The Dean Sand, Tubb Sand, and 3rd Bone Spring Sand are: a. Shelf Sands b. Not equivalent c. Equivalent in age d. Non-productive.

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Permian Cyclic Strata, Northern Midland and Delaware Basins, West Texas and Southeastern New Mexico
The American Association of Petroleum Geologists Bulletin 
V. 53. No. 11 (November, 1969) •• 2223-2251, 1.'. Figs , 1 Table 
Permian Cyclic Strata, Northern Midland and Delaware Basins, 
West Texas and Southeastern New Mexico' 
Abstract Permian cyclic rocks of Wo l fcampian-Guado l -
upian age in the norlhern Permian Basin, West Texas and 
southeosf New Mexico, are grouped into five regional ly 
extensive l i thofacies: (1) shelf evapor i te-carbonate, (2) 
shelf detr i tus, (3) shelf-margin carbonate, (4) basin cor-
bonate, and (5) basin detri tus. 
Recognition of these l i thofacies wi th in an unconformity-
bounded sequence suggests the fo l lowing sedimentary 
model . During normal sea-level condit ions, Wo l f camp ian-
Guadolup ian shelf-margin reefs and banks formed near 
sea level. The resultant backreef lagoon was shallow but 
very b rood ; therefore litt le terrigenous sand reached the 
distant basin. Deposit ion of shelf-margin carbonate was at 
a maximum and the sediments accumulat ing in the basin 
were chiefly pelagic mud and micrite. Relative lower ing 
of sea level , possibly eustat ic-epeirogenic, in i t ia ted re-
gression, causing continental and nearshore sand ond mud 
to progrode across the lagoon. Cont inued progradat ion 
enabled shelf detritus to enter the basin through numerous 
reentrants and submarine canyons dissecting the shelf 
marg in ; add i t iona l regression suboerial ly exposed the 
shelf clastic beds, prov id ing an unconformity-del imi ted 
datum surface. Flooding of the shelf by transgression re-
stricted the supply of detritus and reactivated normal car-
bonate deposi t ion. Correlat ion of a shelf-detritus top wi th 
a coeval basin-detritus top provides the framework for 
Wol fcampian-Guado lup ion shelf-to-basin correlations. 
INTRODUCTION 
Among the many difficult problems facing 
geologists is the formulation of a valid time-
stratigraphic framework for an area of complex 
lithosomal patterns and relatively steep deposi-
tional topography. Pennsylvanian and Permian 
strata in the Permian Basin of West Texas and 
southeast New Mexico (Fig. 1) exemplify this 
'Manuscript received, June 19, 1968; revised and ac-
cepted, February 2, 1969. 
- Geologist, Humble Oil & Refining Company, 
'Esse Production Research Company. 
Sincere thanks are extended to the Humble Oil & 
Refining Company for permission to publish this 
paper. Fusulinid identifications are by J. W. Skinner 
and G. L. Wilde, Humble Oil & Refining Company; 
timely discussions with them regarding fusulinid bio-
stratigraphic interpretations have contributed greatly to 
this study. R. M. Jeffords, F. A. Johnson, Jr., F. L. 
Peirce, and H. W. Praetorius, Humble Oil & Refining 
Company, and Mrs. R. G. Todd, and H. W. Wheeler, 
University of Washington, critically read the manu-
script. Appreciation is extended to B. J. Walker, Humble 
Oil & Refining Company, draftsman, and Mrs. B A. 
Silver, typist. 
BURR A. SILVERS and ROBERT G. TODD' 
Kingsvi l le, Texas 78363, and Houston, Texas 77001 
problem. Many geologists have recognized 
shelf, shelf-margin, and basin deposits in this 
area (Adams et~al.. 1951: Galley, 1958; King. 
1948; Van Siclen, 1958; Wright," 1962). How-
ever, because depositional topography has been 
accentuated by differential compaction along 
shelf margins, many of the consequent time-
stratigraphic problems are unsolved. Correla-
tion of anachronous lithosomes has resulted in 
erroneous facies, structural, and paleotopo-
graphic interpretations. 
