Stratigraphic and Structural Relations of the Area South of Hot Springs Canyon, Galiuro Mountains, Arizona

Stratigraphic and structural relations of the area south of Hot Springs Canyon, Galiuro Mountains, Arizona

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Authors Goodlin, Thomas Charles

Publisher The University of Arizona.

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Link to Item http://hdl.handle.net/10150/558023 STRATIGRAPHIC AND STRUCTURAL RELATIONS

OF THE AREA SOUTH OF HOT SPRINGS CANYON,

GALIURO MOUNTAINS, ARIZONA

Thomas Charles Goodlin

A Thesis Submitted to the Faculty of the

DEPARTMENT OF GEOSCIENCES

In Partial Fulfillment of the Requirements For the Degreee of

MASTER OF SCIENCE

In the Graduate College

UNIVERSITY OF ARIZONA

1 9 8 5 STATEMENT BY AUTHOR

This thesis has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.

Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author.

APPROVAL BY THESIS DIRECTOR

This thesis has been approved on the date shown below:

7 William R. Dickinson Date Professor of Geosciences ACKNOWLEDGEMENTS

In completing my thesis, I owe gratitude to numerous individuals for their support and ideas. Foremost among them is my advisor, William R. Dickinson, who suggested the topic, offered invaluable advice and insight on countless occassions, both in the office and in the field, and provided thoughtful critical review of the final manuscript.

I am indebted to Roger A. Mark, with whom enumerable hours have been shared in our cooperative projects, for his companionship and enlivened discussions, both related and unrelated to our theses. I also thank Stephen J. Reynolds for many helpful discussions and ideas, and George H. Davis for his critical review of the manuscript.

Generous financial support was provided by the

Laboratory of Geotectonics, University of Arizona. I thank

Muhamed Shafiqullah for dating of igneous rock samples.

Stanley B. Keith kindly supplied petrochemical analyses. I appreciate the help of Dan Campbell and the Nature

Conservancy for access into the Muleshoe Ranch and Preserve.

To my wife, Cestjon L. McFarland, much could be expressed, but in this space I thank her for her loving support, her company on trips to the field area, and for her beautiful coloring of several maps. Finally, I owe much to iv my parents, Robert and Velma Goodlin, for their steadfast support of my education.

z TABLE OF CONTENTS

Page

LIST OF ILLUSTRATIONS...... Vii

LIST OF T A B L E S ...... X

A B S T R A C T ...... Xi

INTRODUCTION . . . . 1

ROCK U N I T S ...... 4

Willow Canyon Formation, Bisbee Group ...... 4 General ...... 4 Lithology ...... 7 Depositional Environment ...... 16 C o n t a c t s ...... 17 A g e ...... 17 Cretaceous Intrusives ...... 18 Muleshoe Volcanics ...... 19 General...... 19 Lithology...... 19 Depositional Environment ...... 23 C o n t a c t s ...... 25 A g e ...... 27 Cascabel Formation ...... 27 General...... 27 Lithology...... 28 Paleocurrents ...... 33 Depositional Environment ...... 34 C o n t a c t s ...... 36 A g e ...... 36 Mineta Formation ...... 37 Galiuro Volcanics ...... 38 Tertiary Intrusives ...... 39 San Manuel Formation ...... 40 Quiburis Formation ...... 41

S T R U C T U R E S ...... 42

Willow Canyon Formation ...... 42 F o l d s ...... 43 Foliation...... 51 L i n e a t i o n s ...... 56 Fractures...... 58

v vi

TABLE OF CONTENTS— Continued

Page

All Other Formations ...... 61 F o l d s ...... 61 Foliation...... 64 L i n e a t i o n s ...... 64 F a u l t s ...... 65 T h r u s t ...... 65 Reverse...... 69 High-angle N o r m a l ...... 69 Low-angle N o r m a l ...... 71 D i s c u s s i o n ...... 77

TECTONIC EVOLUTION ...... 83

APPENDIX 1 ...... 94

REFERENCES ...... 96

x LIST OF ILLUSTRATIONS

Figure Page

1. Location m a p ...... 2

2. Geologic map of the Hot Springs Canyon area, Cochise County, Arizona ...... Pocket

3. Representative columnar sections within the Willow Canyon Formation ...... Pocket

4. Sandstone and mudstone interbeds of the Willow Canyon F o r m a t i o n ...... 9

5. Geologic cross sections through the Hot Springs Canyon area, Cochise County, Arizona . . . Pocket

6. QFL diagram of sandstone compositions, Willow Canyon F o r m a t i o n ...... 12

7. Calcareous nodules in mudstone. Willow canyon Formation ...... 14

8. Porphyritic andesite breccia, Muleshoe Volcanics...... 20

9. Lahar deposit, Muleshoe Volcanics ...... 20

10. Muleshoe Volcanics/Cascabel Formation contact. . 26

11. Boulder conglomerate within lower Cascabel F o r m a t i o n ...... 29

12. Medium-bedded sandstone and matrix-supported pebble conglomerate, middle Cascabel Formation...... 29

13. Conglomerate beds in the upper Cascabel Formation...... 30

14. Paleocurrent rose diagram for Cascabel Formation...... 35

15. Bedding orientation, Willow Canyon Formation? (a) poles to bedding, lower hemisphere equal area projection, and (b) density contour diagram ...... 44 viii

LIST OF ILLUSTRATIONS— Continued

Figure Page

16. Isoclinal fold within fine-grained Willow Canyon sandstone...... 46

17. Polyclinal folds within fine-grained Willow Canyon s t r a t a ...... 47

18. Density contour diagram of fold axes, Willow Canyon Formation ...... 49

19. Density contour diagram of axial surfaces, Willow Canyon Formation ...... 50

20. Folded cleavage cut by subhorizontal foliation within Willow Canyon Formation ...... 52

21. Density contour diagram of foliation, Willow Canyon Formation ...... 53

22. Melange-style deformation of the Willow Canyon Formation within Hot Springs Canyon .... 54

23. Density contour diagram of striations, Willow Canyon Formation ...... 57

24. Pencil cleavage, lower hemisphere equal area projection, Willow Canyon Formation . . . .5 9

25. Density contour diagram of tension fractures, Willow Canyon Formation ...... 60

26. Density contour diagram of bedding orientations, Muleshoe Volcanics ...... 62

27. Density contour diagram of bedding orientations, Cascabel Formation ...... 63

28. Generalized geologic map of Hot Springs Canyon fault showing variable orientation ...... 66

29. Exposure of Hot Springs Canyon fault, placing Willow Canyon Formation above Cascabel F o r m a t i o n ...... 68

30. Sigmoidal sandstone phacoids in expoure above surface of Hot Springs Canyon fault .... 68 ix

LIST OF ILLUSTRATIONS— Continued

Figure Page

31. Exposure of Soza Mesa fault in Hot Springs C a n y o n ...... 75

32. Composite diagram of rotated structural elements within Willow Canyon Formation: from Table 1 ...... 79

33. View of Rincon Mountains from Hot Springs C a n y o n ...... 89 LIST OF TABLES Table

1. Rotation of structures to correct for dip of Galiuro Volcanics ...... ABSTRACT

The rocks of the Hot Springs Canyon area record a history of Mesozoic and Tertiary deposition, and Laramide and mid-Tertiary tectonism. Formations include Upper Juras- sic(?)-Lower Cretaceous Willow Canyon Formation, Upper Cre taceous Muleshoe Volcanics, Upper Cretaceous-Paleocene(?)

Cascabel Formation, Oligocene Mineta Formation, Oligocene

Galiuro Volcanics, Miocene San Manuel Formation, and

Miocene(?)-Pliocene Quiburis Formation. Laramide compression, directed in a N45°E azimuth, caused open to isoclinal folding and thrusting within the Cretaceous units, with syntectonic eruption of the Muleshoe Volcanics and depostion of the Cascabel Formation. Mid-Tertiary crustal extension along a N60°E azimuth resulted in high- and low-

angle normal faulting accompanied by clastic deposition and volcanism. Southwest vergent listric low-angle normal

faults apparently represent the breakaway zone for the

Rincon/Catalina metamorphic core complex to the west, and

form the western structural front of the Galiuro Mountains.

xi INTRODUCTION

The Hot Springs Canyon area lies approximately 60 km east of Tucson in the southern Galiuro Mountains (Figure 1).

The area of study covers approximately 90 square km (Figure

2, in pocket). The eastern portion of the area lies within the Muleshoe Ranch Preserve, owned and operated by the

Nature Conservancy. The area mapped is essentially a window through the mid-Tertiary Galiuro Volcanics, which form the higher elevations of the Galiuro Mountains, and is underlain mostly by older sedimentary and volcanic rocks. This report deals mainly with the southern half of the area, between Hot

Springs Canyon and Teran Basin, although some discussions do pertain to the entire map area.

The area is dissected by Hot Springs Canyon, a major

tributary of the San Pedro River to the west. This canyon

is a deeply incised drainage with local relief of up to 120 m, and provides the best exposures of the rock units in the

area. The creek within the canyon is perennial, and serves

as the home for a rare species of fish, Gila intermedia.

The rest of the area consists of rolling hills with shallow

ly incised drainages. Cliffs and peaks of Galiuro Volcanics

border the area on the north and east. The total vertical

relief is from 1035 to 1600 m above mean sea level. Soza

Mesa stands at 1280 m— the approximate height limit for most

1 2

.MAMMOTH

PIMA CO

COCHISE CO

>• TUCSON

JQNNN'K LYON MILLS)

LITnLE DRAGOON

10 20 KM

Figure 1. Location map. 3 of the study area— and is underlain by pediment gravels of the Quiburis Formation, which underlies the western edge of the area.

The Hot Springs Canyon area was previously unmapped in detail. Prior work in the vicinity includes the thesis work of Jeffrey A. Grover (Grover, 1982, 1984) in Teran

Basin to the south, and work by geologists of the U.S.

Geological Survey (Creasey and Krieger, 1978; Creasey and others, 1981) in the northern half of the Galiuro Mountains.

Much of the geology shown on the southernmost portion of the map (Figure 2, in pocket) is adapted from Grover's fine mapping (Grover, 1982, Figure 2). However, Grover did not differentiate between the Muleshoe Volcanics and Cascabel

Formation of this report, but referred to both as Cretaceous

sediments and volcanics undifferentiated. Field work was

conducted over 53 days during the fall of 1984 in conjunc

tion with Roger A. Mark (Mark, 1985), whose study area

extends north from Hot Springs Canyon. ROCK UNITS

The study area contains a total of nine rock units, ranging in age from Upper Jurassic(?) or Lower Cretaceous to

Pliocene. These include: the Upper Jurassic(?) to Lower

Cretaceous Willow Canyon Formation of the Bisbee Group,

Upper (?) Cretaceous intrusives, the Upper Cretaceous

Muleshoe Volcanics, the uppermost Cretaceous to Paleocene(?)

Cascabel Formation, the Oligocene Mineta Formation, the

Oligocene Galiuro Volcanics, mid-Tertiary intrusives, the

Miocene San Manuel Formation, and the Upper Miocene(?)

Pliocene Quiburis Formation.

Willow Canyon Formation, Bisbee Group

General

The Bisbee Group of southeastern Arizona consists of

Upper Jurassic to Lower Cretaceous sedimentary rocks of intercalated nonmarine and marine facies. These strata are composed of very coarse- to very fine-grained terrigenous rocks and limestones. The rocks of the Bisbee Group, first described by Bumble (1902) in the Mule Mountains, were divided into four formations by Ransome (1904). These consist of the basal Glance Conglomerate, the Morita

Formation, the Mural Limestone, and the Cintura Formation,

4 5 with a range in age from Upper Jurassic to Albian or Ceno manian (Vedder, 1984; Dickinson, and others, in press).

North of the type region of the Bisbee Group, the marine Mural Limestone of Aptian-Albian age is absent. This has required the adoption of a different set of formational names (Tyrrell, 1957; Finnell, 1970) that are applied to the almost exclusively nonmarine Bisbee strata. These strata include the basal Glance Conglomerate, the Willow Canyon

Formation, the Apache Canyon Formation, the Shellenberger

Canyon Formation, and the Turney Ranch Formation. These units crop out in the Whetstone (Tyrrell, 1957? Hayes, 1970;

Archibald, 1982), Empire (Finnell, 1970; Hayes, 1970), Santa

Rita (Hayes, 1970; Drewes, 1971), Rincon (Drewes, 1981),

Santa Catalina (Bykerk-Kauffman, 1984; Janecke, in pre paration), and Galiuro Mountains (Grover, 1982; Goodlin, this report; Mark, 1985).

The Bisbee Group was deposited in the northwestern extremity of the Chihuahua Trough, a marine arm of the early

Gulf of Mexico (Bilodeau, 1979; Dickinson, and others, in press). Bilodeau (1979) suggested that the Chihuahua Trough was an aulocogen-type feature that allowed a marine trans gression to extend northwest from the Gulf of Mexico. The

Mural Limestone marks the farthest encroachment of wide spread marine waters, although Archibald (1982) reports marine sediments locally in the shellenberger Canyon

Formation. The Bisbee Group of the north is seen to 6 represent basal alluvial fans that extended upward into braided and meandering fluvial systems, which in turn fed into tidal and lagoonal or lacustrine environments, and, to the south, culminated in true shallow-marine deposition.

The contacts between the various formations representing different environments are everywhere intertonguing and diachronous.

Strata of the Bisbee Group in the Hot Springs Canyon area are assigned to the Upper Jurassic(?) to Lower

Cretaceous Willow Canyon Formation. Their occurrence repre sents the northernmost exposure recorded for this formation, and the only strata of the Bisbee Group farther north in the general vicinity are assigned to the Glance Conglomerate, which is recognized nearby in the Santa Catalina Mountains

(Bykerk-Kauffman, 1984; Janecke, in preparation). The

Willow Canyon Formation was named by Tyrrell (1957) for

exposures along Willow Canyon on the west flank of the

Whetstone Mountains. He treated the Glance Conglomerate as

the lower member of the formation, but subsequent workers

(Finnell, 1970; Drewes, 1971; Archibald, 1982) regard the

Glance Conglomerate as a separate formation.

