Distribution of Elements in Sedimentary Rocks of the Colorado Plateau A Preliminary Report GEOLOGICAL SURVEY BULLETIN 1107-F Prepared on behalf of the U.S. Atomic Energy Commission Distribution of Elements in Sedimentary Rocks of the Colorado Plateau A Preliminary Report By WILLIAM L. NEWMAN CONTRIBUTIONS TO THE GEOLOGY OF URANIUM GEOLOGICAL SURVEY BULLETIN 1107-F Prepared on behalf of the U.S. Atomic Energy Commission UNITED STATES GOVERNMENT PRINTING OFFICE. WASHINGTON : 1962 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25, D.G. CONTENTS Page Abstract____________________________-__-__-_---_-___-___ 337 Introduction ______________________________________________________ 339 Physical features of sedimentary rocks------_--__----_------------__- 339 Precambrian sedimentary rocks.________________________________ 341 Cambrian system____________________________________________ 342 Ordovician system..___________________________________________ 344 Devonian system._____________________________________________ 344 Mississippian system.._________________________________________ 346 Pennsylvanian system________________________________________ 346 Permian system _______________________________________________ 349 Triassic system______________________________________________ 352 Moenkopi formation _______________________________________ 352 Chinle formation..._______________________________________ 354 Basal sandstone units of the Chinle formation___________ 356 Wingate sandstone_______________________________________ 357 Jurassic system ____________________________________________ 360 Kayenta formation._______________________________________ 360 Navajo sandstone________________________________.________ 362 Carmel formation________________________________________ 362 Entrada sandstone_______________________________________ 365 Curtis formation__________________________________________ 366 Todilto limestone________________________________________ 368 Summerville formation_____________________________________ 370 Cow Springs sandstone_____________________________________ 370 Bluff sandstone__________________________________ 373 Morrison formation______________________________________ 375 Salt Wash member________________________________ 375 Recapture member.___________________________________ 378 Westwater Canyon member___________________________ 378 Brushy Basin member_______________________________ 381 Lower Cretaceous series________________________________________ 381 Upper Cretaceous series_-_______-________________-_____________ 384 Tertiary system_________________________________________ 386 Summary of the physical features of sedimentary rocks___________ 386 nz IV CONTENTS Page Chemical features of sedimentary rocks_____________________________ 388 Approach to the study of chemical features______--_______-___---_ 388 Methods of sampling and sample preparation _________________ 389 Definition of unmineralized sandstone__-________--_-___-___ 389 Analytical methods________-___-_-___-_-_-_-_-._-_------_-__ 390 Statistical treatment of analyses.----_______-__-_-___-_---___ 392 Sandstone ____________________________________________________ 394 Sandstone of the Salt Wash member of the Morrison formation. 394 Average chemical composition_________________________ 394 Distribution of elements in mechanical fractions of sandstone. 397 Stratigraphic variations of elements____________________ 402 Regional distribution of elements_________--_-----_-_---_ 403 Basal sandstone units of the Chinle formation.________________ 405 Average chemical composition_________________________ 408 Regional distribution of elements________________________ 409 Stratigraphic distribution of elements in sandstones of pre- Tertiary age______________________________-_________-___ 411 Mean composition of sandstones_______________________ 411 Relation between composition of sandstone and the distri­ bution of uranium deposits- __________________________ 415 Mudstone._--_____________________-_____-__---_--_______---__ 417 Chemical composition of some mudstones of the Morrison formation_____________________________________________ 418 Red and green mudstone_________-_____---_----_------- 418 Bentonitic and nonbentonitic mudstone__________________ 421 Chemical composition of mudstone of Triassic age_____-.