Permian Shoreline Eolian Complex in Central Arizona: Dune Changes in Response to Cyclic Sealevel Changes

551

PERMIAN SHORELINE EOLIAN COMPLEX I N CENTRAL ARIZONA:

TO CYCLIC SEALEVEL RONALD C.

DUNE CHANGES I N RESPONSE

CHANGES

BLAKEY and

LARRY T.

MIDDLETON,

Arizona U n i v e r s i t y , F l a g s t a f f , Arizona

Department

of

Geology,

Northern

86011

INTRODUCTION I n the

last

f i v e years

the

identification

of

ancient

e o l i a n sandstone

sequences has gone from s p e c u l a t i o n and g e n e r a l i z a t i o n t o d e f i n i t i v e i n t e r p r e tation.

Due t o t h e work o f Hunter (1977, 1980), McKee (1979a,b),

Kocurek and

D o t t (1981), Kocurek (1981a, 1981b), and o t h e r s , t h e i d e n t i f i c a t i o n o f a n c i e n t sequences as e o l i a n seems assured i n imany cases. available t o aid i n identification, the large-scale

With d e f i n i t i v e c r i t e r i a

i t i s possible t o i d e n t i f y the nature o f

c o n t r o l s t h a t produced t h e e o l i a n sandstone body.

Controls

such as c l i m a t e , base l e v e l , sand supply, and t e c t o n i c s , which a c t e d t o produce t h e geometry and i n t e r n a l s t r a t i f i c a t i o n o f e o l i a n sand bodies, can be i d e n t i f i e d and i n some cases q u a n t i f i e d .

The purpose o f t h i s s t u d y i s t o r e l a t e t h e

c h a r a c t e r i s t i c s o f an a n c i e n t e o l i a n compl ex and a s s o c i a t e d marine shore1 ine deposits t o these controls.

A l o c a l l y v e r y w e l l exposed Permian sequence was

chosen f o r s t u d y because o f excel l e n t t h r e e - d i m e n s i o n a l exposures and presence of

t h i n wide-spread

m a r i n e carbonates

useful

for

correlation

i n otherwise

unfossiliferous strata. The s e c t i o n s t u d i e d i n c l u d e s t h e upper t h i r d o f t h e Schnebly H i l l Formation and base o f t h e o v e r l y i n g Coconino Sandstone ( f i g . 1 ) .

The base o f t h e s e c t i o n

i s a r e g i o n a l l i m e s t o n e marker bed, t h e F o r t Apache Member o f t h e Schnebly H i l l Formation o f e a r l y Leonardian age (Blakey, 1980). Rim,

an

Colorado P l a t e a u ( f i g .

2).

central

Mogollon

escarpment

that

The area o f study i s i n t h e

forms t h e s o u t h e r n edge o f t h e

D e t a i l e d work was performed near Sedona, Arizona

and less d e t a i l e d work was done t o t h e southeast a l o n g t h e Mogollon Rim. sequence comprises a p p r o x i m a t e l y 100 m o f c r o s s - s t r a t i f i e d ,

The

ripple-laminated,

and wavy bedded v e r y f i n e - t o medium-grained q u a r t z a r e n i t e t o s u b f e l d s p a t h i c arenite.

The sequence d i s p l a y s a s t r o n g l y c y c l i c c h a r a c t e r w i t h r e p e t i t i o n

d i s t i n c t i v e s t r a t i f i c a t i o n and bedding types.

The v e r t i c a l

c y c l i c nature

accompanied by a m a j o r l a t e r a l f a c i e s change from n o r t h w e s t t o southeast.

Of i S

The

sequence formed i n d o m i n a n t l y e o l i a n d e p o s i t i o n a l systems i n t h e Sedona area and p r e d o m i n a n t l y s h a l l o w marine and sabkha systems t o t h e southeast where abundant sandy mudstone, 1980).

l i m e s t o n e , d o l o m i t e , and gypsum a r e p r e s e n t (Blakey,

552

KAIBAB L S

PERMIAN ... .. .. .... .. .,., . ... . ,, ,

SUPAl GROUP

lm

'EN NSY L V AN IAN

REDWALL LE MISSISSIPPIAN

F i g u r e 1. Columnar s e c t i o n of u p p e r P a l e o z o i c s t r a t a i n s t u d y a r e a showing i n t e r v a l of s t u d y ( i n b r a c k e t ) .

N

F i g u r e 2. I n d e x maps. ( a ) C e n t r a l A r i z o n a showing o u t c r o p o f i n t e r v a l o f study. ( b ) Sedona a r e a showing o u t c r o p of i n t e r v a l o f s t u d y and l o c a t i o n of B e l l Rock and West F o r k s e c t i o n s . ( c ) A r i z o n a showing l o c a t i o n o f maps a, b.

553 Tectonic S e t t i n g The area o f s t u d y l i e s on t h e e a s t f l a n k o f t h e Sedona Arch between two proininant t e c t o n i c f e a t u r e s , Basin ( f i g .

3).

t h e Grand Canyon-Emery P l a t f o r m and t h e Hol brook

The Holbrook Basin was a c t i v e d u r i n g o n l y Schnebly H i l l and

l o w e r Coconino d e p o s i t i o n as i t c o n t a i n s two t o t h r e e t i m e s t h e t h i c k n e s s o f l o w e r Leonardian rocks as s u r r o u n d i n g areas

(Blakey,

1980).

The Sedona Arch

forms t h e western edge o f t h e Schnebly H i l l - D e C h e l l y Sandstone complex.

The

Schnebly H i l l Formation t h i c k e n s across t h e southeast edge o f t h e Sedona Arch i n t o t h e Holbrook Basin and across t h e Mogollon S h e l f . i n t h e Grand Canyon,

West o f t h e Sedona Arch

t h e Schnebly H i l l Formation i s absent;

temporal c o r r e l a -

t i v e s t r a t a may be r e p r e s e n t e d by t h e l o w e r s e v e r a l meters o f Sandstone.

Across t h e a r c h ,

l e s s t h a n 100 km.

t h e Coconino

l o w e r Leonardian s t r a t a t h i c k e n t o over 100 m i n

D u r i n g t h i s t i m e i n t e r v a l subsidence r a t e was much g r e a t e r

t o t h e southeast o f t h e Sedona Arch t h a n i t was t o t h e n o r t h w e s t as evidenced by t h e t h i c k e r isopachs t o t h e southeast ( f i g . 3 ) .

A

6

\ Facies Migration

F i g u r e 3. Maps showing ( a ) t e c t o n i c f e a t u r e s and ( b ) d i s t r i b u t i o n o f environment across A r i z o n a and v i c i n i t y d u r i n g d e p o s i t i o n o f upper Schnebly H i l l Formation and l o w e r Coconino Sandstone. Deposits are t h i n , less than s e v e r a l t e n s o f meters t h i c k , west o f Sedona Arch, b u t t h i c k e n t o over 250 m i n Holbrook Basin.

554 D u r i n g Leonardian t i m e , f a c i e s p a t t e r n s on t h e Colorado P l a t e a u and v i c i n i t y were c o n t r o l l e d by t e c t o n i c elements ( f i g . f a c i e s changes on t h e e a s t

3).

The e o l i a n aspects o f sharp

s i d e o f t h e Sedona Arch and t h e i r response t o

e x t e r n a l c o n t r o l s a r e t h e s u b j e c t o f t h i s paper. Source o f Sand The Coconino e r g i s p a r t o f t h e " g r e a t sand p i l e " o f l a t e P a l e o z o i c and Mesozoic age on t h e Colorado Plateau. study ( f i g .

Paleowind d i r e c t i o n s gathered f o r t h i s

4) and by Reiche (1938) and McKee (1979b) i n d i c a t e r a t h e r c o n s i s Facies r e l a t i o n s h i p s show t h a t t h e sand was

t e n t paleowinds from t h e n o r t h .

f e d i n t o t h e area o f study from t h e n o r t h and n o r t h w e s t (Blakey,

1980).

The

m a t u r i t y o f t h e sandstone suggests t h a t much o f i t was r e c y c l e d from o l d e r

N

N

I

N

I

N

I

'E F i g u r e 4. P a l e o c u r r e n t r o s e diagrams. ( a ) P o l a r - d i p diagram o f sand-flow s t r a t a f a c i e s TWC. ( b ) P o l a r - d i p diagram o f i n t r a s e t s t r a t a f a c i e s IC. Open d o t s r e p r e s e n t E-2 surfaces. ( c ) Rose diagram o f trough-axes dips, f a c i e s TCT. ( d ) Rose diagram o f f o r e s e t d i p s o f c l i m b i n g t r a n s l a t e n t s t r a t a , f a c i e s TCT. ( e ) Foreset d i p o f p o s s i b l e marine s t r a t a , f a c i e s CC. ( f ) Summary rose diagram f o r a l l e o l i a n sand-flow f o r e s e t s and t r o u g h axes ; r i p p l e f o r e s e t s n o t in c l uded.

555 Pennsylvanian and Permian r o c k s t o t h e n o r t h i n Utah,

Wyoming,

and Montana.

Regional f a c i e s p a t t e r n s ( f i g . 3 ) suggest t h a t sand was t r a n s p o r t e d a l o n g t h e e a s t e r n margin o f t h e C o r d i l l e r a n seaway t o t h e southwest and t h e n blown i n l a n d across t h e Grand Canyon-Emery P l a t f o r m by winds from t h e n o r t h (Blakey, 1980). The e r g m i g r a t e d southward and southeastward across t h e Sedona Arch.

Here i t

encountered t h e c o a s t a l complex a s s o c i a t e d w i t h t h e Mogol l o n S h e l f and Hol brook Basin.

FACIES A N A L Y S I S Trough-Cross-Stratified ( i ) Description.

T r a n s l a t e n t F a c i e s (TCT)

The t r o u g h - c r o s s - s t r a t i f i e d

t r a n s l a t e n t f a c i e s (TCT)

comprises trough-shaped s e t s f i l l e d w i t h c l i m b i n g t r a n s l a t e n t s t r a t a ( f i g .

5).

The g r a i n s a r e m o s t l y v e r y f i n e t o f i n e g r a i n e d and m o d e r a t e l y w e l l sorted. The sandstone i s r e d d i s h orange t o moderate r e d d i s h brown. s e t s a r e 3-10

m wide and up t o 1.5

determined by a x i a l (fig.

4c).

plunge d i r e c t i o n

m thick (fig.

6).

i s bimodal-bipolar

The trough-shaped The t r o u g h axes as southwest-northeast

The l a r g e s t t r o u g h s a r e c o s e t s t h a t c o n t a i n s m a l l e r b u t s i m i l a r l y

shaped t r o u g h s t h u s c r e a t i n g a h e i r a r c h y o f s e v e r a l s i z e s o f t r o u g h s ( f i g . Surfaces t h a t bound t h e s e t s , r e g a r d l e s s o f s i z e , a r e c l e a r l y e r o s i o n a l . t r u n c a t e o t h e r trough-shaped

5). They

s u r f a c e s as w e l l as enclosed laminae and do n o t

r e p r e s e n t f o r e s e t s o f m i g r a t i n g bedforms.

The laminae t h a t f i l l and g e n e r a l l y

conform t o t h e t r o u g h shape a r e c l i m b i n g t r a n s l a t e n t s t r a t a o f Hunter (1977).