The Willow Canyon Formation varies widely in thick

ness, ranging from zero to over 900 m. Tyrrell (1957)

measured a maximum 174 m in the Whetstone Mountains, Finnell

(1970) noted 914 m in the Empire Mountains, and Drewes

(1971) described sections up to 670 m in the Santa Rita 7

Mountains. The Willow Canyon Formation is previously unrecognized in the Galiuro Mountains, although Grover

(1982) mapped Bisbee Group in the Teran Basin area without differentiating it into formations. At least 400 m of the

formation are represented in the exposures of the Hot

Springs Canyon area.

The Willow Canyon Formation crops out predominantly in the western half of the area, with the best exposures

occurring in Hot Springs Canyon and to the north in Soza

Wash (Figure 2, in pocket). A large area north of Soza Mesa

is underlain by the formation, with the northernmost

exposure occurring in Cherry Spring Canyon. From Hot

Springs Canyon, a belt of exposures extends south through

Pool and sierra Blanca Canyons, then curves to the east.

The age of this unit is most likely Lower Cretaceous, but

strata of Upper Jurassic age may be included (Dickinson and others, in press).

Lithology

The Willow Canyon Formation in the study area

consists of interbedded sandstone and mudstone in variable

ratios, with less abundant siltstone, local pebble to cobble

conglomerate horizons, and extremely rare limestone beds.

The sandstone is typically thick-bedded, red-brown to olive-

gray, calcite-cemented, fine- to medium-grained, rounded,

moderately-sorted, planar-laminated or cross-stratified

sublitharenite. The mudstone, which commonly contains 8 pebble-sized micritic carbonate nodules and includes siltstone interbeds, is generally red, massive, and non- fossiliferous. The normally graded, clast-supported conglomerate contains only three clast types in variable percentages: limestone, quartzite, and chert. The one limestone bed recognized within the area consists of medium- gray, medium-grained, sandy, unfossiliferous, thin-bedded limestone with red-brown chert stringers; this 3 m thick bed pinched out laterally within about 50 m. Figure 3 (in pocket) illustrates a representative stratigraphic section in the Willow Canyon Formation, and Figure 4 shows typical sandstone and mudstone interbeds.

Individual beds of Willow Canyon sandstone range from 1 cm to 4 m thick, but most commonly are 0.5 to 1 m thick (Figure 3, in pocket). Some outcrops in Sierra Blanca

Canyon display interbedded fine-grained sandstone and mudstone with beds from 1 to 3 cm thick. Other massive sandstone beds several meters thick lack visible internal stratification. Individual packages of sandstone, con taining several beds, can be 25 m thick, although they are generally much less. Laterally, the sandstone and mudstone beds may be quite extensive, whereas lenses of sandstone

also occur within the mudstone. Planar laminations

represent by far the most abundant bedding structures, with

trough and tabular crossbeds secondarily present. Most

bedding contacts are planar, although some scoured surfaces 9

■ VW a W' Jm - i . " s:*rs.

Figure 4. Sandstone and mudstone interbeds of the Willow Canyon Formation— hammer in left-center of photograph» 10 are present. Grading is generally absent from the sandstone, with slight normal grading noted at the. tops of a few beds.

The mudstone occurs as massive bodies packaged between sandstone beds, typically with planar contacts. The mudstone beds are commonly 0.5 to 2 m thick, and range from

0.1 to approximately 5 m. Bedding planes are essentially obscured by pervasive, though highly variable, bedding- parallel foliation that occurs throughout the mudstone of

the study area.

The conglomerate beds, which occur in association with the sandstone, show normal grading and overlie scoured

bases. Their thickness ranges from 0.1 to 4 m, with beds 1

m thick being the most abundant. The beds grade upward from

coarse conglomerate to fine sandstone within 1 to 5 m

stratigraphically. The lateral extent of the conglomerate

beds is difficult to determine, but for the most part they

tend to pinch out over distances of tens of meters.

Conglomerate constitutes perhaps 5% of the formation.

Due to structural complications, the thickness of

the Willow Canyon Formation cannot be determined accurately.

From locally intact sections, it is believed that at least

400 m are present, and probably much more. The geologic

cross-sections (Figure 5, in pocket) indicate a much greater

thickness than stated, but with the complexity of the \ 11 structure it is unknown to what extent the unit might be structurally repeated.

Sandstone. The sandstone consists of orange-red and medium red-brown to light gray and olive-gray, fine- to coarse-grained, rounded, moderately- to well-sorted, thick- bedded sublitharenite with calcite, silica, or hematite cement. Based on point counts on seven thin sections of 400 grains each, quartz constitutes 89% of the grains by volume.

The other constituents include chert grains (6.5%), detrital limestone clasts (4.5%), heavy minerals (2%; magnetite, augite, hematite, and epidote), sandstone and mudstone fragments (1.8%), K-spar (.8%), plagioclase (.25%), and white mica (.2%). Figure 6 illustrates the range in sandstone composition.

Commonly, cement constitutes about 25% of the sandstones, and ranges from 14 to 40% by volume. Calcite is the most abundant cement, forming 20 to 99% of the cement in a given rock, and is often accompanied by microcrystalline quartz that forms from <1 to 65% of the cement. Hematite cement is secondarily present, forming almost all the cement in some beds. Quartz overgrowths also account for approximately 5% of the cement. Calcite has entirely or partially replaced many grains, including quartz overgrowths and quartz grains. Contact relationships indicate that quartz overgrowths formed first, followed and mostly 12

Q QUARTZARENIT

SUBARKOSE SUBLITHARENITE

Q = mono- and poly-crystalline quartz

F = Feldspars

L = Lithics, including chert

Figure 6. QFL diagram of sandstone compositions, Willow Canyon Formation— fields refer to classification of Folk (1974). 13

replaced by calcite or hematite, with microcrystalline quartz ultimately replacing some calcite.

The quartz is predominantly of plutonic origin,

based on the criteria of Folk (1974), with a minor amount of

metamorphic quartz. The majority of quartz grains have

undergone strain, resulting in undulose extinction and

calcite-filled fractures. In addition, embayment and

partial to complete relacement by calcite occurs.

Mudstone. The Willow Canyon mudstone displays

bright red to deep red-brown or red-gray colors. It is

aphanitic and generally featureless in nature. Interbeds of

quartzitic siltstone are associated with the mudstone

(Figure 3). Individual quartz and chert grains, commonly

very fine but up to coarse sand in size, constitute perhaps 1-3% of the rock.

A diagnostic feature of much of the mudstone is the

occurrence of light or medium gray to red-brown calcareous

nodules, whose distribution and size are highly variable.

These are typically subspherical to lobate, and normally

range in size from 0.5 to 5 cm, but can be as large as 15

cm (Figure 7). The nodules are internally structureless and

consist primarily of micrite, but also contain variable

amounts of silt-sized quartz grains. Where present, the

nodules normally constitute 10-30% of the rock, but the true

range extends from <1 to 60%. 14

Figure 7. Calcareous nodules in mudstone, Willow Canyon Formation— both undeformed and deformed nodules are present. Ruler is 15 cm (6 in.). 15

Within the Willow Canyon Formation in other areas, some fossils have been recovered in a dark shale facies not present within the study area. Tyrrell (1957) collected several brachiopod carapaces from some shale beds in the

Whetstone Mountatins, Finnell (1970) found a gastropod in the Empire Mountains, and Drewes (1970) reported the finding of molluscan fauna in the Santa Rita Mountains. In the Hot

Springs Canyon area, no fossil remains were encountered.

Conglomerate. The conglomerate occurs as horizons or lenses within sandstone. It is well-rounded to sub rounded, clast-supported conglomerate composed of limestone, quartzite, and chert pebbles and cobbles. The clasts of the conglomerate normally range in size from 0.5 to 6 cm, although one outcrop exposed low within Hot Springs Canyon contains clasts up to 15 cm in length. The clasts are

typically lobate, with length to width ratios of about 3:2.

Imbrication of pebbles occurs, but is not common.

The counting of 1900 pebbles at 19 locations

provides a mean ratio of 5:4:3 of limestone:quartzite:chert,

but the ratio is highly variable from outcrop to outcrop.

For instance, limestone ranged from 0 to 83%, quartzite from

1 to 86% and chert from 4 to 40%. The limestone clasts are

light to medium blue-gray, fine- to medium-grained and

always well-rounded. The quartzite is white to orange-red,

fine- to medium-grained, well-rounded, well-sorted, and

silica-cemented, with the clasts usually well-rounded. The 16 chert is a light yellow-brown to deep red, and is generally subrounded.

Depositional Environment

The general nature of the depositional system represented by the Willow Canyon Formation is well estab lished. The Willow Canyon Formation is largely a time- equivalent, lateral facies of the underlying Glance

Conglomerate and the overlying Apache Canyon Formation.

Hayes (1970), Bilodeau (1979), Bilodeau and Lindberg (1983),

Archibald (1982), and Dickinson and others (in press) view this as a tripartite system of proximal alluvial fan, distal alluvial fan/braided stream, and lacustrine/playa deposits.

Within this framework, the Willow Canyon Formation represents the braided floodplain and distal alluvial fan environments.

The most obvious feature of the Willow Canyon

Formation in the Hot Springs Canyon area is the persistent interbedding of sandstone and mudstone. The sandstone exhibits abundant planar laminations, planar contacts, and a paucity of grading and lower-flow-regime structures. The mudstone is abundant, comprising 40 to 50% of the formation.

The conglomerates, scoured basal contacts, normal grading, widespread lamination, and local crossbedding suggest braided stream deposition. The dominant lithofacies imply deposition on a broad, relatively flat alluvial plain with 17 occasional sheet-flood events and braided-stream channelling, but with extensive overbank deposition. The micritic nodules indicate pedogenic nodules of incipient soil development (caliche), although well developed paleosol horizons were not recognized. The presence of limestone indicates local intertongueing with lacustrine environ ments, perhaps associated with floodplain lakes.

Contacts

Within the study area, the basal contact of the formation is everywhere structural. The same is true for the upper contact, except where Galiuro Volcanics rest unconformably upon the Willow Canyon Formation, or where pediment gravels of the Quiburis Formation overlie the unit.

Although unseen, the base of the Campanian-Maastrictian

Muleshoe Volcanics is presumed to rest unconformably upon the older Willow Canyon Formation (Figure 5, in pocket).

Age

The only age controls within the entire Bisbee Group are found within the Glance Conglomerate and the Mural

Limestone (Dickinson and others, in press). The Glance

Conglomerate is generally Lower Cretaceous in age, although it has been shown to include Upper Jurassic rocks in the vicinity of the Huachuca Mountains (Kluth, 1983; Vedder,

1984). Since the Glance Conglomerate and the Willow Canyon 18

Formation are roughly syndepositional (Bilodeau, 1979), the

Willow Canyon Formation in the Hot Springs Canyon area is most likely Early cretaceous in age, but could also include

Upper Jurassic strata.

Cretaceous Intrusives

Several porphyritic andesite dikes intrude the

Willow Canyon Formation north of Soza Mesa (Figure 2, in

pocket). These consist of small bodies, usually less than

25 m across, that contain phenocrysts of plagioclase, horn

blende, and biotite. Some contacts have been structurally

altered, but, where, preserved they are clearly intrusive.

Within the Willow Canyon Formation in lower Hot

Springs Canyon, a dark blue-green to brown diorite dike

intrudes the country rock (Figure 2). This medium-grained

diorite contains plagioclase, hornblende, biotite, and

pyroxene visible in hand sample. The dike is highly

deformed, with significant epidote and chlorite alteration.

Preliminary Rb-Sr isotopic analysis suggests that this rock

is of Cretaceous age (Shafiqullah, pers. commun.).

The lithologic similarity of these andesitic and

diabase intrusives to the Muleshoe Volcanics suggest that

they represent the near-surface to hypabyssal expression of

overlying Upper Cretaceous volcanics. 19

Muleshoe Volcanics

General

The Campanian-Maastrichtian Muleshoe Volcanics, herein named after the Muleshoe Preserve and Ranch of the

Nature Conservancy, consist largely of andesitic breccia, but also includes tuff, lahar deposits, lava, conglomerate, sandstone, and mudstone. Whole-rock chemical analysis on two samples indicates a calc-alkalic to calcic petro chemistry (Appendix 1). The volcanics crop out pre dominantly along the eastern side of the area in large

continuous exposures, but also to the south in Teran Basin

and to the northwest in Soza Wash (Figure 2, in pocket).

Lithology

The dominant lithology of the Muleshoe Volcanics is

monolithologic, gray to dark purple-gray, porphyritic

hornblende-biotite andesite breccia (Figure 8). The breccia

clasts are subangular and range in diameter from 2 mm to 60

cm, with an average of approximately 6 cm. The matrix and

clasts are of similar composition and appearance, with the

clasts being a shade darker. The breccia beds are massive,

although a trachytic texture is locally developed within the

clasts. Bed thickness is difficult to determine, but is

probably on the order of 5 to 15 m. Lava flows of

porphyritic hornblende andesite crop out in small

percentages, and are similar in petrology to the breccias.

One sample of the hornblende andesite produced a K-Ar age on 20

Figure 8. Porphyritic andesite breccia, Muleshoe Volcanics— Hot Springs Canyon.

Figure 9. Lahar deposit, Muleshoe Volcanics— Hot Springs Canyon. Clasts occur in excess of 1.5 m diameter. 21 hornblende of 73.7 -h 1.8 m.y.B.P. (Shafiqullah and others,

1980). Whole-rock chemical analysis on one andesite sample indicates 60.7 weight percent Si02 (Appendix 2).

Lahar deposits constitute perhaps 20% of the

Muleshoe Volcanics. These medium to light gray beds may be predominantly andesitic, or contain a variety of inter mediate to silicic volcanic clasts. The clasts, which are

angular to rounded and 2 mm to 2 m in diameter, are

dominantly porphyritic andesite, but include abundant

porphyritic dacite and some banded, vitrophyric rhyolite. The clasts of some beds are monolithologic. More commonly,

the clasts are mixed volcanics that constitute 5 to 30% of

the rock, and float in a coarse to aphanitic matrix (Figure

9). Rarely, rounded sandstone clasts from the Willow Canyon

Formation, up to 1 m in diameter, and limestone clasts are

included within the flows.

