Geology and Fuel Resources of the Fruitland Formation and Kirtland Shale of the San Juan Basin, New Mexico and Colorado By JAMES E. FASSETT and JIM S. HINDS GEOLOGICAL SURVEY PROFESSIONAL PAPER 676 A subsurface and surface study of the coal-bear­ ing Fruitland Formation, the Kirtland Shale, and associated rocks, with emphasis on the relation between regional stratigraphy and the distribution, thickness, and quality of coal UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1971 • • < ~ UNITED STATES DEPARTMENT OF THE INTERIOR ROGERS C. B. MORTON, Secretary GEOLOGICAL SURVEY W. A. Radlinski, Acting Director Library of Congress catalog-card No. 75-611172 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 ~~ 72 3656 309 CONTENTS Page Abstract------------------------------------------- 1 Geology of the San Juan Basin-Continued Introduction ______________________________________ _ 1 Stratigraphy-Continued Purpose and scope _____________________________ _ 1 Upper Cretaceous rocks-Continued Page Location and extent of area _____________________ _ 2 Kirtland Shale ________________________ _ 23 Earlier investigations ___________________________ _ 2 Definition ________________________ _ 23 Lithology _________________________ _ Surface geology ____________________________ _ 2 24 Subsurface geology _________________________ _ 3 Contacts-------------------------- 24 Present study_- ___________ - ___________________ _ 3 Mode of deposition ________________ _ 25 Fossils and age ____________________ _ GeographY------------------------------------­ 3 25 Drainage---------------------------------- 3 Extent and thickness-----------~---- 26 Landforms ________ -- ______________________ _ 3 Paleocene rocks ___________________________ _ 28 Access------------------------------------ 4 Ojo Alamo Sandstone __________________ _ 28 Geology of the San Juan Basin ______________________ _ 4 Definition ________________________ _ 28 Geologic setting _______________________________ _ 4 General features ___________________ _ 28 Electric-log interpretation ______________________ _ 4 Contacts~------------------------- 29 Stratigraphy __ -- ______ --------- ___ - ___________ _ 6 Fossils and age _________ ------------ 31 Upper Cretaceous rocks ____________________ _ 6 Upper Cretaceous, Paleocene, and younger rocks _______________________________ _ Lewis Shale ___________________________ _ 6 33 Huerfanito Bentonite Bed __________ _ 6 Animas Formation and younger rocks ____ - 33 Structure _____________________________________ _ Pictured Cliffs Sandstone _______________ _ 8 34 Definition ________________________ _ 8 Geologic history _______________________________ _ 37 Lithology _________________________ _ 8 Fucl resources------------------------------------ 39 8 Oil and gas ____________ - ______ ----------------- 39 Contacts-------------------------- Uranium _____________________________________ _ Mode of deposition ________________ _ 9 44 Fossils and age ____________________ _ 15 Coal------------------------------------------ 44 Extent and thickness _______________ _ 16 Origin and distribution _______ ----- __ ------ __ 44 Fruitland Formation ___________________ _ 17 Correlation _______________________________ _ 54 Definition- _____________ ----------- 17 Character and qualitY----------------------- 57 Lithology _________________________ _ . 17 Overburden _______________________________ _ 63 Contacts-------------------------- 19 Itesources--------------------------------- 67 Mode of deposition ________________ _ 19 Development______________________________ ~ 70 Fossils and age _______________ ·----- 19 Iteferences cited __________ ------------------------ 71 Extent and thickness----------··----- 22 Index------------------------------------------- 75 ILLUSTRATIONS Page PLATE 1. Geologic map of the San Juan Basin, northwestern New Mexico and southwestern Colorado __________ In pocket 2. List of wells, and stratigraphic cross sections showing the interval from the Huerfanito Bentonite Bed of the Lewis Shale to the base of the Ojo Alamo Sandstone, the Animas Formation, or the Nacimiento Formation, San Juan Basin, Colorado and New Mexico _____________________________________ In pocket 3. Sections of coal beds in the Fruitland Formation in the San Juan Basin, northwestern New Mexico and southwestern Colorado ___________________________________________________________________ - In pocket FIGURE 1. Index map showing the location of the San Juan Basin---------------------------------------------- 2 2. Induction-electric log and lithologic column of the type well of the Huerfanito Bentonite Bed of the Lewis Shale showing the interval from below the Huerfanito through the lower part of the Ojo Alamo