Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah Andrew Rupke and Taylor Boden

Proceedings of the 48th Annual Forum on the Geology of Industrial Minerals Scottsdale, Arizona | April 30 - May 4, 2012

Arizona Geological Survey Special Paper 9 Chapter # Proceedings of the 48th Annual Forum on the Geology of Industrial Minerals Scottsdale, Arizona | April 30 - May 4, 2012

Arizona Geological Survey

M. Lee Allison, State Geologist and Director

This publication was prepared by an agency of the State For information on the mission, objectives or geologic of Arizona. The State of Arizona, or any agency thereof, products of the Arizona Geological Survey visit www.azgs. or any of their employees, makes no warranty, expressed az.gov. or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any Manuscript approved for publication in 2014. Printed by the information, apparatus, product, or process disclosed in Arizona Geological Survey. All rights reserved. this report. Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the State of Arizona.

Officers and Organizers of the 48th Annual Forum on the Geology of Industrial Minerals Board of Directors Forum Steering Committee Bates Scholarship Trustees - RLBMSF President – Mark Wolf Lynne Carpenter George Edwards Vice President – Thomas Newman Dale Scott Roger Sharpe Secretary – Stan Krukowski Dave Crouse Peter Harben Treasurer – Vanessa Santos Greta Orris Vanessa Santos Gretchen Hoffman Members Marion Wiggins Lynne Carpenter Tom Newman Nelson Shaffer Dale Scott

Special Paper 9

Recommended Citation: Rupke, A. and Boden, T., 2015, Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah. Proceedings of the 48th Annual Forum on the Geology of Industrial Minerals, Phoenix, Arizona, April 30 - May 4, 2012. Arizona Geological Survey Special Paper #9, Chapter 8, 23 p. TABLE of CONTENTS

ABSTRACT 2 INTRODUCTION 2 Purpose and scope 2 Study area 3 Methods 5 REGIONAL GEOLOGY AND STRUCTURE 5 POTASH RESOURCES 7 General 7 Potash maps 7 Cycle 5 potash 8 Cycle 9 potash 12 Cycle 13 potash 14 Cycle 18 potash 15 CONCLUSIONS 20 ACKNOWLEDGEMENTS 20 REFERENCES 22

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 1 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah Andrew Rupke1 and Taylor Boden Utah Geological Survey, P.O. Box 146100, Salt Lake City, UT 84114-6100 [email protected]

ABSTRACT anticline, the potash deposits in that area have the advantage of being relatively shallow, although Strong international demand and high potash structural complexity at the anticline may present prices have prompted a number of companies to difficulties for extraction. conduct or plan potash exploration in the already In the Hatch Point and Hart Point areas, potash productive Paradox Basin of southeastern Utah. in salt cycles 13 and 18 may represent potential In response to potash interest in the area, the Utah resources. A few data points show potash grades of School and Institutional Trust Lands Administration cycle 13 above 10% K2O in the west-central part of the contracted the Utah Geological Survey to evaluate study area, and projected thicknesses are generally less potash beds in the Pennsylvanian Paradox Formation than 10 ft. Mapping indicates that high-grade areas of in about 900 square miles of northern San Juan cycle 18 potash (>15% K2O) may be widespread in the County, including the Hatch Point, Hart Point, and southwestern part of the study area, including in the Lisbon Valley areas. The Paradox Formation is an Hatch Point and Hart Point areas. Limited chemical evaporite sequence containing up to 29 recognized analyses are available for cycle 18, but a number of salt cycles that are numbered sequentially from top (1) boreholes show high gamma-ray signatures indicating to bottom (29), and the most significant potash beds high-grade potash. Projected thickness of high-grade in the study area are in salt cycles 5, 6, 9, 13, 16, 18, potash in cycle 18 is variable, but ranges up to about 19, 20, 21, and 24. Data on these beds were compiled 30 ft. In contrast to Lisbon Valley, topography is from published and unpublished sources containing the primary control for overburden thickness where information on 132 potash exploration boreholes and potential resource is present in cycles 13 and 18— oil and gas wells in and around the area. From the overburden is thick at Hatch Point and Hart Point compiled data we created isopach, grade, overburden mesas, and is relatively thin in the valley to the west. thickness, and structure contour maps of potash beds. For the maps, we interpolated the data using an INTRODUCTION inverse-distance-squared weighting, with an anisotropy Purpose and scope applied to take the Paradox Basin’s northwest-trending The Utah School and Institutional Trust Lands geometry into account. Results suggest that multiple Administration (SITLA) commissioned the Utah salt cycles in the study area may represent a potash Geological Survey (UGS) to prepare a report on resource; however, the resource comprises different potash resources over a region that covers the Hatch beds in different areas. The primary potash-bearing Point, Hart Point, and Lisbon Valley areas of San Juan mineral of most of the potential resources in the basin County, Utah. Due to recent increases in potash prices, is sylvite, but carnallite is also present in some areas. the potash-bearing Paradox Formation of the Paradox In the Lisbon Valley area, data suggest a potential Basin has drawn interest from a number of mining resource in salt cycles 5 and 9. Analyses from both and exploration companies. These companies have cycles show greater than 20% weight equivalent leased and applied for rights to large tracts of SITLA

K2O, and mapping suggests reasonably sized areas of and Bureau of Land Management (BLM) property. above 15% K2O. Potash thickness in high-grade areas Two companies have recently drilled for potash is typically 10 ft. or less for cycle 5 and from about within the study area: K2O Utah, LLC (90% owned 5 to 15 ft. for cycle 9. Generally, data indicate that by Potash Minerals Ltd., formerly known as Transit potash in cycle 9 would be a better target as it tends Holdings Ltd.) drilled in the Hatch Point area, and to be higher grade and more extensive than potash in North American Potash Developments Incorporated cycle 5. Because Lisbon Valley represents a structural (formerly known as Ringbolt Ventures Limited) drilled in the Lisbon Valley area. 2 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah This paper presents isopach, grade, overburden from oil and gas well gamma-ray logs. While a thickness, and structure contour maps of the potash reasonable amount of data are available, additional beds in the study area that likely have the most drill holes in key areas would provide a more complete economic potential. The maps were generated from and reliable picture of the potash resource within the compilation and analysis of existing potash data from study area. wells drilled in and around the study area to provide Study area a better picture of the potash resource. Limited The study area is situated in northern San Juan potash drilling has occurred in the study area and County and encompasses nearly 873 square miles few chemical analyses are available for most of the (559,000 acres) (figure 1). The area includes primarily study area, so much of the potash data is interpreted BLM and SITLA land with a small amount of private

Spanish Valley Utah

Colorado River

Manti-La Sal Study National Forest Hatch Point Area

Lisbon Valley

Hart Point Canyonlands National Park

Ü Manti-La Sal National Forest 0 5 10 15 20 Miles

Figure 1. Study area. Blue dots represent locations of potash exploration boreholes and oil and gas wells used for potash bed mapping.