Tuffs from silicic to intermediate compositions

occur throughout the Muleshoe Volcanics, forming perhaps 10%

of the formation. They are moderately welded, medium

grained, and usually about 10 m thick. The most abundant

are rhyolite to rhyodacite tuffs, milky white to medium gray

in color and including phenocrysts of K-spar, quartz,

plagioclase, biotite, and minor hornblende. Medium gray t dacite(?) tuffs include K-spar (up to 1 cm in length),

plagioclase, biotite, and hornblende. Dark gray andesite

tuffs, weathering to brown-gray, contain plagioclase. 22 hornblende, and biokite. The tuffs are locally exposed over distances of 2 or 3 km, as along the western edge of the exposure in Hot Spring Canyon (Figure 2, in pocket), but they cannot be correlated throughout the area.

Within a tuff exposed near the top of the formation in Hot Springs Canyon (32°, 21.04'; 110°, 17.24'), an age of

76.5 + 1.8 m.y.B.P. was obtained from a K-Ar date on biotite

(Shafiqullah, per. com., 1985). This tuff consists of moderately welded, porphyritic, biotite-hornblende rhyodacite tuff with a devitrified groundmass and a very high phenocryst content. The phenocrysts consist of K-spar, quartz plagioclase, biotite, hornblende, and iron oxides.

The tuff also includes small clasts of andesite (<4 cm diameter), gray-white pumice, and very rare rounded quartzite clasts. Whole rock chemical anlysis indicates

70.1 weight percent Si02 and the presense of normative corundum, possibly in part due to alteration (Appendix 1).

Volcaniclastic beds consisting of sandstone, mudstone, and conglomerate form perhaps 10% of the Muleshoe

Volcanics. The beds are planar and medium-bedded with some cross-stratification and channelling present. Quartz bearing sandstone occurs as lenses within the brown, lamin ated mudstone. Rare clast-supported, rounded, pebble to cobble conglomerate with andesite and quartzite clasts and a coarse- to medium-grained, lithic sandstone matrix also occurs in association with the mudstone. Exposures of the 23 mudstone occur predominantly south of Hot Springs Canyon, below the mid-Tertiary Galiuro Volcanics to the east. These exposures appear to be included in the upper portion of the

Muleshoe Volcanics. Pebble to cobble conglomerates of clast-supported, rounded andesite clasts are locally present as well.

An estimated 700 m of the Muleshoe Volcanics are exposed along Hot Springs Canyon. Due to sparse exposures of bedding planes and structural complications, the true thickness is not exactly known and may range from 500 to

1000 m. As the depositional base is nowhere exposed, strata hidden from view have an indeterminate thickness.

Depositional Environment

The variety of volcanic deposits present— including autobrecciated flows, lavas, lahars, tuffs, and reworked sediments— indicate that the late Campanian to early

Maastrichtian Muleshoe volcanics represent an andesitic stratovolcano deposit. By the nature of this deposit, it was probably not regionally extensive, although correlatives are present within the region.

Isolated exposures of volcanics of similar age and

lithology occur in southeastern Arizona. Within a 100 km

radius are the Glory Hole Volcanics (Galiuro Mountains, 40

km north), the Williamson Canyon Volcanics (Mescal

Mountains, 70 km north), the Salero Formation (Santa Rita 24

Mountains, 80 km southwest), and the Old Yuma Andesite

(Tucson Mountains, 85 km west). The Late cretaceous Glory

Hole Volcanics, dated at 64.4 + 1.3 m.y.B.P. (Shafiqullah and others, 1980), consist of tuffs, flow-breccias, bedded volcanic sediments, and lavas of andesitic to dacitic compostion. These light brown to gray to purple-gray porphyritic andesites and dacites are calc-alkalic (Keith,

1978). The Late Cretaceous Williamson Canyon Volcanics include green-gray or grayish-purple agglomerates, tuffs, tuff-breccias, lavas, flow-breccias, and conglomerates

(Simons, 1964). These porphyritic hornblende andesites or dacites have been dated at 77.5 + 1.4 m.y.B.P. and are alkali-calcic (Keith, 1978). The Salero Formation, dated at

75 m.y.B.P. (Drewes, 1971) and also alkali-calcic (Keith,

1978), consists of dacite and andesite lava and tuff- breccia, rhyodacite tuffs, and sedimentary rocks dated at 75 m.y.B.P. (Drewes, 1971). The Old Yuma Andesite, mapped only in reconnaissance fashion by Knight (1967), consists of over

650 m of purple-gray porphyritic andesite. The age is most likely Upper Cretaceous, for it lies above 75 my old volcanics and predates at least part of the Laramide deformation, but could also be early Tertiary. The Glory

Hole Volcanics, although younger, provide the best correlation with the Muleshoe Volcanics; in addition, the

Old Yuma Andesite may correlate, but dating and chemical analysis is required to verify this. 25

Contacts

The base of the Muleshoe Volcanics is unexposed. I Presumably, the formation either unconformably overlies the rocks of the Bisbee Group, or conformably overlies unseen coarse elastics such as the Santonian-Campanian Fort

Crittenden Formation, as in the case of the Salero Volcanics

in the Santa Rita Mountains (Drewes, 1971). In either case, a regional unconformity separates the Lower Cretaceous

Bisbee Group and the Upper Cretaceous rocks of southeastern

Arizona (Dickinson and others, in press).

The upper contact is clearly depositional, at least

locally, with the overlying Cascabel Formation. In Hot

Springs Canyon, the uppermost Muleshoe is volcaniclastic

conglomerate, essentially composed entirely of volcanic

clasts. This lithology grades upward into polymictic

Cascabel conglomerate, with the contact between the two

formations placed at the lowest bed containing a

predominance of sedimentary clasts (Figure 10). Elsewhere,

the gradational nature of this contact is less evident. The

contact is locally abrupt, with Cascabel conglomerate

resting directly on Muleshoe andesite, but everywhere lacks

angular discordance. To the south, there is map evidence

that the Muleshoe and Cascabel intertongue, as seen in the

complex relationships of T. 13 S., R. 20 E., S. 11-12

(Figure 2, in pocket).

f 26

Figure 10. Muleshoe Volcanics/Cascabel Formation contact— the trace of contact runs through valley from lower right to upper left, placing Cascabel Formation (lower left) above Muleshoe Volcanics (upper right) in a depositional relationship. Galiuro Volcanics form the tall peaks in the distance. View is N15°W. 27 Age

The age of the Muleshoe Volcanics is determined by two K-Ar dates of 73.7 + 1.8 (Shafiqullah and others, 1980) and 76.5 + 1.8 m.y.B.P. (Shafiqullah, pers. common.), which indicate a late Campanian to early Maastrichtian age for the formation. The discrepancy between the two dates is not statistically significant (Shafiqullah, pers. common.)

Cascabel Formation

General

Conformably overlying the Muleshoe Volcanics is the coarsely clastic Maastrichtian-Paleocene(?) Cascabel

Formation, another new stratigraphic unit introduced by this report and Mark (1985). Named after the community of

Cascabel, 3 km southwest of the map area where Hot Springs

Canyon joins the San Pedro River, this formation consists dominantly of pebble to boulder conglomerate and coarse- to

fine-grained sandstone. Grover (1982) recognized these

strata in Teran Basin as uppermost Cretaceous or Lower

Paleocene in age, but did not assign them to a formation.

In the type locality of Hot Springs Canyon, three informal

members are recognized: lower cobble to boulder

conglomerate, middle fine-grained sandstone with pebble

conglomerate interbeds, and upper cobble to boulder

conglomerate. For a more detailed discussion of this unit,

refer to Mark (1985). 28

Lithology

Approximately 950 m of the Cascabel Formation are present in the exposures of Hot Springs Canyon. The* dominant lithology of the unit is red-brown to brown-gray cobble to boulder conglomerate, with subordinate light red- brown to red-gray sandstone. Some mudstone beds with interbedded sandstone and conglomerate crop out to the east

(Mark, 1985). Within the excellent exposures of Hot

Springs Canyon, three informal members are recognized. The lateral continuity of these units is problematical, as they cannot be recognized outside of the canyon.

The lower member consists of approximately 400 m of thick-bedded, clast- and matrix-supported, cobble to boulder conglomerate (Figure 11) that grades upward into interbedded conglomerate and sandstone near its top (see Mark, Figure 8,

1985). The middle member consists of about 150 m of medium- bedded, massive to crossbedded, fine to coarse sandstone with minor pebble conglomerate interbeds (Figure 12). This in turn grades upward into another 400 m of thick-bedded, clast and matrix supported, cobble to boulder conglomerate of the upper member (Figure 13).

Conglomerate. The conglomerate occurs as generally massive beds from 0.5 to 5 m thick of both matrix and clast- supported conglomerates in which grading is rarely present.

Bedding planes are commonly planar, with larger clasts protruding into the overlying beds, and scoured and 29

Figure 12. Medium-bedded sandstone and matrix- supported conglomerate, middle Cascabel Formation— Hot Springs Canyon. 30

Figure 13. Conglomerate beds in upper Cascabel Formation— predominantly matrix-supported. Hot Springs Canyon. 31 channelled bases secondarily present. The lateral extent of some beds may be several hundred meters. Amalgamated conglomerate beds produce impressive exposures of coarse clastic sequences within Hot Springs Canyon. Thin sandstone interbeds occur locally within the conglomerate.

The clasts within the conglomerate are generally rounded to well rounded, with only a few subrounded to subangular clasts. The clasts average around 4-6 cm in diameter, but they range in size from small pebbles to generally 1 m in diameter, with one clast seen to measure 3 m across. Clast packing of the conglomerate ranges from 20% to 65%. Imbrication of clasts occurs, but is not abundant.

Sandstone forms the majority of the clasts, with volcanics constituting nearly one-third of the clasts. Clast counts of 100 clasts at 40 localities produced the following per centages:

Sandstone— 61% Volcanics— 29% Limestone— 4% 1 Siltstone/mudstone— 4% Chert— 1% Granite— <1% Conglomerate— <1%

No systematic change in rock type percentages was noted between the top and bottom of the formation, although local variation between beds can be high. Significantly, all rock types were present at all levels of the formation.

Most clasts can be recognized as locally derived.

The sandstones are mostly red to red-brown sublitharenite 32 to quartzarenite and, along with the siltstone/mudstone and conglomerates, were mostly derived from the Willow Canyon

Formation. The volcanic clasts, predominantly tuffs and porphyritic andesite were derived mainly from the Muleshoe

Volcanics. The limestone and chert apparently were derived from the Paleozoic rocks of southeastern Arizona, or reworked from conglomerates of the Bisbee Group. Finally, the granite clasts are porphyritic medium-grained, two-mica granites, common to some local Precambrian granites of 1.4 b.y.B.P age (Krieger, 1974; Shafiqullah and others, 1980;

Thorman, 1981). Thorman (1981) describes two such

Precambrian granites in the Pinalefio Mountains to the northeast— the Stockton Pass and Treasure Park Granites— whose descriptions closely resemble that of the Cascabel granite clasts. Paleocurrent data (discussed below) support the Pinaleno Mountains as a potential source area.

Sandstone. The sandstone occurs mainly as light red-brown to red-gray planar beds that are 0.3 to 2 m thick, and either massive or crossbedded and planar-laminated. The massive beds, common to the middle member of the Hot Springs

Canyon exposures, contain pebbles in small percentages and

are more poorly sorted with larger representation of very

fine grains. The bounding contacts are generally planar.

The crossbedded and laminated strata exhibit normal grading

and locally scoured bases. 33

Petrologically, these are poorly to moderately sorted, fine- to coarse-grained, subangular to subrounded, calcite-cemented lithic and lithic-feldspathic sandstones with a high percentage of volcanic rock fragments. Little calcite cement is actually present, for lithic fragment compaction left little pore space. Calcite, however, has significantly replaced some grains, especially the volcanic fragments.

Volcanics. Three volcanic horizons, each 10 to 20 m thick, are intercalated with the sediments of the Cascabel

Formation. Within Hot Springs Canyon is a light gray, moderately welded, porphyritic, biotite rhyodacite tuff with a devitrified groundmass and a very high phenocryst content

(dated at 68.6 +_ 1.6 m.y.B.P., Shafiqullah, pers. commun.)

In Teran Basin, Grover (1982) mapped a tuff (dated at 64.4 4;

1.4 m.y.B.P.) consisting medium gray, weakly welded, por phyritic, biotite rhyodacite tuff with a devitrified groundmass and a very low phenocryst content. Stratigraph- ically above the tuff in the same location is an undated, dark gray, aphanitic andesite. This lava pinches out to the south, but contributed clasts to the conglomerate beyond its pinchout (Figure 2, in pocket).

Paleocurrents

Imbricated clasts within Cascabel conglomerate provide reasonable measurements for paleocurrent 34 calculation. Figure 14 clearly indicates a south trend

in sediment transport. Two stereographic rotations of the data were required to remove the influence of folding on

the strata. Mark (1985) and I chose to utilize two sepa

rate fold axes, 20°, S15°W for the Hot Springs Canyon

Area and 11*, S40°E (determined from Figure 27) for all

other measurements. The fact that these rotations improved

the paleocurrent data seems to justify this approach,

although it introduces potential error through simplifica tion.

Depositional Environment

The matrix-supported conglomerates and massive sand

stones of the Cascabel Formation clearly represent debris-

flow deposits. Clast-supported conglomerates and cross-

bedded, laminated and graded sandstones with scoured bases

indicate braided stream deposition. The extremely coarse

nature of these deposits, the occurrence of both debris-flow

and braided-stream deposition, and the recognition of

locally derived sediments indicate an alluvial fan environ

ment. The informal members of the Hot Springs Canyon

exposures imply early basin filling, gradation into deposits

more distal in nature, and finally a return to more proximal

deposition in an alluvial fan system. Paleocurrents

indicate drainage to the south and southwest, implying the 35

Figure 14. Paleocurrent rose diagram for Cascabel Formation— vector mean equals 17% and is shown at one quarter its true length. 36 existence of highlands to the north and northeast from which the debris was shed.

Regionally, no rock units directly correlate with the Cascabel Formation. The conglomeratic deposits of the

Fort Crittenden Formation of the Santa Rita Mountains to the southwest closely resemble the Cascabel Formation, but are slightly older (Drewes, 1971; Dickinson and others, in press).