__--__ 422 Chemical composition of some mudstones of Precambrian, Paleo­ zoic, Cretaceous, and Tertiary ages._______________________ 425 Limestone ____________________________________________________ 427 Chemical composition of carbonate rocks of Precambrian and Paleozoic ages_________________________________________ 427 Stratigraphic variations in composition of carbonate rocks______ 428 Chemical composition of gypsum from the Paradox member of the Hermosa formation of Pennsylvanian age_______________ 429 Distribution of selenium_________________________-___-__________ 430 Summary of the chemical features of sedimentary rocks ____________ 431 Literature cited___________________________________________________ 434 Index._______________________________________________________ 441 CONTENTS ILLUSTRATIONS FIGURES 42-68. Maps of the Colorado Plateau showing outcrop pattern and other features of rock units. page 42. Precambrian age___ _______ _____________________ 342 43. Cambrian system, ____________________________ 343 44. Devonian system_____________________________ 345 45. Mississippian system,-__-______-_-_----__----__- 347 46. Pennsylvanian system._________________________ 348 47. Permian system_______________________________ 350 48. Moenkopi formation____________________________ 353 49. Chinle formation_-________________-_-___-_-._ 355 50. Basal sandstone units of the Chinle formation.____ 358 51. Wingate sandstone.____________________________ 359 52. Kayenta formation___ _________________________ 361 53. Navajo sandstone__________ ___________________ 363 54. Carmel formation. _____________________________ 364 55. Entrada sandstone._____________________________ 366 56. Curtis formation.______________________________ 367 57. Todilto limestone and the Pony Express limestone member of the Wanakah formation.__________ 369 58. Summerville formation.________________________ 371 59. Cow Springs sandstone-________________________ 372 60. Bluff sandstone_-_-__---_------------__-------_ 374 61. Morrison formation.-__-______-.-__-_-______-___ 376 62. Salt Wash member of the Morrison formation.___ 377 63. Recapture member of the Morrison formation.___ 379 64. Westwater Canyon member of the Morrison forma­ tion- __-____-_____-__.__-_________________ 380 65. Brushy Basin member of the Morrison formation-_ 382 66. Lower Cretaceous series______---_---_---_-_---_- 383 67. Upper Cretaceous series_______________________ 385 68. Tertiary system______________________________ 387 VI CONTENTS Page FIGURE 69. Map of the Salt Wash member of the Morrison formation showing areas of high concentrations of elements that may be contained in minerals derived from crystalline rocks or volcanic sources-__-_____________-__--_--________-____ 404 70. Map of the Salt Wash member of the Morrison formation showing areas of sandstone containing at least 10 ppm vanadium. ____________________________________ ___ 406 71. Map of the Salt Wash member of the Morrison formation showing distribution of copper in sandstone____________ 407 72. Map of the Colorado Plateau showing areas of sandstone of the Shinarump member of the Chinle formation containing above-average amounts of elements commonly found in heavy minerals_____________________________________ 410 73. Index map of the Colorado Plateau showing sources of samples of sandstone from some of the principal formations._____ 412 74. Scatter diagram showing the correlation between the number of known uranium deposits per 1,000 cubic miles of sand­ stone and the estimated geometric mean concentration of potassium in late Paleozoic and Mesozoic sandstones of the Colorado Plateau__________--_______------_______---_- 416 75. Scatter diagram showing the correlation between the number of known uranium deposits per 1,000 cubic miles of sand­ stone and the estimated geometric-mean concentration of vanadium in late Paleozoic and Mesozoic sandstones of the Colorado Plateau___________________________ 417 76. Index map of the Colorado Plateau showing sources of samples of mudstone, limestone, and gypsum____________________ 419 77. Frequency distribution of uranium and manganese in "bleached" and unbleached mudstone of the Moenkopi formation ___________________________________________ 424 TABLES [Tables 20-35 in pocket] Page TABLE 1. Original volumes of sediments of some of the principal rock units on the Colorado Plateau.________________________ 340 2. Volume of limestone, mudstone, and sandstone of the Paleozoic and Mesozoic systems of the Colorado Plateau___________ 388 3. Notation used in reporting semiquantitative spectrographic analyses_ _ _________________________________________ 391 4. Standard sensitivities for elements determined by the semi- quantitative spectrographic method and special sensitivities attained in this investigation_________________________ 392 5. Geometric-mean composition and estimated arithmetic-mean composition of unmineralized sandstone of the Salt Wash member of the Morrison formation.._______ ____________ 395 CONTENTS VII Page TABLE 6. Mineral components of sandstone of the Salt Wash member