MULE CREEK REGIONAL SOURCE

WESTERN NEW MEXICO

Perlitic lava dated to 17.7 mya at the Antelope Creek East locality of the Mule Creek Regional Source, western New Mexico

Mule Creek Caldera and Ash-flow Sheet

Collections from: Sections 1,2,3,10,11,12 R21W, T14S; Sections 5,6 R20W, T14S USGS Mule Creek 7.5' Quad, Gila National Forest, Grant County, New Mexico; and a road cut at the junction of AZ Hwy 78 and Coal Canyon R32E, T14S (no sections delimited), Greenlee County, Arizona.

Mule Creek is probably the geographically largest obsidian source in the Southwest. The obsidian is found in a very extensive late Tertiary ash-flow sheet that covers portions of Greenlee County, Arizona, Catron and Grants Counties, New Mexico and may extend over to the Mogollon Mountains to the east (see Gwynn Canyon source below) (Rhodes and Smith 1972; Weber and Willard 1959). Samples collected from the Mule Creek area in New Mexico and near Ash Peak, Arizona are chemically identical, while some samples from Mule Creek and Gwynn Canyon are similar. The nodules, up to 10 cm in diameter, may have been pyroclasts within the large ash flow. The nodule density in some areas reaches 100 per 5m2, especially on the top of the ash hills. Erosion into the San Francisco and Gila River systems is very possible.

The aphyric glass ranges from opaque black to translucent smoky gray with some gray banding. In 200 specimens collected, three are mahogany-brown and black banded similar to Slate Mountain (Wallace Tank) material. Some of the cortex exhibits a silver sheen, but most is a thin black-brown. The material is a fair medium for tool production, but is very brittle much like Los Vidrios. The pressure reduction potential is, however, very good. Interestingly, Mule Creek obsidian was extremely rare in Arizona Archaic sites, while Cow Canyon was very common (see Shackley 2005). This is probably a function of the lower quality of Mule Creek material, particularly since Gwynn Canyon is further from the Arizona sites.

Marekanites in perlitic lava matrix at the Antelope Creek East locality (shown above) New Mexico

New images from October 2008:

 

 

 

Large perlitic "obsidian zone" east of the area shown above.  Marekanites common throughout this perlitic lava.  Marekanites from this area are eroding into Antelope Creek, Harden Cienga Creek and into the San Francisco River, and west into the Gila River.

 

 

 

 

 

 

 

 

 

 

High marekanite density in region shown in image above. Dark dots in foreground are marekanites.

 

 

 

 

 

 

 

The overall density of obsidian flakes and cores was relatively low (<1 per 20 m2), probably due to the sheer extent of the deposit. A few rejected biface fragments (laterally fractured) and utilized flakes (<10) were recorded. Published references include Findlow and Bolognese (1982a and 1982b), Rhodes and Smith (1972), and Weber and Willard (1959).

Updated 1995: One of the most startling recent discoveries is the chemical variability in the Mule Creek obsidian. In the earlier study, I noted two "outliers" collected at Mule Creek with significantly higher rubidium concentration values (Shackley 1988:767). These outliers have now been identified as a distinct chemical group, often mixed in the regional Gila Conglomerate with three other chemical groups. The geology in the area is complex and has been studied by Ratté, and others for some time (Brooks and Ratté 1985; Ratté 1982; Ratté and Brooks 1983, 1989; Ratté and Hedlund 1981; Rhodes and Smith 1972). Primary in situ perlite localities for three of the chemical groups have been located.