Contacts

The basal contact of the Cascabel Formation is depositional, at least locally, with the Muleshoe Volcanics

(see above). The upper contact of the Cascabel Formation is everywhere an angular unconformity. In Teran Basin, Grover

(1982) mapped a clearly unconformable contact with the

Oligocene Mineta Formation. Elsewhere, the Oligocene

Galiuro Volcanics or the Pliocene Quiburis Formation unconformably overlie the unit, or the contact is structural.

Age

The age of the Cascabel Formation is reasonably well constrained by dates within the underlying Muleshoe

Volcanics and two interbedded tuffs within the the upper part of the Cascabel Formation. The dates within the

Muleshoe, as described above, are 76.5 + 1.8 m.y.B.P.

(Shafiqullah, pers. commun.) and 73.7 +_ 1.8 m.y.B.P. 37

(Shafiqullah and others, 1980). Within Hot Springs Canyon, a rhyodacite tuff rests depositionally on Cascabel rocks but is separated from the main homoclinal section by a fault that could represent substantial offset. K-Ar isotope dating on biotite produced an age of 68.6 + 1.6 m.y.B.P. for this tuff (Shafiqullah, pers. commun.). Although the normal fault does not allow exact positioning within the Cascabel section, this tuff most likely lies somewhere in the upper part of the Cascabel Formation. To the south in Teran

Basin, Grover (1982) mapped and dated a felsic tuff within

Cascabel beds at 64.4 Jh 1.4 m.y.B.P. The age difference between these two tuffs is not statistically significant

(Shafiqullah, pers. commun.), so by averaging the available data, the approximate age of the Cascabel Formation is about

75 to 66.5 m.y.B.P., or Maastrichtian in age. However, the younger tuff indicates that the formation could include some

Paleocene rocks.

Mineta Formation

The mid-Oligocene Mineta Formation crops out in the southern map area within Teran Basin, where Grover (1982)

described a sequence of approximately 1,000 m of non-marine

conglomerates, sandstones, limestones, and evaporites. In

the vicinity of Teran Basin, the Mineta Formation unconform-

ably overlies the Cascabel Formation, but elsewhere the

contact is structural. The Mineta Formation is conformably 38 overlain by the Galiuro Volcanics. The mid-Oligocene age for the Mineta Formation is derived from radiometric dates and supported by paleontology.

Grover interpreted the formation as representing alluvial-fan, fluvial, and lacustrine strata with inter calated lavas and tuffs. He suggested that the Mineta

Formation was deposited syntectonically with mid-Tertiary extension, and cited evidence for rotation of the beds during the period of deposition. Imbrication measurements

indicate a paleocurrent flow to the southwest. Refer to

Grover (1982, 1984) for additional information.

Galiuro Volcanics

A thick sequence of the Oligocene Galiuro Volcanics

forms the high peaks and cliffs that border the map area on

the east and north. In addition, faulting has downdropped

the volcanics, allowing exposures of the unit on the west

side. An unconformity divides the Galiuro Volcanics into

two parts, with the lower part dominated by lava flows and

the upper part by ash-flow tuffs (Creasey and Krieger,

1978). In the study area, a dark brown to brown-gray,

porphyritic, biotite andesite containing large (1 to 2 cm)

plagioclase phenocrysts, and often referred to as "turkey

track" andesite, commonly forms the basal member. Also

included within the lower part of the unit are andesite to

rhyodacite ash-flow tuffs and latite lavas. The volcanics 39 have an irregular basal contact (with relief up to 50 m), apparently reflecting deposition filling the lows of an erosional topography. To the south in Teran Basin, the basal contact is conformable where the volcanics overlie the

Mineta Formation (Grover, 1982). The lower member is unconformably overlain by a thick sequence of felsic tuffs resting on a contact formed by an erosional unconformity that demonstrates local relief up to 300 m (Creasey and

Krieger, 1978). The ash-flow tuffs consist of orange-yellow to pink-gray, weakly welded, biotite rhyodacite and rhyolite.

The Galiuro Volcanics are dated at between 29 and 23 m.y.B.P. (creasey and Krieger, 1978). The data from Creasey and Krieger (1978, Figure 8) suggest that the Galiuro

Volcanics exposed within the study area are between 29 and

26 m.y.B.P. Detailed discussions of the Galiuro Volcanics are presented Cooper and Silver (1964), Creasey and Krieger

(1978), and Creasey and others (1981).

Tertiary Intrusives

At least two stages of Tertiary intrusions are evident in the map area. The first includes rhyolite to rhyodacite dikes that intrude the three Cretaceous units.

Their involvement with the latest Cretaceous-early Tertiary deformational event (discussed below) indicates that these intrusions predate the Oligocene Mineta Formation. Some of 40 these dikes could be Uppermost Cretaceous in age, but con tact relations favor an early Tertiary age. In Hot Springs Canyon, numerous milky white, biotite rhyolite to rhyodacite dikes intrude the Muleshoe Volcanics. One clearly intrudes the Cascabel, indicating emplacement occurred no sooner than early Cascabel time. In Soza Wash, a green-gray rhyodacite dike with a sugary groundmass intrudes the Willow Canyon

Formation. This dike apparently intruded along foliation, but is also involved in the deformation.

Many younger dikes and plugs from basaltic andesite to rhyolite intrude rocks of Mineta age or older. Grover

(1982) reports numerous dikes within the Mineta Formation in

Teran Basin, and dikes of the same type occur throughout the map area. These include aphanitic andesites, "turkey track" andesites, and biotite rhyodacites to rhyolites. One north trending "turkey track" andesite dike extends continuously over several kilometers, intruding mainly Muleshoe

Volcanics, but also the lowermost Galiuro Volcanics near the Muleshoe Ranch (Figure 2, in pocket). These dikes apparently represent a subsurface expression of the Galiuro

Volcanics.

San Manuel Formation

The Miocene San Manuel Formation is exposed on the western edge of the study area, west of the Teran Wash fault. This formation, miscorrelated by Grover (1982) with the Paige Gravels of Lingrey (1982), consists of medium to 41 massive-bedded, pebble to cobble conglomerate, conglomeratic sandstone, and sandstone. The calcite-cemented conglomerate predominantly contains clasts of granodiorite porphyry derived from the Prercambrian Johnny Lyons pluton

(Scarborough and Wilt, 1979), but also includes clasts of

Paleozoic limestone, sandstone, quartzite, and chert.

Clasts derived from Cretaceous and Tertiary rocks are not present. Grover (1982) reports paleocurrent data indicating sediment transport to the north or northeast. Depostion was in an alluvial fan environment (Krieger, 1974; Grover, 1982) during the Early(?) Miocene (Krieger, 1974). The formation is unconformably overlain by the Quiburis Formation.

Quiburis Formation

The Upper Miocene(?) Pliocene Quiburis Formation, a pebble to boulder conglomerate, caps many of the area's hills and forms the western boundary for the map area

(Figure 2, in pocket). Clasts within these exposures are subangular, or rounded where reworked, and derived from the adjacent hills. Clasts of Galiuro Volcanics are the most abundant, but include clasts derived from all units lying uphill from the deposits. The alluvial and fluviolacustrine deposits of the Quiburis Formation represent Upper

Miocene(?) to Pliocene basin fill in the San Pedro Valley, with the oldest portion dated at 5.2 + 0.5 m.y.B.P.

(Scarborough, 1975). The basal contact is everywhere an angular unconformity. STRUCTURES

The rocks of the Hot Springs Canyon area have experienced deformation by folding and faulting wherein they record highly varying degrees of strain. The strata of the

Willow Canyon Formation are highly deformed, the Muleshoe

Volcanics and the Cascabel Formation are moderately deformed, and the remaining units are only weakly deformed or undeformed. Due to the disparity of strain, all struc tures except faults are described separately for the Willow

Canyon Formation and all other formations. The secondary structures of the area include folds, foliations, lineations, and tension fractures, as well as thrust faults,

reverse faults, and both high- and low-angle normal faults.

The following structural descriptions follow the conventions

recommended by Davis (1984).

Willow Canyon Formation

The most highly strained rocks of this formation are

exposed in Hot Springs, Pool, and Sierra Blanca Canyons,

with generally less intense deformation present to the

north. The folds and foliations occur widely throughout the

area, but do not uniformly deform the Willow Canyon

Formation, for some exposures are distinctly more deformed

than others.

42 43

Folds

The folding style of the Willow Canyon Formation, with small to large, tight to isoclinal folds and small- scale polyclinal folds, contrasts with the larger or broad, open to tight folds present within the Muleshoe Volcanics and Cascabel Formation. Bedding readings within the Willow

Canyon Formation indicate a complexly folded unit. Figure

15a illustrates that bedding occurs in nearly every orienta

tion; however, a general preference for north-striking, west-dipping bedding orientations emerges from statistical analysis (Figure 15b).

Isoclinal to very tight folds (with interlimb angles

less than 30 degrees) have small to large amplitudes, gently inclined to recumbent axial surfaces, and gently to subhor-

izontally plunging hinge lines. These folds demonstrate a

general preference for fold axes oriented north to northeast

and gently plunging in either direction, with subhorizontal

to moderately southwest-dipping axial surfaces. The folds are

elliptical in form, exhibit bedding-plane striations, and

demonstrate slight thickening of sandstone beds and severe

attenuation of mudstone beds within hinge zones (Figure 16).

These characters follow the flexural-flow folds of Ramsay's

Class 1C (Ramsay, 1967). In areas such as Hot Springs

Canyon, folds have resulted in thick sequences of overturned section. 44

282 pts

Figure 15. Bedding orientation, Willow Canyon Formation: (a) poles to bedding, lower hemisphere equal area projection, and (b) density contour diagram— in (a), points represent upright bedding and pluses represent overturned bedding. Contour lines in (b) represent 2%-4%-6% per 1% area. 45

Figure 15. Continued. 46

Figure 16. Isoclinal fold within fine-grained Willow Canyon sandstone— Hot Springs Canyon. 47

Figure 17. Polyclinal folds within fine-grained Willow Canyon strata— Sierra Blanca Canyon. 48 The polyclinal folds are tight to open and asymmetric, have small to medium amplitudes, range from elliptical to chevron in form, commonly thin in their hinge areas, and possess curviplanar axial surfaces (Figure 17).

Some degree of disharmonic folding is present. The limbs may range in length from 1 cm to 3 m. The shapes and sizes

of individual folds within a wave train vary widely.

Bedding thicknesses are either be maintained or thinned

within hinge zones. The interlimb angles are usually tight

to open, but isoclinal folds do occur. The folds are

rootless, as they are cut off on either side by faults and

shear zones. Bedding-plane striations are common,

indicating flexural folding. The characteristics of these

flexural slip and flexural flow folds best follow Ramsay's

Classes 1A and IB (Ramsay, 1967). These folds, which are

exposed in abundance in Hot Springs, Pool, and Sierra Blanca

Canyons, selectively deform fine-grained rocks, and fold

both bedding and cleavage. Although the polyclinal folds do

not demonstrate a consistent orientation, they generally

have fold axes that plunge 10-15°, N50°W and axial surfaces

oriented N67°W, 38°NE (Figures 18 and 19). This orientation

differs from that observed for the isoclinal to very tight

folds (see above). 49

• • •

61 pts

Figure 18. Density contour diagram of fold axes, Willow Canyon Formation— contour lines represent 3%-5%-8% per 1% area. 50

61 pts

Figure 19. Density contour diagram of axial surfaces, Willow Canyon Formation— contours represent 3%-5%-8% per 1% area. 51

Foliation

Within the Willow Canyon Formation, a spaced cleavage is locally present, while a bedding-parallel

foliation disrupts to varying degrees all mudstone and

siltstone, plus some sandstone and conglomerate. The

spaced cleavage, which occurs in only the more highly

deformed rocks, contains microlithon domains 0.5 to 4 cm

wide and very thin partings. The cleavage occurs in

areas of isoclinal to tight folding, and is oriented

subparallel to the axial surfaces of these folds. This

association with the folds, as well as a similar

orientation, suggests that the cleavage derived from

isoclinal to tight folding as an axial surface cleavage.

The cleavage is commonly folded by tight to open polyclinal

folds (Figure 20).

The cleavage is cut by shallowly dipping, through-

going shear zones that commonly cut the cleavage at low

angles. However, where the cleavage is folded, the

foliation cuts it at high angles (Figure 20). The shear

zones contain a bedding-parallel foliation that consists of

curviplanar, anastomosing discontinuities. The disconti

nuities are either striated surfaces or brecciated zones.

Figures 15b and 21 illustrate the subparallel relationship

of this foliation with gently west-dipping bedding. The

throughgoing foliation locally cuts bedding, usually in

folded areas, but not in any systematic way. This foliation 52

Figure 20. Folded cleavage cut by subhorizontal foliation within Willow Canyon Formation— hammer in lower right. Hot Springs Canyon. 53

93 pts

Figure 21. Density contour diagram of foliation, Willow Canyon Formation— contours represent 3.5%-5% per 1% area. 54

Figure 22. Melange-style deformation of the Willow Canyon Formation within Hot Springs Canyon. 55 is interpreted as slip planes that accomplished shear of top to the northeast or to the southwest, as based on striation orientations (below).

Where the deformation is more severe, a phacoidal texture— or boudinage— develops, producing lenses of sand stone in a highly sheared mudstone and siltstone matrix.

Locally, the highly deformed rocks resemble the deformational style of a melange. Figure 22 and Column A of Figure

3 (in pocket) illustrate such an area of strong deformation in Hot Springs Canyon. The mudstone is highly sheared, whereas internally the sandstone phacoids tend to resist severe deformation. The foliation within the mudstone wraps around the sandstone phacoids. In such highly deformed areas, the attitude of the foliation undulates up to 60 degrees.

Within the extensive exposures along Hot Springs

Canyon, the foliation is pervasive. On outcrop scale, however, foliation does not uniformly affect the rocks, especially in the less deformed areas, but rather arbitrarily divides the rock into structural horizons of alternating high and low degrees of strain. In less deformed areas, like the exposures north of Soza Mesa, typically only mudstone and very fine sandstone exhibit foliation. This style of deformation indicates folding and shearing of layers characterized by high ductility contrast (Donath and Parker, 1964). 56

Lineations

Associated with the foliation planes within the

Willow Canyon Formation are abundant striations exposed on shear surfaces. The striations, which indicate slip lines along these planes, exhibit a wide range of orientations, trending between N25*E and N80°E, with an average of N45°E, and plunging shallowly to moderately in either direction

(Figures 23 and 2, in pocket).

