U.S. DEPARTMENT OF INTERIOR U.S. GEOLOGICAL SURVEY OPEN-FILE REPORT 99-20-E WESTERN PHOSPHATE PROJECT Formation: Phosphoria Sec-Twn-Ra: Sec. 22, T. 6 S., R. 43 E. Lat: approx. 42 deg., 53.00' N. Member: Meade Peak Phosphatic Shale Long: Measured By: Tysdal, Johnson, Grauch, Herring, Desborough approx. 111 deg., 24.60' W. Quadrangle: Wayan West Notes: Logging of core Mine: 6000 Cr (ppm) 0 20000 Mn (ppm) 0 60000 Fe (ppm) 0 5000 Ni (ppm) 0 15000 Cu (ppm) 0 0 250 Zn (ppm) 5000 As (ppm) 0 1000 0 Se (ppm) 250 Pb (ppm) 0 Rb (ppm) 300 Sr (ppm) 0 Zr (ppm) 800 0 UNIT 2500 Enoch Valley Mo (ppm) DESCRIPTION Rex Chert Chert: lt gray; 185 INTRODUCTION 0 1/2000 500 Date Logged: 0 wpsJ LITH. FEET Section: Phosphorite: dk gray; pelletal, med grained; some pellets are silicified in uppermost Upper Waste part of interval; dense; white to lt gray specks of secondary minerals. Upper Waste Mudstone: dk gray; some zones are silty; carbonaceous; 1-2 in. fragments. Mudstone: dk gray; some zones are carbonaceous; v lt weight, punky; 1-2 in. The U.S. Geological Survey (USGS) has studied the Permian Phosphoria Formation in southeastern Idaho and the entire Western U.S. Phosphate Field throughout much of the twentieth century. In response to a request by the U.S. Bureau of Land Management, a new series of resource, geological, and geoenvironmental studies was undertaken by the USGS in 1998. To accomplish these studies, the USGS has formed cooperative research relationships with two Federal agencies, the Bureau of Land Management and the U.S . Forest Service, tasked with land management and resource conservation on public lands; and with five private companies currently leasing or developing phosphate resources in southeastern Idaho. The companies are Agrium U.S. Inc. (Rasmussen Ridge mine) , Astaris LLC (Dry Valley mine), Rhodia Inc. (Wooley Valley mine, inactive), J.R. Simplot Company (Smoky Canyon mine), and Monsanto Co. (Enoch Valley mine). Some of the mineralogical research associated with this project is supported through a cooperative agreement with the Department of Geology and Geological Enginee ring, University of Idaho. Present studies consist of integrated, multidisciplinary research directed toward (1) resource and reserve estimations of phosphate in selected 7.5-minute quadrangles; (2) elemental residence, mineralogical and petrochemical characteristics; (3) mobilization and reaction pathways, transport, and fate of potentially toxic elements associated with the occurrence, development, and societal use of phosphate; (4) geophysical signatures; and (5) improving the understanding of deposit origin. Because raw data acquired during the project will require time to interpret, the data are released in open-file reports for prompt availability to other workers. Open-file reports associated with this series of studies are submitted to each of the Federal and industry cooperators for comment; however, the USGS is solely responsible for the data contained in the reports. Upper Waste MEASURED SECTIONS fragments. 180 Mudstone: dk gray; sl calcareous to dolomitic in lower 0.7 in., particularly in 0.04 in. Stratigraphic sections of the Phosphoria Formation were measured and sampled by the USGS at several places in southeastern Idaho. The sections, generally lacking interpretation and explanatory notes, are published as preliminary reports as they are assembled (Tysdal and others, 1999, 2000a, 2000b, and 2000c). No thin section, X-ray, or analytical technique has been used to augment the descriptions of the rock units in these reports. The descriptions are accompanied by a computer-generated lithologic log. Informal bed designation names (A, B, C, D, etc.) introduced by Hale (1967, p. 152), and used generally throughout southeastern Idaho, are shown in the unit column along with some local, informal unit names. The