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 3 land that is concentrated on the east side of the area. the primary targets being potash in salt cycles 5 and Canyonlands National Park defines the western 9. Other companies, primarily the Pure Oil Company, boundary of the study area, Manti-La Sal National drilled a number of oil and gas wells in Lisbon Forest defines the southwestern boundary, and the Valley during the early 1960s. Hodges and Banfield flanks of the La Sal Mountains occur along much of (1962) and Hite (1978) provided potash information the northeastern boundary. A short segment of the from analytical data and gamma-ray log data that Colorado River is within the extreme northwestern were gleaned from both the potash and oil-and-gas part of the study area, and is near much of the western exploration and production wells. In response to the boundary. Some of the primary physical features results of potash exploration, the BLM designated an in the study area are Hatch Point, which is a large, area of Lisbon Valley as a Known Potash Leasing Area relatively flat mesa that extends from the central part (KPLA) in 1960, which allowed the leasing of potash of the area towards the northwest, and Lisbon Valley, on BLM ground. Gwynn and Tripp (2009) prepared which is an asymmetric, northwest-trending valley in a potash resource evaluation of Lisbon Valley for the the eastern part of the study area (figure 1). Elevations BLM and the BLM increased the area of the Lisbon range from over 7000 ft. in the southwest on the flanks Valley KPLA in response. of the Abajo Mountains and the northeast on the At Hatch Point and other parts of this study flanks of the La Sal Mountains to about 4000 ft. at the area, less potash exploration has occurred and less Colorado River in the northwest. information is publicly available. However, Britt Previous work and potash activity (1977) reviewed numerous gamma-ray logs from oil Extensive work has been done on the geology and gas wells and cataloged potential potash horizons and potash resources of the Paradox Basin, and this for the Anaconda Company. The wells investigated by section highlights some of the more significant and Britt (1977) cover much of the study area, including relevant work. Some of the most important and early Hatch Point and Lisbon Valley. Some limited potash work on the Paradox Formation was conducted by data are available for the northern Hatch Point area Hite (1960a, b), who detailed and correlated 29 from a few unpublished Anaconda reports, including different salt cycles within that formation, providing reports by Swinney (1962), Trimble (1962), Blanc a stratigraphic framework for potash exploration in (1963), and Trimble (1966). In 1981, Woodward- the Paradox Basin. Shortly thereafter, Hite (1961) Clyde Consultants (1982b) completed a core hole also produced a map estimating the extents of salt near Gibson Dome (south of Hatch Point) as part of a and potash within the Paradox Basin, and Elston U.S. Department of Energy (DOE) study examining and Shoemaker (1961) published a structure contour the Paradox Basin for nuclear waste disposal. Some map of the top of the Paradox Formation salt that potash chemical analyses, as well as gamma-ray covers the Paradox Basin, including the study area. logs, are available from this study (Woodward-Clyde Ritzma and Doelling (1969) provided a good, general Consultants 1982b, Hite 1982, Hite 1983). Kohler geological description of the potash resources in San (2009) prepared a report for the BLM suggesting that Juan County. A number of geologists have mapped additional exploration was necessary in the Hatch the surficial geology in and around the study area, but Point area to define a KPLA. This report was solicited most recently Doelling (2004) compiled the geology by the BLM in response to prospecting permit of the La Sal 30′ by 60′ quadrangle, which covers applications from K2O Utah, LLC in the area. Tripp nearly all of the study area. Surficial mapping of the and Tabet (2011) made a similar recommendation to southwestern part of the study area is covered by BLM. Potash Minerals Ltd. has released information Witkind (1964; 2007 [digital]) and Lewis and others online from their evaluation of the Hatch Point area (2011). Case and Joestings (1972), Hildenbrand and and recent drilling program in which three exploration Kucks (1983), and Bankey and others (1998), all from holes were completed (Potash Minerals 2012). the U.S. Geological Survey, published gravity and Massoth and Tripp (2011) published a database magnetic surveys that cover the study area. that catalogs the tops and bottoms of Paradox Extensive potash exploration has occurred in Formation salt cycles in numerous wells throughout Lisbon Valley relative to other parts of the study area. the Paradox Basin in Utah, primarily using publicly From 1958 through 1961, Superior Oil Company available gamma-ray logs. Massoth (2012) is currently drilled 17 potash exploration holes in the valley, with expanding the database to include more detailed

