Description of Indicator Plants and Methods of Botanical Prospecting for Uranium Deposits on the Colorado Plateau
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Description of Indicator Plants and Methods of Botanical Prospecting for Uranium Deposits on the Colorado Plateau GEOLOGICAL SURVEY BULLETIN 1030-M This report concerns work done on behalf of the U. S. Atomic Energy Commission and is published with the permission of the Commission Description of Indicator Plants and Methods of Botanical Prospecting for Uranium Deposits on the Colorado Plateau By HELEN L. CANNON A CONTRIBUTION TO THE GEOLOGY OF URANIUM GEOLOGICAL SURVEY BULLETIN 1 03 0 - M This report concerns work done on behalf of the U. S. Atomic Energy Commission and is published with the permission of the Commission UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1957 UNITED STATES DEPARTMENT OF THE INTERIOR FRED A. SEATON, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 50 cents (paper cover) CONTENTS Page Abstract________________________________________________________ 399 Introduction._____________________________________________________ 399 Colorado Plateau soils and ground-water conditions-___________________ 400 Plants in relation to ground water.__________________________________ 401 Plant associations and indicator plants on the Colorado Plateau.________ 402 How to prospect by plant analysis.__________________________________ 405 How to use indicator plants in prospecting.___________________________ 407 Selected bibliography. _____________________________________________ 411 Illustrations and descriptions of indicator plants.______________________ 413 Glossary__ _ _____________________________________________________ 514 Plant index_______________________________________________________ 515 ILLUSTKATIONS Page FIGUKE 74. Dead plants of Astragalus paltersoni useful in fall and winter in deciding where to drill._________________ 409 75. Index map of part of the Colorado Plateau showing location of mining districts._____________________ 410 76. 77. Astragalus pattersoni A. Gray, or Patterson poison- vetch___________ _ ________________ 414, 415 78, 79. Astragalus preussi A. Gray, or Preuss poisonvetch__ 416, 417 80, 81. Astragalus thompsonae S. Wats., or Thompson loco 418, 419 82, 83. Astragalus confertiflorus A. Gray, or blue poison vetch. 420, 42] 84, 85. Astragalus bisulcatus (Hook.) A. Gray, or two-grooved poisonvetch______________________ 422, 423 86, 87. Astragalus missouriensis Nutt., or Missouri milkvetch. 424, 425 88, 89. Astragalus lonchocarpus Torr., or long-seeded milk- vetch-_-._________________._________________ 426, 427 90, 91. Astragalus dodgianus Jones, or Dodge milkvetch_ __ 428, 429 92, 93. Astragalus tenellus Pursh, or looseflower milkvetch. 430, 431 94, 95. Astragalus aculeatus A. Nels., or spiny milkvetch__ 432, 433 96, 97. Allium acuminatum Hook., or tapertip onion, and re lated species_________________________________ 434, 435 98, 99. Calochortus nuttalli Torr. & Gr., or Sego lily, mari- posa______________________________ 436,437 100, 101. Zigadenus gramineus Rydb., or grassy deathcamas.. 438, 439 102, 103. Stanleya pinnata (Pursh) Britt., or desert princesplume. 440, 441 104, 105. Lepidium montanum Nutt., or mountain pepperweed._ 442, 443 106,107. Lepidium lasiocarpum Nutt., or hairy-pod pepperweed_ 444, 445 108, 109. Sisymbrium altissimum (L.) Britt., or tumblemustard. 446, 447 ill IV CONTENTS Page FIGUBE 110, 111. Cryptantha fiava A. Nels., or cryptanth, and related species._____________________________________ 448, 449 112,113. Oenothera caespitosa Nutt., or tufted evening-primrose. 450, 451 114, 115. Oenothera albicaulis Pursh, or whitestemmed evening- primrose. ____________________________________ 452, 453 116,117. Eriogonuminflatum Torr.,or deserttrumpet eriogonum- 454, 455 118, 119. Eriogonum fusiforme Small, or deserttrumpet______ 456, 457 120, 121. Eriogonum ovalifolium Nutt., or silver plant or cushion eriogonum______________-----_------------__- 458, 459 122, 123. Eriogonum unibellatum Torr., or sulfur eriogonum__ 460,461 124, 125. Eiymus salina Jones, or salina wildrye_____________ 462, 463 126, 127. Stipa comata Trin. & Rupr., or needleandthread_____ 464, 465 128, 129. Oryzopsis hymenoides (Roem. & Schult.) Ricker, or Indian ricegrass_______________ _______________ 466, 467 130, 131. Aster venustus Jones, or woody aster_______________ 468,469 132, 133. Townsendia incana Nutt., or hoary townsendia______ 470,471 134,135. Aplopappus armeriodes A. Gray, or goldenweed_ _ _ _ _ 472,473 136, 137. Grindelia sguarrosa (Pursh) Dunal, or curlycup gum- weed______________________________________ 474, 475 138, 139. Senecio longilobus Benth., or threadleaf groundsel____ 476,477 140, 141. Euphorbia fendleri Torr. & Gr., or sandmat or fendler euphorbia and related prostrate species __________ 478, 479 142, 143. Mentzelia multiflora (Nutt.) A. Gray, or desert blaz- ingstar____________________-_______----___-__ 480, 481 144, 145. Solidago petradoria Blake, or rock goldenrod________ 482, 483 146, 147. Tetradymia spinosa Hook. & Arn., or cottonthorn horsebrush__________________________________ 484, 455 148, 149. Cowania stansburiana Torr., or Stansbury cliflfrose.