units within the measured sections were sampled for geochemical and petrological analysis and some were also evaluated with a variety of geophysical techniques. English units of measurement are used throughout this report to facilitate direct correspondence with units in the extensive historical literature on the Phosphoria and with current industry usage. Measurements record true thickness; adjustments were made for the dip of beds at the time of measurement. The measured section, wpsJ, presented in this report differs from the others in that it is the log of a drill core (Core EVF 23-2) from the Enoch Valley mine property. The other major difference in this measured section report is that the descriptive, lithologic log is accompanied by semiquantitative chemical analyses of 13 elements: As, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Rb, Se, Sr, Zn, and Zr (see brief discussion below). Please NOTE that these chemical data are to be used for comparative purposes only; quantitative analyses of the core can be found in Herring and others (1999 and 2001). The data were gathered in order to quickly and economically de velop a picture of chemical variations on a very fine scale (sample intervals of approximately 3 inches in the core box) and to guide detailed sampling of the core for rigorous chemical analyses. The Phosphoria Formation in the vicinity of the measured sections consists of three members, which in ascending order are the Meade Peak Phosphatic Shale, the Rex Chert, and the informally named cherty shale (McKelvey and others, 1959; Montgomery and Cheney, 1967; Brittenham, 1976). The measured section here focuses on the Meade Peak Phosphatic Shale Member. The Meade Peak unconformably overlies the Grandeur Tongue of the Permian Park City Formation, and the cherty shale member is overlain by the Triassic Dinwoody Formation. Uppermost strata of the Phosphoria Formation were not recovered in the core of section wpsJ. Strata in the measured section dip between 45 and 60 degrees, but average about 50 degrees (unpublished data, Monsanto Co.). The dip is in good agreement with that of the two previously measured sections (wpsA and wpsB) at the Enoch Valley mine (Tysdal and others, 1999). The apparent thickness of the informal units in the three sections (wpsJ, wpsA, and wpsB) are generally similar with the exception of bed A in section wpsB. As noted in Tysdal and others (1999) the variations in bed A seem to be due to tight folding. Faults that are nearly bedding-parallel might also contribute to minor variations in thickness of the units. Upper Waste thick laminae; v carbonaceous in middle 0.7 in., friable, disaggregated; finely laminated; solid core. Mudstone: dk gray; carbonaceous; vuggy--dissolution along laminae 175 Upper Waste in some core segments. Mudstone: gradational from strata below to those above: 172-173.4 ft interval Upper Waste is lt brownish gray; dolomitic. 171.4-172 ft interval is v silty; laminated. 170.4171.4 is med gray. Lesigang banding occurs throughout lower 1.8 ft of unit. Core entirely fragmented. 170 Mudstone: dk gray; v carbonaceous. Siltstone: dk gray; noncalcareous; carbonaceous; 0.25-1 in. thick bedding in some 1-2 in. fragments; abundant white specks of a secondary mineral. Phosphorite: dk gray; pelletal, f to med grained; silicified locally, with lt blue quartz Upper Waste Upper Waste Upper Waste Upper Waste locally replacing pellets and matrix; white secondary minerals, some acicular; 1-2 in. 165 fragments. Mudstone: dk gray; faint lamination; gradational into overlying unit; solid core, except that lower 0.6 in. fragmented into 1-2 in. size chips. Phosphorite: dk gray; pelletal, cse grained. Phosphorite: dk gray; pelletal, f to cse grained; carbonaceous; some laminae; 160 slickensides; local white specks of secondary minerals within some layers. Phosphorite: dk gray; pelletal, f to cse grained; abundant white specks of secondary D Bed D Bed D Bed D Bed SEMIQUANTITATIVE ANALYSES OF SELECTED ELEMENTS D Bed minerals; 0.5-1 in. fragments. Phosphorite: dk gray; pelletal, f to cse grained; abundant white specks of secondary minerals; 0.5-1 in. fragments. 