Synthesis of late Paleozoic and Mesozoic eolian deposits of the ...

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Many eofian sandstones have one or more margins that were removed by later erosion or are covered by younger strata and no subsurface data is available. This is most common along the western and southern margins of the region of study. Late Paleozoic eolian deposits Introduction The late Paleozoic eolian sandstones range in age from Atokan to late Leonardian and possibly Guadalupian (Fig. 2). They are divided here into five erg-bearing sequences: Pennsylvanian, Wolf- campian, Leonardian I, Leonardian II and Leonardian III. Each sequence is intercalated with or bracketed by fossil-bearing rocks. Penn- sylvanian eolian deposits are primarily distributed north of the Ancestral Rockies, whereas Permian ergs are extensively distributed to the southwest of these major barriers. Figure 4 shows the distribution of late Paleozoic tectonic elements that af- fected Pennsylvanian and Permian deposition. Pennsylvanian eolian deposits Pennsylvanian eolian deposition is widespread and has been documented from the lower Casper Formation (Steidtmann, 1974), lower Tensleep Sandstone (Mankiewicz and Steidtmann, 1979; Kerr, this volume) and Quadrant Sandstone (Saperstone and Ethridge, 1984) in Wyoming and adjacent Montana and Colorado, in the lower Weber Sandstone of Utah, Wyoming and Col- orado (Bissell and Childs, 1958; Driese and Dott, 1984), and from the Honaker Trail Formation of the Hermosa Group of southeastern Utah (Loope, 1984). In addition, eolian sandstone is present in the Manakacha and Wescogame Formations of the Supai Group in northern Arizona but has yet to be documented in the literature. The Pennsyl- vanian age of each of the above is well documented by intercalated fossil-beating marine rocks. Figure 5 and Table 2 present the data base for Pennsylvanian and Permian eolian deposits. The Pennsylvanian deposits, although almost certainly a series of separate ergs ranging from Atokan to Virgilian in age, are herein isopached on a single map. Eolian-bearing units consist of several stratigraphic units across Wyoming, southern Montana, northern Utah and northern Col- orado (Fig. 6). The lack of detailed stratigraphic and sedimentologic data prevent further subdivi- sion. The eolian deposits in southeastern Utah and the Grand Canyon region do not have sufficient data available to construct isopachs; only their known and inferred lateral distribution are shown. For simplicity, the northern sand body will be referred to as the Tensleep complex and it also includes part of the Weber, Quadrant and Casper stratigraphic units. The Tensleep forms a broad sheet across the Central and Northern Rocky Mountain region that generally ranges to 100 m thick but the erg-bearing interval locally exceeds 300 m in northern Utah and 500 m in southwest- ern Montana (Bissell and Childs, 1958; Mallory, 1967; Saperstone and Ethridge, 1984). Figure 7A, B and C shows the Tensleep and related units in cross-section. Although the unit is renowned for exposures of large-scale, high-angle sand-flow strata that dip to the south and southeast (Steidt- mann, 1974; Mankiewicz and Steidtmann, 1979), detailed sedimentologic studies have documented a broad variety of eolian stratification styles in- cluding small-scale trough and planar-tabular wind-ripple cross strata, horizontal to gently in- clined wind-ripple strata, and wet and dry inter- dune deposits (Mankiewicz and Steidtmann, 1979; Driese and Dott, 1984; Saperstone and Ethridge, 1984; Kerr, this volume; J. Haslett, pets. commun., 1986). In addition, each of the above authors have noted interbedding of eolian and marine-sabkha strata within the Tensleep Sandstone, especially near erg-deposit margins. The Tensleep complex is a north-northwest- trending sandstone body (Fig. 6) bordered by marine clastic and carbonate rocks to the west (Oquirrh and Wood River Groups and related rocks), marine carbonate to the east (lower Min- nelusa Formation and related rocks), and fluvial clastic rocks to the south (Maroon Formation and Fountain Arkose; Maughan and Wilson, 1960). Little is known about the erg margins to the north, although Stewart and Walker (1980) reported Pen- nsylvanian eolian deposits in the Rockies of southern Canada.
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Page 1 and 2: Sedimentary Geology, 56 (1988) 3-12
Page 3 and 4: method of presentation because of t
Page 5: The presentation of each eolian-bea
Page 9 and 10: 46 ° 41 o 36' 31 ° 117 ° 112 °
Page 11: 46 ° ;I , 41 ° 117 ° 112 ° ~ '
Page 15: 117 ° 112 ° #-v~ ~ + / .~.,
Page 18 and 19: 46 ° 41 ° 36 ° 31 c 117 ! ° 112
Page 21 and 22: pp. 23-26 46 ° 41 o 36 ° 31 ° 11
Page 23: - 4' 117 ° 112 ° 107 ° 102 ° '
Page 26 and 27: 28 east into the Central Colorado t
Page 28 and 29: 30 Blakey (1986) documented the pre
Page 30 and 31: 32 A WYOMING : COLOR, DO A I SOUTH'
Page 32 and 33: 34 the southern Monument Uplift and
Page 34 and 35: , 117 ° 112 ° 107 ° 102 ° 40o~
Page 37 and 38: pp. 39-42 46 ° 41 ° 36 ~ 31 c -v_
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Page 42 and 43: G (B) SOURCES OF DATA FOR MIDDLE JU
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Page 47: 117 ° 112 ° 107 ° 102 ° ! l I
Page 50 and 51: 52 C) A ID.~HO I WYOMING NORTHERN W
Page 52 and 53: 54 during the Jurassic Period (Pete
Page 54 and 55: 56 called the "Reservation facies".
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58 A A' WYINE NEICO WIND RIVER LARA
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60 F F' SS AT MESITA Recopture Mbr
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62 member is unconformably overlain
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64 B UTAH [ ARIZONA LAKE POWELL " I
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66 misleading. The eolian beds are
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117 ° 112 ° 107 ° 102 ° ' ¢ '
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pp. 71-74 46 ° 41 ° 36 ° 31'= 11
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~o ~o o o o I I | I + O I I I -----
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76 the logs so the contour lines ar
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78 TABLE 1 Methodology used in cons
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80 TABLE 2 (continued) Section Auth
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88 TABLE 4 Data base for Wingate Sa
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100 TABLE 6 (continued) Section Aut
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118 Deposits of the Western Interio
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120 Arizona, New Mexico, and Utah.
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122 O'Sullivan, R.B., 1984. Stratig
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124 Thaden, R.E., Thrites, A.F. and
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