The concept of depositional topography is not 
new. Rich (1951) recognized the importance 
of differentiating among horizontally bed-
ded rocks deposited above wave base (unda-
form), those laid down on the slope (clino-
form), and tho.se tleposited in deeper water on 
the sea floor Ifondoform). Van Siclen (1958) 
later applied Rich's concepts to Late Pennsyl-
vanian and Earlv Permian (Wolfcampian) 
strata on the Eastern shelf of the Midland 
Basin. Meissner ( 1967) and Jacka and St. Ger-
main (1967) described sea-level changes in 
Middle Permian (Guadalupian) strata of the 
Delaware Basin and spectilated on how these 
changes affected depositional topography and 
lithofacies. Meissner's approach to Guadalu-
pian shelf-to-basin correlations is similar to 
ours, but many of his correlations are different, 
particularly in the early (iuadalupian beds. 
This paper is the outgrowth of a detailed 
stratigraphic study in the northern part of the 
Midland and Delaware Basins (Fig. I ) . The 
study comprised six phases: ( I ) sample de-
scription of key wells including those on cross-
sections .A-E (Figs. 9^13). (2) use of com-
mercial and Humble sample descriptions of 
additional wells to (ill in data, (3) determination 
of depositional environments for lithic types, 
(4) systematic integration of biostratigraphic 
data (primarily fusulinid control) with physical 
stratigraphic data, (5) ilevelopment of shelf-
to-basin correlations based on these data, and 
(6) formulation ol a sedimentary model which 
best explains the phvsic.il correlations and deli-
neated environments, thus facilitating interpre-
tation of areas v\herc subsurface control was 
sparse. 
2 2 2 3 
http://tho.se
2224 Burr A. Silver and Robert G. Todd 
FIG. 1.—Major Permian geologic features, including location of cross sections. West Texas and southeastern 
New Mexico. Modified after McKee et al. (1967). Sections A-A' through F-E' are Figures 9-13. 
SHELF SEQUENCE 
1 2 
HONOLULU GREAT WESTERN 
N a 1 Bminard Na i B I O O I M 
GR Res. GR Res. 
BASIN SEQUENCE 
LIMESTONE1 
DOLOMITE 
O SANDSTONE 
SHALE 
3 
FELMONT 
N0.1 PDvrall 
GR Res. 
4 
HUMBLE 
N0.1 Cox 
GR Res. 
lOVP 
I 
3 
I 
F-IG. 2.—Leonardian sedimentary cycles, Midland Basin, West Texas. Vertical scale in feet. to 
DELAWARE BASIN MIDLAND BASIN 
1 
SHELL 
N0.1 Bootleg Ridge Unit 
GR Res. 
4 
HUMBLE 
N0.1 Cox 
GR Res. 
to 
lO 
0^ 
DO 
c 
o 
3 a. 
o 
o-
n 
O 
o a. a. 
FIG. 3.—Comparison of Delaware Basin and Midland Basin Leonardian sedimentary cycles, West Texas and 
southeastern New Mexico. Vertical scale in feet. 
I 
3 
n 
I 
Fui. 4.—Depositional environments related to normal sea level, Stage I, northern Permian Basin, southeastern 
New Mexico and West Texas. Approximate vertical exaggeration X 10. See footnote 4 for spelling of sebkha. 
lO 
to 
to 
OD 
JKL.ER 
WARD I M I \VARD 
'Bast 
E* 
T E X A C O 
#1 DC State 
Sec 3 BIk 18 
• 
SHELF E V A P O R I T E 
AND C A R B O N A T E 
B A S I N D E T R I T A L 
S H E L F - M A R G I N 
C A R B O N A T E 
B A S I N C A R B O N A T E 
SHELF D E T R I T A L 
FtG. 13.—West-east cross-section E-E', Guadalupian physical stratigraphic framework, northern Permian Basin, 
Ward and Winkler Counties, Texas. Location shown in Figure 1. Vertical scale in feet. 