Elongated carbonate nodules and conglomerate clasts occur in the foliated rocks (Figure 7). This is not a pervasive feature, but rather is locallized within closely spaced structural horizons of high strain. While many of the undeformed nodules are nearly spherical, random measure ment of 31 nodules indicates roughly a 3:2 aspect ratio prior to deformation. Through measuring 47 deformed nodules, an average aspect ratio of 4.7:1 was observed, with the highest recorded at 30:1. The limestone nodules— if assumed initially spherical and to have maintained equal volume— thereby indicate elongation of 115%, with the most severely deformed indicating 450%. These numbers are clearly approximate, but they do suggest the degree of deformation to which these rocks have been subjected. In addition, the conglomerate clasts also have aspect ratios up to 3:1, although this is not continuous even on outcrop scale. The orientation of the longest aspect of both the nodules and clasts trends approximately near N25°E. 57

141 pts 58 A pencil cleavage is locally developed in the finer grained rocks of the Willow Canyon Formation. These features show a common orientation of approximately N25° E, and plunge moderately in either direction (Figure 24). This is subparallel to the fold axes of the isoclinal folds, but not to axes of polyclinal folds. The pencils, therefore, apparently relate to the isoclinal folds.

Numerous fractures within the Willow Canyon

Formation contain calcite crystal fibers. However, only sparse data was collected on these linear features.

Fractures

Calcite-filled tension fractures are common in the sandstones of highly deformed areas within the Willow Canyon

Formation. These fractures extend from 5 cm to 3 m in length, with separations of 1 mm to 1 cm. Some outcrops possess more than one set of such fractures with strikes differing by up to 40 degrees. However, the stereographic representation of the fractures indicates a clear trend in strike orientation of approximately N40°W to east-west

(Figure 25), with a majority clustering at N75°W, subvertical. In addition, thin sections reveal calcite-filled cracks in nearly every instance. These closely spaced cracks are nearly perpendicular to bedding wherever seen, and presumably are oriented parallel to the larger fractures. 32 pts

Figure 24. Pencil cleavage, lower hemisphere equal area projection, Willow Canyon Formation. N

64 pts

Figure 25. Density contour diagram of tension fractures, Willow Canyon Formation— contours represent 3%-5%-8% per 1% area. 61

All Other Formations

Folds

Folding within the Muleshoe Volcanics and the

Cascabel Formation is not so pronounced. The folds are open to tight, upright to steeply inclined, moderately plunging to subhorizontal, large amplitude, and apparently near- cylindrical. The scale of the folds is too large for outcrop observation, stereographic representation of bedding orientations within these formations indicate folding with axes along a northwest trend (Figures 26 and

27). The bedding orientations within the Muleshoe Volcanics show an overall trend of folding with the axial surface oriented N45°W, 88*SW and the fold axis 10°, N45°W. Folding indicated by bedding orientations within the Cascabel

Formation is similarly oriented, with an axial surface of

N50°W, 82°SW and a fold axis of 9°, S50°E. Although the actual folds within these formations generally favor a northwest strike and trend, they display a variety of orientations (Figure 2, in pocket). Striations on bedding planes indicate flexural slip folding.

In the San Manuel Formation, Grover (1982) reported large upright, subhorizontal, northeast-trending anticlines adjacent to the Teran Wash Fault. A fold of similar type is seen in the Hot Springs Canyon exposure. These were inter preted by Grover to represent reverse drag associated with syntectonic deposition of the San Manuel Formation during 62

112 pts

Figure 26. Density contour diagram of bedding orientations, Muleshoe Volcanics— contours represent 3%-5%-8% per 1% area. 63

354 pts

Figure 27. Density contour diagram of bedding orientations, Cascabel Formation— contours represent 2%-5%-8% per 1% area.

) 64 movement along the Teran Wash Fault. This would apear to be a valid explanation.

Neither the Mineta Formation nor the Galiuro

Volcanics display folding. However, both units exhibit uniformly inclined bedding. The orientation of the Mineta beds averages N33°W, 35-40°NE. (Grover, 1982), while the Galiuro Volcanics average N20°W, 20°NE. The Quiburis

Formation retains its original gently dipping bedding orientation (Scarborough, 1976).

Foliation

A planar fabric is locally present within outcrops of Muleshoe Volcanics and Cascabel Formation. This folia tion evidently indicates shearing along fault zones. Also, localized spaced cleavage was observed in the Cascabel

Formation, but was not studied in detail. This cleavage, with spacing of 10 to 20 cm, is weakly developed in some sandstone beds, but is difficult to recognize within conglomerate beds. Neither the Muleshoe volcanics nor the

Cascabel Formation possess a penetrative cleavage or foliation such as present in the Willow Canyon Formation.

Lineations

Numerous striations occur in the Muleshoe Volcanics and Cascabel Formation. Their orientation is also pre dominantly northeast-southwest. However, these are 65 bedding-plane or fault-surface striations, and not associated with a foliation.

Pencil cleavage was locally recognized in the fine grained strata of the Cascabel.Formation. A small sampling indicates a trend of north-northwest with a subhorizontal plunge in either direction.

Faults

Thrust The Hot Springs Canyon fault is a north- to northwest-striking, west- to southwest-dipping fault that places Willow Canyon Formation above the Cascabel Formation in an apparent thrust relationship. The fault generally dips approximately 25 degrees to the southwest, but ranges in dip from nearly horizontal to 40 degrees (Figures 2 and

5, in pocket). Triangulation solutions for localized orientations on the fault indicate that the fault is folded, as illustrated by Figure 28.

The Hot Springs Canyon fault everywhere places

Willow Canyon Formation above Cascabel Formation. In Hot

Springs Canyon, the fault cuts up-section to the west

through the Cascabel Formation. However, this is not seen

throughout the area, for to the south the fault cuts down-

section to the west (Figures 2 and 5, in pocket). This

relationship requires some folding of the Cascabel Formation

prior to movement on the Hot Springs Canyon fault. In the 66

Figure 28. Generalized geologic map of Hot Sprii Canyon fault showing variable orientation— from Figure 2, 67

northern part of the map map area, undisturbed Galiuro

Volcanics overlie the fault, indicating that fault movement

predated extrusion of the volcanics (Figure 2, in pocket).

Numerous normal faults displace the trace of the Hot Springs

Canyon fault, and nowhere does the Hot Springs Canyon fault

cut other faults. Based on these relations, the fault

appears to represent the oldest recognized fault in the

study area, although minor faulting associated with folding

of the Cascabel Formation and Muleshoe Volcanics could

predate movement on the Hot Springs Canyon Fault. Exposure of the fault surface is generally very

poor, except in Hot Springs Canyon (Figure 29). In the

canyon, a foliated and partially brecciated zone aproxi-

mately 0.4 m thick characterizes the contact. Above this

zone, sigmoidal sandstone phacoids float in a sheared

mudstone matrix with an average orientation of N25*W, 35*NE

(Figure 30), although phacoids of other orientations are

also present. These phacoids could represent small-scale

duplexing indicative of downdip movement to the west-

southwest. In the same exposure in a 2 to 3 m horizon below

the fault zone, small normal faults spaced every 0.5 to 1 m

drop blocks 2 to 30 cm down to the southwest. In an

exposure north of Soza Mesa and perhaps 10 m below the fault

(T. 12 S., R. 20 E., s. 21), several small thrust(?) faults,

with orientations N45-50°W, 0-50°NE, occur within the Cascabel Formation. 68

Figure 29. Exposure of Hot Springs Canyon fault, placing Willow Canyon Formatin above Cascabel Formation--a large isoclinal fold is apparent within the Willow Canyon strata in the right of the figure.

Figure 30. Sigmoidal sandstone phacoids in exposure above surface of Hot Springs Canyon fault— the fault zone appears in bottom left of figure at sunlight/shade contact. 69

North of Soza Mesa, the Hot Springs Canyon fault is repeated several times by normal faulting. In the southeast part of the map area (Figure 2, in pocket, T. 13 S., R. 20

E., S. 11), a similarly oriented fault that places Willow

Canyon Formation above Muleshoe Volcanics in a thrust relationship may represent a displaced portion of the Hot

Springs Canyon fault.

Reverse

Several reverse faults in the study area involve the three Cretaceous formations, but are not seen to cut any

Tertiary strata. No systematic orientation was noted for four mapped reverse faults (Figure 2, in pocket). The faults are cut by younger normal faults. The querried reverse

fault in the southeast part of the map area (T. 13 S.,

R. 20 E., S. 11) forms an important contact between the

Muleshoe Volcanics and the Cascabel Formation. This faulted

contact, which juxtaposes a thick section of eastward

dipping Cascabel Formation and Muleshoe Volcanics, could be

either a normal or reverse fault. The trace of this fault

across topography suggests a reverse fault (Figures 2 and 5,

in pocket).

High-angle Normal

Numerous high-angle normal faults cut the area,

juxtaposing units in locally complex relationships. These

faults exhibit a strong preference for a north to northwest 70 strike orientation (Figures 2 and 5, in pocket). The faults downdrop blocks both to the northeast and southwest, with crosscutting relationships and interplay with the Galiuro

Volcanics failing to demonstrate a timing relationship between the two directions, striations indicate normal movement, commonly with a small oblique component, but no systematic favoring of right- or left-slip movement. Many of the faults are high-angle features because they trace straight across topography. However, as few of the faults are well exposed, direct observations of dip are restricted.

Movement along the high-angle normal faults both predated and postdated eruption of the Oligocene Galiuro

Volcanics. Individual faults either terminate against or cut through the basal contact of the Galiuro Volcanics.

However, only one fault, to the east near the Muleshoe

Ranch, demonstrably offsets the Pliocene Quiburis Formation.

Displacements have not been calculated for these faults, but they range from tens to hundreds of meters.

On a smaller scale, abundant north- to northwest- striking normal faults, commonly closely spaced, produce small offsets from 1 to 15 m within the Willow Canyon

Formation, Muleshoe Volcanics, and Cascabel Formation.

Striations indicate normal movement. These faults are best seen in the exceptional exposures of Hot Springs Canyon. In the Willow Canyon Formation, at least, the faults downdrop blocks almost exclusively to the west or southwest. 71

Low-angle Normal

At least five low-angle normal faults of substantial significance are recognized within the study area. These low-angle structures postdate much of the high-angle faulting, although numerous high-angle faults cut the low- angle faults. In the southern map area, two southerly dipping subparallel normal faults exhibit a rather sinuous trace. These faults apparently merge to the east, and are cut by normal faults to the east, and by either the Teran

Basin or Teran Wash faults to the west. Dips range from

13 to 37 degrees to the south. The surfaces of these faults are highly irregular, but all low angle faults in the \ map area are characteristically nonplanar. Neither fault demonstrably cuts either the Mineta Formation or the

Galiuro Volcanics. The orientation of the Mineta Formation in Teran Basin rolls over towards its northern structural boundary (Figure 2, in pocket), suggesting the presence of a rollover anticline. The timing of movement on these low-angle faults is clearly during or after Mineta deposition, and perhaps prior to eruption of the Galiuro Volcanics.

Significantly, no exposures of the Mineta Formation occur

north of this structural boundary, whereas 1,000 m (Grover,

1982) are present to the south in Teran Basin. Grover

reported syndepositional rotation of the Mineta Formation;

if these faults controlled Mineta deposition, they may thus 72 be listric in form. In addition, several small high-angle normal faults cut the low-angle faults.

The southern of the two east-west-trending, low- angle faults sets Muleshoe Volcanics and Cascabel Formation down against Willow Canyon Formation. Its original fault plane may have been inherited by the Teran Basin fault

(discussed below), and if so was quite sinuous (Figure 2, in pocket). The more northerly of the faults exhibits a similar nonplanar surface. This fault sets Willow Canyon

Formation, which is above the Hot Springs Canyon thrust, down against Cascabel Formation in the center and Willow

Canyon Formation to the west and east. In Sierra Blanca

Canyon this fault, which dips south 25 degrees or less, is well exposed as a brecciated fault zone, and includes striations averaging 6°, S69°W. This segment of the fault was mapped by Grover as an intraformational thrust fault, but a tenuous correlation across poorly exposed ground to the east suggests that the segment connects with the northern of the two low-angle normal faults. Thrusting on this fault cannot be completely ruled out, however, for along the middle portion of the exposed fault trace older rocks overlie younger, and Grover (1982) reported a small outcrop of

Precambrian Pinal Schist in the hanging wall. However, this

same relationship can be achieved through normal faulting by

first thrusting the Willow Canyon Formation above the

Cascabel Formation along another fault surface, then later 73 dropping the older rocks into juxtaposition with the younger formation. Thrusting of the Willow Canyon Formation is required, but not necessarily along this fault. In the hanging wall within Sierra Blanca Canyon, Grover (1982) recognized a system of closely spaced, east-west striking, steeply dipping normal faults that are incongruous with his thrusting hypothesis, but which he explains as an extensional overprint superimposed on a Laramide thrust.

While this interpretation cannot be ruled out as a possibility, the more simplified explanation calls for the fault to have formed originally through normal movement.

To the south, Grover (1982) mapped the Teran Basin fault, which strikes northwest and dips 35 to 40 degrees southwest. This fault, which offsets Galiuro Volcanics approximately 1,400 m in a normal sense, trends into the southern of two east-west oriented low-angle normal faults, and then arcs to the west at their junction. Grover interprets the Teran Basin Fault to continue from this junction as a tear segment to the southwest, a notion supported by drag folding (Grover, 1982, Figure 29). In my view, the Teran Basin fault probably inherited and reactivated the existing fault plane of the southern east- west-trending, low-angle normal fault along this segment.

Backtilted strata in the hanging wall indicate that the fault is probably listric (Grover, 1982). A curious bend in the fault occurs in the southwest exposures, and shifts the 74 strike from northeast to northwest, then again to the west

(T. 13 S., R. 20 E., S. 15-16; Figure 2, in pocket).