4 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah information on potash-bearing horizons. appropriate grade values. Our interpreted potash grade The only potash production from the Paradox values are also recorded in our spreadsheet. Tentative Basin has come from the Cane Creek mine just plans have been made to make the potash data north of the study area. Significant potash resource spreadsheet publicly available in a future UGS open- evaluation began in the Cane Creek area in 1956, and file report. Texas Gulf Sulfur Inc. began underground room-and- Using the potash data spreadsheet, we created a pillar mining in 1964. In 1970, due to gas pockets, GIS geodatabase, which allowed for interpolation and high temperatures, and ore zone complexity, solution creation of isopach, grade, overburden thickness, and mining began and underground mining was abandoned structure contour maps. We used a standard inverse- (Morgan and others 1991, Anderson 2008). In 1988, distance-squared interpolation technique, and applied Moab Salt, Inc. purchased the operation, and the a northwest-trending anisotropy to the interpolation ownership transferred again in 2000 when Intrepid Oil to account for the shape of the Paradox Basin and the and Gas bought the operation (Anderson 2008). The orientation of major geologic structures. operator is currently known as Intrepid Potash, Inc. Sylvite was initially exploited from evaporite cycle 5 REGIONAL GEOLOGY AND at Cane Creek, but currently sylvite from both cycles 5 and 9 is solution mined. Intrepid’s capacity for STRUCTURE potassium chloride production at the Cane Creek mine is currently about 100,000 short tons per year (Intrepid The study area is in the Paradox Basin, a Potash 2010). sedimentary basin in which extensive evaporites Methods were deposited during the Pennsylvanian. The basin Data used for potash evaluation and map creation is elongate northwest, stretching from southwestern were compiled from 132 potash exploration holes Colorado through east-central Utah (figure 2). The and interpreted gamma-ray logs from oil and gas basin formed southwest of, and adjacent to, the wells. The well locations in and around the study Uncompahgre Uplift, which shed clastic material into area are shown in figure 1. Compiled information the basin. A high-angle reverse fault that separates includes depth of potash beds, interpreted or measured these two features created thousands of feet of vertical thickness of potash beds, potash mineralogy (sylvite, displacement from the Pennsylvanian to the Triassic carnallite, mixed, etc.), chemical analyses or inferred (Hite and Cater 1972, Hintze and Kowallis 2009). The grade from gamma-ray, peak reading API units (the deepest portion of the basin is in the northeast, near the unit of radioactivity used for natural gamma-ray logs), basin-bounding fault. and data sources for the information. We prepared The rocks in the basin are a thick sequence of a spreadsheet of the data, and recorded potash Pennsylvanian Paradox Formation evaporites and information from salt cycles 5, 6, 9, 13, 16, 18, 19, thinner shelf carbonates, known as the Pennsylvanian 20, 21, and 24. The spreadsheet borrowed extensively Pinkerton Trail and Honaker Trail Formations. from Massoth (2012), but other important data sources Deposition occurred in a restricted marine basin, with include Hodges and Banfield (1962), Britt (1977), the carbonates being more prevalent on the margins Hite (1978), Hite (1982), Kohler (2009), Massoth and of the basin and the evaporites more prevalent in Tripp (2011), and Transit Holdings Ltd. (2011). We the central basin. Hite and Cater (1972) suggested also used the Utah Division of Oil, Gas, and Mining that marine water entered the basin across a broad (2011) online oil and gas database extensively to carbonate shelf in the southwest. The thick and review geophysical logs of relevant wells. Using widespread evaporite sequence that formed during published and unpublished information, previous the life of the restricted basin can be subdivided into interpretations, and peak gamma-ray API readings, we 29 depositional cycles as catalogued by Hite (1960a, selected thicknesses and grades for each potash bed b). Figure 3 shows an example of the detailed saline of each well for use in the preparation of interpolated and clastic stratigraphy of the Paradox Formation maps presented in this study. Nelson’s (2007) from a well drilled north of the study area. The cycles published methodology for correlation of API to K O generally follow a pattern of organic-rich black shale 2 at the base overlain by silty dolomite, anhydrite, and grade (percent K2O is the typical format for reporting grade of a potash bed) was also used in determining halite (with or without potash), such that each cycle

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 5 Study Area Paradox Basin Potash Extent Paradox Basin Salt Extent Uncompahgre Uplift GRAND F Anticlinal Structure EMERY ParadoxF County Boundary F F State Boundary F F F F F F WAYNE F F F F F F GARFIELD Basin

SAN JUAN

KANE Ü

0 10 20 30 40 Utah Miles Colorado

Arizona New Mexico

Figure 2. The Paradox Basin as defined by potash and salt extents. The potash extent, salt extent, and anticline locations are from Hite and Cater (1972). represents a regressive sea-level phase (Hite and and Doelling 1969). In the study area, a sequence Cater 1972). Hite and Cater (1972) noted that the tops of Permian through Jurassic rocks is exposed above of the cycles represent disconformities following a the Pennsylvanian rocks, with limited exposures of transgressive influx of fresher water into the basin. Cretaceous beds in the southeast. No surface exposures Many of the cycles are laterally continuous, but not of the Paradox Formation are present within the study all cycles are present across the whole basin due, in area. part, to a shifting depositional center in the basin. Hite Perhaps during, but certainly shortly after and Cater (1972) estimated the original thickness of deposition of the Paradox Formation, folding, likely the evaporite section, prior to deformation, at 5000 genetically related to the Uncompahgre uplift, formed to 6000 ft., but current, post-deformation thicknesses a series of northwest-trending anticlines in the Paradox range from 0 to 14,000 ft. (Hintze and Kowallis 2009). Basin that were accentuated by the plasticity of salt. Following restricted-marine deposition in the Paradox Development of the salt anticlines continued at least Basin, mostly nonmarine, red-bed sediments were into Cretaceous time (Ritzma and Doelling 1969, deposited in the area through the Jurassic (Ritzma Hite and Cater 1972). Presently, a number of the salt 6 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah anticlines in the interpreted the fault as a normal fault that retains its Paradox Basin northeast dip in the subsurface. Drilling results suggest form valleys due complex folding of salt beds in the subsurface (Hite to salt dissolution. 1978). Most of the study area contains POTASH RESOURCES nearly flat- lying, relatively General undeformed In the Paradox Formation, potash is known to sedimentary occur in 18 of the 29 evaporite cycles (Hite 1960a, rocks, but a b). Within the study area, the primary potash-bearing few of the salt cycles are 5, 6, 9, 13, 16, 18, 19, 20, 21, and 24. salt-anticline Historically, the shallower beds were considered to structures are also have the most economic potential, particularly beds present in the area 5, 9, 13, and 18. The primary potash minerals found (figure 2). The in the Paradox Basin, and the study area are sylvite most dramatic (KCl) and carnallite (KCl·MgCl2·6H2O), and these of these folded minerals are generally found in the central part of the features in the basin (figure 2). Current interest in the area revolves study area is the around sylvite, as pure sylvite has an equivalent Lisbon Valley weight percent of 63.17 K2O. Sylvite is the primary anticline, which potash mineral at Intrepid’s mine, and their sylvite ore has a distinctive ranges in quality from above 10% to over 20% K2O. low-gravity Pure carnallite has an equivalent weight percent of signature on the just 16.95 K2O, and can be more difficult to process Bouguer gravity for a potash product due to the soluble magnesium map in figure 4. component (Prud’homme and Krukowski 2006). Lisbon Valley If carnallite were to become a significant target, is a northwest- magnesium compounds may be produced as a by- trending valley product. that exposes Potash maps Pennsylvanian The maps in the following sections present Honaker Trail information on potash thickness, potash grade, Formation in its overburden thickness, and structure contours for cycles core and is cut 5, 9, 13, and 18 in the study area. Maps were also on the northeast created for cycles 6, 16, and 19, but cycles 5, 9, 13, Figure 3. Detailed stratigraphic side by the Lisbon and 18 appear to represent the most economic potash column of the Paradox Formation. Valley fault. horizons. Insufficient data were available to produce The column is from the Cane Creek The anticline is maps for cycles 20, 21, and 24. Thicknesses on the anticline area (T. 26 S., R. 20 E.), asymmetrical and maps generally represent the entire thickness of the which is north of the study area. The the axial surface potash section. However, particularly where chemical diagonal hatch pattern represents trace lies close to analyses but no gamma-ray logs are available, the halite, the vertical hatch represents shaly units, and the solid black the Lisbon Valley thicknesses may represent only a portion of the entire indicates the presence of potash fault. Hite (1978) potash zone. Grade values should be considered minerals. Modified from Morgan and and Woodward- estimates and generally represent a maximum grade others (1991). Clyde Consultants within a potash zone, as only the maximum gamma- (1982a) ray peak for a potash zone was recorded for this interpreted the Lisbon Valley fault as a reverse fault study—potash beds with multiple gamma-ray peaks that reverses its northeast surface dip in the subsurface, were not catalogued and divided. In most cases, the but others (Parker 1981, Doelling 2004) have maps should be interpreted as representing a maximum

