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

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52 C) A ID.~HO I WYOMING NORTHERN WIND SOUTH-CENTRAL IO,~HO ~, RIVER MTNS. I SUNDANCE FM" I TWIN CREEK LS ;- ~-----~...~A P!PER F M I d-2 J-I~ • GYPSUM SPRINGS F M ~ ' ~ . . -- . • :..>..OGG~T. sA.oSTO~:.....i. :..:... ..:..:'.~~- ):::::i::.~.:::i i:~;.i.~.~;..i:i i>.:-::.>i!i..:::::::.i:!::.i;:.::::;::.-:!~~s ,,: . . . : . . . . . > . . . ~ RoC'~-~ f~ f 000[~ :500 m l I ill I t i 50oHI e°° O 50 km IH IO0 B B' u T~H I COLOR~DO OLUO U/NTA MTNS VERNAL I h~EEKER I - T W I N ~ K "ES REUS$ SS ' ": :~T':'. " NUGGET NAVAJO SANDSTON'E' " " Upper port .~ T ¢ :: ,' : . "~.'. ". , ; ~ ; : : "." :'." .'" " "i "~ ~'.: :'." " "L < Lower port" *::.~ ~¢" ~-~ ~ C~IN ~-3 - ~_-//~'--- -- EL_- - -:- _...-C, ~. ........ LH.oo - LL./.-.\Iooo~ . .... ~w~:. IH oo Lower Port j" ANKaREH FM 0 50~m oLUo C C' ZION L,aKE SALT ,~NTICLINE CANYON POWELL REGION i'ii!J?i:iiil ii i'i! ~ j . 2 ~ A P SS CARMEL FM AND PAGE SS g: ::; i: i: : :: :. : / ~ ° ~ " * ,,,Ooorn3OOm " • . .~ •..-.S "'" .'. , ! "- ' " O 40 m~ 5OO~ 2OO ~ t KAYENTA \ ~ " ~Tenny Tongue Conyon Tongue I w ~ ~ ~ = r J O 40 km In IOO oLUo transition zone 0 ~O 0 C~- Cg~oeF¢ Fig. 19. Restored cross-sections showing eolian deposits in Lower Jurassic II rocks. Locations shown on Fig. 17. also thinned eastward depositionally, but lack of stratigraphic markers within these deposits makes this difficult to confirm. The role of intertonguing of the crossbedded eolian beds with other strata must be understood when evaluating thickness variations in the late Early Jurassic. Hypothesized intertonguing of the Navajo Sandstone with the Middle Jurassic Carmel Formation reported by earlier workers (Wright and Dickey, 1963) is now known to involve another formation (the Page Sandstone) rather than the A I Navajo. Accordingly, the Aztec, Navajo, Glen Canyon and Nugget Sandstones are now thought to be unconformably overlain everywhere by Mid- dle Jurassic or younger strata (Peterson and Pipiringos, 1979). On the other hand, intertonguing at the base of the Aztec and Navajo Sand- stones has been documented by several workers (Harshbarger et al., 1957; Averitt, 1962; Wilson, 1965; Middleton and Blakey, 1983). How much lateral replacement of the uppermost or eolian part of the Nugget Sandstone by underlying strata
of the Bell Springs Member of the Nugget (Pipiringos, 1968; Doelger and Steidtmann, 1985) has not, to our knowledge, been determined but it is not considered to be appreciable. The direction of lateral replacement of Navajo or Aztec tongues by units in the underlying Kayenta Formation is only documented in a few areas, but where it has been determined it is consistent with paleowind patterns determined from crossbedding dip vector studies. Harshbarger et al. (1957, p. 22, pl. 2) report southeastward gradation of Navajo tongues into the Kayenta Formation in northeastern Arizona, which is parallel to the southeastward direction of eolian transport in this area during Early Jurassic time (Peterson, this volume). It is highly likely that the Lamb Point and Shurtz Sandstone Tongues of the Navajo in southwestern Utah (Averitt, 1962; Wil- son, 1965) are different names in different areas for the same tongue of the Navajo. If this correla- tion is correct, the tongue thins southwestward in the same direction (Fig. 19) that the winds moved in this area (Peterson, this volume). During Early Jurassic time an Andean:type magmatic arc extended northwestward from southern Arizona into California (Bilodeau and Keith, 1986). Eolian strata included in the isopach interval (Fig. 18) lap southward onto older rocks in this area, apparently because the erg migrated into highlands produced by uplift in the arc. Inter- fingering or interbedding of the eolian sand with arc volcanics was documented by Marzolf (1983a) and Bilodeau and Keith (1986). In this area, the upper boundary of the Lower Jurassic Series (and thus of the isopach interval) is difficult to de- termine owing to the difficulty of distinguishing Middle Jurassic volcanics that postdate strata of the isopach interval from Early Jurassic volcanics that were coeval with the eolian beds. Clearly, a study of the isotopic dates of the volcanics in this area is sorely needed. In summary, the isopach interval thins eastward owing primarily to truncation beneath the J-2 unconformity, and probably to some as yet undetermined amount of depositional thinning. The lower contact of the isopach interval is di- achronous, becoming younger generally toward the south owing to interfingering with and lateral replacement by non-eolian units in the Kayenta Formation and probably with non-eolian strata in the lower part of the Nugget and Glen Canyon Sandstones. In southern Arizona and California, the eolian unit appears to thin southward by onlap where it rests on the landward side of the Early Jurassic Andean-type magmatic arc. Intertonguing and southward regional replacement of the lower part of the Aztec and Navajo Sandstones by non- eolian units should be reflected in southward thinning of the isopach interval, but this is not ap- parent from the isopach map (Fig. 18). Although there may be several explanations for this, the simplest and most appealing is that the intertonguing does not involve an appreciable thickness of beds (100 m or less in most locations). Also, the zone of intertonguing is at or near the southern margin of Jurassic outcrops on the Col- orado Plateau so trends to the south are uncertain. Several positive and negative structural ele- ments (Fig. 20) are reflected by the configuration of the isopach lines. In northeastern Utah and adjacent areas, a trough is reflected as a west- southwest-trending area of thick Nugget and Glen Canyon Sandstones that coincides roughly with the present-day Uinta Mountains structural element. The Uinta Mountains element is known to have been active, either as a positive or negative structural feature, since Precambrian time (Bryant, 1985; Hansen, 1986) and movement in the Jurassic is therefore not unexpected. A parallel trend of thick Nugget Sandstone just northwest of the Uinta trough may reflect a separate trough or, by reconfiguring the isopach lines around the thin area between the two thick areas, both thick areas combined may reflect a somewhat complicated but considerably larger Uinta trough. Another thick trough-like area is suggested by the configuration of the isopach lines in southern Arizona but stratigraphic complexities and uncertainties as well as incomplete sections make such an interpre- tation speculative. A broad structural bench or terrace identified as the Monument bench (Fig. 20) is identifiable in southeastern Utah in the vicinity of the present-day Monument upwarp. Isopach and facies studies in this area indicate that this feature was tectonically active, either as a structural bench or uplift, all 53
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 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_
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 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 86 and 87: 88 TABLE 4 Data base for Wingate Sa
Page 98 and 99: 100 TABLE 6 (continued) Section Aut
Page 100 and 101:
102 TABLE 6 (continued) Section Aut
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
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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