__ 486, 487 150, 151. Purshia tridentata (Pursh) DC., or antelope bitter- brush...____________________________________ 488, 489 152, 153. Hedysarum boreale Nutt., or northern sweetvetch_ _ 490, 491 154, 155. Castilleja integra Gray, or Indian paintbrush or painted- cup____________-____-_----__---------_---_ 492, 493 156,157. Plantago purshi Roem. & Schult., or woolly indianwheat. 494,495 158, 159. Atriplex confertifolia (Torr.) S. Wats., or shadscale saltbush__________.__________________________ 496, 497 160, 161. Atriplexcanescens (Pursh) Nutt., or fourwing saltbush__ 498,499 162, 163. Sarcobatus vermiculatus (Hook.) Torr., or black grease- wood.___________________________________ 500, 501 164, 165. Ephedra sp., or jointfir or mormon tea____________ 502, 503 166, 167. Opuntia engelmanni Salm-Dyck, or Engelmann prickly- pear, and other species_______________________ 504, 505 168, 169. Mirabilis multiflora A. Gray, or Colorado four-o'clock. 506,507 170, 171. Fraxinus anomala Torr., or singleleaf ash___________ 508,509 172, 173. Hymenopappus filifolius Hook., or fineleaf hymenopap- pus____-_________._____ __ 510,511 174, 175. Actinea acaulis (Pursh) Spreng., or stemless actinea__ 512, 513 DESCRIPTION OF INDICATOR PLANTS AND METHODS OF BOTANICAL PROSPECTING FOR URANIUM DEPOSITS ON THE COLORADO PLATEAU By HELEN L. ABSTRACT Two methods of botanical prospecting for uraniferous deposits on the Colo rado Plateau are useful in semiarid country in prospecting for ore-bearing beds at depths as much as 70 feet. By one method, tips of tree branches are sampled and analyzed for uranium content. Generally more than 1 part per million of uranium in the ash indicates favorable ground for further geologic exploration. The second method, that of mapping indicator plants, is used in semiarid parts of the Plateau at low altitude. The distribution of indicator plants is con trolled by the availability of chemical constituents of the ore, such as selenium, sulfur, and calcium. Plants of the genus Astragalus are most useful in prospect ing for uranium deposits of high selenium content; plants of the genera Allium and Eriogonum are most useful as indicators of deposits with a high sulfur content. Fifty indicator plants commonly associated with carnotite deposits and plants tolerant of mineralized ground are described and illustrated. INTRODUCTION Two methods of botanical prospecting for uranium deposits have been applied on the Colorado Plateau. One method is based on a chemical analysis for the uranium content of deep-rooted plants that absorb uranium from the ore bodies; the other is based on distribution studies of indicator plants that are commonly associated with uranium deposits. A third method, that of determining morphological or physiological changes in plants growing in ore deposits, has been dis carded in this area. The general principles on which methods of pros pecting were developed are described in earlier reports (Cannon, 1952; 1953). The first method makes it possible to detect uranium-bearing mate rial through a maximum of 70 feet of barren rock by means of tree root-systems, which act as conduits for the upward migration of soluble salts to the ground surface. The method is applicable where the mineralized bed crops out in a broad, flat bench so that plant samples can be collected on a grid pattern to outline mineralized zones at depth; and also where the mineralized bed crops out in a sharp cliff that is commonly obscured by talus or slump. Here a line traverse 399 400 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM parallel to the cliff may be desirable. The samples are either analyzed in the field by a quick test for uranium or are sent to a chemical lab oratory for quantitative assay. Prospecting by indicator plants is the less expensive of the two methods and consists of mapping the areal distribution of key indi cator plant species. Indicator plants and also plants tolerant of mineralized ground, and therefore common in uranium districts, are described, illustrated, and evaluated in this report. The information has been compiled not as a key for species identification but as a sorting device that will enable geologists and prospectors to identify, in a pre liminary way, the plants that may be useful in prospecting an area. The information was gathered while botanical prospecting studies were being made on the Colorado