Climbing Translatent S t =Grain

Flow-Grain Fall

F i g u r e 5. Transverse and 1o n g i t u d i n a l s e c t i o n drawings o f f a c i e s TCT. Arrows show wind d i r e c t i o n as shown by f o r e s e t laminae o f c l i m b i n g t r a n s l a t e n t s t r a t a (towards southwest).

556

F i g u r e 6. C h a r a c t e r i s t i c s o f f a c i e s TCT. ( a ) Eroded t r o u g h s u r f a c e s ; w i d t h of v i e w a p p r o x i m a t e l y 2 rn. ( b ) Troughs i n t r a n s v e r s e v i e w on c l i f f w a l l ; f i g u r e f o r scale. ( c ) Oblique view o f c l i m b i n g t r a n s l a t e n t s t r a t a w i t h u n u s u a l l y w e l l preserved w i n d - r i p p l e f o r e s e t s ; wind blew from r i g h t t o l e f t ( t o w a r d s s o u t h w e s t ) ; l e n s cap 54 mm. ( d ) Longitudinal view o f climbing t r a n s l a t e n t s t r a t a showing t r u e t h i c k n e s s o f l a m i n a e . A l l p h o t o s a t West Fork.

These s t r a t a a r e exceed n g l y even and u n i f o r m t h r o u g h o u t t h e f a c i e s and d i s p l a y o c c a s i o n a l t o abundant r i p p l e f o r e s e t 1arni nae ( f i g . upwards and r a n g e f r o m 2-5 mm t h i c k . were examined i n t h e f a c i e s ,

6).

Most 1ami nae c o a r s e n

Several hundred r i p p l e f o r e s e t

laminae

and a l t h o u g h d i f f i c u l t t o measure e x a c t d i r e c t i o n

o f d i p , a l l c l e a r l y show a g e n e r a l s o u t h t o west d i p d i r e c t i o n . Not

all

of

the

strata

i n the

strata.

A

TCT

facies

are trough

climbing

translatent

laminae,

t h e forrner s u g g e s t i n g t h a t a n g l e - o f - r e p o s e

few beds d i s p l a y

shaped o r

sand-flow

and

contain

grain-fall

sedimentation took place.

Small cone-shaped sand f l o w d e p o s i t s a r e i n t e r b e d d e d w i t h c l i m b i n g t r a n s l a t e n t s t r a t a i n some s e t s ( f i g .

6).

M i n o r amounts o f s l u m p i n g and s m a l l - s c a l e s o f t -

557 sediment f a u l t i n g a l s o occur w i t h i n t h e f a c i e s . o b s e r v e d by McKee, e t a l .

S i m i l a r f e a t u r e s have been

(1971) i n modern dunes.

The t r o u g h - c r o s s - s t r a t i f i e d

sandstone comprises cosets which form t a b u l a r -

shaped beds up t o 6 m t h i c k .

The f a c i e s i s most abundant i n t h e l o w e r p a r t o f

t h e i n t e r v a l o f s t u d y , e s p e c i a l l y w i t h i n a few t e n s o f i n e t e r s o f t h e u n d e r l y i n g F o r t Apache Member ( f i g . 7 ) . (ii)

Interpretation.

TCT i s d o m i n a t e d by c l i m b i n g t r a n s l a t e n t

Facies

Sharp ( 1 9 6 6 ) , H u n t e r (1977,

strata.

1981),

and Kocurek and l l o t t ( 1 9 8 1 ) have

documented t h e w i n d r i p p l e o r i g i n f o r t h e s t r a t a .

The m a j o r c h a r a c t e r i s t i c s ,

t l i i n e v e n l y spaced l a m i n a e o f equal t h i c k n e s s , c o a r s e n i n g - u p w a r d s l a m i n a e , and rare

ripple

yeometry

foreset

and

laminae

distribution

are

of

e x t e n s i v e l y developed

cli-nbing

translatent

i n the facies.

strata

d i f f e r e n t t h a n t h a t r e p o r t e d i n modern o r a n c i e n t dunes.

in

facies

The TCT

is

There a r e t h r e e ways

i n w h i c h t r o u g h s o f t h e s i z e i n q u e s t i o n can f o r m i n e o l i a n d e p o s i t s .

1) I n

s t r o n g l y l u n a t e dunes c a l l e d a k l e - ( B r o o k f i e l d , 1977) o r o t h e r s i n u o u s - c r e s t e d t r a n s v e r s e dunes; 2 ) as m i g r a t i n g s c o u r p i t s g e n e r a l l y i n t h e l e e of l a r g e r dunes ( D a v i d R u b i n , p e r s . comm.); and 3 ) as d e p r e s s i o n s a s s o c i a t e d w i t h b l o w o u t dunes;

(Mckee,

1979a;

Ah1 b r a n d t and F r y b e r g e r ,

1980).

Migrating s l i p -

f a c e s on a k l e - dunes as d e s c r i b e d by B r o o k f i e l d w o u l d a p p a r e n t l y p r o d u c e t r o u g h cross s t r a t i f i c a t i o n .

C l e a r l y t h i s i s n o t t h e case w i t h f a c i e s TCT as s l i p -

f a c e d e p o s i t s a r e uncommon.

M i g r a t i n g scour p i t s ,

f e a t u r e s c a r v e d by v o r t e x

e d d i e s a s s o c i a t e d w i t h s i n u o u s - c r e s t e d b e d f o r m s , l e a v e a r a t h e r complex t h r e e d i i i i e n s i o n a l s w a l e and s w e l l t o p o g r a p h y r a t h e r t h a n t h e r e g u l a r e l o n g a t e p a t t e r n we o b s e r v e ( D a v i d R u b i n , p e r s . comm.). From t h e dunes,

relatively

few d e s c r i p t i o n s

smooth s c o u r e d d e p r e s s i o n s

sedimentary

structures

(McKee,

and

discussions

o f inodern b l o w - o u t

f i l l e d w i t h t r o u g h s t r a t a a r e t h e expected

1979a;

Ah1 b r a n d t

and

Fryberger,

1980).

The

s t r a t a d i p a t r e l a t i v e l y l o w a n g l e s due t o t h e i n i n o r o c c u r r e n c e o f s l i p - f a c e deposits complex

and

may

wind

Browns

varying

orientation

(Ahlbrandt

of

dunes

d i p s (Ahlbrandt, than

processes. iaLisS

TC:

direction, 1980).

representing

I n t h e Miocene

t r o u g h axes formed by p r o b a b l e

a r e n o t i n phase w i t h i m m e d i a t e l y u n d e r l y i n g a v a l a n c h e - f o r m e d p e r s . comm.,

those

of

1983).

the

Schnebly

Mean t r o u g h - a x e s

D i p a n g l e s o f f a c i e s TCT a r e c o n s i d e r a b l y Hill

and

i s e'Bx,;:tl-

wituh

Coconino

formed

by

avalanche

d i p d i r e c t i o n o f f a c i e s TCT v a r i e s by a b o u t 60"

from s l i p faces o f t h e avalanche d e p o s i t s ( f i g . E . _ .

dip

and F r y b e r g e r ,

Park F o r m a t i o n o f n o r t h w e s t C o l o r a d o ,

blow-out lower

show

distribution

rjlther

4).

The p a t t e r n o f t r o u g h s i n

s t r a i g h t t r o u g h axes.

The u p p e r ( u p w i n d )

p a r t o f t h e a x i s d i p s more s t e e p l y ( r a r e l y up t o 22") whereas t h e r e m a i n d e r o f -L _I I ~ ak-,\ L,'; 3=-,L.',., '$y--?-lJ1,: 1 0 - c . ~ +.h?n and t v o i c a l l y i s n e a r l y f l a t f a r t h e r down t h e t r o u g h .

T h i s i s t r u e o f b o t h t h e s o u t h w e s t - and n o r t h e a s t -

BELL ROCK

WEST FORK KEY

strata type

INTRASET H GF/SF

LAMIlATED DOLOl’ITE

facies

IC

F T . APACHE llBR

Apache Member

F i g u r e 7. D e t a i l e d columnar s e c t i o n s a t West Fork and B e l l Rock. Facies WBR shown on column where t o o t h i n t o show on drawing. F a c i e s TCT and CC a r e differentiated for clarity.

559 t r e n d i n g troughs.

T h i s suggests t h a t t h e scours were carved by bimodal winds,

p o s s i b l y onshore dnd o f f s h o r e winds,

and t h a t t h e c l i m b i n g t r a n s l a t e n t s t r a t a

t h a t f i l l t h e t r o u g h s were produced by n o r t h e a s t e r l y ( o f f s h o r e ) breezes. Intraset-Cross-Stratified ( i ) Description. by

thick

(up

to

Facies (IC)

The i n t r a s e t - c r o s s - s t r a t i f i e d

12

sedimentary s t r u c t u r e .

m)

tabular

bodies

with

f a c i e s ( I C ) i s dominated

extremely

ranges from p a l e r e d d i s h orange t o p a l e g r a y i s h orange. bound t h e i n t r a s e t s

are subparallel

t a b u l a r s e t s up t o 0.3 (figs.

4b,

8).

complex

internal

The sand i s c h i e f l y f i n e g r a i n e d and w e l l s o r t e d and

m thick;

erosional

The s u r f a c e s which

planes which d e f i n e i n c l i n e d

t h e s u r f a c e s d i p south-southwest a t 18-22'

The i n c l i n e d e r o s i o n s u r f a c e s , p r o b a b l y second-order bounding

s u r f a c e s o f B r o o k f i e l d (1977), become i n d i s c e r n i b l e near t h e base o f t h e coset and d i s a p p e a r between c l i m b i n g t r a n s l a t e n t s t r a t a ( f i g . 9b).

They a l s o become

i n d i s t i n c t between a n g l e - o f - r e p o s e laminae h i g h e r up t h e f a c e o f t h e f o r e s e t s (fig.

8).

Set

thicknesses,

as

defined

s u r f a c e s , a r e remarkably c o n s t a n t ( f i g .

by

distance

between

second-order

9).

-

0 1 2 3 M Climbing Translatent S t r a t a Ripple Laminae =Grain Flow-Grain Fall (dashed in intraset) F i g u r e 8. Transverse and l o n g i t u d i n a l s e c t i o n drawings o f f a c i e s IC. Arrows show wind d i r e c t i o n as i n d i c a t e d by f o r e s e t d i p d i r e c t i o n s (towards south). R i p p l e laminae formed by eol ian and subaqueous ri p p l es.

560

C h a r a c t e r i s t i c s o f f a c i e s IC. ( a ) Complex i n t r a s e t s a t B e l l Rock; F i g u r e 9. a p p r o x i m a t e l y 4 m o f s e c t i o n shown. ( b ) L o n g i t u d i n a l v i e w a t West F o r k ; a p p r o x i m a t e l y 2 in o f s e c t i o n shown. ( c ) O b l i q u e v i e w a t same l o c a t i o n as b ; 4 - 5 m o f s e c t i o n shown. ( d ) T r a n s v e r s e v i e w a t West Fork. Major second-order e r o s i o n s u r f a c e s d i p t o w a r d camera ( s o u t h ) a t 18-22". I n t r a s e t s d i p south-southwest. Notebook i s 17 cm t a l l .