file:///VARD
Permian Cyclic Strata 2237 
It is the intent of this study to place the Per-
mian Basin into a regional framework charac-
terized by cyclic changes in sea level during 
Early and Middle Permian time. A sedimentary 
model is used to show how it may explain the 
origin of the cyclic lithofacies and permit in-
terpretation of their synchronous patterns. The 
stratigraphic intervals discussed include the 
late Wolfcampian, Leonardian, and Guadalu-
pian Series. A complex stratigraphic nomencla-
ture has evolved to differentiate among shelf, 
shelf-margin, and basin beds; where possible, 
however, this nomenclature is avoided in order 
to emphasize the gross stratigraphic relations. 
Geologists generally employ two suites of 
terms to refer to depositional topography— 
shelf, shelf margin, and basin; or undaform, 
clinoform, and fondoform (Rich, 1951). Al-
though both suites have certain fundamental 
limitations, the use of shelf, shelf margin, and 
basin most accurately describes environment 
and site of accumulation of late Wolfcam-
pian-Guadalupian strata in the northern Per-
mian Basin. Most objectionable is the term 
basin. Unfortunately it has been applied to a 
site of sediment accumulation irrespective of 
original depositional environments and/or 
preservational patterns. To avoid confusion the 
term Basin is used with a capitalized proper 
name to refer to a preserved thick sedimentary 
section regardless of its depositional environ-
ment (e.g., Midland Basin, Delaware Basin); 
however, when basin remains in lower case let-
ters, it denotes an environment of deposition 
seaward of a shelf margin and below normal 
wave base. 
SEDIMENTARY MODEL 
Late Wolfcampian, Leonardian, and Guad-
alupian rocks are characterized by large-scale 
cyclic lithosomes. For example, Leonardian 
shelf rocks (Fig. 2) are typified by alternating 
carbonate and terrigenous clastic beds. Shelf 
and shelf-margin carbonates commonly are 
light-colored, dolomitized micritic and micri-
tic-skeletal limestone. Vugs filled with anhy-
drite are perhaps the most striking characteris-
tic of these shallow-water carbonate rocks. 
Varicolored shale, siltstone, and sandstone beds 
commonly intercalated with evaporite beds 
constitute shelf clastic rocks. Basin carbonate 
lithofacies (Fig. 2) are characteristically dark 
micritic and micritic-skeletal limestone. Dark 
claystone, siltstone, and sandstone typify basin 
terrigenous rocks. Four complete cycles of car-
bonate and clastic beds are recognized in the 
Midland Basin both on the shelf and in the 
basin. Similar cycles are present in the Dela-
ware Basin (Fig. 3) . For example, two wells in 
the Delaware Basin, the Shell No. 1 Bootleg 
Ridge Unit and the Continental No. 6 Bell 
Lake Unit, are correlated with the Felmont No. 
1 Powell and the Humble No. 1 Cox wells in 
the Midland Basin (Fig, 3) . The following sed-
imentary model is an attempt to explain the 
lithic cyclicity and juxtaposition of depositional 
environments observed in upper Wolfcampian, 
Leonardian, and Guadalupian strata of the 
northern Midland and Delaware Basins. 
Depositional Environments 
Continental.—Lithologic and biotic data sug-
gest an arid to semiarid climate during Early 
Permian time (Walker, 1967, p. 364). Fluvial 
sediment transport, therefore, was not region-
ally important and is considered subordinate to 
eolian sediment transport, much like that in the 
modern environmental setting described by 111-
ing et al. (1965) for the Persian Gulf. Early 
and Middle Permian continental strata consist 
of a redbed sequence of terrigenous sand and 
shale. Generally, shale lithic types are red and 
green quartzose clayite (Clark, 1954, p. 4) and 
siltite with interbeds of gray to brown mud-
rock. 