Ashy, perlitic lava at the Mule Mountain Locality

At least four distinct chemical groups are evident, distinguished by Rb, Y, Nb, and Ba, and a lesser extent Sr, and Zr concentration values, and are named after the localities where marekanites have been found in perlitic lava: Antelope Creek; Mule Mountains; and Mule Creek/North Sawmill Creek all in New Mexico. Additionally, during the 1994 field season, a fourth sub-group was discovered in the San Francisco River alluvium near Clifton, Arizona and in older alluvium between Highway 191 and Eagle Creek in eastern Arizona north of Clifton. While in situ nodules have not yet been found they are certainly located somewhere west of Blue River and north and west of the San Francisco River since none of this `low zirconium' sub-group was discovered in alluvium upstream from the juncture of the Blue and San Francisco Rivers. The genetic relationship is apparent in the trace element matrix plot (Shackley 1995:Figure 2), and signifies the very complex nature of the Mule Creek silicic geology, with subsequent depositional mixing in the Gila Conglomerate. Glass at other Tertiary sources in the Southwest, such as Sauceda Mountains and Antelope Wells, also appear to exhibit more than one chemical mode, although not as distinct as Mule Creek (LeTourneau 1994; Shackley 2005). The Mule Creek case is unusual because the chemical groups are not always spatially discrete and occur together in the extensive Gila Conglomerate which is mainly composed of Mule Creek rhyolite and tuffs in the area where the marekanites do occur (see Ratté and Brooks 1989). After fieldwork in 2009 it appears that the North Sawmill Creek chemical group extends within the Gila Conglomerate nearly to the Arizona state line.

Updated June and September 2013: Another locality of Antelope Creek was investigated.  This locality was discovered during the University of Arizona Field School's general survey of the area by Dan Welch one of the crew chiefs at the same time that the Keck Foundation Obsidian Field School was in the area. This locality is characterized as a regolith containing rhyolite lava, dacite, and andesite with abundant obsidian marekanites that overlies an ash flow or ignimbrite at the head of Antelope Creek as it erodes north into Harden Cienega Creek and down into the San Francisco River, a completely different environment from the eastern locality characterized by a large perlitic dome complex with remnant marekanites.  Located about 4 km directly west of the original eastern locality, the marekanites are an excellent vitreous media for tool production and many of the marekanites are well over 7 or 8 mm in diameter.  The character of these marekanites is quite a bit better than the perlitic nodules at the eastern locality, even though the absolute number of nodules may be less.  Consequently, the number of reduced cores and flakes is much higher at the western locality as would be expected with this better raw material.  The megascopic character is also different.  While there are many marekanites in the western locality that are nearly opaque like in the east, there are many that are nearly transparent, or at least more translucent.  It is likely that the western locality is THE prehistoric source for Antelope Creek obsidian in the Southwest.  The Y versus Nb plot below indicates that there is no significant difference in elemental chemistry between the two localities.  See SPOT image below for relevant locations.

 

Table 1. Elemental composition of Mule Creek Regional Source Groups. All measurements in parts per million (ppm).

