Spanish Peaks Radiogenic Elements

Whole rock analyses performed for this study (samples beginning with "sp") for Rb, Sr, Sm, Nd, U, Th, and Pb were performed by D. M. Unruh at the U.S.G.S. in Lakewood, Colorado according to procedures given in Stille et al. (1986, and references therein) with some modification. Samples were spiked with 87Rb-84Sr, 149Sm-150Nd, and 230Th-236U-233U-205Pb-enriched tracers and decomposed in HF-HNO3 solution in PFA-teflon, screw-cap bombs.

Sample 87Rb/86Sr error 87Sr/86Sr error 87Sr/86Sri 147Sm/144Nd error 143Nd/144Nd error EpsilonNd 206Pb/204Pb error 207Pb/206Pb error 208Pb/206Pb error 207Pb/204Pb error 208Pb/204Pb error
sp101 0.1730 0.0019 0.7048 0.0000 0.7048 0.1054 0.0002 0.5125 0.00001 -3.00 17.8130 0.0170 0.8694 0.0003 2.1000 0.0012 15.4870 0.0160 37.4070 0.0530
sp118 0.1470 0.0016 0.7044 0.0000 0.7044 0.1039 0.0001 0.5122 0.00001 -8.20 17.4410 0.0110 0.8873 0.0003 2.1290 0.0012 15.4760 0.0140 37.1310 0.0440
sp119 0.0527 0.0006 0.7044 0.0000 0.7044 0.1268 0.0001 0.5124 0.00002 -5.10 17.7950 0.0180 0.8704 0.0004 2.0946 0.0013 15.4890 0.0200 37.2730 0.0550
sp121 0.2753 0.0030 0.7064 0.0000 0.7064 0.1134 0.0001 0.5122 0.00002 -7.70 18.4550 0.0110 0.8432 0.0003 2.0312 0.0012 15.5600 0.0140 37.4870 0.0450
sp124 0.6465 0.0073 0.7052 0.0000 0.7052 0.1742 0.0001 0.5122 0.00001 -9.20 17.4270 0.0110 0.8871 0.0003 2.1136 0.0013 15.4600 0.0140 36.8340 0.0440
sp131 0.0748 0.0013 0.7046 0.0000 0.7046 0.0926 0.0001 0.5124 0.00001 -3.90 17.6950 0.0160 0.8733 0.0003 2.1109 0.0013 15.4530 0.0180 37.3530 0.0520
sp134 0.5990 0.0067 0.7049 0.0000 0.7047 0.0996 0.0002 0.5124 0.00001 -4.30 17.6710 0.0150 0.8750 0.0003 2.1044 0.0016 15.4630 0.0170 37.1870 0.0530
sp20 0.1321 0.0014 0.7046 0.0000 0.7046 0.1105 0.0002 0.5124 0.00001 -4.30 18.3370 0.0110 0.8470 0.0003 2.0452 0.0015 15.5300 0.0140 37.5030 0.0480
sp21B 0.0795 0.0015 0.7043 0.0002 0.7043 0.0972 0.0001 0.5125 0.00001 -2.70 18.2050 0.0150 0.8520 0.0003 2.0779 0.0013 15.5100 0.0160 37.8280 0.0510
sp33 0.3252 0.0036 0.7042 0.0000 0.7041 0.1047 0.0002 0.5126 0.00001 0.00 18.3690 0.0160 0.8469 0.0003 2.0532 0.0015 15.5560 0.0170 37.7150 0.0530
sp34-ts 0.1176 0.0020 0.7044 0.0000 0.7043 0.1073 0.0001 0.5126 0.00004 -1.50 18.0710 0.0190 0.8583 0.0003 2.0753 0.0013 15.5110 0.0190 37.5030 0.0550
sp37 0.1385 0.0029 0.7056 0.0000 0.7055 0.1112 0.0001 0.5126 0.00002 -1.10 18.3100 0.0010 0.8484 0.0003 2.0754 0.0012 15.5300 0.0140 38.0000 0.0046
sp46 0.0522 0.0006 0.7041 0.0000 0.7041 0.1062 0.0003 0.5125 0.00002 -1.90 18.0540 0.0160 0.8584 0.0004 2.0903 0.0015 15.4985 0.0180 37.7385 0.0540
sp51 0.1064 0.0016 0.7049 0.0000 0.7049 0.1076 0.0002 0.5126 0.00002 -0.80 18.0620 0.0150 0.8592 0.0006 2.0875 0.0021 15.5180 0.0190 37.7040 0.0590
sp65 0.0438 0.0006 0.7044 0.0000 0.7044 0.1033 0.0001 0.5126 0.00002 -1.40 18.0490 0.0130 0.8602 0.0003 2.0957 0.0014 15.5260 0.0160 37.8250 0.0490
sp70 0.1430 0.0024 0.7046 0.0002 0.7046 0.0878 0.0001 0.5124 0.00002 -4.50 17.5650 0.0120 0.8793 0.0003 2.1168 0.0013 15.4450 0.0150 37.1820 0.0460
sp73 0.3433 0.0038 0.7074 0.0000 0.7073 0.0986 0.0001 0.5126 0.00001 -0.80 17.9140 0.0120 0.8652 0.0003 2.0963 0.0013 15.4990 0.0150 37.5530 0.0470
sp95 0.1302 0.0014 0.7061 0.0000 0.7060 0.1047 0.0001 0.5125 0.00001 -2.70 17.8110 0.0120 0.8679 0.0003 2.0986 0.0015 15.4590 0.0150 37.3780 0.0490
bj-b6 0.0960 0.7054 0.0001 0.7054
bj11 0.0990 0.7046 0.0001 0.7046
bj15 0.0600 0.7047 0.0001 0.7047
bj19 0.0540 0.7074 0.0001 0.7074
bj2 0.0510 0.7052 0.0001 0.7052
bj2-11 0.0810 0.7055 0.0001 0.7044
bj23 0.4000 0.7077 0.0002 0.7076
bj25 0.1810 0.7091 0.0001 0.7094
bj29 0.1410 0.7052 0.0001 0.7052
bj29inc. 0.0320 0.7048 0.0001 0.7048
bj3 0.1090 0.7047 0.0001 0.7047
bj34 0.1700 0.7049 0.0002 0.7049
bj37 0.1630 0.7042 0.0001 0.7042
bj5 0.0770 0.7048 0.0002 0.7048
bj53b 0.2400 0.7058 0.0002 0.7057
bj6 0.2000 0.7047 0.0001 0.7046
bj64 1.7330 0.7090 0.0001 0.7085
bj65 0.2260 0.7046 0.0001 0.7045
bj8 0.7046
bj8-18 1.1190 0.7049 0.0001 0.7049
bj8-40 0.0810 0.7054 0.0001 0.7054
bj8-W 0.7058