Shelf.—Continental sediments were bordered 
by broad supratidal and intertidal flats com-
posed of sabkha' (salt flat) and laminated algal 
deposits. The tidal-flat beds are composed gen-
erally of irregularly laminated, dolomitized mi-
critic limestone with interbeds of quartzitic 
clayrock and siltrock. Nodular anhydrite com-
monly is associated with dolomite. Stromatoli-
tic algae produce most of the characteristic 
laminae. 
Supratidal and intertidal flats were bordered 
by extremely wide lagoons which, during nor-
mal sea level, probably extended 10-150 mi 
shelfward. Lagoonal beds consist of thinly lam-
inated, medium-crystalline, dolomitized micri-
tic-skeletal limestone. Laminations have been 
destroyed locallv by burrowing animals and 
soft-sediment deformation. 
.Shell mar^'(«. -Shelf-margin beds are subdi-
vided into three main groups, each reflecting 
the influence of sea-floor topography, relation 
to effective wave base, and relative change in 
"Editor's footnote: Because writers have used a 
variety of spellings, Kinsman (1969, p, 832) proposed 
that sabkha be used as a standard spelling. Illustrations 
for this paper were drafted prior to that proposal, and 
the form sehkha is used on them. 
2238 Burr A. Silver and Robert G. Todd 
sea level. These beds are characterized by 
bank, reef, and forebank or forereef debris. In 
general, bank environments were dominant 
during Wolfcampian and Leonardian time, 
whereas reefs were characteristic of the Guad-
alupian. Banks consist of oolite bars and non-
wave-resistant skeletal buildups which are dis-
tinctly bedded. Biota is dominated by crinoid 
remains, fusulinids, and calcareous algae; 
brachiopods, corals, bryozoans, and sponges 
are common. Guadalupian reef facies are char-
acterized by calcareous sponges, numerous 
types of calcareous algae, bryozoans, and spe-
cialized brachiopods all incorporated into a 
massive wave-resistant framework. Both banks 
and reefs bordered foreslopes of moderately 
steep depositional topography. Foreslope de-
posits are distinguished from shallow-water 
bank and reef beds by their darker color, com-
mon presence of silicified fossils, and by nu-
merous shelf-derived lithoclasts. Deposition was 
the result of several mass-transport processes 
such as slow creep and suspension, and tur-
bidity currents. 
Basin.—Two lithic types, carbonate and ter-
rigenous detritus, constitute basin deposits. The 
carbonate type is dark, laminated micrite. The 
sparse fossils include fusuhnids and other fora-
minifers, crinoid columns, siUceous sponge spi-
cules, and ammonoids. Most of the micrite in 
the basin probably was derived from the shelf 
and shelf margin by transport in suspension. 
Mass transport of coarse carbonate detritus 
through submarine canyons as subaqueous 
slides or turbidite flows resulted in extensive 
redeposition of shallow-water carbonates in 
deeper water. These beds are characterized by 
a displaced shallow-water biota, clasts of both 
shelf and basin origin, graded bedding, and sili-
cification of fossils. Terrigenous detritus con-
sists of quartzose clayrock and siltrock, with in-
tercalated beds of dark micritic limestone that 
are regionally extensive. Generally these rocks 
lack fossils except where they interfinger with 
shelf-margin strata. Base level shifted fre-
quently during low-water stands, resulting in 
reworking of sediment. 
Cyclic Depositional Environments 
A series of. block diagrams (Figs. 4-7) dia-
grammatically depicts a falling sea level and its 
control of sedimentary patterns. Major cyclic 
fluctuation of base level with intermittent still-
stands contemporaneous with subsidence are 
the major controlling processes of this environ-
mental model. It is suggested that cyclic 
changes in sea level caused cyclic depositional 
patterns. 