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 7 -1000 -2000 2000 -177 -1000

3000 2000 Ü 5000 -181 4000

0 2 4 30006 8 10 4000 2000 Miles2000 1000 4000 1000 3000 2000 0 -191 -201 Gravity (mGal) -211 T. 28 S. T.

1000 -221

-231

2000 -241

-251 2000 T. 29 S. T.

-2000 -1000 -3000 1000 2000 0 Lisbon Valley3000

4000 3000

T. 30 S. T. 1000 2000

1000 T. 31 S. T.

4000 R. 25 E.

R. 23 E. R. 24 E.

Surface Faults T. 32 S. T. R. 22 E. Top of Paradox Salt Contour

R. 21 E. Study Area

Figure 4. Bouguer gravity and structure contour map of study area. Structure contours are in feet relative to mean sea level and represent the top of the salt of the Paradox Formation. Structure contours are from Elston and Shoemaker (1961). Gravity data are from the Pan American Center for Earth and Environmental Studies (2011). Surface faults are from Doelling (2004), Witkind and others (2007), and Lewis and others (2011). Location of study area shown in figures 1 and 2. grade and maximum thickness for a given potash zone, For this reason, overburden thickness and structure so the grade posted on the map will not necessarily contour maps do not show information northeast of the be representative of the entire thickness shown on the Lisbon Valley fault. map. Cycle 5 potash Interpolated map data in portions of the study Where present, potash in cycle 5 is generally area with large data gaps should be used with caution. reported to be sylvite, but in the western part of the These areas are primarily in the central and southwest study area there is essentially no potash (figure 5). parts of the study area. Also, few data points exist In the eastern portion of the study area, some cycle northeast of the Lisbon Valley fault so changes that 5 potash beds are present, and in one drill hole the may occur across the fault are not well represented. thickness reaches 58 ft. However, most holes with 8 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah Potash Isopach Map - Cycle 5 !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( Ü !( !(

!( !( !( 0 2 4 6 8 10 !( Miles !( !( !( T. 28 S. T. !( !( !( !(

!( !( !( !(

!( !( !( !( !( !( T. 29 S. T. !( !( !( !( !( !( !( !( !( !(!( !( !( !( !( !( !( !(!( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( T. 30 S. T. !( !( !(

!( !(

!( !( !( !( T. 31 S. T.

R. 25 E.

R. 23 E. R. 24 E. T. 32 S. T. Estimated Thickness (ft.) !( R. 22 E. 0 - 4 R. 21 E. 4 - 8 8 - 12

!( Well Used for Interpolation 12 - 16 Fault 16 - 20 Possible Area of Cycle 5 Dissolution 20 - 40 40 - 60

Figure 5. Potash isopach map of cycle 5. Note that color gradient is not linear. Wells outside study area used in interpolation are not shown. The northwest-trending potash zone, mostly in townships T. 30 S., R. 23 E. and T. 31 S., R. 24 E., is primarily a function of one hole on the border of T. 30 S. and T. 31 S. that has a very thick potash occurrence in cycle 5. The zone is likely much smaller than is represented on this map.

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 9 potash show thicknesses of less than 20 ft., and the top of the potential ore zone, commonly underlain where the highest grades are present, thicknesses are by a gradational zone that decreases in sylvite content generally 10 ft. or less (figures 5 and 6). Hite (1978) with increasing depth. Seven chemical analyses are noted that the highest grades of potash in cycle 5 are at available for cycle 5, and they average 19.1% K2O; the Estimated Potash Grade Map - Cycle 5 !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( Ü !( !(

!( !( !( 0 2 4 6 8 10 !( Miles !( !( !( T. 28 S. T. !( !( !( !(

!( !( !( !(

!( !(

!( !( !( !( T. 31 S. T.

R. 25 E.

R. 23 E. R. 24 E. T. 32 S. T.

Estimated!( Grade R. 22 E. R. 21 E. } Little or no potash } 15 to 20% K2O

20 to 25% K2O

!( Up to 5% K2O Well Used for Interpolation } Fault } 5 to 10% K2O Possible Area of Cycle 5 Dissolution

} 10 to 15% K2O

Figure 6. Estimated potash grade map of cycle 5. Wells outside study area used in interpolation are not shown.

10 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 10% or greater K O with thicknesses mostly ranging highest grade is 24.5% K2O. The analyses are from 2 Lisbon Valley and are reported by Hite (1978) and from 4 to 10 ft. In those same areas, overburden Hodges and Banfield (1962). The interpolated maps depth ranges from about 2400 to 4500 ft. (figure 7). suggest that areas in Lisbon Valley contain potash with These depths are relatively shallow, but structural Overburden Thickness and Structure Contour Map - Cycle 5 Ü

0 2 4 6 8 10 Miles 500 T. 28 S. T.

Insufficient Data T. 29 S. T.

1000 1000 T. 30 S. T.