155 D Bed Measured section wpsJ is accompanied by profiles of semiquantitative concentrations of As, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Rb, Se, Sr, Zn, and Zr. The values were determined with a portable x-ray fluorescence analyzer manufactured by the Niton Corporation. Analyses employing x-ray fluorescence (XRF) instruments such as the one used in this study are highly dependent on the geometry of the material being analyzed and the correction procedures used in the analyses. The analytical scheme used in this study incorporated minimal, manufacturer supplied, correction procedures and variable sample geometries resulting in, at best, semiquantitative measurements. Further, the technique only measures surf ace compositions (x-ray penetration is generally less than 1 mm/0.04 in); in this case, a maximum surface area of approximately 0.75 in 2 was analyzed. Orientation of the sample surfaces was irregular (flat surfaces are ideal). Many samples were comprised of a chaotic assemblage of chips gathered at approximately the correct interval (sample spacing was nominally 3 inches, uncorrected for dip). The total number of measurements made is 1097. Values below the detection limit are shown on the profiles as 0. Detection limits ranged from about 15 to 500 ppm depending on the element and the sample analyzed. Table 1 shows the number of analyses with values above the detection limit and the ap proximate detection limit as well as the mean, standard deviation, and maximum of the values above the detection limit for each element. High concentration values for several elements are truncated in the profiles so that variations i n the lower values are not obscured. Comparisons between the XRF analyses in this report and the more reliable chemical values for the same strata reported in Herring and others (1999 and 2001) indicate that the major chemical trends shown here are reliable and that occasional high values are similarly located. D Bed Phosphorite: and lesser interbedded mudstone. Phosphorite: dk gray; pelletal, f to D Bed cse grained; dense. Mudstone: dk gray; noncalcareous. Local white specks of secondary minerals. slickensides; 0.5-2 in. fragments. Phosphorite: dk gray; pelletal, cse grained; dense; local white specks of secondary D Bed D Bed minerals; slickensides. Phosphorite: dk gray; pelletal, f grained; dense; finely laminated, planar; 150 slickensides. This interval "represented" by about 4 in. of core fragments. Phosphorite: dk gray; pelletal, v f grained; earthy; some slickensides. This interval D Bed D Bed D Bed "represented" by about 2 in.of core fragments. Middle Waste Phosphorite: dk gray; f grained, pelletal to nonpelletal; planar fine laminae; laminae Middle Waste emphasized by white secondary minerals. This interval "represented" by about 4 in. 145 of core fragments. Middle Waste Phosphorite: dk gray; f grained, pelletal to nonpelletal; planar fine laminae; laminae Middle Waste emphasized by white secondary minerals. This interval "represented" by about 4 in. Table 1 Element Concentrations (approximate ppm) Determined by Portable XRF Analyzer of 1-3 in. core fragments. Phosphorite: dk gray; f grained, pelletal to nonpelletal; planar fine laminae; laminae emphasized by white secondary minerals. This interval "represented" by about 6 in. 140 Middle Waste of 0.5-1 in. core fragments. Element Number of analyses above detection limit Approximate detection limit Mean Standard deviation Maximum Phosphorite: dk gray; planar laminae; one fragment displays microripple crosslaminae; specks of white secondary minerals, which in upper few inches are confined to specific laminae; specks are soluble in water; 1-2 in. fragments. Middle Waste Phosphorite: dk gray; pelletal locally, f grained; locally silty; some planar laminae; 1 in. fragments. 