Samples begining with "blsp" are from:

Budding, K. E., and Lawrence, V. A. 1983. Geochemical Analyses of rock, stream-sediment, and heavy-mineral-concentrate samples collected from the Spanish Peaks Wilderness Study Area, Huerfano and Las Animas Counties, Colorado. U. S. Geological Survey Open-File Report 83-391.

Samples begining with "bj" are from:

Jahn, B. 1973. A Petrogenetic Model for the Igneous Complex in the Spanish Peaks Region, Colorado. Contributions to Mineralogy and Petrology 41:241-258.

Samples begining with "rj" are from:

Johnson, R. B. 1968. Geology of the Igneous Rocks of the Spanish Peaks Region Colorado. U. S. Geological Survey Professional Paper 594-G, 47p.

Samples begining with "K" are from:

Knopf, A. 1936. Igneous Geology of the Spanish Peaks Region, Colorado. Geological Society of America Bulletin 47:1727-1784.

Samples begining with "rs" are from:

Smith, R. P. 1975. Structure and Petrology of Spanish Peaks Dikes, South Central Colorado. Ph.D. Thesis, University of Colorado at Boulder, 191 p.

Smith, R. P.. 1979. Early Rift Magmatism at Spanish Peaks, Colorado in Rio Grande Rift: Tectonics and Magmatism, Reicker, R. E. (ed.), American Geophysical Union, Washington, D. C., 313-321.