3000

2000 2000

2000 T. 31 S. T.

R. 25 E.

R. 23 E. R. 24 E. 3000 T. 32 S. T.

R. 22 E. Overburden Thickness (ft.) R. 21 E. >1,500 - 2,000 >2,000 - 2,500 >2,500 - 3,000 >3,000 - 3,500 Fault >3,500 - 4,000 Possible Area of Cycle 5 Dissolution >4,000 - 4,500 >4,500 - 5,000 >5,000 - 5,500 >5,500 - 6,000 >6,000 - 6,500

Figure 7. Overburden thickness and structure contours of the top of potash in cycle 5. Structure contours represent elevation above sea level of the top of the potash (or salt cycle where potash is absent). The contour interval is 500 ft. Information is not presented northeast of the Lisbon Valley fault due to insufficient data.

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 11 deformation in Lisbon Valley would likely add to widespread, and where present, averages nearly 15 ft. extraction complexity. thick (average was calculated from well occurrences, Cycle 9 potash not aerial extent from mapping) (figure 8). Although present throughout much of the study area, the grade In and near the study area, potash in cycle 9 is is quite low in most areas except for the eastern part mostly sylvite, but some occurrences of carnallite of the study area (figure 9). In the Lisbon Valley are reported in drillholes. Cycle 9 potash is area and to the south, a number of wells indicate

Potash Isopach Map - Cycle 9 !( !( !( !( !( !( !( !( !( !(

!( !( !( !( !( !( !( !( Ü !( !(

!( !( !( 0 2 4 6 8 10 !( Miles !( !( !( T. 28 S. T. !( !( !( !(

!( !( !( !(

!( !( !( !( !( !( T. 29 S. T. !( !( !( !( !( !( !( !( !( !( !(!( !( !( !( !( !( !(!( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( T. 30 S. T. !( !( !(

!( !(

!( !( !( !( T. 31 S. T.

R. 25 E.

R. 23 E. R. 24 E. T. 32 S. T. Estimated Thickness (ft.) R. 22 E. 0 - 4 R. 21 E. 4 - 8 8 - 12 !( Well Used for Interpolation 12 - 16 Fault 16 - 20 Possible Area of Cycle 9 Dissolution 20 - 40 40 - 60

Figure 8. Potash isopach map of cycle 9. Note that color gradient is not linear. Wells outside study area used in interpolation are not shown.

12 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah Estimated Potash Grade Map - Cycle 9 !( !( !( !( !( !( !(

!( !(

!( !( !( !( !( !( !( !( Ü !( !(

!( !( !( 0 2 4 6 8 10 !( Miles !( !( !( T. 28 S. T. !( !( !( !(

!( !( !( !(

!( !(

!( !( !( !( T. 31 S. T.

R. 25 E.

R. 23 E. R. 24 E. T. 32 S. T. Estimated Grade R. 22 E. R. 21 E. } Little or no potash } 15 to 20% K2O

!( Well Used for Interpolation } Up to 5% K2O } 20 to 25% K2O Fault } 5 to 10% K2O } 25 to 30% K2O Possible Area of Cycle 9 Dissolution

} 10 to 15% K2O

Figure 9. Estimated potash grade map of cycle 9. Wells outside study area used in interpolation are not shown.

potentially high grades of potash. Twelve chemical interpolated as relatively high-grade potash, so analyses are available for wells in Lisbon Valley that additional drilling would be important to confirm

show K2O contents up to 33%, and average 23.4% the presence of high-grade potash in these elongate

K2O. Potash bed thicknesses in the areas of higher tail areas. Relatively thin overburden and high-grade grade are variable, but typically range from about 5 potash coincide near Lisbon Valley, and in some of to 15 ft. Significant gaps exist between data points these areas overburden thickness is less than 3000 ft. in the northern and southern mapped extents that are (figure 10). However, where cycle 9 potash is mapped

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 13 as high grade near the southeastern boundary of the Cycle 13 potash study area, overburden thickness reaches over 7000 ft. Both sylvite and carnallite, often in combination, Similar to cycle 5, structural complexity of potash in are found in cycle 13 in and around the study area. The cycle 9 at Lisbon Valley would need to be considered thickness of cycle 13 potash generally increases from in extraction scenarios. southwest to northeast across the study area (figure 11). Where present in the wells we examined, cycle 13

Overburden Thickness and Structure Contour Map - Cycle 9 500 Ü

0 2 4 6 8 10 Miles T. 28 S. T.

0 Insufficient Data T. 29 S. T.

2000 4000

1000 T. 30 S. T. 3000

1000 1000 2000 T. 31 S. T.

2000 R. 25 E.

R. 23 E. R. 24 E. T. 32 S. T.

R. 22 E. Overburden Thickness (ft.) R. 21 E. >2,000 - 2,500 >2,500 - 3,000 >3,000 - 3,500 >3,500 - 4,000 Fault >4,000 - 4,500 >4,500 - 5,000 Possible Area of Cycle 9 Dissolution >5,000 - 5,500 >5,500 - 6,000 >6,000 - 6,500 >6,500 - 7,000 >7,000 - 7,500

Figure 10. Overburden thickness and structure contours of the top of potash in cycle 9. Structure contours represent elevation above sea level of the top of the potash (or salt cycle where potash is absent). The contour interval is 500 ft. Information is not presented northeast of the Lisbon Valley fault due to insufficient data.

14 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah is indicated by only Potash Isopach Map - Cycle 13 a few wells. One of !( !( !( !( !( !( the wells is the DOE

!( core hole drilled near

!( !( !( Gibson Dome, where !( !( !( !( !( Ü the 6.2 ft. of sylvite !(!( !(

!( !( have an average !( 0 2 4 6 8 10 grade of 16.5% K O !( Miles 2 !( !( !( (Hite 1982). The T. 28 S. T. !( !( !( !( high-grade area is in

!( !( !( !( the thinner portions of cycle 13 where !( !( !( !( !( !( !( !( the thickness ranges !( !( !( !( !( from about 4 to !( T. 29 S. T. !( !( 10 ft. Overburden !( !( !( !( !(!( !( !( !( !( !( thickness over most !(!( !( !( !( !( !( !( !( !( !( !( !( !( of this area ranges !( !( !( !( !( !( !( !( !( !( !( !( !( from about 3500 to !( !( !( !( !(

T. 30 S. T. 4000 ft. (figure 13). !( !( !( A small number of

!( wells define an area !(

!( of moderate- to high- !( !( !( !( grade potash in cycle T. 31 S. T. 13 in the central R. 25 E. part of the study area, so additional R. 24 E. R. 23 E. drilling here could

T. 32 S. T. lead to expansion or Estimated Thickness (ft.) contraction of the R. 22 E. 0 - 4 area with high-grade R. 21 E. potash potential. 4 - 8 Cycle 18 potash 8 - 12 Published