135 Siltstone: dk gray; upper part contains some phosphorite, dk gray, Middle Waste pelletal; 0.25-0.5 in. fragments. Mudstone: dk gray. About 4 in.of core fragments "represent" this interval. As 111 Cr 431 Cu 56 Fe 1069 Mn 66 Mo 736 Ni 631 Pb 11 Rb 873 Se 745 Sr 1050 Zn 1058 Zr 887 40 350 120 450 500 15 200 40 15 20 15 70 10 70 30 210 1300 800 5700 380 220 1300 9900 6300 55,500 2600 3300 15,600 70 80 700 610 500 4700 70 50 210 70 30 290 110 300 6700 340 300 2100 2100 2800 46,600 130 80 490 Siltstone: dk gray; local mudstone zones, mainly in upper half of unit; sl fetid; fragments less than 0.25 to 1 in. 130 Siltstone: dk gray; organic rich; fetid; finely laminated; 0.1-0.25 in. thick carbon seams, or v carbonaceous siltstone; abundant white specks of secondary minerals, some acicular; mostly 0.25-1 in. fragments. Middle Waste Mudstone: dk gray; finely laminated; abundant white films, along fractures--?gypsum; other white secondary minerals are Middle Waste REFERENCES CITED acicular; mostly fragments less than 0.25 in. 125 Mudstone: and siltstone, interbedded. Mudstone, as in overlying unit; siltstone as in underlying unit. Brittenham, M.D., 1976, Permian Phosphoria carbonate banks, Idaho-Wyoming thrust belt, Mountain Association of Geologists 1976 symposium, Denver, p. 173-191. Middle Waste Siltstone: dk gray; finely laminated; bands 0.25-1 in. thick; ?graded; fetid; local 0.1-0.5 in. thick carbon seams in 129.4-131 ft interval, in two Middle Waste Hale, L.A., 1967, Phosphate exploration using gamma radiation logs, Dry Valley, Idaho, in Hale, L.A., ed., Anatomy of the western phosphate field: Salt Lake City, Intermountain Association of Field Geologists, 15 th Annual Field Conference Guidebook, p. 147-159. Middle Waste Herring, J.R., Desborough, G.A., Wilson, S.A., Tysdal, R.G., Grauch, R.I., and Gunter, M.E., 1999, Chemical composition of weathered and unweathered strata of the Meade Peak Phosphatic Shale Member of the Permian Phosphoria Formation. A. Measured sections A and B, central part of Rasmussen Ridge, Caribou County, Idaho: U.S. Geological Survey Open-File Report 99-147-A, 24 p. Middle Waste Herring, J.R., Grauch, R.I., Siems, D.F., Tysdal, R.G., Johnson, R.A., Zielinski, R.A., Desborough, G.A., Knudsen, A., and Gunter, M.E., 2001, Chemical composition of strata of the Meade Peak Phosphatic Shale Member of the Permian Phosphoria Formation. C hannel-composited and individual rock samples of measured section J and their relationship to measured sections A and B, central part of Rasmussen Ridge, Caribou County, Idaho: U.S. Geological Survey Open-File Report 01-195, 72 p. zones, each 4-6 in. thick; basal 1.2 ft contains 0.5-1.5 in. dia irregularly shaped diagenetic nodules that cut acorss depositional layers. 120 in Hill, J.G., ed., Symposium on geology of the Cordilleran hingeline: Rocky Siltstone: med gray; 127.4-128 ft interval is calcareous; fetid; porous; white specks of secondary minerals throughout. Mudstone: dk gray; local diagenetic nodules, to 1 in. dia; dense--?phosphatic; lower 4 in. is claystone (?altered mudstone), spongy, with 0.04 in. dia holes--?molds of microfossils; white specks of secondary minerals throughout; small fragments only. 115 Mudstone: dk gray. Poor recovery--drilling mud and filler. Mudstone: dk gray; finely laminated; some phosphate zones 1-2 in. thick; well indurated; coherent core. Middle Waste McKelvey, V.E., Williams, J.S., Sheldon, R.P., Cressman, E.R., Cheney, T.M., and Swanson, R.W., 1959, The Phosphoria, Park City, and Shedhorn formations in the western phosphate field: U.S. Geological Survey Professional Paper 313-A, 47 p. Mudstone: dk gray; phosphorite zones throughout unit; mostly small fragments. 