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

lay in a sheltered lowland area protected from Salt
Wash fluvial processes by the Monument high.
Westerly to southwesterly winds transported the
eolian sand (Peterson, this volume), indicating that
it was derived largely from the Salt Wash alluvial
complex farther west. The topographic high also
produced a turbulent area on its leeward side that
favored the accumulation of wind-borne sand. The
structurally deepest part of the Late Jurassic San
Juan basin lay a few tens of kilometers south of
the Bluff-Junction Creek eolian complex (Santos
and Turner-Peterson, 1986), so the sand accu-
mulated on a structural slope or bench on the
northern flank of that basin. This compares well
o
n," z
with the structural-topographic setting of the Per-
mian Schnebly Hill-De Chelly eolian-bearing se-
quence on the sloping flank of the Holbrook basin.
The area of highest percentages of crossbedded
sandstone in the Bluff-Junction Creek forms a
sinuous belt extending northeastward from the
Monument high in southeastern Utah (Fig. 34).
The belt lies roughly parallel to wind flow (Peter-
son, this volume) and tends to lie either along the
thickest part of the complex or on the downwind
side of the northeast-trending lobe of the complex.
Although the Bluff and Junction Creek are readily
identified on drill hole logs, no attempt was made
to interpret the percent of eolian sandstone from
C C'
WYOMING I S. DAKOTA
WES TERN 'u SOU THERN
BLACK HILLS ] BLACK HILLS
(A) ~ ,. ~ ,UNKPAPA SS~ ~ LAKOTA FORMATION UNKPAPA SS~_ I
J-5 Redwoter Shale Mbr. Windy Hill Mbr. -= irdy Hil~ j.41
~ Z O SPEARFISH FM ~PR~GS rM ~ocKaae Beaver Mar.
TRIASSIC
0 I0 mi. ft 2001].]60 m
V-----V-n , m
0 I0 20 km 0 u'J O
D D'
NEW MEXICO I COLORADO
SAN JUAN BASIN I SOUTHWESTERN COLORADO
_~' ~ ~ Brushy Basin Member
/ ........ Canyon Memb.r ~, ,~ "~'-~_~ ~'~.~ ~
Recaplure 0 q" ~
•. ,~i,~ :':';'::
~!.s~.~...:.....:.~ ~ , , ~'~ ~-,,~-~.
'" "'"~':;":'~ Todilto Mefnber~. ...... .,.,.,:,,:.(.:.:'::.,:..,', OC -~
... .....(:-.::;I:~:EN'rRAOA' SS ~:~(.~.!!.!:-:::~(~!:,~!:::'.I:~::I.-.:.'.~:.):>"" " UNCOMPAHGRE
' ;,.:..::::'..::..;..'~:...!!...~::.:.:~:::...~;:.~:.,::.:-"" " UPLIFT
0 ~5 30 mi m ioorh3o 0 it
~ 1 50
0 50 km
0 0
Fig. 35. Restored cross-sections of Upper Jurassic eolian deposits of the Morrison Formation. Locations shown on Fig. 21.
I
I
i
75