Sea-level stage I.—During normal sea-level 
stand (Fig. 4 ) , shelf-margin reefs and banks 
formed near sea leyel. The resultant lagoon was 
shallow but very broad; therefore little terrige-
nous sand reached the distant basin. Deposition 
of shelf-margin carbonates was at a maximum 
and the main sediments in the basin were pe-
lagic mud and micrite. 
Sea-level stage / / . - A t sea-level stage 11 
(Fig. 5), shelf-margin strata were partly subaer-
ially exposed but still were forming actively at 
a lower elevation. Islands developed along the 
topographically highest parts of the shelf mar-
gin. The lagoon was constricted and was bor-
dered landward by an extensive algal flat. 
Locally, barrier islands developed during this 
sea-level stage. Continental and sabkha environ-
ments prograded basinward from their location 
at normal sea-level stand. Pelagic mud and mi-
crite were the doin.inant lithic types deposited 
in the basin. 
Sea-level stage III.- Ax this substantially 
lower sea level (Fig. 6 i . continental and near-
shore clastic beds continued to prograde sea-
ward. Sabkha and algal-flat deposits replaced 
previous lagoonal setliments. Reefs and/or 
banks ceased to develop and were replaced by 
an extensive stable land surface dissected by 
canyons and tidal channels. Tidal and near-
shore currents and local rivers swept land detri-
tus into canyon heads which were formed most 
commonly near salieni features on the shelf 
margin. This clastic material was transported 
down the canyons bv iraction, slow creep, or 
turbulent flow. Channel and overbank systems 
distributed clastic material in the form of pro-
grading submarine fans along the basin floor. 
Sea-level stage /K. - A t maximum low-water 
stand (Fig. 7) , land-derived detritus, at least 
locally, prograded completely across the shelf. 
Sediment transport was at maximum, so that 
sheetlike sands, perhaps more correctly de-
scribed as coalescing eolian and fluvial sands, 
prograded over the supratidal flat to the shelf 
edge. Lagoonal and shelf-margin environments 
were exposed subaerially before being covered 
bv prograding continental-derived sediments. 
Base level shifted frequently during maximum 
low-water stand; major degradation prior to 
burial beneath prograding continental sedi-
scale, but was a locallv important process. De-
ments probably did not occur on a regional 
trital sediment was carried across the shelf 
margin bv suspension or through submarine 
Permian Cyclic Strata 2239 
canyons by a combination of mass transport, 
slow creep, and tidal and nearshore currents. 
Interpretation of Time Surfaces 
Time-surface configuration.—The deposi-
tional environments are represented by five 
major lithofacies: (1) shelf detritus (continen-
tal and nearshore terrigenous clastic material), 
(2) shelf evaporite-dolomite (supratidal-flat 
and lagoonal strata), (3) shelf margin (oolite 
banks, reefs, etc.), (4) basin carbonate (pe-
lagic micrite), and (5) basin detritus (subma-
rine fan, turbidite, and bypass terrigenous clas-
tic material). 
If topography is assumed to have been mono-
clinal at time-surface T^ (Fig. 8) , the sedimen-
tary evolution as suggested in Figures 4 and 5 
occurred from Ti through T4. Time-surfaces T,, 
and T3 indicate that sedimentation rates were 
greater at the shelf margin than on the shelf or 
in the basin and that sedimentation was pro-
gradational. Time-surfaces T5 and T,, are in-
terpreted from the sedimentary model and sug-
gest that sedimentary rates were greater at the 
shelf margin than on the shelf, and were slowest 
in the basin. Figure 7 is not depicted precisely 
in upper Figure 8, but is approximated by the 
interval between T^ and T^. Transport of sedi-
ment in suspension over the shelf margin was 
probably a more important process during Wolf-
campian and Leonardian time than during the 
Guadalupian.

The Dean Sand, Tubb Sand, and 3rd Bone Spring Sand are: a. Shelf Sands b. Not equivalent c. Equivalent in age d. Non-productive.

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