110 Mudstone: dk gray; local phosphorite, pelletal, f grained; partly finely laminated; Montgomery, K.M, and Cheney, T.M., 1967, Geology of the Stewart Flat quadrangle, Caribou County, Idaho: U.S. Geological Bulletin 1217, 63 p. typically 1-3 in. fragments. Phosphorite: dk gray; pelletal, med grained; mudstone, finely laminated, in 0.5-1 in. thick fragments; generally forms tiny chips; calcareous siltstone forms 3-4 in. Middle Waste Tysdal, R.G., Johnson, E.A., Herring, J.R., and Desborough, G.A., 1999, Stratigraphic sections and equivalent uranium (eU), Meade Peak Phosphatic Shale Member of the Permian Phosphoria Formation, central part of Rasmussen Ridge, Caribou County, Idaho: U .S. Geological Survey Open-File Report 99-20-A. Middle Waste Tysdal, R.G., Herring, J.R., Desborough, G.A., Grauch, R.I., and Stillings, L.A., 2000a, Stratigraphic sections and equivalent uranium (eU), Meade Peak Phosphatic Shale Member of Permian Phosphoria Formation, Dry Valley, Caribou County, Idaho: U.S. Geol ogical Survey Open-File Report 99-20-B. fragments in middle of unit. Mudstone: dk gray; local phosphorite horizons; finely laminated; one 105 6 in. length of core contains two 0.25-0.5 in. thick carbon seams (106-106.7 ft interval); 0.04 in. dia orange-rimmed white "specks" locally-- ?microfossils, ?"nodules". Tysdal, R.G., Grauch, R.I., Desborough, G.A., and Herring, J.R., 2000b, Stratigraphic sections and equivalent uranium (eU), Meade Peak Phosphatic Shale Member of the Permian Phosphoria Formation, east-central part of Rasmussen Ridge, Caribou County, Idah o: U.S. Geological Survey Open-File Report 99-20-C. Mudstone: dk gray; finely laminated; generally broken into 1 in. pieces, except for local 3-4 in. fragments that are calcareous; carbonaceous throughout, with some zones v carbonaceous; some carbon-rich laminae are shiny, sheared into slickensides. 100 Dolomite: med gray; v f grained; abundant 0.04 in. thick calcite veinlets; Tysdal, R.G., Herring, J.R., Grauch, R.I., Desborough, G.A., and Johnson, E.A., 2000c, Stratigraphic sections and equivalent uranium (eU), Meade Peak Phosphatic Shale Member of Permian Phosphoria Formation, Sage Creek Area of Webster Range, Caribou Count y, Idaho: U.S. Geological Survey Open-File Report 99-20-D. Middle Waste fragments of megafossils (?brachiopods) are isolated--floating--within dolomite; nearly continuous core. Mudstone: dk gray; finely laminated; weakly calcareous; v carbonaceous; highly Middle Waste ACKNOWLEDGMENTS fragmented. 1-4 in. thick dolomite beds; v f grained; cut by calcite veinlets; 95 fragments of megafossils. Mudstone: dk gray. Lower 2/3 of core is calcareous to dolomitic, and locally The core is from the Enoch Valley mine property, operated by Monsanto Co. We thank Monsanto for providing access and we thank company personnel who freely discussed the geology of the area. Middle Waste dolomite containing abundant calcite-filled fractures. Gradational contact into upper 1/3, which forms small fragments; finely laminated; v carbonaceous, sparse carbonaceous seams. 90 Middle Waste Mudstone: dk gray. Lower 2/3 of core is calcareous to dolomitic, and locally dolomite containing abundant calcite-filled fractures. Gradational contact into upper 1/3, which forms small fragments; finely laminated; v carbonaceous, sparse Middle Waste carbonaceous seams. Dolomite: med gray; v f grained; abundant calcite-filled fractures; fairly sharp upper contact. 