TANK MOUNTAINS

WESTERN ARIZONA

This is source is the farthest western source in Arizona. The source is located on the Yuma Proving Grounds in the central Tank Mountains UTM Zone 11 809360m Easting by 3673520m Northing, Department of Defense Palomas Mountain Quad 1:50,000 scale, north central Yuma County. The first samples were recovered by John R. Cook during a helicopter archaeological reconnaissance of the proving grounds in 1988. The nodules were within the Quaternary alluvium and embedded within a silicic ash flow. The five nodules analyzed are all less than three centimeters in diameter, but appear to be excellent media for tool production (since this time an additional ten samples have been analyzed some 5 cm in diameter; see Shackley 1991).

The source area was recorded by Rogers as A-111 (SDMOM) as a San Dieguito (Paleoindian) through Amargosa (Archaic) period site (1966:177). Rogers notes that the environment would be sufficient for late period occupation, but he recorded no late material, nor the obsidian nodules. Cook recovered a late period triangular concave based point produced from the Tank Mountain material at White Tanks. A photograph of the tanks in Rogers (1966:70) shows the ash flow tuff environment. The tanks have been eroded into the tuff sediments. Presumably the material has eroded into the local washes, but recent archaeological survey in the area has failed to locate any geological obsidian in surrounding alluvium (Jerome Schaefer: personal communication 1989). The source was published in Kiva (Shackley 1991).

Elemental concentrations for Tank Mountain source standards. All measurements in parts per million (ppm).

SAMPLE Ti Mn Fe Rb Sr Y Zr Nb Ba
WT1 608 389 10256 160 147 28 122 24 946
WT2 564 387 10256 159 145 27 126 19 938
WT3 560 439 10643 167 147 23 124 15 866
WT4 1250 435 10994 172 157 21 118 22 712
WT5 735 418 10302 160 142 22 121 17 870
WT6 647 475 11117 167 149 26 126 22 813
WT7 582 473 11372 178 157 26 129 22 1028
WT8 785 512 11915 181 160 25 129 19 937
WT9 639 442 10687 159 148 24 123 20 946
WT10 563 410 10490 163 149 25 119 20 930
WT12 549 403 10588 161 145 24 124 18 934
LOC 3 661 407 10835 165 147 23 124 18 930
LOC 2-1 668 448 11046 170 151 24 127 20 802
LOC 2-2 618 428 10520 168 149 25 130 21 905
WT11 527 382 10328 152 142 24 120 26 760

Mean and central tendency for the data in the table above

This page maintained by Steve Shackley (shackley@berkeley.edu).
Copyright 2018 M. Steven Shackley. All rights reserved.
Revised: 03 November 2018

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