!( Well Used for Interpolation 12 - 16 information reveals little data on the Fault 16 - 20 predominant potash Possible Area of Cycle 13 Dissolution 20 - 40 mineral in cycle 18; however, carnallite 40 - 60 has been encountered 60 - 80 in some areas. In a few areas, salt cycle 18 has two distinct Figure 11. Potash isopach map of cycle 13. Note that color gradient is not linear. Wells outside study area used in interpolation are not shown. potash beds, but among the various averages about 20 ft. thick. The thickest occurrence data sources, less than 15 wells were identified as of potash 13 in the study area is 62 ft. in Lisbon having two separate beds. The zone of little or no Valley, and cycle 13 also thickens significantly in the potash between the beds is generally between 30 and northernmost part of the study area. A few areas of 50 ft. thick. Disagreement exists on the stratigraphic high-grade potash are indicated by the maps, but most position of the upper and lower potash beds of cycle are relatively small (figure 12). The largest high-grade 18 among some of the sources, but for mapping in this area is in the west-central part of the study area, and Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 15 cycle 18 averages Estimated Potash Grade Map - Cycle 13 about 16 ft. thick, !( !( !( !( !( !( and is 83 ft. at !( its thickest. Our

!( !( !( !( mapping suggests !( !( !( !( Ü !(!( large areas of !(

!( !( potentially high- !( 0 2 4 6 8 10 !( grade potash in the Miles !( !( !( southwest half of T. 28 S. T. !( !( !( !( the study area that !( !( !( !( range in thickness from about 6 to 30 !( !( !( !( !( !( !( !( ft. (figure 15). As !( !( !( !( !( !( noted previously, T. 29 S. T. !( !( !( !( supporting !( !( !(!( !( !( !( !( !( !(!( !( well data in the !( !( !( !( !( !( !( !( !( !( !( !( !( !( central and far !( !( !( !( !( !( !( !( !( !( !( southwestern study !( !( !( !(

T. 30 S. T. area could provide !( !( !( a higher level

!( !( of confidence to !( define the large, !( !( !( !( high-grade areas. T. 31 S. T. A few isolated R. 25 E. data points from Lisbon Valley also R. 24 E. R. 23 E. show elevated

T. 32 S. T. K2O content. A Estimated Grade chemical analysis R. 22 E. of potash from R. 21 E. cycle 18 is } Little or no potash } 15 to 20% K2O available from the Gibson Dome !( Well Used for Interpolation } Up to 5% K2O DOE core in the Fault west-central part } 5 to 10% K2O of the study area. Possible Area of Cycle 13 Dissolution The results of the analysis show 8.2 } 10 to 15% K2O ft. of sylvite at 22.1% K O (Hite Figure 12. Estimated potash grade map of cycle 13. Wells outside study area used in interpolation are 2 not shown. 1982). Overburden study, we gave Massoth’s (2012) data preference over thicknesses other sources. Massoth (2012) included the lower bed vary significantly in areas where high-grade potash as part of a net potash thickness for bed 18 where he is indicated in cycle 18 (figure 16). The thinnest identified it. overburden is in the western part of the study area, Potash in salt cycle 18 is present throughout most and the overburden thickens quickly approaching of the study area, with the thickest known occurrences Hatch Point and Hart Point. Overburden thicknesses in Lisbon Valley and in the south-central portion of generally range from over 4000 to about 6500 ft. in the study area (figure 14). Where present, the potash in the high-grade areas. The small, high-grade area in the

16 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah Overburden Thickness and Structure Contour Map - Cycle 13 Ü

1000 0 2 4 6 8 10

-500 Miles T. 28 S. T.

Insufficient Data -500 T. 29 S. T.

0 0 0 3000 T. 30 S. T.

2000

500

1000

1000 1500 T. 31 S. T.

R. 25 E.

2000 R. 23 E. R. 24 E. T. 32 S. T. Overburden Thickness (ft.) R. 22 E. >1,500 - 2,000 R. 21 E. >2,000 - 2,500 >2,500 - 3,000 >3,000 - 3,500 >3,500 - 4,000 Fault >4,000 - 4,500 >4,500 - 5,000 Possible Area of Cycle 13 Dissolution >5,000 - 5,500 >5,500 - 6,000 >6,000 - 6,500 >6,500 - 7,000 >7,000 - 7,500 >7,500 - 8,000

Figure 13. Overburden thickness and structure contours of the top of potash in cycle 13. Structure contours represent elevation above sea level of the top of the potash (or salt cycle where potash is absent). The contour interval is 500 ft. Information is not presented northeast of the Lisbon Valley fault due to insufficient data.

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 17 northwest part of the study area has an overburden very thin in Lisbon Valley, but little or no high-grade thicknesses of less than 4000 ft. Overburden is also potash is known in the area.

Potash Isopach Map - Cycle 18 !( !( !( !( !( !(

!( !( !( !( !( !( !( !( Ü !(!( !(

!( !( !( 0 2 4 6 8 10 !( Miles !( !( !( T. 28 S. T. !( !( !( !(

!( !( !( !(

!( !( !( !( !( !( !( !(

!( !( !( !( !( !( T. 29 S. T.

!( !( !( !( !(!( !( !( !( !( !(!( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !(

!( !( !( !( !( T. 30 S. T. !( !( !(

!( !(

!( !( !( !( T. 31 S. T.

R. 25 E.

R. 23 E. R. 24 E. T. 32 S. T.

R. 22 E. Estimated Thickness (ft.) R. 21 E. 0 - 4 4 - 8 8 - 12 !( Well Used for Interpolation 12 - 16 Fault 16 - 20 20 - 40 40 - 60

Figure 14. Potash isopach map of cycle 18. Note that color gradient is not linear. Wells outside study area used in interpolation are not shown.

18 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah Estimated Potash Grade Map - Cycle 18 !( !( !( !( !( !(

!( !( !( !( !( !( !( !( Ü !(!( !(

!( !( !( 0 2 4 6 8 10 !( Miles !( !( !( T. 28 S. T. !( !( !( !(

!( !( !( !(

!( !( !( !( !( !( !( !(

!( !( !( !( !( !( T. 29 S. T.

!( !( !( !( !(!( !( !( !( !( !(!( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !( !(

!( !( !( !( !( T. 30 S. T. !( !( !(

!( !(

!( !( !( !( T. 31 S. T.