85 Carbon Seam: black. Dolomite: dk gray; calcareous; carbonaceous; strongly fetid; slickensides in graphitic Middle Waste Middle Waste rock; gradational upper contact; forms 1-2 in. fragments. Middle Waste Dolomite: med gray; v f grained; abundant calcite fracture fillings 0.04 in. thick; 80 intact core. Middle Waste 75 Mudstone: dk gray; 0.4-0.4 in. thick lt gray calcareous laminae spaced as much as 0.5 in. apart throughout this unit, producing a banding that is only faintly visible; v local disrupted layers produced by water escaping; discontinuous black lensoid shaped ?claystone? distributed through this unit--?layers pinched out during compaction of water-saturated sediment . 70 Siltstone: med gray; mostly calcareous--?comminuted fossil debris; mudstone, dk Middle Waste gray, forms thin to thick zones within the siltstone; upper 2/3 of unit is a breccia 65 formed by soft-sediment deformation--probably a slump deposit. We interpret the mud Middle Waste to have been >50 percent water and to have flowed during compaction; in contrast, the siltstone contained much less water and behaved as coherent beds that broke into Middle Waste cohesive fragments during flowage of the mud. Mudstone: dk gray; much of upper half of unit is calcareous; finely laminated dk gray and black; less of the med gray, cse gr laminae present than in underlying unit; Middle Waste some microripples; v dk gray diagenetic? nodules; white calcite 60 veinlets, possible shell fragments (?brachiopods). Mudstone: dk gray; v sl calcareous; ?phosphatic; 0.25-1.0 in. fragments; sheared, Middle Waste slickensides. Mudstone: dk gray; slightly calcareous; finely laminated; local laminae and zones Middle Waste 0.04-0.2 in. thick of med gray mudstone, v calcareous; upper surfaces of some med gray laminae appear rippled, BUT may be due to soft-sediment deformation. Some med gray laminae are discontinuous--?starved ripples. This 55 interval contains abundant 0.04-0.2 in. thick discontinuous lt gray calcareous Middle Waste laminae; some may be starved microripples--OR previously were continuous laminae that were pulled apart due to flowage of more water-rich dk gray sediment layers above and below, whereas the lt gray less water-rich layers "broke" and pulled Middle Waste apart; fluid escape structures disrupt 0.2-0.4 in. thick rippled and ?graded beds. Mudstone: dk gray; slightly calcareous; finely laminated; local laminae and zones 0.04-0.2 in. thick of med gray mudstone, v calcareous; upper surfaces of some of the 50 Middle Waste med gray laminae appear rippled, BUT undulatory upper surface could be due to soft-sediment deformation. Some med gray laminae are discontinuous--?starved ripples. Discontinuous (interrupted) lt to med gray layers/laminae that appear to have formed by deposition, followed by fluid flow of water-rich dk gray finer grained mudstone; lt to med gray layers contained less water and behaved as more or C Bed C Bed less coherently, separating into pull-apart fragments. Also some "knots" of 0.08-0.2 45 in. dia lt gray carbonate. Mudstone: dk gray; slightly calcareous; finely laminated; local laminae and zones C Bed 0.04-0.2 in. thick of med gray mudstone, v calcareous; upper surfaces of some of the med gray laminae appear rippled, BUT undulatory upper surface could be due to C Bed soft-sediment deformation. Some med gray laminae are discontinuous--?starved ripples. Mudstone: med-dk gray; fainly laminated; entire interval is more calcareous than 40 units directly above and below; abundant calcite veinlets. Mudstone: dk gray; slightly calcareous; finely laminated; local laminae and zones 0.04-0.2 in. thick of med gray mudstone, v calcareous; upper surfaces of some of the med gray laminae appear rippled, BUT upper surface could be due to soft- C Bed sediment deformation. Some med gray laminae are discontinuous--?starved ripples. Mudstone: same as overlying unit. 35 C Bed Siltstone: med gray; calcareous; fetid; veinlets of white calcite along sparse fractures. Phosphorite: dk gray; pelletal, cse grained; some laminae. Phosphorite: dk gray; pelletal, f to cse grained; fractures coated by films of white, False Cap B Bed Prepared in Cooperation With: U.S. Bureau of Land Management U.S. Forest Service Agrium U.S. Inc. Astaris LLC J.R. Simplot Company Rhodia Inc. Monsanto Company noncalcareous mineral. Interval represented by about ten 1-2 in. dia fragments. Phosphorite: dk gray; pelletal, cse grained; some laminae. 