5

The i n t r a s e t l a m i n a e between s e c o n d - o r d e r e r o s i o n s u r f a c e s d i p t o t h e s o u t h o r t o t h e west a t 16-28'

( c a l c u l a t e d inean d i p = 22.40)

a s s o r t m e n t s o f sand f l o w ,

grain f a l l ,

l a t t e r d o m i n a t e t h e base o f t h e f o r e s e t s Abundant within

reactivation the

intraset

surfaces laminae.

and

and c o m p r i s e complex

and c l i m b i n g t r a n s l a t e n t

The

where d i p s become n e a r l y h o r i z o n t a l .

ininor

These

strata.

trough-shaped

form t h i r d - o r d e r

scours bounding

are

present

surfaces

of

ripples

on

B r o o k f i e l d (1977). Minor bedding tracks

sedimentary planes

and

with

trails,

structures crests

include

oriented

pull-apart

parallel

laminae

l a m i n a e due t o c o m p r e s s i o n a l f o r c e s .

raindrop to

prints, foreset

due t o t e n s i o n a l

wind dip, forces,

unidentified and

folded

The f a c i e s f o r m s a t a b u l a r l i t h o s o m e up

561 t o 12 m t h i c k b u t t y p i c a l l y

i s much t h i n n e r due t o t r u n c a t i o n by o v e r l y i n g

strata.

be i n t e r b e d d e d o r

The

facies

I C may

gradational

with

f a c i e s TCT

p r o d u c i n g a complex s u b f a c i e s o f t r o u g h and i n t r a s e t c r o s s s t r a t i f i c a t i o n . ( i f ) Interpretation.

F a c i e s I C was d e p o s i t e d by l a r g e s o u t h w a r d - m i g r a t i n g

compound t o complex ( t e r m s o f McKee, 1979a) e o l i a n dunes. was

likely

formed

by

B r o o k f i e l d (1977). angle-of-repose

dunes

migrating

over

The u p p e r f o r e s e t s of

a

large

The i n t r a s e t p a t t e r n draa

as

described

by

t h e d r a a were l a r g e l y t h e s i t e o f

g r a i n f a l l and sand f l o w d e p o s i t i o n b u t t h e l o w e r reaches were

o c c u p i e d by dunes t h a t m i g r a t e d o b l i q u e t o t h e m a j o r s l i p f a c e o f t h e draa.

A t t h e base

Numerous examples o f dunes on d r a a s a r e p r o v i d e d by W i l s o n (1973). of

t h e dune,

w i n d r i p p l e s m i g r a t i n g a c r o s s t h e base o f t a n g e n t i a l s l i p f a c e s

p r o d u c e d c l i m b i n g t r a n s l a t e n t s t r a t a w h i c h g r a d e i n t o and wedge o u t between t h e more s t e e p l y d i p p i n g sand f l o w d e p o s i t s ( f i g .

9b,c),

a f e a t u r e common on many

modern dunes ( H u n t e r , 1977). P r o c e s s e s o p e r a t i n g on t h e s l i p f a c e of t h e l a r g e d r a a must have been v e r y complex.

As v e r y l i t t l e i s known a b o u t t h e i n t e r n a l

d i r e c t comparison i s p o s s i b l e . internal Fryberger, the

top

structure

is

1980; W i l s o n , of

the

very

intricate

1971, 1973).

thicker

(McKee,

1979a,

sequences

1977; McKee,

climbing translatent

1982;

Ahlbrandt

document 1979a).

sedimentation

ripples.

W i t h renewed a v a l a n c h i n g , Large-scale

by

s t r a t a commonly o v e r 1 i e s s e c o n d - o r d e r

s u g g e s t s t h a t between p e r i o d s o f a v a l a n c h i n g , wind

and

Where p r e s e n t h i g h e r

e r o s i o n s u r f a c e s and i s o v e r l a i n by g r a i n f a l l and sand f l o w d e p o s i t s . dune s l i p face.

no

The sand f l o w and g r a i n f a l l l a m i n a e a t

preserved

avalanching o r suspension (Hunter, on t h e i n t r a s e t s ,

s t r u c t u r e o f draas,

What l i t t l e work has been done i n d i c a t e s t h a t

reactivation

angle-of-repose or

This

r i p p l e s c l i m b e d w e l l up o n t o t h e climbing o f

strata buried the superimposed

dunes

p r o b a b l y formed t h e s e c o n d - o r d e r s u r f a c e and t h e c y c l i c sequence was repeated. The dunes w h i c h d e p o s i t e d t h e i n t r a s e t l a m i n a e moved a c r o s s ,

down,

and l o c a l l y

u p t h e f a c e o f t h e draa.

Tabu1 a r - and W e d g e - C r o s s - S t r a t i f i e d ( i ) Description.

The t a b u l a r -

F a c i e s (TWC)

and wedge-cross

s t r a t i f i e d facies

c o n t a i n s t h e l a r g e s t s e t s i n t h e S c h n e b l y H i l l and Coconino sequence.

(TWC)

The sand

i s f i n e t o medium g r a i n e d and i s v e r y w e l l s o r t e d .

Color ranges from y e l l o w i s h

o r a n g e t o p a l e g r a y i s h orange t o y e l l o w i s h g r a y .

The f a c i e s i s d o m i n a t e d by

angle-of-repose laminae ( f i g .

f o r e s e t s (mean d i p = 22.2") 10).

c o m p r i s i n g g r a i n f a l l and sand f l o w

The f o r m e r appear as e x t r e m e l y t h i n l a m i n a e between sand

f l o w l a m i n a e w h i c h r a n g e up t o s e v e r a l c e n t i m e t e r s t h i c k . and r e p t i l e t r a c k s a r e found on f o r e s e t s u r f a c e s .

Rare w i n d r i p p l e s

Slump s t r u c t u r e s o f v a r y i n g

s c a l e s , many c o m p a r a b l e t o t h o s e d e s c r i b e d by Mckee e t a l . ,

(1971) and f o u n d i n

562

-

Climbing Translatent S t r a t a Grain Flow Grain Fall

0

10 2 0 M

F i g u r e 10. T r a n s v e r s e and 1 o n g i t u d i n a l s e c t i o n d r a w i n g s o f f a c i e s TWC. Arrows show w i n d d i r e c t i o n as i n d i c a t e d b y d i p s o f s a n d - f l o w s t r a t a ( c h i e f l y towards south).

the

Coconino

of

Grand

throughout t h e facies.

Canyon

(McKee,

1979a)

are

sporadically

distributed

C l i m b i n g t r a n s l a t e n t s t r a t a f o r m a s m a l l component o f

f a c i e s TWC and a r e c h i e f l y c o n f i n e d t o t h e base o f t h e f o r e s e t s

(fig.

11).

Toes o f sand f l o w c r o s s s t r a t a commonly i n t e r f i n g e r w i t h c l i m h i n g t r a n s l a t e n t strata. The c r o s s s t r a t a a r e g r o u p e d i n t o wedge- and t a b u l a r - s h a p e d s e t s t h a t range up t o 10 m i n t h i c k n e s s ( f i g . spond t o f i r s t - o r d e r shaped s e t s .

11).

Subparallel continuous planes t h a t corre-

b o u n d i n g s u r f a c e s o f B r o o k f i e l d (1977) e n c l o s e t h e wedge-

The e r o s i o n p l a n e s t h a t

f o r m wedge-shaped

cosets d i p a t low

a n g l e s and up t o 20" down w i n d and c o r r e s p o n d t o s e c o n d - o r d e r b o u n d i n g s u r f a c e s o f B r o o k f i e l d (1977). wedge-s haped c o s e t s.

Third-order

b o u n d a r y s u r f a c e s a r e p r e s e n t w i t h i n some

Some compl ex wedge-s haped c o s e t s d i s p l a y in t r a s e t c r o s s

s t r a t i f i c a t i o n similar t o that i n facies

IC.

Trough-shaped s e t s a r e p r e s e n t

t h o u g h n o t common i n f a c i e s TWC and may be 30 m i n w i d t h . Most

foreset

l a m i n a e and many s e c o n d - o r d e r

s o u t h i n f a c i e s TWC ( f i g .

4).

The l a r g e ,

bounding surfaces

southward-dipping

n e n t among t h e t h i n n e r s e t s o f t h e o t h e r f a c i e s ( f i g .

(ii)I n t e r p r e t a t i o n . e o l i a n dunes and draas.

dip t o the

s t r a t a a r e promi-

12).

F a c i e s TWC was d e p o s i t e d by l a r g e s o u t h w a r d - m i g r a t i n g A l t h o u g h modern, a c t i v e l a r g e dunes and d r a a s c o n t a i n -

563

F i g u r e 11. C h a r a c t e r i s t i c s o f f a c i e s TWC. ( a ) Stacked s e t s i n Coconino Sandstone n e a r West F o r k ; f i g u r e n e a r b o t t o m g i v e s s c a l e . (b) Grain-fall and s a n d - f l o w s t r a t a i n l a r g e s e t a t West Fork. (c) Detail of toe of large dune. L i g h t - c o l o r e d g r a i n - f a l l and c l i m b i n g t r a n s l a t e n t s t r a t a i n t e r t o n g u e w i t h sand-flow toes (dark). Lens cap i s 54 mm. ( d ) Wind r i p p l e s on a n g l e o f - r e p o s e f o r e s t a t West F o r k .

i n g s i l i c i c l a s t i c g r a i n s have n e v e r been t r e n c h e d t o g r e a t d e p t h s ,

studies ot

s u r f i c i a l p r o c e s s e s and s t r u c t u r e s and m i g r a t i o n o f s u p e r i m p o s e d dunes p r o v i d e some c l u e s as t o t h e t y p e o f i n t e r n a l s t r a t i f i c a t i o n t h a t , n i g h t be p r o d u c e d (Wilson,

1972; H u n t e r ,

1977; McKee,

1979a; R u b i n and H u n t e r ,

1982). Ahlbrandt

and F r y b e r g e r ( 1 9 8 0 ) i l l u s t r a t e d t h e i n t e r n a l f e a t u r e s o f d i s s e c t e d b a r c h a n o i d dunes f r o m t h e Sand H i l l s o f Nebraska.

Comparison o f f e a t u r e s o f modern dunes

564

F i g u r e 12. Sequences o f f a c i e s i n u p p e r S c h n e b l y H i l l F o r m a t i o n and l o w e r Fort C o c o n i n o Sandstone. ( a ) E n t i r e i n t e r v a l o f s t u d y a t B e l l Rock. Apache L i m e s t o n e i s a t base o f p h o t o . N e a r l y 200 rn shown. ( b ) M i d d l e and u p p e r i n t e r v a l o f s t u d y n e a r Sedona a t S c h n e b l y H i l l . A p p r o x i m a t e l y 100 m shown. I n both photos l i g h t e r colored proininantly c r o s s - s t r a t i f i e d u n i t s a r e composed o f f a c i e s TWC and I C . Darker u n i t s are combinations o f facies WBK, TCT, and CC.

565 w i t h t h o s e o f f a c i e s TWC c o n f i r m t h e e o l i a n o r i g i n .

Toes o f sand f l o w s t r a t a

that interfinger with climbing translatent strata are a distinctive feature o f inodern ( H u n t e r ,

1977) and a n c i e n t ( H u n t e r ,

1981) dunes.