R. 25 E.

R. 23 E. R. 24 E. T. 32 S. T. Estimated Grade R. 22 E. R. 21 E. } Little or no potash } 15 to 20% K2O

!( Well Used for Interpolation } Up to 5% K2O } 20 to 25% K2O Fault } 5 to 10% K2O

} 10 to 15% K2O

Figure 15. Estimated potash grade map of cycle 18. Wells outside study area used in interpolation are not shown.

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 19 CONCLUSIONS wells in the central and southwestern parts of the study area would also help better define the true extent of Results from mapping potash thickness and grade potentially economic potash zones. Insufficient data suggest that potash resources do exist in the study area. are available in these areas to properly interpolate In the eastern part of the study area, particularly in the thicknesses and grades with much confidence. Lisbon Valley area, high grades of potash are present Additional work for the area could also include a in salt cycles 5 and 9; chemical analyses show grades more detailed evaluation of gamma-ray logs. This study only considered the highest gamma-ray API for for cycle 5 above 20% K2O, and above 30% K2O for cycle 9. Results indicate that high-grade potash in a particular horizon, but many of the potential potash cycle 9 tends to be somewhat thicker and higher grade horizons included multiple smaller peaks. For smaller than in cycle 5. Cycle 9 potash is also much more areas of interest, a valuable exercise could entail more extensive throughout the study area, but is only high detailed log analysis and estimate thickness and record grade in Lisbon Valley and nearby areas. Extraction peak API for subhorizons within the potash zones of of potash from the salt anticline in Lisbon Valley interest. would have the benefit of shallower potash, but the added difficulty of more structural complexity. Some ACKNOWLEDGEMENTS of the structural complexity can be seen in the abrupt thickness changes present in Lisbon Valley. However, We thank Thomas B. Faddies, assistant director some of the additional detail in Lisbon Valley is also of minerals, and the Utah School and Institutional likely a function of close well spacing relative to the Trust Lands Administration for providing funding for rest of the study area. this study. Thanks to Christian Hardwick, UGS, for In the southwest half of the study area, mapping preparing a GIS gravity layer from the Pan American indicates that high grades of potash with variable Center for Earth and Environmental Studies (2011) thickness (generally less than 30 ft.) may be present data. over large areas in cycle 18. One chemical analysis as well as more numerous gamma-ray data suggest sizable areas of better than 20% K2O in cycle 18. A few wells also indicate that some high-grade potash is present in the west-central part of the study area in cycle 13, but it is much less extensive than cycle 18. The extent of higher-grade potash in cycles 13 and 18 needs to be better defined. Additional exploration in the central part of the study area could potentially expand (or reduce) the size of high-grade areas in these cycles. Additional information on the potash mineralogy would be important for these cycles to better understand the extent of carnallite in both horizons. For most of the study area, overburden is controlled by a combination of topography and the gentle northeast-dip of strata. Depths to cycles 13 and 18 are shallower in the west part of the area in the valley adjacent to the Colorado River, and increase significantly to the east once under the mesas that constitute Hatch Point and Hart Point. Generally, the potash resource definition for the study area would benefit from additional coring and chemical analyses from potash horizons, particularly outside of Lisbon Valley. Such additional data would help to calibrate grades inferred from gamma-ray responses with actual analyses. Additional exploration

20 Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah Overburden Thickness and Structure Contour Map - Cycle 18 Ü

0 2 4 6 8 10 Miles T. 28 S. T.

1000

-500 Insufficient Data 0 -500 T. 29 S. T.

1000

2000 T. 30 S. T.

1000

0 -500 500 500 T. 31 S. T.

R. 25 E.

R. 23 E. R. 24 E. T. 32 S. T. Overburden Thickness (ft.)

R. 22 E. >1,500 - 2,000 R. 21 E. >2,000 - 2,500 >2,500 - 3,000 >3,000 - 3,500 >3,500 - 4,000 >4,000 - 4,500 >4,500 - 5,000 Fault >5,000 - 5,500 >5,500 - 6,000 >6,000 - 6,500 >6,500 - 7,000 >7,000 - 7,500 >7,500 - 8,000 >8,000 - 8,500

Figure 16. Overburden thickness and structure contours of the top of potash in cycle 18. Structure contours represent elevation above sea level of the top of the potash (or salt cycle where potash is absent). The contour interval is 500 ft. Information is not presented northeast of the Lisbon Valley fault due to insufficient data.