9 ft of section is 30 represented by about six 1 in. long fragments of core. Phosphorite: dk gray; pelletal. Three core fragments 1-2 in. long represent unit. Phosphorite: dk gray; mostly finely laminated; contains local 0.04-0.08 in. thick laminae of pelletal phosphorite; fetid; phosphorite sheared to slickensides locally; fractures locally coated with calcite films. 25 B Bed Siltstone: (False Cap) dk gray; weakly calcareous; finely laminated; indurated. Phosphorite: dk gray; pelletal layers locally; finely laminated; fetid; some fractures coated with mineralized films. Poor recovery of rock in this interval. Siltstone: dk gray; calcareous; indurated; cut by calcite veinlets along fractures; sulfide veinlets or splotches. B Bed B Bed B Bed Phosphorite: dk gray; pelletal. 20 B Bed Siltstone: dk gray; calcareous; well indurated; cut by calcite-filled fractures. Phosphorite: dk gray; finely laminated; fetid. 15 B Bed DESCRIPTION ABBREVIATIONS Dolomite Dolomite: med gray; upper 7 in. is silty, laminated, and contains laminae of pelletal phoshorite; lower 6 in. contains yellow films of mineral coatings; calcareous veinlets 10 present throughout. Carbon Seam Cap Rock Phosphorite: dk gray; local pelletal layers; finely laminated; isolated fragments of megafossls (?brachiopods) replaced by secondary minerals. 10 Mudstone: dk gray; v silty; upper 2/3 is calcareous; fetid; sparse fragments of fossils; Chert A Bed local vugs; well indurated; phosphatic laminae in lower 6 in. Fracture surfaces are coated with films of calcite and, in upper 1 ft, sulfides. 5 Footwall Siltstone Mudstone Phosphorite: dk gray; interlaminated with f and cse pellets; well laminated. Upper 1 ft is brownish gray, probably due to abundant silt. 5 Phosphorite Siltstone: dk gray; pelletal phosphatic laminae and thin zones present throughout unit; weakly fetid. Footwall Siltstone Siltstone Dolomite: dk gray; silty; well indurated; orangish yellow films of secondary minerals 0 coat fractures in upper 1 ft. Dolomite: ochre color; silty; deeply weathered; Mn laminae. 0 Phosphorite: dk gray; pelletal, f grained; fossil fragments, finely communited; highly fractured. Element (ppm) 300 Mudstone: dk gray; silty; finely laminated; fetid. LITH. FEET B Bed 0 EXPLANATION B Bed Mudstone: dk gray; phosphatic. V poor recovery. Footwall Siltstone cse dia dil dk eU f ft gr in. lith lt med ppm sl v coarse diameter dilute dark equivalent uranium fine feet grain inches lithology light medium parts per million slightly very Fish-scale Bed Grandeur Tongue Dolomite: med gray-brown; f to med crystalline, recrystallized; local vugs, some larger ones (to 0.5 in.) lined with calcite crystals; recrystallized fragments of Grandeur Tongue megafossils; films of hydrocarbons distributed irregularly; fetid; Mn dendrites in uppermost 1 ft of unit. -5 Dolomite: med gray-brown; f to med crystalline, recrystallized; local vugs, some larger ones (to 0.5 in.) lined with calcite crystals; recrystallized fragments of megafossils; films of hydrocarbons distributed irregularly; fetid. This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards. Any use of trade, product, or firm names is for descriptive purposes only and does not imply an endorsement by the U.S. Government. STRATIGRAPHIC SECTION AND SELECTED SEMIQUANTITATIVE CHEMISTRY, MEADE PEAK PHOSPHATIC SHALE MEMBER OF PERMIAN PHOSPHORIA FORMATION CENTRAL PART OF RASMUSSEN RIDGE, CARIBOU COUNTY, IDAHO By R.I. GRAUCH, R.G. TYSDAL, E.A. JOHNSON, 2001 J.R. HERRING and G.A. DESBOROUGH