Sandstone------------------------------------------------~-------------------------- 5 3. Logs of two wells showing the response of the curves to the Huerfanito Bentonite Bed ____ -- __ ------------ 7 4. Map showing the North American epeiric seaway ________________________ -_------------------------- 10 5. Diagrammatic cross sections showing regressive, stable, transgressive, and regressive phases of the Pictured Cliffs shoreline ______________________________________________________ ------------------------ 11 m IV CONTENTS Page FIGURE 6. Photographs of outcrop of Fruitland Formation on Lewis Shale ________________________· ______________ _ 13 7. Isopach map of the interval between the Huerfanito Bentonite Bed of the Lewis. Shale and the top of the Pictured Cliffs Sandstone-------------------------------------------------------------------- 14 8. Electric log and lithologic column of the cored portion of borehole GB-1, Project Gasbuggy _____________ _ 18 9. Map showing subsurface extent of the Fruitland Formation, the Kirtland Shale, and the Ojo Alamo Sand- stone-------------------------------------------------------------------------------------- 20 10. Generalized section showing relative stratigraphic positions of samples collected for pollen and spore analysis on MesaPortales--------------------------------------------------------------------------- 22 11. Isopach map of the Fruitland Formation and Kirtland Shale ________________________________________ _ 27 12. Photographs of pinchout of basal bed of Ojo Alamo Sandstone on the south edge of Mesa Portales _______ _ 30 13. Isopach map of the interval between the Huerfanito Bentonite Bed of the Lewis Shale and the base of the Ojo Alamo Sandstone---------------------------------------------------------------~------- 32 14. Structure map of the San Juan Basin-------------------------------------------------------------- 35 15. Contour map of the Huerfanito Bentonite Bed ____________________________________________________ _ 36 16. Diagrammatic paleogeographic map showing the environments of deposition of the Fruitland Formation and the Kirtland Shale _________________________________________________________________________ _ 37 17. North-south cross sections showing the evolution of the San Juan Basin area ___________________________ _ 40 18. East-west cross sections showing the evolution of the San Juan Basin area ____________________________ _ 41 19. Map of oil and gas fields and coal mines in the Fruitland Formation and the Kirtland Shale _____________ _ 43 20. Logs through the lower part of the Fruitland Formation ____________________________________________ _ 51 21. Isopach map showing total coal thickness in the Fruitland Formation ________________________________ _ 53 22. Isopach map showing the thickest coal beds in the Fruitland Formation _____________________________ _ 55 23-26. Maps showing: 23. Locations and as-received Btu values of coal samples---------------------------------------- 61 24. Distribution of ash in coal samples from the Fruitland Formation ____________________________ _ 62 25. Distribution of moisture- and ash-free Btu values of coal samples from the Fruitland Formation __ 64 26. Distribution of fixed-carbon percentage of coal samples from the Fruitland Formation ___________ _ 65 27. Isopach map showing average thickness of overburden on Fruitland Formation coal deposits ___________ _ 66 TABLES Page TABLE 1. Selected palynomorphs from samples from the San Juan Basin_______________________________________ 23 2. Statistical summary of oil and gas pools of the Kirtland Shale and the Fruitland Formation______________ 42 3. Wells and measured sections used for plotting coal resources----------------------------------------- 45 4. Analyses of coal samples from the Fruitland Formation ___ ------------------------------------------- 58 5. Average percent of total coal in beds of indicated thickness in areas with given total coal thickness________ 67 6. Fruitland Formation coal resources in millions of short tons under indicated overburden, arranged by States according to bed thickness and total coal thickness______________________________________________ 68 7. Coal resources of the Fruitland Formation---------------~----------------------------------------- 71 8. Production and dates of operation of coal mines in the Fruitland Formation____________________________ 71 GEOLOGY AND FUEL RESOURCES ·oF THE FRUITLAND FORMATION AND KIRTLAND SHALE OF THE SAN JUAN BASIN, NEW MEXICO AND COLORADO By JAMES E. FASSETT and JIM S. HINDS ABSTRACT The thickest coal occurs adjacent to and southwest of major stratigraphic rises of the Pictured Cliffs Sandstone. The coal The San Juan Basin is an asymmetric structural basin in occurs in elongate tabular bodies whose long