The h i g h c o n s i s t e n c y

of d i p d i r e c t i o n i n l a r g e - s c a l e s e t s composed o f g r a i n - f l o w s t r a t a s u g g e s t t h a t

s l i p f a c e s were s t r a i g h t t r a n s v e r s e bedforms

and p a r a l l e l

4;

(fig.

b a r c h a n and t r a n s v e r s e - r i d g e (Ah1 b r a n d t

and

compares w i t h v a l u e s o f 22'

and 24'

for

dunes r e s p e c t i v e l y i n t h e Sand H i l l s o f Nebraska

1980).

Fryberger;

a characteristic o f

6 o f A h l b r a n d t and F r y b e r g e r ,

compare w i t h f i g .

The mean d i p a n g l e o f 22.2'

1980).

f r o m dune t o dune,

The

abundance

of

second-order

s u r f a c e s c o m p a r a b l e t o t h o s e d e s c r i b e d b y B r o o k f i e l d (1977) dunes m i g r a t i n g a c r o s s draas.

bounding

i s attributed t o

The bedforins m i g r a t e d i n r e s p o n s e t o r e g i o n a l

winds from t h e north. C o m p l e x l y C r o s s - S t r a t i f i e d F a c i e s (CCY

( i )D e s c r i p t i o n .

The c o m p l e x l y c r o s s - s t r a t i f i e d

facies

(CC) i n c l u d e s a

v a r i e t y o f c r o s s - s t r a t i f i c a t i o n t y p e s o f f i n e - t o medium-grained r e d d i s h - o r a n g e sandstone.

s e t s and c o s e t s a r e up t o 1 m t h i c k and 3 o r more

Cross-stratified

meters wide ( f i g .

13).

I n d i v i d u a l s e t s r a n g e f r o m t r o u g h , t o wedge,

t o tabular

and c o m p r i s e m o s t l y m e g a r i p p l e f o r e s e t l a m i n a e t h a t d i p a t 15-20'. angle dipping lamination i s a l s o present.

Compound c r o s s s t r a t i f i c a t i o n i s

Set b o u n d a r i e s d i p i n v a r y i n g d i r e c t i o n s and t h e l a m i n a e o f a d j a c e n t

abundant.

s e t s coinmonly d i s p l a y a h e r r i n g b o n e p a t t e r n ( f i g . a r e abundant and complex. trough

A complex

axes.

current-ri pple

stratification

wedge,

o r trough-shaped sets.

to

shape

or

13d).

Reactivation surfaces

Most t r o u g h s e t s show n o r t h - s o u t h o r i e n t a t i o n o f heirarchy o f

tabular, the

Some low.

on

orientation

of

stratification

megari p p l e the

scales

stratification

within

small

compound

Many i n d i v i d u a l l a m i n a e do n o t c o n f o r m confining

set,

c o n t r a s t s w i t h f a c i e s TCT.

Some s e t s a r e s i g m o i d a l

p a r t i a l l y preserved topsets,

f o r e s e t s , and b o t t o m s e t s .

a

slump s t r u c t u r e s a r e p r e s e n t .

characteristic

that

i n c r o s s s e c t i o n showing These i n d i c a t e t h a t t h e

m e g a r i p p l e s w h i c h d e p o s i t e d t h e s e t s were 12-15 cm h i g h . and small-scale

includes

Uncommon wavy b e d d i n g

One sequence o f f a c i e s CC shows

i n t e r b e d d e d p l a n a r - t a b u l a r s e t s 0.3 m t h i c k and r i p p l e l a m i n a t e d u n i t s 6-10 cm thick (fig.

13a).

F a c i e s CC forms t a b u l a r packages up t o 4

(ii)I n t e r p r e t a t i o n . s t r a t i f i e d translatent

m thick.

F a c i e s CC s u p e r f i c i a l l y r e s e m b l e s t h e t r o u g h - c r o s s -

facies

(TCT) b u t l a c k s c l i m b i n g t r a n s l a t e n t s t r a t a and

c o n t a i n s a broader range o f s t r a t i f i c a t i o n types.

Most larninae appear t o be o f

s a n d f l o w o r i g i n d e p o s i t e d as f o r e s e t s o f m i g r a t i n g b e d f o r m s o f d i f f e r e n t s i z e s and shapes. directions. facies

D i v e r g e n t d i p d i r e c t i o n s on t h e l a m i n a e i n d i c a t e v a r y i n g c u r r e n t Because t h i s

another

depositional

facies

lacks characteristics

environment

i s suggested.

o f the other eolian Many o f t h e f o r e s e t

l a m i n a e f o r m complex b u n d l e s o f s m a l l r i p p l e c r o s s s t r a t i f i c a t i o n superimposed

566

F i g u r e 13. C h a r a c t e r i s t i c s o f f a c i e s CC. (a) P l a n a r - t a b u l a r cross s t r a t i f i c a t i o n w i t h i n t e r c a l a t e d wavy-bedded s a n d s t o n e a t B e l l Rock. F o r e s e t s d i p t o n o r t h , t h e o p p o s i t e t r e n d o f most e o l i a n s t r a t a . (b,c) D e t a i l s o f b e d d i n g and s t r a t i f i c a t i o n a t B e l l Rock. Note c o m p l e x i t y o f s e t s and abundant r e a c t i v a t i o n s u r f a c e s . ( d ) Complex polymodal foresets and p o s s i b l e swash l a m i n a t i o n a t S c h n e b l y H i l l . Scale i n centimeters, n o t e b o o k i s 17 cm h i g h .

on l a r g e r bedforms.

These f e a t u r e s p r o b a b l y formed i n subaqueous c o n d i t i o n s

and a few d e f i n i t e w a v e - r i p p l e

laminae support t h i s .

t i n u o u s s t r a t a may have been formed by wave swash. bound and l a c k s f l u v i a l associated

with

marine

Low-angle d i p p i n g conThe f a c i e s i s n o t channel

f a c i e s a s s o c i a t i o n s and t h e r e f o r e i s c o n s i d e r e d t o be conditions.

The

complex

c l o s e l y r e s e m b l e modern s h o r e 1 i n e sand b o d i e s .

stratification

P a r t i c u l a r l y c l o s e resemblance

i s n o t e d w i t h b a r r e d c o a s t l i n e s i l l u s t r a t e d by D a v i d s o n - A r n o t t (1976) and Greenwood and D a v i d s o n - A r n o t t

sequences

and Greenwood

( 1 9 7 9 ) and i n t e r t i d a l shoal deposits

567 d e s c r i b e d by Boersina and T e r w i n d t (1981).

The a p p a r e n t absence o f m a r i n e t r a c e

f o s s i l s f r o m t h i s f a c i e s m i g h t be e x p l a i n e d by r e l a t i v e l y r a p i d d e p o s i t i o n and b u r i a l o f t h e sand. Wavy Bedded t o R i p p l e - L a m i n a t e d F a c i e s (WBR)

( i) D e s c r i p t i on.

The wavy bedded t o r i p p l e-1 ami n a t e d f a c i e s

p r i s e s t h e most h e t e r o g e n e o u s f a c i e s varieties

i n the interval

o f study.

(WBR) comThe s e v e r a l

a r e d e s c r i b e d as d i s c r e t e s u b f a c i e s b u t many g r a d a t i o n a l

forms a r e

present. Ripple-laminated

s a n d s t o n e and sandy mudstone i s t h e most w i d e l y d i s t r i b u t e d

The s u b f a c i e s c o n t a i n s s e v e r a l t y p e s o f r i p p l e-1 ami n a t e d s a n d s t o n e

s u b f a c i es.

and mudstone.

D i s t i n c t i v e wave-ripple

medium-grained

sandstone

(fig.

14).

bedding

i s most common i n f i n e -

Wave r i p p l e s may c o m p r i s e t h i n l a y e r s

l a m i n a e t h i c k o r sequences n e a r l y 1 m t h i c k .

several

to

The w a v e - r i p p l e

t u r e s d i s p l a y b u n d l e - w i s e a r r a n g e m e n t as d e s c r i b e d by de Raaf. e t a1

struc-

., ( 1 9 7 7 ) .

O t h e r r i p p l e l a m i n a e a r e l e s s d i s t i n c t as t o wave- o r c u r r e n t - r i p p l e o r i g i n and consist o f indistinct

r i p p l e laminae,

most commonly i n sandy mudstone.

The

r i p p l e s o c c u r as l e n s e s o f s l i g h t l y c o a r s e r s e d i m e n t 3-12 nnn t h i c k and 12-100 m long.

Flaser-like

l a m i n a e o f mudstone s e p a r a t e t h e r i p p l e forms.

In rare

p l a n - v i e w e x p o s u r e s , t h e r i p p l e s d i s p l a y an u n d u l a t o r y t o l i n g u o i d form. Wavy-bedded swell

s a n d s t o n e i s coinmonly

f i n e t o medium g r a i n e d and c o n s i s t s o f

and s w a l e t o p o g r a p h y w i t h a m p l i t u d e s o f up t o s e v e r a l c e n t i m e t e r s and

lengths

of

irregular

m.

0.5

Many

packages

of

variations

are present

cross-stratified

and some packages c o n t a i n

sandstone.

Laminations

a r e somewhat

i n d i s t i n c t and t y p i c a l l y y i e l d a m a s s i v e appearance. Crinkly-bedded

sandstone

i s f i n e t o medium g r a i n e d and c o n t a i n s c r i n k l e d

laminae w i t h several centimeters o f r e l i e f .

Individual

layers are extremely

c o n t i n u o u s and t h e h o m o g e n e i t y o f t h e u n i t i s c o n t i n u o u s f o r hundreds o f m e t e r s o r more. Lenticular abundant

in

bedding facies

and

flaser-bedded

WBR.

Individual

e n c l o s e d i n f i n e r sandy mudstone ( f i g .

sandstone

ripple

lenses

observed

dips

sets t h a t truncate adjacent

a r e 10".

Set

l a m i n a e a r e v e r y t h i n , 0.5-1.0

thicknesses

m.

mudstone

are

25-50

is

locally

mm l o n g and

14c).

Plane-bedded s a n d s t o n e i s an uncommon s u b f a c i e s . b r o a d wedge-shaped

and

The p l a n e beds f o r m v e r y

s e t s a t low angles.

r a n g e f r o m 7-25

Maximum

cm and i n d i v i d u a l

The s a n d s t o n e i s f i n e t o medium g r a i n e d and

very well sorted. F a c i e s WBR f o r m s an i m p o r t a n t b u t v a r i a b l e p e r c e n t a g e o f t h e u p p e r S c h n e b l y

H i l l Formation.

I n d i v i d u a l u n i t s o f t h e f a c i e s may c o n t a i n one o r more o f t h e

subfacies but a l l

were n e v e r o b s e r v e d i n t h e same u n i t .

sequence v a r i e s g r e a t l y ,

Although v e r t i c a l

a somewhat t y p i c a l v e r t i c a l s u c c e s s i o n i n c l u d e s b a s a l

568

F i g u r e 14. C h a r a c t e r i s t i c s o f f a c i e s WBR. ( a ) Wavy bedded sequence t h a t s h a r p l y t r u n c a t e s l a r g e e o l i a n dune s e t at H e l l R o c k ; pen on h e d d i q g plane i s 16 cin l o n g . ( b ) D e t a i l o f w a v e - r i p p l e l a m i n a e a t same l o c a t i o n . (c) P r o b a b l e l e n t i c u l a r b e d d i n g a t Be1 1 Rock. ( d ) T y p i c a l heterogeneous sequence w i t h v a r i o u s t y p e s o f i r r e g u l a r t o r i p p l e b e d d i n g a?d s m a l l - s c a l e c r o s s s t r a t i f i c a t i o n a t B e l l Rock.

ripple-mdrked t o flaser-bedded sandstone w i t h o r w i t h o u t stone. local

Sequences commonly ball-and-pillow

sandy inudstone,

m e d i a l wavy and r i p p l e bedded

l e n t i c u l a r b e d d i n g , and u p p e r c r i n k l y - b e d d e d c o a r s e n upwards.

structure,

and

poorly

p r e s e n t i n many sequences o f f a c i e s WBR. a l w a y s s h a r p and ,isconforrnab’e

sand-

Small - s c a l e c o n t o r t e d bedding, cross-stratified

sandstone

is

The b a s a l c o n t a c t o f a sequence i s

w i t h o r w i t h o u t basal l o a d s t r u c t u r e s .