Unfortunately, poor exposure in these low-lying hills dis courages detailed study of this curvature. Several high- angle faults produce small offsets of this curved fault.

The Soza Mesa fault is a low-angle normal fault that forms a very sinuous trace across the topography on the western side of the map area (Figures 2 and 5, in pocket).

This fault, which strikes roughly N30°W and dips 10 to 30 degrees southwest (averaging 15 degrees), everywhere places

Galiuro Volcanics above older units. A slight increase in the backtilting of the Galiuro Volcanics above the fault suggests that the Soza Mesa fault is listric in nature. Normal faulting occurs in the Galiuro volcanics above the

Soza Mesa fault and commonly drops blocks down to the west or northwest. Although the Soza Mesa fault is usually poorly exposed, one exposure in Hot Springs Canyon (Figure

31) shows a 40 cm thick zone of fault gouge accompanied by striations within the rocks just above and below the zone that trend, on the average, 9°, S30°W. However, it is uncertain how accurately these striations represent the direction of movement on the fault. The fact that the Soza

Mesa Fault is cut by only two high-angle faults of sub stantial displacement indicates that it represents one of the youngest faults in the area. Movement of the hanging wall of 2 to 4 km to the southwest is estimated to have 75

Figure 31. Exposure of Soza Mesa fault in Hot Springs Canyon— the fault dips 10 degrees southwest at this locallity. 76 occurred along the S25°W trend of the striations. This calculation is based on recognition of the near-basal strata of the Galiuro Volcanics exposed in the hanging wall, and matching them with the Galiuro Volcanics exposed in the footwall to the northeast. Error is introduced by poor control on striation orientations, on the geometry of the fault surface, and on possible displacement of the basal contact of the Galiuro Volcanics prior to Soza Mesa fault movement.

To the northwest in Cherry Spring canyon, a steeply- dipping normal fault, antithetic to the range front, clearly cuts the Soza Mesa Fault, downdropping Galiuro Volcanics to the northeast. The trace of this N15°W striking fault becomes complex in a shear zone in the vicinity of Soza Wash to the southeast. Further south and to the north the

Quiburis Formation covers the fault.

The youngest fault recognized in the western part of the map area, along with the one in Cherry Spring Canyon, is the Teran Wash fault. First described by Grover (1982), this northwest-strikng, southwest-dipping, low-angle normal

fault downdrops the San Manuel Formation into juxtaposition with the older Mineta Formation and the Galiuro Volcanics.

The Teran Wash fault is inferred to cut the Soza Mesa Fault,

although their junction in the southwest is obscured by the

Quiburis Formation. The strike of this fault averages about

N10°W, but ranges from about due north to N45°w, with a dip 77 of 35 to 45 degrees to the west and southwest. Striations trend S76°W to S84°W (Grover, 1982; this report), indicating normal, downdip movement. Folds in the San Manuel Formation

interpreted as reverse drag (Grover, 1982) probably formed as the San Manuel Formation was deposited syntectonically with movement on the fault. A relatively large displace ment, probably hundreds of meters, is required on this fault

to expose only the San Manuel Formation in the hanging wall

without allowing exposure of the unit to the east of the

fault.

Discussion

The structural elements of the Hot Springs Canyon

area document two major tectonic episodes that affected

southeastern Arizona: Laramide compression and mid-Tertiary

extension. In order to accurately evaluate the origins of

the observed structural elements within the study area, the

rotation of earlier structures by later events must be

considered. The consistent eastward dip of Galiuro

Volcanics indicates that the area has undergone a rotation

that brought this unit from approximately flat-lying during

deposition to the present average bedding orientation of

N20°W, 20°SW (Figure 2, in pocket). Assuming rigid block

rotation, the orientation of all older structural elements

therefore require a counter-rotation of equal value to

restore them to pre-Galiuro orientations. The results of 78 Table 1. Rotation of structures to correct for dip of Galiuro Volcanics— the rotation is 20° clockwise about a pole of N20°W.

Structure Unrotated Rotated

Willow Canyon Foramtion:

Fold Axes 13°, N50°W 22°, N44°W

Axial Surfaces N67°W, 38°NE N86°E, 28°NW

Foliation N-S, 20°W N9°W, 40°SW

Striations 0°, N45°E* 19° , S44°W

Pencil Cleavages 0°, N25°E* 14°, S23°W

Tension Fractures N75°W, 90° * N76°W, 79°NE

Muleshoe Volcanics:

Fold Axes 10°, N45°W 18°, N40°W

Axial Surfaces N45°W, 88°SW N46°W, 74°NE

Cascabel Formation:

Fold Axes 9°, S50°E 18°, N51°W

Axial Surfaces N50°W, 82°SW N58°W, 81° NE

Faults:

Hot Springs N25°W, 25°SW* N23°W, 45°SW Canyon fault

* = approximate orientation

this correction appear in Table 1 and Figure 32.

Significantly, this rotation steepens the original orienta

tion of the Hot Springs Canyon fault to a southwest dip of approximately 45 degrees. 79

STR •

PEN •

Figure 32. Composite diagram of rotated structural elements within Willow Canyon Formation: from Table 1— the structures include fold axes (FA), axial surfaces (AS), foliation (FOL), striations (STR), pencil cleavage (PEN), and tension fractures (TF). 80 Although the Hot Springs Canyon fault places Willow

Canyon Formation above Cascabel Formation in an apparent thrust relationship, conflicting outcrop evidence (see above) does not distinguish clearly between either thrust/reverse slip or normal slip along the fault.

However, field relationships in the northern part of the map area indicate that fault movement predated the eruption of the Oligocene Galiuro Volcanics. Folding of the Cascabel strata prior to movement on the fault (Figures 2 and 5, in pocket), and folding of the fault surface (Figure 28) suggest that the fault formed in a compressional regime, which favors a thrust/reverse origin during Laramide

deformation.

The fault would appear simply a northeast vergent

thrust/reverse fault were it not for the sigmoidal sandstone

phacoids. These phacoids imply hanging-wall movement to the

southwest (Figure 30), although inconsistencies in their

orientations raise some doubt as to their validity as

vergence indicators. A southwest-vergent thrust/reverse

fault would appear unlikely because the corrected fault

orientation would require a post-movement clockwise rotation

in excess of 45 degrees around a northwest-trending pole— a

requirement unsupported by data. Normal faulting cannot be

discounted, because it is supported by the phacoid and

fault-plane orientations. 81 Three alternate explanations for the puzzling relationships along the Hot Springs Canyon fault may be considered. First, normal faulting could have reactivated the surface of a northeast-vergent thrust fault, resulting in an extensional overprint on a Laramide thrust. However, this would be difficult if the fault surface were already folded. Second, splays of Oligocene-Miocene low-angle normal faults, which are oriented in a similar fashion, may have locally incorporated or offset the older fault surface.

This could be the case in the Hot Springs Canyon exposure

(Figures 29 and 30), thereby creating a local normal-slip signature to the Willow Canyon/Cascabel contact. Third, normal faulting could have downdropped Willow Canyon

Formation from a separate, structurally higher thrust fault, in which case the thrust is unexposed in the study area. If the fault were normal-slip, gentle folding of the fault surface might be explained through rollover folding.

However, low-angle normal faults in the region are considered to be Oligocene-Miocene in age (Davis, 1981;

Lingrey, 1982), including the low-angle faults of the map area, which cut the Galiuro Volcanics (Figure 2, in pocket).

The fault, therefore, cannot easily be strictly attributed to low-angle normal faulting, but probably is essentially thrust/reverse-slip in nature, and possibly modified or locally offset by segments of minor low-angle normal faults. 82 Several thrusts occur south of the study area. In

Teran Basin, Grover (1982) mapped two opposing north trending thrusts that placed Precambrian Pinal Schist above

Bisbee Group, Mesozoic(?), and Paleozoic strata. A belt of north-northeast-vergent thrust and reverse faults, cut by

Eocene intrusives (K-Ar dates of 50 to 55 m.y.B.P., Marvin and others, 1978) trends across the southern end of the

Little Dragoon Mountains (Cooper and Silver, 1964; Drewes,

1981). A narrow band of west-vergent thrust faults, placing

Precambrian basement above Paleozoic and Mesozoic strata, cuts across the northwestern tip of the Johnny Lyon Hills

(Cooper and Silver, 1964). If the Hot Springs Canyon fault is of thrust-slip origin, movement probably occurred between

68.6 +_ 1.6 and 50 m.y.B.P., or following deposition of the

Cascabel tuff and before the emplacement of plutons that cut thrust faults in the Little Dragoon Mountains. TECTONIC EVOLUTION

The structural elements of the Hot Springs Canyon area record a complex history of Upper Cretaceous and

Tertiary tectonic evolution. In addition, the Bisbee Group deposits provide evidence for Late Jurassic(?) to Early

Cretaceous block-faulting (Bilodeau, 1979; Dickinson, 1981;

Bilodeau and Lindberg, 1983). Laramide influence extended

from roughly 90 to 50 m.y.B.P. in southeastern Arizona

(Davis, 1979). Mid-Tertiary extension closely followed

Laramide deformation, and lasted roughly until 15 m.y.B.P.

(Lingrey, 1982). Extension continued with Basin and Range

tectonism until approximately 5 m.y.B.P. (Stewart, 1978;

Davis and Coney, 1979; Coney, 1980; Lingrey, 1982).

In latest Jurassic(?)-Early Cretaceous time,

vertical movements along northwest- to west-northwest

trending normal faults exposed outside of the study area

created basins filled by Bisbee Group sediments (Bilodeau,

1979; Dickinson, 1981; Bilodeau and Lindberg, 1983). During

this period, the Willow Canyon Formation was deposited in a

braided floodplain to distal alluvial fan environment. A

period of nondeposition and erosion followed deposition of

the Bisbee Group, with the lacuna between Bisbee and Fort

Crittenden deposition evidently no more than 10-15 my

83 84

(Dickinson and others, in press). In the study area, the

Willow Canyon-Muleshoe(?) lacuna would apparently have been longer.

The onset of Laramide compressional deformation in

southeastern Arizona began approximately 90 to 85 m.y.B.P.

(Coney, 1972; Davis, 1979; Shafiqullah and others, 1980;

Drewes, 1976, 1978, 1981; Dickinson, 1981). In the Santa

Rita Mountains, this tectonic episode resulted in the depo

sition of the Fort Crittenden Formation in several intermon-

taine basins over the period of 85 or 80 to 75 m.y.B.P.

(Dickinson and others, in press). The coarse elastics of

this formation contain abundant volcanic clasts (Drewes,

1971). Locally, sedimentary strata generally correlative

with the Fort Crittenden Formation are interbedded with

andesitic volcanics, and rest with angular unconformity on

previously folded Bisbee strata (Drewes, 1971; Dickinson and

others, in press). The Fort Crittenden Formation therefore

postdates the first compressional pulse, and signals the

first stage of Laramide volcanism in the region (Drewes, 1971, 1981).

An intense latest Cretaceous and Paleocene pulse of

Laramide plutonism and volcanism immediately followed Fort

Crittenden deposition, extending from roughly 77.5 to 57.5

m.y.B.P. (Shafiqullah and others, 1980? Dickinson and

others, in press). At approximately 75 m.y.B.P., inter

mediate volcanism flared in southeastern Arizona, resulting 85 in the thick deposits of the Muleshoe Volcanics, the

Williamson Canyon Formation, the Salero Formation, the slightly younger Glory Hole Volcanics, and the Old Yuma

Andesite(?). This magmatic event was calc-alkalic to calcic in the Hot Springs Canyon area, anomalous to the regional trend that witnessed alkali-calcic eruptions prior to 71 m.y.B.P., followed by calc-alkalic eruptions (Keith, 1978).

This trend may reflect a then-shallowing subducted slab beneath the western margin of North America (Coney and

Reynolds, 1977; Keith, 1978). The Muleshoe event included the emplacement of dikes, and may have been accompanied by normal faulting.

Following extrusion of the Muleshoe Volcanics, the alluvial fan system of the Cascabel Formation overrode the

\ area, as debris was shed from highlands to the north- northeast. This deposition presumably occurred in an intermontaine basin formed during the middle stages of

Laramide deformation in southeastern Arizona. Davis (1981) describes the development of west-northwest trending high- angle fault zones during Laramide time; such a structure poses a probable source for Cascabel detritus. Also, infrequent volcanic events persisted throughout Cascabel time.

Most of the clasts present in the Cascabel Formation

(over 90%) were derived from the two immediately subjacent units: the Willow Canyon Formation and the Muleshoe 86

Volcanics. However, a small portion were not, including the

two-mica granite clasts. These clasts apparently originated

from Precambrian intrusives to the north-northeast in the

direction of the Pinaleno Mountains, most likely from

closer, more western exposures of the Stockton Pass or

Treasure Park Granites of the Pinaleno Mountains (Thorman,

1981). The occurence of these granite clasts throughout the

Cascabel Formation indicates that the source area was

exposed throughout Cascabel time. The mid-Tertiary deposits

of the Frog Spring and Greasewood Mountain volcanics rest

unconformably on the Stockton Pass Granite, requiring

exposure of the granite at least by Miocene time (Thorman,

1981). However, the presense of granite clasts within the

Cascabel Formation would suggest that the Pinaleno Mountains

were uplifted in early Laramide time, and possibly have

remained a structural high since latest Cretaceous time.

The persistence of the same clast types throughout the

Cascabel Formation also indicates that successive unroofing

of concordant stratigraphy did not control the derivation of

Cascabel sediments, which rather reflect uplift and erosion of a complex region.

Laramide tectonism in southeastern Arizona, as

described by Davis (1979), resulted in a region of

inhomogeneous structural style and intensity which he

divided into numerous domains characterized by either

"homoclinal" or "cylindrical" bedding configurations. The 87 cylindrical domains contain "gentle to tight, low-plunging cylindrical macroscopic folds and, in the case of tight folding, co-spatial reverse and thrust-slip faults, and axial-plane cleavage" (Davis, 1979). Major exposed Laramide faults are localized thrusts and reverse faults that bound basement-cored uplifts (Davis, 1979). The flanks of these uplifts apparently controlled the vergence of local structures, and vergence is therefore variable, both towards and away from the craton. The compressional features of the

Hot Springs Canyon area indicate a northeast-southwest

Laramide compression (Table 1, Figure 32). More specifically, the direction of greatest principal stress (determined from fold, striation, and foliation orientations) ranges from

N40°E to N50°E and subhorizontal, which agrees well with the regional average of N44°E determined by Davis (1981). This deformation evidently occurred in several stages, beginning with the formation of isoclinal to very tight folds and associated axial-surface cleavage, followed by polyclinal

folding, and climaxing with shear along shallow-dipping slip planes that resulted the melange-style deformation.

