uplift; Ku, Kaibab uplift; Mu—Monument uplift; SJu—San Juan uplift; Uu—Uinta uplift. See text for discussion.

View larger version (27K): [in this window] [in a new window]   Figure 14. Regional cross-section showing present-day elevations of reconstructed stratigraphic successions of Paleocene to Pleistocene age in relation to modern Colorado Plateau topography. Note that the elevation of strata in the southern (left) part of the cross section has been restored (vertical arrows above present base of Te) to account for structural lowering of the southern Colorado Plateau margin (see text). Unrestored elevations of top of eolian succession at (1) Escondida Mountain and (2) Escudilla Mountain shown by tic marks and circled numerals. Approximate 35 Ma chronostratigraphic datum, given by base of volcaniclastic unit of Cañon del Leon (35.6 Ma; Chamberlin and Harris, 1994) at Escondida Mountain and by the Bishop Peak Tuff (35.1 Ma, projected from nearby Alpine1/Federal well) at Escudilla Mountain; A range of elevations for the reconstructed 27- to 26-Ma top surface of the Chuska erg is depicted, using end-members based on steep versus average slopes of modern ergs (see text). The topographically highest points in the Chuska Mountains and San Juan Mountains are projected from areas north of the line of section.

View larger version (16K): [in this window] [in a new window]   Figure 15. Late Eocene to Recent aggradation and exhumation history of the central and southern Colorado Plateau relative to present-day elevations, based on a conservative (minimum) estimate of elevation of Chuska erg surface. Note that the Chuska Sandstone and Bidahochi Formation outcrops are 100 km apart.