The t o p

may be g r a d a t i o n a l o r s h a r p . Climbing t r a n s l a t e n t s t r a t a sections t o t h e northwest.

f o r m an i m p o r t a n t component o f f a c i e s WBR i n

F a r t h e r s o u t h e a s t t h e s t r u c t u r e i s r a r e o r absent.

569 ( i i ) Interpretation.

F a c i e s WBR i n c l u d e s a v a r i e t y o f i n t e r d u n e and e x t r a -

dune d e p o s i t s ( t e r m i n o l o g y o f Lupe and A h l b r a n d t , strata,

c o n t o r t e d laminae,

common i n t h e f a c i e s , 1981b).

wavy

laminae,

wave

1975).

Climbing t r a n s l a t e n t

r i p p l e s and c u r r e n t

a r e common i n modern wet i n t e r d u n e d e p o s i t s

ripples, (Kocurek,

Climbing t r a n s l a t e n t s t r a t a o f t h i s facies sharply truncate underlying

dune d e p o s i t s and g r a d e upwards and l a t e r a l l y i n t o t h e s a n d - f l o w t o e d e p o s i t s o f a d v a n c i n g dunes

(fig.

llc).

f i rst-order

bounding surfaces

Brookfield,

1977; Kocurek,

They f o r m i n t e r d u n e d e p o s i t s w h i c h o v e r l i e

o v e r w h i c h d r a a s advanced (Wi 1 son,

1971,

1972;

Some u n i t s o f f a c i e s WBR s h a r p l y t r u n c a t e

1981b).

u n d e r l y i n g f a c i e s , t y p i c a l l y t h i c k e n t o t h e s o u t h e a s t , and g r a d e l a t e r a l l y i n t o a s s o c i a t e d sabkha and s h a l l o w i n a r i n e d e p o s i t s . sequences common.

similar

Wave-generated

t o t h o s e d e s c r i b e d by de Raaf,

et al.

s t r u c t u r e s and

(1977) a r e l o c a l l y

Here f a c i e s WBR i s an e x t r a d u n e r a t h e r t h a n i n t r a d u n e d e p o s i t .

F i n e - G r a i n e d C1 a s t i c and C a r b o n a t e F a c i e s Southeastward

along

the

Mogollon

the

Rim,

eolian

and

associated

rocks

d e s c r i b e d above g r a d e l a t e r a l l y i n t o complex sequences o f f i n e - g r a i n e d c l a s t i c , carbonate, supratidal, Blakey,

and e v a p o r i t e u n i t s o f s h a l l o w m a r i n e , and

1980).

lagoonal

origin

and

r e s t r i c t e d marine,

Gerrard,

These r o c k s i n c l u d e r i p p l e - l a m i n a t e d

c r a c k s and s a l t c r y s t a l c a s t s , mite,

(Peirce

1966;

Gerrard,

sabkha, 1966;

sandy mudstone w i t h mud

f o s s i l i f e r o u s t o o o l i t i c c a l c a r e n i t e and d o l o -

l a m i n a t e d t o f e n e s t r a l d o l o m i c r i t e , and gypsum and g y p s i f e r o u s mudstone.

The f a c i e s change between m o s t l y e o l i a n s t r a t a i n n o r t h e r n Oak Creek Canyon t o nearly

totally

(Blakey,

non-eolian

strata

near

Ft.

Apache t a k e s

place over

200

km

1980).

SEQUENCES AND CYCLES V e r t i c a l Sequence F i g u r e 7 shows t h e v e r t i c a l sequence of f a c i e s and t h e i r i n t e r p r e t a t i o n i n t h e u p p e r S c h n e b l y H i l l F o r m a t i o n and l o w e r m o s t Coconino Sandstone a t West F o r k o f Oak Creek cyclic;

1.

Canyon and B e l l

Rock.

The p a t t e r n of

vertical

succession

is

t h e f o l l o w i n g s a l i e n t p o i n t s a r e noted: All

cycles

s t a r t w i t h some a s p e c t

of

f a c i e s WBR,

generally

ripple-

l a m i n a t e d sandy mudstone, w h i c h d i s c o n f o r m a b l y o v e r l i e s t h e t o p o f t h e p r e v i o u s c y c l e.

2.

C y c l e s c o a r s e n upwards.

3.

S c a l e o f c r o s s s t r a t i f i c a t i o n t e n d s t o become l a r g e r t o w a r d s t o p o f many

cycles.

4.

A t y p i c a l c y c l e a t West F o r k c o n s i s t s of a s h a r p d i s c o n f o r m i t y a t t h e

base, WBR,

TCT,

I C and TWC.

570 5.

A t y p i c a l c y c l e a t B e l l Rock c o n s i s t s o f a sharp d i s c o n f o r m i t y a t t h e

base, WBR, CC, TCT, I C and TWC. 6.

F a c i e s WBR, CC and TCT dominate t h e l o w e r i n t e r v a l and f a c i e s I C and TWC

dominate t h e upper i n t e r v a l ( f i g . 7 ) .

7.

Rocks o f t h e Schnebly H i l l Formation below t h e i n t e r v a l o f study a t B e l l

Rock a r e 150 m t h i c k and comprise d o m i n a n t l y f a c i e s WBR and m i n o r f i n e - g r a i n e d c l a s t i c and carbonate f a c i e s .

Rocks o f t h e Coconino Sandstone above t h e i n t e r -

v a l o f s t u d y a t b o t h B e l l Rock and West Fork a r e 250 m t h i c k and a r e composed o f f a c i e s TWC w i t h some I C .

The i n t e r v a l o f s t u d y r e p r e s e n t s t h e c y c l i c change

from f a c i e s WBR a t t h e bottom t o f a c i e s TWC a t t h e top. L a t e r a l Sequence F i g u r e 1 5 shows t h e somewhat g e n e r a l i z e d l a t e r a l d i s t r i b u t i o n o f f a c i e s of t h e i n t e r v a l o f s t u d y from n o r t h w e s t t o southeast o v e r a d i s t a n c e o f a p p r o x i m a t e l y 100 km. 1.

The f o l l o w i n g s a l i e n t p o i n t s a r e noted:

From southeast t o northwest,

f a c i e s WBR grades l a t e r a l l y i n t o f a c i e s CC

and TCT which i n t u r n grade i n t o f a c i e s I C and TWC. 2.

The sequence coarsens t o t h e northwest.

-

0

5 10 1

Fort Apache Member

5

E ~ S 3~Inland Dune

0Sabkha-

ESJ Coastal Dune

Extradune

E93 Marine Carbonate

F i g u r e 15. G e n e r a l i z e d c r o s s s e c t i o n o f upper Schnebly H i l l Formation and l o w e r Coconino Sandstone. I n t e r p r e t a t i o n s based on d i s t r i b u t i o n o f following facies: I n l a n d dune--TWC, I C ; Coastal dune--TCT, I C ; Sabkhainterdune-extradune--WBR, CC. Heavy h o r i z o n t a l 1 i n e s r e p r e s e n t e r o s i o n s u r f a c e carved by r a p i d marine t r a n s g r e s s i o n .

571 3.

Scale o f cross s t r a t i f i c a t i o n increases towards t h e northwest.

4.

F a c i e s WBR t h i n s and p i n c h e s o u t t o t h e n o r t h w e s t and f a c i e s TWC and I C

t h i n and p i n c h o u t t o t h e s o u t h e a s t . 5.

S u c c e s s i v e l y h i g h e r t o n g u e s o f f a c i e s I C and TWC e x t e n d f a r t h e r t o w a r d s

t h e s o u t h e a s t and s u c c e s s i v e l o w e r tongues o f f a c i e s WBR e x t e n d f a r t h e r n o r t h west. 6.

From s o u t h e a s t t o n o r t h w e s t , t h e i n t e r v a l o f s t u d y changes f a c i e s f r o m

WBR t o TWC.

T h i s i s e x a c t l y t h e same f a c i e s change t h a t t a k e s p l a c e v e r t i c a l l y

a t the Bell

Rock s e c t i o n .

The v e r t i c a l change o f f a c i e s r e f l e c t s t h e h o r i -

zontal d i s t r i b u t i o n o f facies a t a given i n t e r v a l . INTERPRETATION OF SEQUENCES Sequence o f E v e n t s Based upon t h e i n t e r p r e t a t i o n and d i s t r i b u t i o n o f f a c i e s ,

the depositional

h i s t o r y o f t h e u p p e r S c h n e b l y H i l l F o r m a t i o n and l o w e r C o c o n i n o Sandstone can be d e v e l o p e d . shows

a

F i g u r e 15 shows t h e g e n e r a l d i s t r i b u t i o n o f f a c i e s and f i g u r e 16

northwest-southeast

i n t e r v a l o f study.

cross

section

of

two

typical

cycles

base o f each c y c l e i s c l e a r l y e r o s i o n a l and t h e b a s a l f a c i e s , t h e southeast.

from

They p r o v i d e t h e b a s i s f o r t h e f o l l o w i n g d i s c u s s i o n . WBR,

the The

thickens t o

F a c i e s WBR where c l e a r l y e x t r a d u n a l as shown i n f i g u r e 16 was

d e p o s i t e d i n a m o d e r a t e l y l o w e n e r g y c o a s t a l complex w i t h i n t e r t i d a l and l e n t i c u l a r b e d d i n g ) p o s s i b l y s u b t i d a l

( c u r r e n t - and w a v e - r i p p l e

(flaser

bedding),

and s u p r a t i d a l -sabkha ( s a l t c r y s t a l c a s t s , wavy and c o n t o r t e d b e d d i n g ) e n v i r o n ments r e p r e s e n t e d . F a c i e s CC,

where p r e s e n t ,

pretation of

facies

i s a l w a y s a s s o c i a t e d w i t h f a c i e s WBR.

CC as some t y p e o f

b a r o r shoal

The i n t e r -

i n a wave-

or tidal-

d o m i n a t e d c o a s t l i n e s u g g e s t s t h a t h i g h e r e n e r g y c o a s t a l c o n d i t i o n s sometimes a f f e c t e d t h e dominantly r e s t r i c t e d shore1 ine. Facies

TCT,

interpreted

as

i s closely

blow-out

coastal

translatent

strata

f a c i e s CC.

V e r t i c a l and l a t e r a l s t r a t i g r a p h i c

associated w i t h

dunes facies

filled

with

climbing

WBR and l e s s commonly

p o s i t i o n o f f a c i e s TCT ( f i g s .