In the regional perspective, the Willow Canyon rocks

of the Hot Springs Canyon area are anomalously highly

deformed. The striking contrast between the juxtaposed

Willow Canyon Formation and Cascabel Formation/Muleshoe

Volcanics suggests that the former was subjected to deforma

tion at a lower structural level. Additionally, with the \

88 onset of Laramide compression documented at 15 to 20 my prior to the deposition of the Cascabel Formation (Coney,

1976; Davis, 1979; Drewes, 1981; Dickinson, 1981; Dickinson and others, in press), the Willow Canyon Formation was probably subjected to a longer period of deformation. Also,

the melange style deformation present locally could be

attributed to poor induration of the then relatively young

Willow Canyon Formation at the time of deformation.

Quiescence followed the magmatism and deformation of

the Laramide orogeny, as southeastern Arizona was apparently

subjected to extended erosion and/or nondeposition in the

Eocene (Mackin, 1960; Coney, 1976; Shafiqullah and

others, 1980). No sedimentary rock units of this age are

recognized in the region.

Extensional stresses during Oligocene-Miocene time,

perhaps due to spreading of an overthickened crustal welt

(Coney and Harms, 1984), resulted in the formation of the

Rincon/Catalina metamorphic core complex, which lies west of

the study area and across the San Pedro Valley (Figure 33).

Davis and Coney (1979) reported that the associated crustal

attenuation must have produce extreme thinning in both

basement and cover, and resulted in extensional basins.

This extension caused crustal lengthening along a N60 E

azimuth (Crittenden, 1980; Davis, 1981).

This area underwent a multiphase extensional

tectonic evolution, similar to that which Lingrey (1982) 89

Figure 33. View of the Rincon Mountains from Hot Springs Canyon— the trace of the Soza Mesa fault can be seen just above the saguaro cactus, placing Oligocene Galiuro Volcanics on Cretaceous Willow Canyon Formation. View is S55°W. 90 described for the Rincon/Catalina metamorphic core complex.

In the Oligocene, the intial phase of extension resulted in the formation of metamorphic tectonites in the decollement zone and deposition of the Mineta Formation in half-graben basins (Grover, 1982, 1984). Abundant high-angle normal

faulting occurred in the Hot Springs Canyon area, and

probably low-angle listric(?) normal faulting in the

southern part of the map area, causing rotation and

southwest displacement of the Mineta sediments. Mineta

Formation sedimentation ended abruptly with the eruption of

the Galiuro Volcanics about 28 m.y.B.P. (Grover, 1982,

1984). This mid-Tertiary magmatic event included the

emplacement of numerous dikes.

Extensional faulting persisted into the Miocene

following eruption of the Galiuro Volcanics, with the

continued formation of high-angle normal faults, and the

intiation of low-angle normal faults, which resulted in

southwest displacement of hanging walls on the Soza Mesa and

Teran Basin faults. Grover (1982) calculated 1.4 km net

slip on the Teran Basin fault along 37°, S42°W. Movement on

the Soza Mesa fault, which displaced the hanging wall of

Galiuro Volcanics 2 to 4 km to the southwest, was probably

in a similar direction. This movement coincided with the

development of the extensional San Pedro detachment fault,

with 10 to 20 km normal displacement to the southwest during

the period confined to 26 to 17 m.y.B.P.(Lingrey, 1982). To 91

the south in the Johnny Lyon Hills and Little Dragoon

Mountains, Dickinson (1984) reinterpreted the Lime Peak

fault as an Oligocene and/or Miocene detachment fault.

These detachment faults are part of a Miocene listric normal

faulting event that resulted in extension on a crustal scale

in a direction of N60°E ± 10 (Crittenden, 1980; Davis,

1981). The link in time and space between the Soza Mesa and

Teran Basin faults and the detachment faults appears

certain. The range front of the Galiuro Mountains has been

considered the breakaway zone for the Rincon/Catalina

metamorphic core complex extension (Davis and Hardy, 1981).

The Soza Mesa and Teran Basin faults apparently represent

the transition between distended ground of the San Pedro

Valley and Rincon/Catalina metamorphic core complex and

unextended ground of the Galiuro Mountains. Some tilting of

the Galiuro Mountains has occurred, but this could be

ascribed to possible listric normal faulting to the east of

the study area, and thus not directly associated with the

San Pedro detachment.

West-southwest displacement on the low-angle Teran

Wash fault followed movement on the Soza Mesa fault, and was

apparently accompanied by deposition of the San Manuel

Formation. High-angle normal faulting continued in the

study area, causing some displacements of the low-angle

normal faults, most notably the east-vergent fault in the

northwest part of the map area (Figure 2, in pocket). 92

Lingrey (1982) noted a period of high-angle faulting between

18 and 17 m.y.B.P., which may coincide with faulting in the

study area.

After a mid-Miocene period of relative quiescence,

the region experienced a period of Basin and Range normal

faulting between approximately 12 and 5 m.y.B.P.

(Scarborough and Pierce, 1978; Shafiqullah and others,

1980). The Basin and Range faults, which in general

correspond with the uplifts and depressions of the present-

day mountains and valleys, do not appear to have

significantly participated in forming the western structural

front of the Galiuro Mountains (Figure 5). Numerous small,

north- to northwest-trending, high-angle normal faults,

presumably of Basin and Range age, offset the Hot Springs

Canyon and Teran Basin areas (Grover, 1982), but no west

dipping faults significantly cut the southwest-dipping low-

angle normal faults. This strongly suggests that low-angle

normal faults form the structural range front that

delineates the San Pedro Valley from the Galiuro Mountains.

The structural front of the Galiuros is therefore generally

an older feature, rather than a younger product of high-

angle Basin and Range faults.

Finally, the alluvial and fluviolacustrine deposits

of the Pliocene Quiburis Formation, which form an angular

unconformity with the substrata, apparently postdate the

main Basin and Range event, although one high-angle normal fault cuts this unit near the eastern edge of the study area. APPENDIX 1

SAMPLE: ANDESITE NEAR TOP OF SECTION

ALUMINUM SATURATION INDEX (A/CNK): 0.91

OXIDE WT PCT CAT PCT FACTOR WT PCT CAT PCT

SI02 60.70 60.04 A 43.66 60.45 TI02 0.64 0.48 F 44.87 26.26 AL203 14.70 17.14 M 11.47 13.29 FE203 6.30 1.59 FEO 0.0 3.10 MNO 0.10 0.08 A 37.79 55.35 MGO 1.61 2.37 C 23.37 20.60 CAO 3.79 4.02 F 38.84 24.05 NA20 4.66 8.94 K20 1 .47 1 .85 CO 2 0.0 0.0 NA 46.98 60.35 P205 0.47 0.39 K 14.82 12.53 S 0.0 0.0 CA 38.21 27.12 H20 3.30 TOTAL 97.74

PETROLOGIC INDICES FACTOR

SOLIDIFICATION INDEX (KUNO) 11 .39 Q 19.44 THETA (SUGIMORA) 31.11 A 10.70 SIGMA (RITTMANN) 2.12 P 69.86 DIFFERENTIATION INDEX 70.81 F 0.0 LARSON :FACTOR 10.64 MODIFIED LARSON FACTOR 7.01 AGPAITIC COEFFICIENT(KN/A) 0.63

BARTH NORMATIVE MINERALOGY (IN ORDER OF ABUNDANCE) SALIC MINERALS 86.68 PERCENT ALBITE 44.68 QUARTZ 16.85 ANORTH 15.87 ORTHO 9.27

FEMIC MINERALS 13.32 PERCENT ENSTAT 4.75 FERROS 3.81 MAGNET 2.39 APATIT 1.05 ILMEN 0.95 WOLLAS 0.37

MINERAL DISTRIBUTION

PLACIOCLASE 60.56 PCT AN- 26. AB- 74 CPX 0.74 PCT EN- 28. FS- 22 WO- 50 OPX 8.19 PCT EN- 55. FS- 45

94 95

APPENDIX 1— Continued

SAMPLE: ASH-FLOW TUFF NEAR TOP OF SECTION

ALUMINUM SATURATION INDEX (A/CNK): 1.16

OXIDE WT PCT CAT PCT FACTOR WT PCT CAT PCT

SI02 70.14 68.65 A 67.39 77.97 TI02 0.29 0.21 F 24.77 13.54 AL203 13.89 16.03 H 7.84 8.49 FE203 2.40 1 .32 FEO 0.0 0.45 MNO 0.06 0.05 A 61 .09 73.80 MGO 0.76 1.11 C 16.46 13.38 CAO 1 .76 1 .85 F 22.45 12.82 NA20 3.12 5.92 K20 3.41 4.26 C02 0.0 0.0 NA 37 .64 49.24 P205 0.19 0.16 K 41.13 35.41 S 0.0 0.0 CA 21 .23 15.35 H20 2.15 TOTAL 98.17

PETROLOGIC INDICES FACTOR

SOLIDIFICATION INDEX (KUNO) 7.79 Q 36.52 THETA (SUGIMORA) 40.29 A 22.98 SIGMA (RITTMANN) 1.57 P 40.50 DIFFERENTIATION INDEX 87.42 F 0.0 LARSON FACTOR 22.11 MODIFIED LARSON FACTOR 12.06 AGPAITIC COEFFICIF.NT(KN/A) 0.64

BARTH NORMATIVE MINERALOGY (IN ORDER OF ABUNDANCE)

SALIC MINERALS 95.33 PERCENT QUARTZ 33.84 ALBITE 29.61 ORTHO 21.29 ANORTH 7.91 CORUND 2.68

FEMIC MINERALS 4.67 PERCENT ENSTAT 2.22 MAGNET 0.86 HEMAT 0.75 ILMEN 0.43 APATIT 0.42 MINERAL DISTRIBUTION

PLAGIOCLASE 37.52 PCT AN- 21. AB- 79. OPX 2.22 PCT EN-100. FS- 0.

Chemical analyses of two Muleshoe Volcanics samples. The calculated differentiation index includes normative corundum. Total iron, reported as Fe203, is partitioned into FeO and Fe203 using the Ti02 correction factor of Irvine and Baragor (1971). REFERENCES

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Creasey, S. C., Jinks, J. E., Williams, F. E. and Meeves, H. L., 1981, Mineral resources of the Galiuro Wilderness and contiguous further planning areas, Arizona: U. S. Geol. Survey Bull. 1490, 94 p.

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______1981, Regional strain analysis of the superposed deformations in southeastern Arizona and the eastern Great Basin, iji Dickinson, W. R., and Payne, W. D., eds.. Relations of tectonics to ore deposits in the southern Cordillera: Arizona Geol. Soc. Digest, v. XIV, p. 155-172.

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Davis, G. H. , and Hardy, J. J., 1981, The Eagle Pass detachment, southeastern Arizona: Product of mid- Miocene listric(?) normal faulting in the southern Basin and Range: Geol. Soc. America. Bull., v. 92, p. 749-762. 98

Dickinson, W. R., 1981, Plate tectonic evolution of the southern Cordillera, iji Dickinson, W. R., and Payne, W. D., eds., Relations of tectonics to ore deposits in the southern Cordillera; Arizona Geol. Soc. Digest, v. XIV, p. 113-135.

______1984, Reinterpretation of Lime Peak thrust as a low- angle normal fault; Implications for the tectonics of southeastern Arizona; Geology, v. 12, p. 610-613.

Dickinson, W. R., Fiorillo, A. R., Hall, D. L., Monreal, R., Potochnik, A. R., and Swift, P. N., in press, Creta ceous strata of the Basin and Range Provence; iji Arizona Geol. Soc. Digest.

Donath, F. A., and Parker, R. B., 1964, Folds and folding; Geol. Soc. Am. Bull., v. 75, p. 45-62.

Drewes, H., 1971, Mesozoic stratigraphy of the Santa Rita Mountains, southeast of Tucson, Arizona; U. S. Geol. Survey Prof. Paper 658-C, 81 p.

______1976, Laramide tectonics from Paradise to Hell's Gate, souteastern Arizona; Ariz. Geol. Soc. Dig., v. X, p. 151-167.

______1978, The Cordilleran orogenic belt between Nevada and Chihuahua: Geol. Soc. America Bull., v. 89, p. 641-657.

______1981, Tectonics of southeastern Arizona: U. S. Geol. Survey Prof. Paper 1144, 90 p.

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Finnell, T. L., 1970, Formations of the Bisbee Group, Empire Mountains Quadrangle, Pima County, Arizona, rn Cohee, G. V., Bates, R. G., and Wright, W. B., eds., Changes in stratigraphic nomenclature by the U. S. Geol. Survey Bull., v. 1294-A, p. 28-35.

Folk, R. L., 1974, Petrology of sedimentary rocks: Hemphill Publishing Company, Austin, Texas, 182 p.

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______1984, Petrology, depositional environments and structural development of the Mineta Formation, 99

Teran Basin, Cochise County, Arizona: Sedimentary Geol., v. 38, p. 87-105.

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Inman, K. F., 1982, Depositional environments and sandstone petrography of upper Cretaceous sedimentary rocks, Adobe Canyon, Santa Rita Mountains, southeast Arizona [M. S. report]: Tucson, Ariz, Univ. Ariz. 42 p.

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Ramsay, J. G., 1967, Folding and fracturing of rocks: McGraw Hill Book Company, New York, 560 p.