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 21 Smith, K.G., editor, Geology of the Paradox Basin REFERENCES fold and fault belt: Durango, Colorado, Four Corners Geological Survey 3rd Annual Field Conference Anderson, P.B., 2008, Potash and oil and gas development— Guidebook, p. 86-89, 2 plates. potential conflicts and solutions, northern Paradox Hite, R.J., 1961, Potash-bearing evaporite cycles in the salt Basin, Utah: unpublished report prepared for the Utah anticlines of the Paradox Basin, Colorado and Utah, School and Institutional Trust Lands Administration, 29 in Short papers in geologic and hydrologic sciences: p. U.S. Geological Survey Professional Paper 424-D, p. Bankey, V., Grauch, V.J.S., and Kucks, R.P., 1998, Utah D135-D138. aeromagnetic and gravity maps and data—a website for Hite, R.J., 1978, The geology of the Lisbon Valley potash distribution of data (on-line version). http://pubs.usgs. deposits, San Juan County, Utah. U.S. Geological gov/of/1998/ofr-98-0761/utah.html Accessed December Survey Open-File Report 78-148, 21 p. 16, 2011. Hite, R.J., 1982, Potash deposits in the Gibson Dome area, Blanc, R.P., 1963, Cane Creek area potash project: southeast Utah. U.S. Geological Survey Open-File unpublished report prepared for the Richfield Oil Report 82-1067, 8 p. Corporation Production Department – Research Hite, R.J., 1983, Preliminary mineralogical and geochemical Division [copy obtained from Anaconda Collection, data from D.O.E. Gibson Dome corehole No. 1, San American Heritage Center, University of Wyoming]. Juan County, Utah. U.S. Geological Survey Open-File Britt, T.L., 1977, Geologic report on the Robert’s potash Report 83-780, 57 p. property, Grand County, Utah: unpublished report for Hite, R.J., and Cater, F.W., 1972, Pennsylvanian rocks and the Anaconda Company [copy obtained from Anaconda salt anticlines, Paradox basin, Utah and Colorado, in Collection, American Heritage Center, University of Mallory, W.W., editor, Geologic atlas of the Rocky Wyoming]. Mountain region: Rocky Mountain Association of Case, J.E., and Joestings, H.R., 1972, Regional geophysical Geologists, p. 133-138. investigations in the central Colorado Plateau: U.S. Hodges, P.A., and Banfield, A.F., 1962, Potash resources Geological Survey Professional Paper 736, 31 p., 4 of Lisbon Valley, San Juan County, Utah: unpublished plates. Behre Dolbear & Company report to Superior Oil Doelling, H.H., 2004 (digital release 2006), Geologic map Company [copy obtained from Anaconda Collection, of the La Sal 30′ x 60′ quadrangle, San Juan, Wayne, American Heritage Center, University of Wyoming]. and Garfield Counties, Utah, and Montrose and San Intrepid Potash, 2010, Annual report 2010. http://investors. Miguel Counties, Colorado: Utah Geological Survey intrepidpotash.com/phoenix.zhtml?c=218952&p=irol- Map 205DM, CD-ROM, scale 1:100,000. reportsAnnual Accessed December 2011. Elston, D.P., and Shoemaker, E.M., 1961, Preliminary Kohler, J.F., 2009, Determination whether prospecting is structure contour map on top of salt in the Paradox necessary—potassium prospecting permit applications, Member of the Hermosa Formation in the salt anticline UTU-086426 to UTU-086431, UTU-086568 to UTU- region, Colorado and Utah: U.S. Geological Survey Oil 086602, San Juan County, Utah (T. 28-30 S., R. 20-23 and Gas Investigations Map OM-209, scale 1:250,000. E.): U.S. Bureau of Land Management Mineral Report Gwynn, J.W., and Tripp, B.T., 2009, Lisbon Valley potash Form 3060-1, May 12, 2009, 39 p. resource evaluation, San Juan County, Utah: Report by Lewis, R.Q., Sr., Campbell, R.H., Thaden, R.E., Krummel, Utah Geological Survey prepared for Bureau of Land W.J., Jr., Willis, G.C., and Matyjasik, B., 2011, Management, 25 p. Geologic map of Elk Ridge and vicinity, San Juan Hildenbrand, T.G., and Kucks, R.P., 1983, Regional County, Utah (digitized and modified from U.S. magnetic and gravity features of the Gibson Dome Geological Survey Professional Paper 474-B, published area and surrounding region, Paradox Basin, Utah—a in 1965): Utah Geological Survey Miscellaneous preliminary report. U.S. Geological Survey Open-File Publication 11-1DM, 1 plate, 12p., GIS data, scale Report 83-359, 34 p. 1:62,500. Hintze, L.F., and Kowallis, B.J., 2009, Geologic history Massoth, T.W., 2012, Well database and maps of salt cycles of Utah: Provo, Brigham Young University Geology and potash zones of the Paradox Basin, Utah. Utah Studies, Special Publication 9, 225 p. Geological Survey Open-File Report 600. Hite, R.J., 1960a, The stratigraphy of the saline facies of Massoth, T.W., and Tripp, B.T., 2011, Well database of salt the Paradox Member of the Hermosa Formation of cycles of the Paradox Basin, Utah. 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Pan American Center for Earth and Environmental Studies, Woodward-Clyde Consultants, 1982a, Geologic 2011, Gravity database of the US. http://research.utep. characterization report for the Paradox Basin study edu/Default.aspx?tabid=37229 Accessed October 2011. region, Utah study areas: Prepared for Battelle Parker, J.M, 1981, Lisbon field area, San Juan County, Memorial Institute Office of Nuclear Waste Isolation Utah, in Wiegand, D.L., editor, Geology of the Paradox ONWI-290, 5 vol. Basin: Rocky Mountain Association of Geologists 1981 Woodward-Clyde Consultants, 1982b, Gibson Dome No. 1 Field Conference, p. 89-100. borehole, Gibson Dome study area of the Paradox Basin Potash Minerals Ltd., 2012, Potash Minerals Limited: region, San Juan County, Utah: Completion Report by Online, http://potashmin.com.au/, accessed June, 2012. Woodward-Clyde Consultants for the Batelle Memorial Prud’homme, M., and Krukowski, S.T., 2006, Potash Institute, Office of Nuclear Waste Isolation ONWI-388, in Kogel, J.E., Trivedi, N.C., Barker, J.M., and 6 vol. Krukowski, S.T., editors, Industrial minerals and rocks—Commodities, markets, and uses: Society for Mining, Metallurgy, and Exploration, Inc. publication, p. 723-741. Ritzma, H.R., and Doelling, H.H., 1969, Mineral resources, San Juan County, Utah, and adjacent areas—Part I, petroleum, potash, groundwater, and miscellaneous minerals: Utah Geological and Mineralogical Survey Special Studies 24, 125 p. Swinney, C.M., 1962, Cane Creek area potash project: unpublished Anaconda Copper Company Inter-Office Communication to M.L. Natland, March 16, 1962, variously paginated [copy obtained from Anaconda Collection, American Heritage Center, University of Wyoming]. Trimble, R.B., 1962, Potash project Lockhart area, San Juan County, Utah: unpublished report for Swinney, M., Blanc, R., and Conrad, S., September 20, 1962, 2 p. [copy obtained from Anaconda Collection, American Heritage Center, University of Wyoming]. Trimble, R.B., 1966, Cane Springs potash core holes, San Juan County, Utah: Unpublished report prepared for Schwade, I.T. [copy obtained from Anaconda Collection, American Heritage Center, University of Wyoming]. Tripp, B.T., and Tabet, D.E., 2011, Determination of whether prospecting is necessary for the Hatch Point area, covering potassium prospecting permit applications UTU-086426 to UTU-086431, UTU- 086568 to UTU-086602, San Juan County, Utah (T. 28- 30 S., R. 20-23 E.): U.S. Bureau of Land Management Mineral Report Form 3060-1, March 14, 2011, 29 p. Utah Division of Oil, Gas, and Mining, 2011, LiveData search—online oil and gas information system, Utah Division of Oil, Gas, and Mining. http://oilgas.ogm. utah.gov/Data_Center/LiveData_Search/main_menu. htm Accessed October, November, and December 2011. Witkind, I.J., 1964, Geologic map of the Abajo Mountains area, San Juan County, Utah: U.S. Geological Survey

Potash Bed Mapping in the Paradox Basin, Northern San Juan County, Utah 23