15, 16) s t r o n g l y s u p p o r t t h e c o a s t a l p o s i t i o n o f t h i s e o l i a n f a c i e s . F a c i e s I C commonly o v e r l i e s and g r a d e s i n t o f a c i e s WBR a n d / o r TCT.

As t h e

l a r g e d r a a s t h a t f o r m e d f a c i e s I C approached t h e c o a s t a l e n v i r o n m e n t s m a l l e r dunes formed on t h e d r a a s , p e r h a p s i n r e s p o n s e t o complex c o a s t a l w i n d regimes. Some o f t h e s m a l l e r dunes can be c l e a r l y seen t o have c l i m b e d up t h e f a c e o f t h e s o u t h w a r d - a d v a n c i n g draa. F a c i e s TWC,

i n t e r p r e t e d t o have been d e p o s i t e d by s o u t h w a r d - p r o g r a d i n g

l a r g e dunes and d r a a s ,

gradationally overlies facies

IC.

However,

very

higher i n

t h e s e c t i o n and t o t h e n o r t h w e s t t h e f a c i e s may d i r e c t l y o v e r l i e f a c i e s WBR. I n t h i s l a t t e r s i t u a t i o n f a c i e s WBR i s wet i n t e r d u n e r a t h e r t h a n an e x t r a d u n e

572

NW

‘West

/

Head of Oak Creek

Fork

t

Schnebly Hill

/

t

Bell Rock /

SE

0

0

Km

1 0 =Inland

Dune

=Coastal

Dune

I - 1 Sabkha -Extradune -Shallow Marine F i g u r e 16. Cross s e c t i o n and columnar s e c t i o n s showing d i s t r i b u t i o n o f f a c i e s and i n t e r p r e t a t i o n o f environments w i t h i n two i d e a l i z e d c y c l e s . Heavy h o r i z o n t a l l i n e s r e p r e s e n t s u r f a c e s o f e r o s i o n r e l a t e d t o r a p i d marine transgression. See F i g u r e 15 f o r a d d i t i o n a l e x p l a n a t i o n .

deposit.

Facies WBR i s t h e n a s s o c i a t e d w i t h t h e f i r s t - o r d e r

as d e f i n e d by B r o o k f i e l d (1977) and Kocurek (1981b).

bounding surfaces

Where TWC succeeds I C ,

t h e t r a n s i t i o n from more complex c o a s t a l dunes a f f e c t e d by s h i f t i n g land-sea and sea-land breezes t o l a r g e r b u t somewhat s i m p l e r p r o b a b l y t r a n s v e r s e i n l a n d dunes, i s documented. The sequences o f environments t h u s documented i n v e r t i c a l succession suggest t h e f o l l o w i n g events:

1. 2.

Sharp, wide-spread e r o s i o n a l s u r f a c e i s carved on t o p o f p r e v i o u s c y c l e . Low-energy w i t h o c c a s i o n a l h i g h e r energy c o a s t a l and shore1 i n e d e p o s i t s

formed on t h e surface. 3.

seaward.

As sand blew from i n l a n d , a band o f dune sand developed and prograded Complex onshore and o f f s h o r e winds formed blow-out dunes which were

f i l l e d i n with wind-ripple

deposits.

As t h e sand p i l e moved seaward, l a r g e

draas e n t e r e d t h e area and prograded o v e r t h e c o a s t a l

blow outs.

Complex

c o a s t a l winds coupled w i t h r e g i o n a l winds from t h e n o r t h formed compound and complex dunes o r draas.

573 As t h e e r g c o n t i n u e d t o s l o w l y m i g r a t e southward, l a r g e i n l a n d dunes and

4.

d r a a s m a n t l e d t h e a r e a and a complex o f d u n e - i n t e r d u n e d e p o s i t s was formed. The v e r t i c a l

5.

succession

o f dunes and c o a s t a l d e p o s i t s documents t h e

g r a d u a l change f r o m s h a l l o w m a r i n e , s a b k h a - s u p r a t i d a l , dunes.

c o a s t a l dunes, t o i n l a n d

The same p a t t e r n was p r e s e n t l a t e r a l l y o v e r a d i s t a n c e o f a p p r o x i m a t e l y

50 km a t any g i v e n t i m e . 6.

The s u c c e s s i o n

was

a b r u p t l y terminated by a p e r i o d o f

e r o s i o n and

a n o t h e r c y c l e was i n i t i a t e d . 7.

Later

e a r l i e r ones.

pulses

of

prograding

dunes

moved

farther

southeastward

than

T h i s p r o b a b l y r e f l e c t s i n c r e a s e d s u p p l y o f sand as t h e m a i n e r g

i n i g r a t e d s l o w l y southward. CONTROLS OF DEPOSITION AND CYCLES The o r i g i n of t h e e r o s i o n s u r f a c e s t h a t f o r m t h e base o f t h e c y c l i c sequence j u s t d e s c r i b e d i s c r i t i c a l t o u n d e r s t a n d i n g t h e causes and c o n t r o l s o f c y c l i c sedimentation.

Obvious f a c t o r s i n t h e c o n t r o l o f e o l i a n sedimentation i n c l u d e

1) w i n d d i r e c t i o n ,

velocity,

and c o n s i s t e n c y ;

2) sand s u p p l y ;

3) c l i m a t e and

v e g e t a t i o n ; 4 ) s i z e and shape o f t h e b a s i n o f e o l i a n d e p o s i t i o n ; 5 ) base l e v e l ;

6) w a t e r t a b l e h e i g h t ;

and 7)

r e l a t i o n s w i t h a d j a c e n t e n v i r o n m e n t s and t h e i r

g r o w t h and decay w i t h r e s p e c t t o e o l i a n d e p o s i t i o n . Changes i n Wind The m i g r a t i o n o f an e r g i s a v e r y s l o w g e o l o g i c p r o c e s s Brookfield,

1977).

(Wilson,

1972;

It w o u l d seem u n l i k e l y t h a t any seasonal o r l a r g e r c y c l i c

w i n d p a t t e r n s c o u l d p r o d u c e t h e l a r g e e x t e n t o f t h e s u r f a c e s t h a t u n d e r l i e each cycle.

R a t h e r , w i n d p a t t e r n s were p r o b a b l y r e l a t e d t o p r o x i m i t y of t h e c o a s t -

l i n e and t h u s had g r e a t c o n t r o l on dune t y p e f r o m i n l a n d t o t h e c o a s t .

Modern

c o a s t a l dune complexes l i k e t h o s e i n t h e Namib D e s e r t show g r e a t w i n d v a r i a t i o n s and changes i n dune t y p e and f o r m f r o m t h e c o a s t t o i n l a n d (Breed, al.,

et

1979). Sand S u p p l y Sand s u p p l y was d i r e c t l y r e l a t e d t o t h e p o s i t i o n o f t h e m a i n body o f t h e

Coconino e r g a t any g i v e n t i m e d u r i n g d e p o s i t i o n o f t h e i n t e r v a l o f s t u d y . This

i s d i r e c t l y shown by t h e f a r t h e r

southeastward progradation o f

inland

dunes i n y o u n g e r c y c l e s as t h e e r g complex m i g r a t e d s o u t h w a r d i n t o t h e a r e a o f study.

However,

t h e sharp basal e r o s i o n surfaces

s u g g e s t t h a t t h e r e was a

t e m p o r a r y c u t o f f o f sand s u p p l y a t t h e base o f each new c y c l e .

The e r o s i o n

s u r f a c e c u t i n t o t h e e r g f r o m s o u t h e a s t t o n o r t h w e s t and a l l o w e d s h o r e l i n e and

.

574 s h a l l o w marine c o n d i t i o n s t o move f a r i n l a n d t o t h e n o r t h w e s t o v e r p r e v i o u s e r g It t h e n t o o k t h e e r g some l o n g p e r i o d o f t i m e t o m i g r a t e back i n t o

deposits.

t h e area from t h e n o r t h w e s t , t h u s r e p l e n i s h i n g sand i n t o t h e c o a s t a l areas. C l i m a t e and V e g e t a t i o n C l i m a t e and v e g e t a t i o n were obvious f a c t o r s t h a t a l l o w e d t h e growth and m i g r a t i o n o f t h e Coconino erg.

The c l i m a t e was h o t and a r i d as shown by t h i c k

s a l t d e p o s i t s i n t h e a d j a c e n t Holbrook Basin ( P e i r c e and Gerrard, 1966). ever,

How-

t h e r e i s no evidence t h a t changing c l i m a t e o r c l i m a t i c c y c l e s i n f l u e n c e d

t h e deposits o f the i n t e r v a l o f study other than t h e s h i f t i n g c l i m a t i c b e l t s a s s o c i a t e d w i t h t h e a l t e r n a t i n g i n l a n d and c o a s t a l c o n d i t i o n s . S i z e and Shape o f t h e Basin and Base Level The Sedona Arch d i v i d e d c e n t r a l

Arizona i n t o two t e c t o n i c elements.

The

broad, p r o b a b l y t o p o g r a p h i c a l l y and t e c t o n i c a l l y f e a t u r e 1 ess Grand Canyon-Emery P l a t f o r m p r o v i d e d b o t h an avenue o f t r a n s p o r t a t i o n and s i t e f o r accumulation o f sediments o f t h e Coconino erg. across t h e p l a t f o r m .

The Coconino c o n t a i n s no known marine d e p o s i t s

The Holbrook Basin and a d j a c e n t Mogollon S h e l f were areas

o f much more r a p i d subsidence as shown by t h e 100-m-thick

zone o f i n t e r t o n g u i n g A t times

o f t h e i n t e r v a l o f s t u d y which i s n o t p r e s e n t across t h e p l a t f o r m .

t h e Holbrook Basin and Mogollon S h e l f were low enough t o a l l o w m a r i n e d e p o s i t s t o form on t h e s o u t h e a s t margin o f t h e Sedona Arch.

The r e l a t i o n s h i p between

changing subsidence r a t e s and area o f f a c i e s change seems v e r y d i r e c t .

Thus

t h e s u b t l e change i n t e c t o n i c regime from n o r t h w e s t t o s o u t h e a s t seems t o have a strong c o n t r o l

on t h e f a c i e s .

It seems u n l i k e l y ,

subsidence

i n the

study are d i r e c t l y

cycles.

rates

however,

t h a t changing

related t o individual

Some 30 c y c l e s a r e p r e s e n t i n t h e B e l l Rock s e c t i o n ( f i g .

seems l u d i c r o u s t o c a l l cycles.

area o f

upon 30 episodes

7 ) and i t

o f c y c l i c subsidence t o form t h e

I n s t e a d , changing base l e v e l , sea l e v e l i n t h i s case, would appear t o

be a more l i k e l y cause.

The w e l l documented Permian e u s t a t i c s e a l e v e l changes

due t o g l a c i a t i o n ( C r o w e l l , 1978) would cause s e a l e v e l change t o f l u c t u a t e and these

fluctuations

would

be b e s t

recorded

i n the

s h e l v e s and b a s i n s w i t h c o n n e c t i o n t o t h e open ocean.

stratigraphic

record o f

Subsidence e a s t o f t h e

Sedona Arch as documented by t h i c k e n i n g o f s e c t i o n and i n c r e a s e d marine deposi t i o n (Blakey, level,

1980),

k e p t t h e area low enough t h a t d u r i n g h i g h stands o f sea

m a r i n e d e p o s i t s were formed.