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i < j ! 1 5 6 6 6 3 pUB OJJJBSBK

A. ' ■ ! ' : 4 , \ .:. i A - { < Mciinva Nisva Nvwai - , - r :: .... - ... ' I y . UB O j U B 8 B Sji\ z i

9001 128 48 Figure 1 icr 22' 30 32° 24' 30' 2 17' 30" 32* ha Zone Shear ^Complex /; 2 / . / _ Z Goodlin, Goodlin, Striations within Kb north Kb withinStriations f oa ea 1 points. 41 Mesa— Soza of /

<45 ’ r - ^ 2 ' 46/// K 's’ c . .hss Gocecs 1985. Geosciences, S.Thesis, M. K \24 5K A \ X - v 8 / 28. o Srns ayn 3 points. 13 Canyon— Springs Hot of south Kb within Striations o Srns ayn 0 points. 90 Canyon— Springs Hot in Kb within Striations /To V . s 7 ;Kc \ X

\ ■t 'JgU V j Kb - x 1 E 2 E R 20 19 ER \ \ /22 \u N \38^ 8 3 ' \ T V ^ 'Vo o / l t

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9 ^ X . • •./ X z / 7-' •« \ 56, * \ / Z % 7 b K ? ■A 0 38 ^ 30 X X r Kt \4 , / \54 ^ Kct r ^ i&Z Y45 A 26V 4 8 ^j _ ^ _ 28 W^Ajk >k E>- L # 17\ vD 7\ \ \ X 1 14 f18 y fz. . i X ; W v 0 s ,\2 'So\62 22 \ , VsV 50 1 'A . d K - ^ o ^ > Kc > ' \ X ^ I V “ 21. / ’ / l Xy1 UlDX y \\ 7 ™ 4 S ^ » ^ S 4 ™ v< /3 > : 4 # % x . u!D \ \ c K . x 7= N m ' - x - ' m N 1 1 1 -Va >4 / - f X 7= ' b 4 Z' ^T X T '^ Z J 'X Z Kb 34^ X 6 X Z - c \ Kc f c K / l j k H « x ______1 115 1 V \ m T -V 7\,41 x/ x/XsdT d s X / x / )x o [50 to /< Hz X V 4 6 ^tl l3 t 76 ^ # 2 5 V ^ T ^ 8 p»> 28 33X A T«i m ^ Km " 4 F x F 4 " u \ \ > A \^)/ ) ^ \ \A\ yx 55 .y>x m V70 EA BSN FAULT BASIN TERAN \62 3! \ .4 . x A / X'»“ v/ ~ 5 , " . V ^ \ v A U' Km \ - - V33^^ k

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x 3 \ / / 26 t , v / - X ae opld rm . . elgcl uvy . mnt tpgahc maps topographic minute 7.5 Survey Geological S. U. from compiled Base \ „ 2 E R 21 E R 20 E 2 \ H HT PIG CNO AREA CANYON SPRINGS HOT THE _°a \ “ / \ al ° /_ hms . odi, 8: oto suh f o Srns Canyon. Springs Hot of south portion 985: 1 Goodlin, C. Thomas " x X i-^ X x" oe A Mr, prin ot o Ht pig Canyon. Springs Hot of north portion : 5 1 8 9 Mark, A. Roger n 1 mnt tpgahc a Wnhse Ms. Arizi Mts.. Winchester map topographic minute 15 and Tc I vZ(X5 OHS CUT, ARIZONA COUNTY, COCHISE

X — II - I—I l-H I—II—I hry pig ek n Sz Ms, A r Mesa, iz Soza and Peak Spring Cherry 193 i i M T T I ONOU ITRA 4 FEET 40 INTERVAL UR NTO CO x:/%- r - % / : x • otenot oto o mp adapted map of portion Southernmost GEOLOGIC MAP MAP GEOLOGIC easen scin 0 eet) e fe 50 section stern a (e n rvsd rm rvr 1982. Grover, from revised and - x o\i x x V ' ?x 24, 0 0 ,0 4 :2 1 E L A C S (?) Xy /X (7?>) X X X X I ^ — X z A . - r > 6 d j Z # o z x ;v OF 1 u e f © > ^a^jf$1 f v j utesfc©?> ^ a ^ t w • > x C • v ' ' . _j o _;j . . / a , A 7 i By / !< — : % w . C. X. —->A' l y ly 4

> r — XL < z 77

KILOMETER1

/A 1 MILE 7X /

titoZ ahd hr approximately where Dashed striationZ al, hwn dp n ted n pug of plunge and trend and dip showing Fault, otd hr covered. uncertain, where where dotted querried located, ecl laae ih tie n dp f bedding. of dip and strike with cleavage pencil ees fut R n phon side. upthrown on R fault, Reverse , onhon ie U utrw side. upthrown U, side; downthrown D, otc, ahd hr approximately where dashed Contact, hut al, ateh n pe plate. upper on sawteeth fault, Thrust tie n dp f vrund bedding. overturned of dip and Strike rn ad lne f ecl cleavage; pencil of plunge and Trend o age oml al, hachers fault, normal angle Low tie n dp f foliation. of dip and Strike tie n dp f bedding. of dip and Strike n onhon side. downthrown on 0 15 20 sli adeie rylt, n "uky rc" type track" "turkey and rhyolite, esite, and asaltic B ebe o obe ogo rt, usoe siltstone, mudstone, erate, conglom cobble to Pebble located. sli adst, aie cnlmeae rhyolite, erate, conglom latite, andesite, asaltic B atoe adtn, usoe ad conglomerate. and mudstone, sandstone, uartzose Q c Pbl t budr ogo rt, sandstone, erate, conglom boulder to Pebble Kc, c, gibie lw dtd t 44 14 (Grover, 1.4 ± 64.4 at dated flows Ignimbrite Kct, Dated flow 73.7 at m.y.b.p.>(Shafiqullah ±1.8 et. aL, 1980) c, neie aa flow. lava Andesite Kcv, m, gibie lw. ae a 7. ± . my b.p. m.y. 1.8 ± 76.5 at Dated flows. Ignimbrite Kmt, m Brci, lw, aa ad ogo erate. conglom and lava, flows, reccia, B Km, "d~ 5 i A nofriy wwwwwwwwww' Unconformity w w w w w w w w w w w w w w w w w w vw Unconformity Unconformity vw w w w w w w w w wwwww nofriy wwwwww w ww w w w wwww Unconformity wwwwwwwwww vvwww Ucnomt vwwwwwvwwwv Unconformity wvwvwwvwwww a aaa w a a a a a a a a aa aaaa aaa 40 24 92 ad 86 16 .. b.p. m.y. 1.6 ± 68.6 and 1982) ilw ayn omto, ibe Group Bisbee Formation, Canyon Willow ebe o ole cnlmerate conglom boulder to Pebble ebe o obe ogo erate conglom cobble to Pebble irt ad neie porphyry. andesite and Diorite a Mne Fr ation Form Manuel San ittn, n mudstone. and siltstone, et ntusive tru In s u o e c ta re C ANATI N IO T A N LA P X E Fr ation Form l e b a c s a C ubrs omation Form Quiburis lso Volcanics uleshoe M ndeie porphyry. esite d an tar Intrusive ry rtia e T air Volcanics Galiuro nt Fr ation Form ineta M

n limestone. and

Unconformity Km Ti

n tuff. and Alluvium

k V

T T sm al Q Tq k

Z / xa tae f niln tp ad syncline, and (top) anticline of trace Axial i k Kmt vrund nile tp ad syncline, and (top) anticlne Overturned ahd hr lctd approximately. located where dashed tAAAAAA/wwwwvww Kcv z w w w w w w w w azw h srain igas o te ibe Group Bisbee the for diagrams striation The xa ted n pug o sal folds, small of plunge and trend Axial hwn ted n pug o axis. of plunge and trend showing hwn ted n pue f axis: of pluge and trend showing r lwr hemisphere projections lower on are oain f rs section. cross of Location hwn gnrl shapes. general showing /r aimti dates. radiometric K/Ar qa ae stereonets. area equal e

CRETACEOUS TERTIARY QUATERNARY ^ 9 7 9 1 | C f g 5

2 ^ 8 GEOLOGIC CROSS SECTIONS THROUGH THE HOT SPRINGS CANYON AREA

wsw e n e COCHISE COUNTY, ARIZONA

5000 Soza Mesa Fault Hot Springs Canyon Fault 1500 SCALE 1:24000 1300 4000 1100 No vertical exaggeration

3000-- by

2000 Thomas C. Goodlin

1000 ---300 Feet Meters Roger A. Mark

See explanation on Figure 2 for section locations and rock descriptions.

Hot Springs Canyon Fault NE WNW e SE

Soza Mesa Fault 4500 Teran Wash Fault -- 1 3 00 4000 — 1100 3500 3000 -- 900 2500

2000--- -- 500 15 0 0-- Kb ? Kb ? 1000--- -- 300

Feet Meters

WSW ENE

5000 Hot Springs Canyon Fault Teran Wash Fault 1400 4000- -1200

- 1000 3000

2000 -

1 000 Figure 5, Goodlin, M. S. Thesis, Geosciences, 1985 Feet Meters £-77?/

ZCS REPRESENTATIVE COLUMNAR SECTIONS WITHIN THE WILLOW CANYON FORMATION

Undeformed

50 - Red mudstone, featureless. A Undeformed section measured near Soza Wash, north

X.v.m •• • $. # • • • ■ # *.• :• *. of Soza Mesa.

Silli Olive-gray, fine-grained, moderately-sorted, trough- crossbedded sandstone with silica and calcite cement. •* \-'V\ *- • - ■ . # v - . ; - • • - * J. . ' % B — Deformed section measured within Hot Springs Canyon— bold solid lines indicate structural contacts. i m w m m .

Sheared red mudstone with calcareous nodules.

Dark red mudstone with calcareous nodules, grades upward

“ — ——:— — into dark red-brown siltstone with fine-grained quartz.

• „ ‘ . .i -»

Medium gray, fine-grained, well-sorted, medium-bedded y.:; sandstone with silica and calcite cement.

Dark red, fine-grained, well-sorted, thick-bedded sandstone 'W with hematite cement. \ v‘ . . .: < .• '.: 7 Red-gray, very fine-grained, well-sorted, thick-bedded . : - sandstone with hematite cement. \. : • I

Red-gray siltstone with fine-grained quartz.

Red mudstone with 5% calcareous nodules.

- -<=>— ------

Red-gray siltstone with quartz and mica or»ins and 1 5 - 2 0 % calcareous nodules.

*. -"o * „ - .‘o- *. . ';r> Red-gray, fine-grained, well-sorted, thick-bedded sandstone 30 - :.v ¥ ; v :"-0 with calcite and silica cement and calcareous nodules.

\ Deformed

Moderately sheared brown-red, fine-grained, well-sorted sandstone with hematite cement. Bright red friable mudstone with calcareous nodules, which increase in percentage near base. Sheared brown mudstone with fine-grained sandstone phacoids. Moderately sheared brown-red, fine-grained sandstone with mudstone lenses. Red-brown, fine-grained, well-sorted with hematite cement, mudstone lenses, and calcareous nodules. Sheared red-brown mudstone with fine-grained sandstone lenses. Red-gray siltstone. Moderately sheared, brown-red, fine-grained, well- Sheared dark red-brown interbedded mudstone and siltstone with calcareous nodules. sorted sandstone with hematite cement, interrupted by sh eared mudstone layer. Red-gray, very fine-grained, well-sorted, thick-bedded Red-brown, very fine-grained, well-sorted sandstone sandstone with hematite cement. with hematite cement.

Olive-gray, fine-grained sandstone in a highly sheared brown mudstone.

20 - f

Sheared dark red-brown interbedded siltstone and mudstone Olive-gray, medium-grained, moderately-sorted, massive with calcareous nodules and sandstone lenses. sandstone with calcite and silica cement.

Highly sheared brown mudstone. Olive-gray, fine-grained, moderately-sorted sandstone with calcite and silica cement. " " Light olive-gray, medium-grained, moderately-sorted, r-1- Sheared red-brown siltstone and mudstone with 1% massive sandstone with calcite and silica cement, and calcareous nodules. cut by tension fractures.

Red-gray, very fine-grained, well-sorted, thick-bedded sandstone with hematite cement. Red-gray, medium-grained sandstone in a highly sheared Brown-gray, fine-grained, sandstone with calcite cement. red-brown mudstone, with calcareous nodules near top.

Red mudstone with calcareous nodules variable from 1 to Medium-gray, fine-grained, moderately-sorted, massive 60%. sandstone with calcite and silica cement, and cut by tension fractures. *o ° _ 5 - _ 10 - Sheared brown mudstone. * r c f *>.* " ( % \ Olive-gray, fine-grained, moderately-sorted, medium-bedded -.v. acs \l^ .\ p'J Red-gray, medium-grained, well-sorted sandstone with * » ire**’.- ^ •' - ^ ' <-*7 ( sandstone with calcite cement and scattered calcareous .•• :•..*? : .~V'.”.V.- y J calcite and silica cement. * *• V' % *'• T ' * • ] nodules. .*; ..« • - '.**• v Red-gray, medium-grained, well-sorted, massive sandstone with calcite and silica cement. <-*. ".- . • ' .* k. <2 • • •.•••••.• • • •.*\___ Gray, medium- to coarse-grained sandstone with normally- »?ov0.»°4 ° ?

A . . » / . . f. J O live-gray, medium-grained,sandstone with calcareous nodules

. 1 ' Highly sheared red-brown mudstone with elongated Gray, medium- to coarse-grained, moderately-sorted, calcareous nodules and a foliation that wraps around medium-bedded sandstone with calcite and silica cement. *. * " * . • m * • sandstone phacoids, one of which is folded.

••-;• : ;.•• ' ... Olive-gray, fine-grained, moderately-sorted, medium-bedded sandstone with calcite cemunt and scattered calcareous Highly sheared red-brown mudstone with small elongated • *. .*.• ••.*..• f X •. •. ..\ .1 X ^ nodules. calcareous nodules. .* . .. • .*. v . V.« »•.•.« #. .•• .•( •. *.. : * *. *'• *. .* J Medium gray, fine-grained, moderately-sorted sandstone with calcite and silica cement. Light olive-gray, medium-grained, moderately-sorted, massive Red-brown mudstone with small percentage quartz grains. sandstone with calcite and silica cement and cut by sub vertical tension fractures. 0 Highly sheared mudstone with elongated calcareous nodules. mudstonc^Z pebble conglom. M siltstone Z N coarse-gr.co$ ss. M fine-gr. ss. medium-gr. ss.

Figure 3, Goodlin, M. S. Thesis, Geosciences, 1985. £ 9 7 9 f

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