CHEMICAL GROUP Mn  Rb  Sr  Y  Zr  Nb  Ba 
Antelope Cr East 334 241 19 39 130 25 126
Antelope Cr East 321 229 17 41 126 23 147
Antelope Cr East 347 230 18 39 128 27 125
Antelope Cr East 330 232 17 40 131 28 132
Antelope Cr East 368 236 16 40 131 29 133
Antelope Cr East 319 234 19 39 127 24 133
Antelope Cr East 392 247 17 42 130 26 133
Antelope Cr East 286 221 17 39 125 29 128
Antelope Cr East 329 242 17 44 130 27 107
Antelope Cr East 393 254 18 42 112 29 94
Antelope Cr East 425 272 16 43 121 26 85
Antelope Cr East 323 227 16 34 110 25 93
Antelope Cr East 356 242 17 44 114 23 89
Antelope Cr East 408 247 17 45 117 31 94
Antelope Cr East 377 252 14 42 120 23 83
Antelope Cr East 422 264 14 46 114 27 89
Antelope Cr East 410 265 12 45 119 24 79
Antelope Cr East 364 251 14 40 114 23 79
Antelope Cr East 369 265 15 41 116 30 82
Antelope Cr East 357 263 8 51 121 33 64
Antelope Cr East 384 254 10 47 116 32 64
Antelope Cr West              
062013-1 356 232 21 38 109 24 40
062013-2 343 224 21 39 110 27 48
062013-3 352 246 21 40 106 26 87
062613-4 380 261 13 51 93 34 <1
062013-5 348 241 18 42 113 27 33
092713-1-6 360 234 21 42 107 22 70
092713-1-11 377 238 19 43 111 26 34
092713-1-1 358 236 19 42 112 27 52
092713-1-9 352 241 21 44 114 25 43
092713-1-10 355 234 20 40 111 24 85
092713-1-3 331 221 20 41 106 26 62
092713-1-4 383 251 17 44 114 22 43
092713-1-8 402 260 21 43 110 29 33
092713-1-7 381 246 21 44 116 29 30
092713-1-5 372 239 24 43 112 29 54
Mule Cr/N Sawmill Cr 543 413 8 76 122 121 43
Mule Cr/N Sawmill Cr 524 399 4 71 119 117 43
Mule Cr/N Sawmill Cr 556 420 6 73 126 125 48
Mule Cr/N Sawmill Cr 538 397 8 69 119 116 46
Mule Cr/N Sawmill Cr 503 391 7 67 120 119 47
Mule Cr/N Sawmill Cr 519 387 7 69 121 117 44
Mule Cr/N Sawmill Cr 570 412 5 70 121 119 47
Mule Cr/N Sawmill Cr 672 403 10 71 125 120 45
Mule Cr/N Sawmill Cr 555 402 7 71 120 113 44
Mule Cr/N Sawmill Cr 558 409 6 70 122 124 44
Mule Cr/N Sawmill Cr 584 412 5 70 121 117 47
Mule Cr/N Sawmill Cr 588 431 6 70 123 121 43
Mule Cr/N Sawmill Cr 612 427 4 75 124 118 45
Mule Cr/N Sawmill Cr 549 410 5 73 124 117 46
Mule Cr/N Sawmill Cr 524 384 6 70 116 111 47
Mule Cr/N Sawmill Cr 550 417 7 69 122 121 45
Mule Cr/N Sawmill Cr 632 444 7 74 131 126 43
Mule Cr/N Sawmill Cr 588 433 5 74 129 123 50
Mule Cr/N Sawmill Cr 605 418 5 73 121 121 44
Mule Cr/N Sawmill Cr 539 390 3 69 115 115 46
Mule Cr/N Sawmill Cr 560 409 6 70 122 116 43
Mule Cr/N Sawmill Cr 565 406 7 71 119 120 45
Mule Cr/N Sawmill Cr 575 409 7 69 118 121 47
Mule Cr/N Sawmill Cr 550 414 4 72 124 120 46
Mule Cr/N Sawmill Cr 608 426 7 74 120 125 45
Mule Cr/N Sawmill Cr 523 393 6 71 119 120 47
Mule Cr/N Sawmill Cr 603 423 3 69 107 124 18
Mule Cr/N Sawmill Cr 628 421 4 69 105 121 16
Mule Cr/N Sawmill Cr 571 401 1 69 102 114 22
Mule Cr/N Sawmill Cr 574 396 5 69 112 118 17
Mule Cr/N Sawmill Cr 644 414 5 68 108 123 17
Mule Cr/N Sawmill Cr 584 414 4 70 107 120 19
Mule Cr/N Sawmill Cr 621 427 3 71 109 123 16
Mule Cr/N Sawmill Cr 649 435 5 77 106 130 23
Mule Mtns 450 179 12 24 118 30 98
Mule Mtns 441 175 10 27 119 33 89
Mule Mtns 454 184 10 22 125 32 88
Mule Mtns 413 176 11 24 117 34 92
Mule Mtns 409 171 12 23 108 34 88
Mule Mtns 438 178 11 25 117 32 85
Mule Mtns 520 177 13 24 121 29 91
Mule Mtns 475 186 11 25 119 28 100
Mule Mtns 463 186 11 25 118 34 86
Mule Mtns 463 187 10 24 121 33 88
Mule Mtns 486 185 8 25 116 32 75
Mule Mtns 535 193 9 27 124 32 75
Mule Mtns 492 192 9 23 129 30 72
Mule Mtns 506 192 9 27 124 33 74
Mule Mtns 500 191 7 25 123 30 74
SF River Alluv. 333 147 12 16 87 27 66
SF River Alluv. 303 188 12 24 90 23 67
SF River Alluv. 573 193 7 30 60 29 68
SF River Alluv. 456 173 17 25 80 17 187
SF River Alluv. 726 215 7 33 67 28 69
SF River Alluv. 536 169 23 29 81 19 168
SF River Alluv. 503 177 22 30 84 23 213