Rapid marine t r a n s g r e s s i o n s

caused by

l a r g e - s c a l e a b l a t i o n o f c o n t i n e n t a l i c e sheets i n t h e s o u t h e r n hemisphere may have advanced r a p i d l y a c r o s s t h e Mogollon S h e l f and i n t o t h e Sedona area.

Late

Q u a t e r n a r y r a t e s o f s e a l e v e l change o f 100 m p e r 15,000 y e a r s have been documented by Curray (1961).

I f s i m i l a r r a t e s o c c u r r e d i n t h e Permian,

a rapid

t r a n s g r e s s i o n a c r o s s a reasonably s t a b l e area l i k e c e n t r a l A r i z o n a would l i k e l y

575 result

in a

"rapid

erosional

t r a n s g r e s s i o n " (Curray,

transgression"

1964).

would l i k e l y be formed.

to

"discontinuous

depositionaj

An e r o s i o n a l p l a n e mantled w i t h t h i n d e p o s i t s

Advancement of t h e e r g accompanying t h e f a l l o f sea

l e v e l would produce common o f f l a p i n t h e r e g r e s s i o n a l sequence.

Coastal f a c i e s

would o v e r l i e o f f s h o r e f a c i e s and be o v e r l a i n by i n l a n d f a c i e s .

The r a t e o f

subsidence of t h e area would equal t h e t h i c k n e s s o f sediment d e p o s i t e d between e r o s i o n s u r f a c e s d i v i d e d by t h e number o f y e a r s between t r a n s g r e s s i o n s . Leonardian was about 18 my l o n g (VanEysinga, one-quarter

1975;

Waterhouse,

1978);

The about

o f t h a t t i m e o r 5 my approximates t h e l e n g t h o f t i m e d u r i n g which

t h e l o w e r Leonardian r o c k s o f t h e i n t e r v a l o f s t u d y were d e p o s i t e d (Blakey, 1980).

Assuming a g l a c i a l c y c l i c i t y o f about 2 m a j o r c y c l e s p e r m i l l i o n y e a r s

a l l o w s t i m e f o r 10 g l a c i a t i o n s d u r i n g upper Schnebly H i l l and l o w e r Coconino time.

The B e l l Rock s e c t i o n c o n t a i n s 30 c y c l e s and t h e i n c o m p l e t e West Fork

section contains

13 c y c l e s .

c o n t a i n about 15 c y c l e s .

A complete s e c t i o n i n t h e West Fork area would The B e l l Rock s e c t i o n i s more basinward and would

l i k e l y r e f l e c t s l i g h t f l u c t u a t i o n s o f s e a l e v e l more than t h e West Fork s e c t i o n . The 15 c y c l e s a t West Fork i s comparable t o t h e c a l c u l a t e d 10 g l a c i a l c y c l e s . The average t h i c k n e s s o f t h e West Fork c y c l e s i s 6 m. p e r 500,000 years.

y e a r s equals a subsidence

Six meters o f s e c t i o n

r a t e o f a p p r o x i m a t e l y 1 in p e r 100,000

The s e d i m e n t a t i o n r a t e was p r o b a b l y g r e a t e r as an unknown amount o f

sediment was removed by each e r o s i o n a l t r a n s g r e s s i o n .

These c a l c u l a t i o n s a r e

approximate and do n o t t a k e i n t o account f a c t o r s o f p r e s e r v a t i o n p o t e n t i a l and non-deposited c y c l e s , something about which we have no i n f o r m a t i o n . Water Table H e i g h t s The h e i g h t o f t h e water t a b l e r e p r e s e n t s t h e l o w e s t l e v e l t o which a dune f i e l d can be d e f l a t e d (Stokes,

1968).

Although B r o o k f i e l d (1977) and Kocurek

(1981b) have d i s c o u n t e d t h e Stokes model as a m a j o r c o n t r o l f o r f o r m a t i o n o f most e o l i a n bounding s u r f a c e s , 1983).

a c t i v e debate c o n t i n u e s (Loope,

1983; Kocurek,

Loope contends t h a t m i n o r f l a w s i n Stokes' drawings s h o u l d n o t j u s t i f y

d i s c a r d i n g t h e model and t h a t modern examples a r e s u p p o r t i v e o f t h e model. Kocurek agrees b u t c o u n t e r s t h a t e x t e n s i v e w a t e r - t a b l e - c o n t r o l l e d t h e a n c i e n t were formed by an " e x t r a - d u n e - f i e l d spread s u r f a c e s ,

event".

surfaces i n

He f e e l s t h a t wide-

n o t a t t r i b u t a b l e t o c l i m b i n g bedforms, " h e r a l d a m a j o r e v e n t

i n t h e a e o l i a n b a s i n " and t h a t "Stokes-type''

bounding s u r f a c e s mark " c o n t a c t s

between p e r i o d s o f a e o l i a n b a s i n e v o l u t i o n . "

H e r e i n l i e s t h e importance o f t h e

difference

between

i n t e r d u n e and

extradune

deposits.

The

base

of

upper

Schnebly H i l l c y c l e s a r e i n i t i a t e d w i t h extradune d e p o s i t i o n and a r e r e l a t e d t o m a r i n e t r a n s g r e s s i o n by drowning o f t h e source area. m a j o r event i n t h e e o l i a n basin. t i o n o f t h e dune f i e l d ,

The s u r f a c e s h e r a l d a

D u r i n g t h e ensuing r e g r e s s i o n and prograda-

t h e u n d e r l y i n g marine-sabkha d e p o s i t s and a s s o c i a t e d

576 w a t e r - t a b l e l e v e l s formed t h e l o w e s t l e v e l s t o which t h e new dune f i e l d s c o u l d be d e f l a t e d . (fig.

Some o f t h e s u r f a c e s near t h e m i d d l e o f t h e B e l l Rock s e c t i o n

7) may have formed i n t h i s manner r a t h e r t h a n as d i s t i n c t e r o s i o n a l

transgressions.

On t h e o t h e r hand, i n t e r d u n e d e p o s i t s w i t h i n t h e main Coconino

e r g a r e p r o b a b l y r e l a t e d t o bedform m i g r a t i o n and c l i m b i n g as d e s c r i b e d by B r o o k f i e l d (1977), Kocurek (1981b), and Rubin and Hunter (1982). differences that

I t i s these

i n mechanisms o f accumulation and p r e s e r v a t i o n o f dune d e p o s i t s

produced t h e s e d i m e n t o l o g i c d i f f e r e n c e s

Coconino and a l l o w d i f f e r e n t i a t i o n

of

between t h e Schnebly H i l l

t h e two d i s t i n c t

and

though g r a d a t i o n a l

geologic units. Re1a t i ons w i t h Adjacent Environments The e o l i a n d e p o s i t s strongly

influenced

of

by

s u p r a t i d a l environments. lagoons,

wave-

and

t h e upper Schnebly H i l l and l o w e r Coconino were

the

adjacent

shallow

marine,

coastal,

sabkha,

and

As e o l i a n dunes m i g r a t e d i n t o sabkha l a k e s o r c o a s t a l

ripple-laminated,

d e p o s i t s o f f a c i e s WBR were formed.

contorted,

and

wavy-bedded

sandstone

An example o f t h i s i s l o c a t e d s e v e r a l km

east o f Sedona where t h e Schnebly H i l l Road crosses t h e o u t c r o p o f t h e i n t e r v a l o f study.

A 15-20 m - t h i c k e o l i a n d e p o s i t o f f a c i e s TWC grades l a t e r a l l y i n

l e s s t h a n 200 m i n t o c r i n k l y - b e d d e d subaqueously d e p o s i t e d 10 m - t h i c k sandstone o f f a c i e s WBR ( f i g .

17).

Dune d e p o s i t s were reworked and r e d i s t r i b u t e d by

waves and t i d e s i n t o f a c i e s CC.

S i m i l a r l y c o a s t a l shoal and beach d e p o s i t s

were reworked by e o l i a n processes. A l t h o u g h adhesion r i p p l e s o r c l i m b i n g adhesion r i p p l e laminae a r e v e r y r a r e , a few poor examples a r e present.

These a r e common f e a t u r e s a s s o c i a t e d w i t h t h e

i n t e r a c t i o n o f e o l i a n and s u p r a t i d a l - s a b k h a environments.

Perhaps some o f t h e

abundant r i p p l e laminae o f f a c i e s WBR a r e a d h e s i o n - r i p p l e post-depositional

laminae o r perhaps

m o d i f i c a t i o n s have d e s t r o y e d t h e f e a t u r e s .

Upper Schnebly H i 11 , Lower Coconino Model The

interpretation

of

the

Coconino and t h e i r v e r t i c a l the depositional

history

of

facies

of

Schnebly H i l l

t h e upper

and lower

and l a t e r a l d i s t r i b u t i o n y i e l d a c l e a r model f o r these deposits

(fig.

18).

The model

depends

s t r o n g l y on o u r i n t e r p r e t a t i o n o f t h e e r o s i o n s u r f a c e s a t t h e base o f each c y c l e as b e i n g formed by r a p i d marine t r a n s g r e s s i o n .

Evidence gathered and

p r e s e n t e d i n t h i s paper i n d i c a t e s t h a t

none o f t h e o t h e r p o s s i b l e c o n t r o l s

c o u l d have caused most o f t h e widespread,

sharp s u r f a c e s i n t h e upper Schnebly

H i l l Formation.

577

F i g u r e 17. D e t a i l e d c r o s s s e c t i o n and p h o t o s showing t e r m i n a t i o n o f e o l i a n dune o r d r a a due t o m i g r a t i o n i n t o aqueous e n v i r o n m e n t , Schnebly H i l l l o c a l i t y . D r a w i n g t o s c a l e w i t h 2X v e r t i c a l e x a g g e r a t i o n .

578

NW

SE TRANSGRESSION /

-

1 inland dunes

PROGRADATION

2 (0

L

1

3 TRANSGRESSION @I

4

F i g u r e 18. Depositional Sedona area.

I

model f o r t h e upper Schnebly H i l l Formation i n t h e '

CONCLUSIONS D e t a i l e d a n a l y s i s o f t h e upper Schnebly H i l l Formation and l o w e r Coconino Sandstone near Sedona, A r i z o n a y i e l d e d t h e f o l l o w i n g f a c i e s and i n t e r p r e t a t i o n : T r o u g h - c r o s s - s t r a t i f i e d sandstone c o n t a i n i n g c h i e f l y c l i m b i n g t r a n s l a 1. t e n t s t r a t a i s i n t e r p r e t e d t o have formed as a c o a s t a l blow-out dune complex.

2.

I n t r a s e t c r o s s - s t r a t i f i e d sandstone formed i n l a r g e dunes and draas t h a t

m i g r a t e d southward i n response t o winds from t h e n o r t h .

3.

T a b u l a r - and wedge-shaped

s e t s o f h i g h - a n g l e g r a i n f a l l and sand f l o w

l a m i n a e formed i n l a r g e p r o b a b l y t r a n s v e r s e dunes and draas t h a t a l s o m i g r a t e d southward.

4.

Complexly c r o s s - s t r a t i f i e d

and wedge-shaped

sandstone w i t h m o s t l y medium-scale t r o u g h -

s e t s was d e p o s i t e d i n b a r s o r s h o a l s i n wave-

or tidal -

dominated shore1 i n e environments. 5.

