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

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32 A WYOMING : COLOR, DO A I SOUTH'CENTRAL WYOMING I F,~ONT RANGE SUNDANCE FORMATION " Jurossic Rocks 90 1 500 60 200 0 I0 20 miles E: ~o ,oo o ,; 2'o,~ 0 0 meters feet Fig. 14. Restored cross-section showing Upper Triassic eolian deposits in Jelm Formation. Location shown on Fig. 12. Member represents the youngest Triassic deposits on the Colorado Plateau. It can perhaps be inferred that youngest Rock Point strata are nearly conformable with overlying Lukachukai units and that it is no coincidence that this is where some of the thickest Triassic eolian deposits occur. The thickest Upper Triassic rocks of the West- em Interior occur across the northern edge and along the east flank of the Defiance upwarp. Thus this long-ranging positive area was a basin during the Late Triassic. This area lies along the Zuni trend as defined by Blakey (this volume). It was in this low area that the only known Triassic eolian deposits on the Colorado Plateau were deposited. In southwestern Colorado, these rocks are assigned to the upper member of the Dolores For- mation (Blodgett, 1984). Eolian deposits consist of cross-stratified sandstone of dune origin and laminated to hummocky sandstone of sand-sheet origin, both intercalated with fluvial and lacustrine deposits (Harshbarger et al., 1957; Stewart et al., 1972; Blodgett, 1984). We are unable to construct either isopach maps or percentage-of-eolian-strata maps from existing literature or unpublished in- formation known to us. Figure 13 shows a rough outline of known and inferred eolian strata in Upper Triassic rocks of the Four Comers region. Temporal correlation with eolian strata of the Jelm Formation to the north is possible but un- proven. Lower Jurassic I erg deposits The Lower Jurassic Wingate Sandstone forms a persistent vertical cliff throughout the canyon- lands of southeastern Utah and adjacent Arizona and Colorado. Plagued by a series of miscorrela- tions, especially in northwestern New Mexico, the presently accepted eastern margin is shown on Fig. 15. Only the southwestern and eastern margins of eolian rocks, where the Wingate intertongnes with the Dinosaur Canyon Member of the Moenave Formation (Fig. 16 and Table 4), are exposed and reasonably well understood. The na- ture of the formation to the west, northwest, and northeast is uncertain although we discuss our inferences later in this paper. As discussed above, the present terminology of the Wingate Sandstone is somewhat confusing. North, northwest and west of Kayenta, Arizona, the Wingate Sandstone unconformably overlies the Upper Triassic Chinle Formation and in this region the formation is undivided. East, southeast and south of Kayenta, the formation includes the lower Rock Point Member which is equivalent to the upper Chinle Formation (Harshbarger et al., 1957). In this region the upper part of the formation (the Wingate Sandstone, undivided to the north) is assigned to the Lukachukai Member. Our isopach and facies map (Fig. 15) concerns only the Wingate Sand- stone (undivided) and Lukachukai Member of the Wingate Sandstone; the Rock Point Member of the Wingate Sandstone (Chinle equivalent) is not included. An eolian origin for most of the Wingate Sandstone has long been accepted; however, the details of eolian sedimentation have yet to appear in the literature. Tabular cosets 2-5 m thick com- prised of trough sets filled with climbing wind-rip- ple lamination have been observed at several local-
WES TERN A BL.4CK MESA KAYEN "r& FM MO NUMEN T VALLEY A' I ':~"~~:~'::!;~ ,~_ ~i:::ii:i-!:::.;::::.;:ii.:/!::;i;.:!~.~:;::::!] I ~ ~ ~,,..~z,-~- ~-.._..:.-...:.:.::: .. ':.'.....,. ~, t • ..'.:...."~ ~ : ~ - ' ~ "':: ..... " ......... " "i." ~'! : ~" .": :'.".::.'".'."" ". ': ~,e~...
Page 1 and 2: Sedimentary Geology, 56 (1988) 3-12
Page 3 and 4: method of presentation because of t
Page 5 and 6: The presentation of each eolian-bea
Page 7 and 8: A A' MCNTANA WYOMING I BIGHORN POWD
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 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_
Page 39: 117 ° 112 ° 107 ° 102 ° ' ¢ '
Page 42 and 43: G (B) SOURCES OF DATA FOR MIDDLE JU
Page 45 and 46: pp. 47"50 46 ° 41 `= 36 c -=-=.=.
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".
Page 56 and 57: 58 A A' WYINE NEICO WIND RIVER LARA
Page 58 and 59: 60 F F' SS AT MESITA Recopture Mbr
Page 60 and 61: 62 member is unconformably overlain
Page 62 and 63: 64 B UTAH [ ARIZONA LAKE POWELL " I
Page 64 and 65: 66 misleading. The eolian beds are
Page 66 and 67: 117 ° 112 ° 107 ° 102 ° ' ¢ '
Page 69 and 70: pp. 71-74 46 ° 41 ° 36 ° 31'= 11
Page 71: ~o ~o o o o I I | I + O I I I -----
Page 74 and 75: 76 the logs so the contour lines ar
Page 76 and 77: 78 TABLE 1 Methodology used in cons
Page 78 and 79: 80 TABLE 2 (continued) Section Auth
Page 80 and 81:
82 TABLE 2 (continued) Section Auth
Page 82 and 83:
Page 84 and 85:
Page 86 and 87:
88 TABLE 4 Data base for Wingate Sa
Page 88 and 89:
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Page 96 and 97:
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100 TABLE 6 (continued) Section Aut
Page 100 and 101:
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118 Deposits of the Western Interio
Page 118 and 119:
120 Arizona, New Mexico, and Utah.
Page 120 and 121:
122 O'Sullivan, R.B., 1984. Stratig
Page 122 and 123:
124 Thaden, R.E., Thrites, A.F. and
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