 

 Table 2.  Major oxides for the Mule Creek localities (all measurements in weight percent)

Locality/Sample#

SiO2

Al2O3

CaO

Fe2O3

K2O

MgO

MnO

Na2O

TiO2

Σ

Ant. Cr. West 092713-1-11

77.894

11.513

0.59

0.978

5.054

0

0.061

3.746

0.052

99.86

Ant. Cr. East 061309-1-6

77.894

11.552

0.625

1.112

5.18

0

0.06

3.969

0.054

99.899

Mule Mtns 061393-1-4

77.954

11.474

0.454

0.705

5.525

0

0.074

3.609

0.107

99.904
 

N Sawmill Cr 061209-1-1

77.589

11.743

0.593

0.929

4.894

0

0.11

3.864

0.05

99.776

RGM1-S4

75.680

12.477

1.3024

1.806

4.550

<.001

0.0379

3.77

0.196

99.782

 

 

 

Y versus Nb bivariate plot of source samples from Antelope Creek East and West localities.

 

SPOT image of the Antelope Creek localities and relevant features

Three-dimensional plot of Rb, Zr, and Ba indicating the compositional differentiation of the sub-sources in the Mule Creek Source Region.

Sr, Rb, and Zr concentration plot of Mule Creek and Gwynn Canyon source data. Note the possible genetic similarity between the Mule Creek and Gwynn Canyon sources, possibly due to the similar (Mogollon-Datil Province) crustal origin. 

 

Nb versus Y bivariate plot of Antelope Creek, Mule Mountains, and Gwynn/Ewe Canyons source standards from Table 1 data.

Rb versus Zr bivariate plot of Antelope Creek, Mule Mountains, and Gwynn/Ewe Canyons source standards from Table 1 data.

 

 

Study area with selected archaeological sites (filled circles), obsidian sources (filled triangles), modern communities (filled squares), and modern drainage system. Mule Creek Chemical Group "in-situ" localities = 1 Antelope Creek; 2 Mule Mountains; 3 Mule Creek/N. Sawmill Creek. Source localities linked to appropriate pages or data.

THE ARCHAEOLOGY OF MULE CREEK

For a number of years now, Archaeology Southwest and the University of Arizona have been working in the Mule Creek valley attempting to unravel the rather complex history of occupation as part of a larger study of late prehistoric social networks and migration (see Mills et al. 2013).  During the late 13th and early 14th century, the occupation of the valley became more ethnically complex with migrants from the Kayenta/Tusayan region of northern Arizona coming into the valley, establishing communities alongside the Salado inhabitants (see Mills et al. 2013).  The obsidian sources in the valley figure prominently in understanding this complex social network that was occurring during the late 13th and 14th centuries.  Archaeology Southwest has created a number of videos that discuss this unique archaeological manifestation from the perspective of principals of the project, including Deb Huntley, Rob Jones, and Katherine Dungan, scholars who have worked in the valley extensively over nearly a decade:

An overview of Mule Creek archaeology with Deb Huntley: http://www.archaeologysouthwest.org/what-we-do/information/video/deb-mcasw/

Obsidian at Mule Creek with Rob Jones: http://www.archaeologysouthwest.org/what-we-do/information/video/rob-mcasw/

Katherine Dungan on the work at Mule Creek: http://www.archaeologysouthwest.org/what-we-do/information/video/katherine-mcasw/

Graphic overview of changes in the social network, and population density in the Southwest A.D. 1200 to 1500: http://www.archaeologysouthwest.org/what-we-do/information/video/social-networks-and-population-density-in-the-late-precontact-southwest/

REFERENCES

     Brooks, W. E., and Ratté, J. C.