Wavy bedded t o r i p p l e - l a m i n a t e d sandstone w i t h a v a r i e t y o f sma 1 - and

medium-scale

sedimentary s t r u c t u r e s formed i n a v a r i e t y o f i n t e r d u n e ,

dune, and s h a l l o w m a r i n e environments.

extra-

579 6.

The above f a c i e s grade l a t e r a l l y southeastward i n t o mudstone, carbonate

and gypsum o f marine, Vertical

and

r e s t r i c t e d inarine, and sabkha o r i g i n .

lateral

facies

distribution

indicate

that

southeastward-

p r o g r a d i n g e o l i a n d e p o s i t s were p e r i o d i c a l l y t r u n c a t e d and o v e r l a i n by marine s h o r e l i n e and a s s o c i a t e d d e p o s i t s .

The r e s u l t i n g sequence i s s t r o n g l y c y c l i c .

L a t e r e o l i a n c y c l e s prograded f a r t h e r southeastward than e a r l i e r d e p o s i t s u n t i l e v e n t u a l l y t h e e n t i r e r e g i o n was b u r i e d by t h e Coconino erg. Erosional

surfaces t h a t

marine transgressions.

base each c y c l e were carved by r a p i d e r o s i o n a l

Permian e u s t a t i c c y c l e s caused by g l a c i a l c y c l e s a r e

b e l i e v e d t o be t h e m a j o r cause.

Subsidence along t h e southeast margin o f t h e

Sedona Arch p r e s e r v e d an average o f 6 m o f sediment between c y c l i c e r o s i o n a l events. The d e p o s i t s o f t h e upper Schnebly H i l l and l o w e r Coconino r e f l e c t changing e o l i a n dune d e p o s i t s and a s s o c i a t e d environments t h a t formed i n response t o v a r i a b l e winds,

sand supply,

a d j o i n i n g environments. connections

between

base l e v e l changes,

tectonics,

and r e l a t i o n s t o

We b e l i e v e t h a t t h i s study has shown r a t h e r c l e a r

process,

product,

and cayse and may p r o v i d e c l u e s f o r

i n t e r p r e t i n g o t h e r a n c i e n t e o l i a n - m a r i n e complexes where these connections a r e more obscure. ACKNOWLEDGEMENTS T h i s paper b e n e f i t e d from reviews by Tom A h l b r a n d t , Mike B r o o k f i e l d , Loope,

Dave

and Jim Steidtmann and t h e i r suggestions f o r improvement a r e g r e a t l y

appreciated.

Some d r a f t i n g was done by Debby Meier.

Raymond o f t h e B i l b y Research Center,

L o u e l l a H o l t e r and Rick

N o r t h e r n Arizona U n i v e r s i t y p r o v i d e d

. t y p i n g and p h o t o g r a p h i c a s s i s t a n c e r e s p e c t i v e l y .

F i e l d t r a v e l was f i n a n c e d by

a NRRI f a c u l t y research grant a t Northern Arizona University.

REFERENCES A h l b r a n d t , T.S., and Fryberger, S.G., 1980, E o l i a n d e p o s i t s i n t h e Nebraska Sand H i l l s . U.S. Geol. Survey Prof. Paper 1120-A, 24 pp. Blakey, R. C., 1980, Pennsylvanian and E a r l y Permian paleogeography, southern Colorado P l a t e a u and v i c i n i t y . In: Fouch, T. 0. and Magathan, E. R. ( e d i t o r s ) , P a l e o z o i c Paleogeography of West-central U n i t e d States, Rocky Mtn. Sect. SOC. Econ. Paleont. and M i n e r a l o g i s t s , pp. 239-257. Boersma, J. R., and T e r w i n d t , J. H. H., 1981, Neap-spring t i d e sequences o f i n t e r t i d a l shoal d e p o s i t s i n a rnesotidal e s t u a r y . Sedimentology, 28:151170. Breed, C. S . , e t al., 1979, Regional s t u d i e s of sand seas u s i n g Landsat (ERTS) imagery. In: McKee, E. D. ( E d i t o r ) , A s t u d y o f g l o b a l sand seas. U.S. G e o l o g i c a l Survey Prof. Paper 1052, pp. 305-398. B r o o k f i e l d , M. E., 1977, The o r i g i n o f bounding s u r f a c e s i n a n c i e n t e o l i a n sediments. Sediinentol ogy, 24:303-332.

580 C r o w e l l , J.C., 1978, Gondwanan g l a c i a t i o n , c y c l o t h e m s , c o n t i n e n t a l p o s i t i o n i n g , and c l i m a t e change. Am. J o u r . Sci., 278:1345-1372. C u r r a y , J. R., 1961, L a t e Q u a t e r n a r y sea l e v e l : a discussion. Geol. SOC. Amer. B u l l . , 72:1701-1712. C u r r a y , J. R., 1964, T r a n s g r e s s i o n s and r e g r e s s i o n s . In: M i l l e r , R. I_. ( E d i t o r ) , Papers i n m a r i n e g e o l o g y , M a c m i l l a n , New York, pp. 175-203. D a v i d s o n - A r n o t t , R. G. D., and Greenwood, B., 1976, F a c i e s r e l a t i o n s h i p s on a b a r r e d c o a s t , Kouchibouguac Bay, New B r u n s w i c k , Canada. I n : D a v i s , R. A, and E t h i n g t o n , R. L. ( E d i t o r s ) , Beach and n e a r s h o r e m a r i n e s e d i m e n t a t i o n . SOC. Econ. P a l e o n t . and M i n e r a l o g i s t s Spec. Pub. 24, pp. 149-168. G e r r a r d , T. A., 1966, E n v i r o n m e n t a l s t u d i e s o f t h e F o r t Apache Member, Supai Formation, East-central Arizona. B u l l . Amer. Assoc. P e t r o l . G e o l o g i s t s ,

50:2434-2463.

R. G. D., 1979, S e d i m e n t a t i o n and Greenwood, B., and D a v i d s o n - A r n o t t , e q u i l i b r i u m i n wave-formed b a r s : a r e v i e w and case s t u d y . Can. J o u r . E a r t h Sciences, 16:312-332. H u n t e r , R. E., 1977, B a s i c t y p e s o f s t r a t i f i c a t i o n i n s m a l l e o l i a n dunes. S e d i i n e n t o l ogy, 24:361-387. H u n t e r , R. E., 1981, S t r a t i f i c a t i o n s t y l e s i n e o l i a n s a n d s t o n e s : Some In: P e n n s y l v a n i a n t o J u r a s s i c examples f r o m t h e Western I n t e r i o r 1J.S.A. E t h r i d g e , F. G. and F l o r e s , R. M. ( E d i t o r s ) , Recent and a n c i e n t noninarine SOC. Econ. P a l e o n t . d e p o s i t i o n a l environments: Models f o r e x p l o r a t i o n . and M i n e r a l o g i s t s Spec. Pub. 31, pp. 315-329. Kocurek, G., 1981a, E r g r e c o n s t r u c t i o n : t h e E n t r a d a Sandstone ( J u r a s s i c ) o f n o r t h e r n U t a h and Colorado. Palaeog. P a l a e o c l i m . P a l a e o e c o l o g y , 36:125-

153.

Kocurek, G., 1981b, S i g n i f i c a n c e o f i n t e r d u n e d e p o s i t s and b o u n d i n g s u r f a c e s i n a e o l i a n dune sands. S e d i m e n t o l o g y , 28:753-780. K o c u r e k , G., 1983, R e p l y : O r i g i n o f f i r s t - o r d e r b o u n d i n g s u r f a c e s i n a e o l i a n sandstones. Sedimentology, i n press. K o c u r e k , G., and D o t t , R. H., Jr., 1981, D i s t i n c t i o n and uses o f s t r a t i f i c a t i o n types i n t h e i n t e r p r e t a t i o n o f eolian deposits. Jour. Sediment. P e t r o l .

51~579-595.

Loope, D.B., 1983, O r i g i n o f e x t e n s i v e p l a n e s i n a e o l i a n s a n d s t o n e s : a d e f e n s e o f Stokes' hypothesis. Sedimentology, i n press. Lupe, R., and A h l b r a n d t , T. S., 1975, Sandstone geometry, p o r o s i t y , and permeability distribution, and fluid migration in eolian system r e s e r v o i r s . U.S. Geol. Survey O p e n - f i l e Rept. 75-357, 23pp. In: McKee, E. D. McKee, E. D., 1979a, S e d i m e n t a r y s t r u c t u r e s i n dunes. G e o l o g i c a l Survey P r o f . Paper ( E d i t o r ) , A s t u d y i n g l o b a l sand seas. U.S. 1052, pp. 83-134. McKee, E. D., 1979b, A n c i e n t s a n d s t o n e s c o n s i d e r e d t o be e o l i a n . I n : McKee, G e o l o g i c a l Survey P r o f . E. D. ( E d i t o r ) , A s t u d y i n g l o b a l sand s e a s : U.S. P a p e r 1052, pp. 187-238. McKee, E. D., 1982, s e d i m e n t a r y s t r u c t u r e s i n dunes o f t h e Narnib D e s e r t , South West A f r i c a . Geol. SOC. America Spec. Paper 188, 64pp. McKee, E. D., Douglass, J. R., and R i t t e n h o u s e , S., 1971, D e f o r m a t i o n o f l e e s i d e l a m i n a e i n e o l i a n dunes. B u l l . Geol. SOC. America, 82:359-378. P e i r c e , H. W., and G e r r a r d , T. A., 1966, E v a p o r i t e d e p o s i t s o f t h e Permian H o l b r o o k B a s i n , A r i z o n a . N o r t h e r n O h i o Geol. SOC. Second Symp. on S a l t , v. 1, pp. 1-10. d e Raaf, J. F. M., Boersma, J. R., and van G e l d e r , A., 1977, Wave-generated s t r u c t u r e s and sequences from a shallow marine succession, Lower C a r b o n i f e r o u s , County Cork, I r e l a n d . S e d i m e n t o l o g y , 24:451-483. R e i c h e , P., 1938, An a n a l y s i s o f c r o s s - l a i n i n a t i o n - - T h e C o c o n i n o Sandstone. J o u r . Geology, 46:905-932. R u b i n , D. M., and H u n t e r , R. E., 1982, Bed f o r m c l i m b i n g i n t h e o r y and nature. Sedi m e n t o l ogy , 29 :12 1- 138. Sharp, R. P, 1963, Wind r i p p l e s . Jour. Geology, 71:617-636. Van E y s i n g a , F.S.B., 1975, G e o l o g i c a l t i m e t a b l e . E l s e v i e r , Amsterdam.

581 Waterhouse, J . B . , 1978, C h r o n o s t r a t i g r a p h y f o r t h e W o r l d Perinian. In: C o n t r i b u t i o n s t o t h e G e o l o g i c Time Scale. Amer. Assoc. P e t r o l . G e o l o g i s t s S t u d i e s i n Geology, No. 6, pp. 299-322. W i l s o n , I . G., 1971, D e s e r t s a n d f l o w b a s i n s and a model f o r t h e development o f ergs. Geog. J o u r n a l , 137:180-199. Wilson, I. G., 1972, Aeolian bedforms--their development and o r i g i n s . S e d i m e n t o l o g y , 19: 173-210. Sed. Geology, 10:77-106. W i l s o n , I. G., 1973, Ergs.