COW CANYON

Sections 2 and 3 R29E, T2S, USGS Pipestem Mtn 7.5' Quad, Apache National Forest, central Greenlee County, Arizona. This is a relatively small source along and east of Arizona Hwy 666 located in a Quaternary rhyolite body. There is some suggestion that this too is a Tertiary rhyolite body remnant surrounded by the Quaternary basalt, but this was difficult to determine for this study. The nodules are found within an eroded rhyolite/ash unit that appears to be a remnant dome structure. Perlite or vitrophyre was not evident. The nodules are common in a rhyolite regolith on top of the dome as well as the rhyolite/ash alluvium at the base of the slopes. Nodules up to 5 cm in diameter are available, but most of the nodules are near or less than 4 cm. The density of nodules is fairly high in places, up to 5 per m². Cortex is mainly a thin gray-black. The interior glass is aphyric and the color is as variable as the mid-Tertiary marekenite sources. The most common color/opacity is a near transparent brown-green sometimes with thin banding. A few specimens exhibit a nearly opaque aphyric gray-green banded megascopic character.

The nodules are eroding and funneled into the Cow Canyon Creek/Turkey Creek system possibly reaching the Blue River 15 km east. Reduced nodules and flakes occur everywhere on the regolith and in the alluvium. The pattern of reduction is similar to Vulture with sporadic bipolar reduction throughout the source area. These specific areas may reach 10-20 per m². Overall the rejected core/flake density is less than 1 per 5m². There are no published sources on this locality other than the county geology map (Wilson and Moore 1958).

[updated 1995] It appears that the secondary depositional extent of this source is much greater than originally mapped (Shackley 1988a). This Tertiary source is eroding east into the Blue River, south into the San Francisco River and west into the Gila River as originally noted, but also erodes in much higher density west into Eagle Creek west of the Blue River, and on south into the Gila River and up to 20 km south into the San Simon River Valley. A number of “pockets” of Cow Canyon glass have been located in the San Simon River Valley in Pliocene/Pleistocene sediments the result of considerably higher sedimentation rates in these periods than currently. The density of nodules at Eagle Creek approximately 15 km west of the primary contexts at Cow Canyon is up to 1 per 10m², and less than 100 times lower in the Gila River (Shackley 1992a). Again, these nodules are mixed with the Mule Creek marekenites in the alluvium.

Raw elemental concentrations for Cow Canyon source standards. All measurements in parts per million (ppm).

`SAMPLE`	`Ti`	`Mn`	`Fe`	`Rb`	`Sr`	`Y`	`Zr`	`Nb`	`Ba`
`CC-1`	`819.97`	`415.20`	`8041.26`	`141.28`	`84.05`	`21.91`	`98.83`	`17.07`	`1001.13`
`CC-2`	`1107.31`	`548.22`	`10010.60`	`150.06`	`114.39`	`22.82`	`148.49`	`21.54`	`851.66`
`CC-3`	`1239.39`	`512.81`	`9920.84`	`141.33`	`112.34`	`24.56`	`142.78`	`17.50`	`823.01`
`CC-4`	`989.57`	`467.11`	`9014.99`	`136.24`	`105.99`	`22.75`	`137.90`	`20.17`	`901.22`
`CC-5`	`1216.74`	`573.37`	`10438.97`	`149.16`	`117.05`	`25.98`	`153.50`	`18.24`	`846.39`
`CC-6`	`1898.13`	`543.88`	`11937.85`	`127.22`	`100.23`	`23.57`	`134.81`	`22.03`
`CC-7`	`1017.91`	`466.28`	`8993.54`	`138.90`	`99.80`	`25.97`	`139.75`	`19.00`	`827.56`
`CC-8`	`1088.52`	`462.75`	`9259.96`	`134.99`	`105.64`	`22.48`	`144.84`	`19.07`	`854.83`
`CC-9`	`1017.80`	`465.47`	`9141.39`	`134.61`	`108.62`	`24.62`	`146.91`	`20.14`	`860.18`
`CC-10`	`1128.09`	`528.50`	`9976.73`	`147.82`	`116.29`	`21.98`	`148.63`	`22.22`	`868.69`
`CC-11`	`993.35`	`461.41`	`9290.82`	`134.36`	`106.57`	`23.84`	`142.93`	`18.46`	`901.92`
`CC-12`	`1344.44`	`633.00`	`11263.37`	`160.94`	`128.52`	`25.72`	`151.09`	`21.98`	`857.01`
`CC-13`	`938.51`	`329.67`	`7725.69`	`112.19`	`93.31`	`24.04`	`127.34`	`20.03`	`922.31`
`CC-14`	`1125.63`	`537.54`	`10124.40`	`144.13`	`111.74`	`23.63`	`143.01`	`19.26`	`875.65`
`CC-15`	`912.66`	`433.56`	`8634.87`	`136.28`	`96.75`	`20.02`	`131.36`	`19.09`	`796.16`
`CCA`	`902.90`	`521.86`	`8744.10`	`136.78`	`104.45`	`20.48`	`131.45`	`15.32`	`838.73`
`CCB`	`1201.34`	`539.25`	`9685.59`	`149.13`	`114.30`	`23.30`	`138.28`	`17.03`	`871.10`
`CCC`	`990.31`	`524.79`	`8774.31`	`137.69`	`106.97`	`21.74`	`132.38`	`18.63`	`851.35`
`CC-16`	`826.36`	`597.74`	`9382.30`	`150.75`	`120.23`	`23.07`	`139.27`	`19.48`
`CC-17`	`950.45`	`578.51`	`9143.96`	`149.15`	`116.95`	`25.30`	`137.41`	`16.36`
`CC-18`	`979.13`	`589.78`	`9159.47`	`146.43`	`120.18`	`25.45`	`141.13`	`21.32`
`CC-19`	`1019.37`	`633.34`	`9475.15`	`152.23`	`123.27`	`26.25`	`145.56`	`21.15`
`CC-20`	`837.72`	`573.51`	`9633.30`	`153.22`	`121.16`	`25.28`	`143.57`	`20.78`