              1985 Geologic map of Bear Mountain Quadrangle, Grant County, New Mexico.  U.S. Geological Survey Miscellaneous Field Studies Map MF-1782.
Findlow, Frank J. and Marisa Bolognese

  1982a  Regional Modeling of Obsidian Procurmement in the American Southwest.  In Contexts for Prehistoric Exchange, edited by J.E. Ericson and T.K. Earle, pp. 53-81.  Academic Press, New York.

1982b  A Preliminary Analysis of Prehistoric Obsidian use Within the Mogollon Area.  In Mogollon Archaeology: Proceedings of the 1980 Mogollon Conference, edited by  P.H. Beckett, pp. 297-316.

     LeTourneau, Philippe D.

             1994  Geologic Investigations of the Antelope Wells Obsidian Source, Southern Animas Mountains, New Mexico.  Paper presented at the 59th Annual Meeting of the Society for  American Archaeology, Anaheim, California.

Mills, B.J., J.J. Clark, M.A. Peeples, W.R. Haas, Jr., J.M. Roberts, Jr., J.B. Hill, D.L. Huntley, L. Borck, R.L. Breiger, A. Clauset, and M.S. Shackley

  2013  Transformation of Social Networks in the Late Pre-Hispanic US Southwest.  PNAS 110:5785-5790.

Ratté, J. C.
  1982  Geologic map of the Lower San Francisco Wilderness Study Area and contiguous roadless area, Greenlee County, Arizona, and Catron and Grant Counties, New Mexico.  U.S. Geological Survey Miscellaneous Field Studies Map MF-1463rA-B.

Ratte, J.C. and Brooks, W.B.

  1983    Geologic map of the Mule Creek Quadrangle, Grant County, New Mexico. U.S. Geological Survey Miscellaneous Studies Map MF-1666.

  1989    Geologic map of the Wilson Mountain Quadrangle, Catron and Grant Counties, New Mexico.  U.S. Geological Survey Geologic Quadrangle Map GQ-1611.

Ratté, J. C., and Hedlund, D.C. 

  1981 Geologic map of the Hells Hole Further Planning Area (RARE II), Greenlee County, Arizona and Grant County, New Mexico.  U.S. Geological Survey Miscellaneous Field Studies Map MF-1344-A.

Ratté, J. C., Marvin, R.F., and Naeser, C.W.

  1984  Calderas and ash flow tuffs of the Mogollon Mountains, southwestern New Mexico.  Journal of Geophysical Research 89:8713-8732.

            Rhodes, R. and E. Smith

             1972  Geology and Tectonic Setting of the Mule Creek Caldera, New Mexico, USA.  Bulletin Volcanologíe 36:401-411.

           Shackley, M.S.

1988  Sources of Archaeological Obsidian in the Southwest: An Archaeological, Petrological, and Geochemical Study.  American Antiquity 53:752-772.

            2005  Obsidian: Geology and Archaeology in the North American Southwest.  University of Arizona Press, Tucson.

Weber, Robert H., and Max E. Willard

  1959  Reconnaissance Geologic Map of Mogollon Thirty-Minute Quadrangle.  New Mexico Institute of Mining and Technology.

This page maintained by Steve Shackley (shackley@berkeley.edu).
Copyright © 2013 M. Steven Shackley. All rights reserved.
Revised: 19 August 2015

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