A Reconnaissance Survey of the Western Part of the Durango-Gallup Coal Field of Colo Rado and New Mexico."
Total Page:16
File Type:pdf, Size:1020Kb
A RECONNAISSANCE SURVEY OF THE WESTERN PART OF THE DURANGO-GALLUP COAL FIELD OF COLO RADO AND NEW MEXICO." By MILLARD K. SHALER. INTRODUCTION. The area of the Durango-Gallup coal field includes 13,500 square miles, of which 1,900 lie in Colorado and the remainder in New Mexico. The total production of coal in this field in 1905 b was about 660,600 short tons, valued at nearly $1,000,000, exclusive of coke, of which about 12,000 short tons were produced. The entire tonnage of the field is estimated at 80,000,000,000 short tons, by figuring con servatively on a total workable thickness of 6 feet underlying the area, although 10 feet is probably a closer approximation of the average. The Durango-Gallup coal field extends from the latitude of Durango, Colo., on the north to the latitude pf Salt Lake, 70 miles south of Gallup, N. Mex., on the south, a distance of about 200 miles. Chama, Elvado, and the Sierra Nacimiento, in longitude 106° 45', are situated near the eastern boundary of the field, and its western limit is the New Mexico-Arizona boundary line. The width of the field is about 150 miles. (See PI. XXII.) In altitude the surface ranges from 5,000 to 9,000 feet, with an average of about 6,500 feet. The topography is varied, but on the whole the country is an open plateau in which the streams have cut valleys nearly 1,000 feet in depth. This paper, as may be seen by reference to the map, treats only of that part of the Durango-Gallup field lying west of longitude 107° 30'; Hence the remainder of the area will be given no further consid eration.0 The principal towns in Colorado within the region here considered are Durango and Mancos, located on the Denver and Rio "This preliminary report will be followed by a fuller description of the entire field, now in prepa ration, which will appear at an early date as a publication of the Survey. & Mineral Resources U. S. Figures for 1906 are not yet available. « For a preliminary report on the entire field, but more particularly on the eastern part of it, see Schrader, F. C., The Durango-Gallup coal field: Bull. U. S. Geol. Survey No. 285,1906, pp. 241-258- 376 U. S. GEOLOGICAL SURVEY BULLETIN NO. 316 PL XXII 10730 ?:&Z±^£^Wrt : ::^ x- x- - :-.. fe ", '&::: :-a-: K///.-;- : :.: ^*/#:^[. 7/tf- .-. -.-.: :; ^ .» .:;;,v.-;.- '.- :/.-Ei.M'u:ER_FAri'ff. /. £? / '. ! . .;.-. .' '%jtf#$&2wi ' '' 's\ \ / / / l> / / z~~:'vd$?-i-'S : :{/ )/ /\ liMaamin^^s^to , / /=; / / '. : : : (. /\//. /I//, / \ I . V-"-L feOjo-Calignle XT.Snr- ^^ -J-f I ''f _jV^"v.-- . x i'rg location of.field relative to cities q^^^ep44^ and transportation lines ^\\v">.i A 7) '~~7 f* Strike and dip X Mines X Prosgects \ Natural exposures 0 ^(JSSaM*'-^ || 7' '"-^iS Known fault Lower part ofMancos shale Supposed fault and unctifferentidted ofder rocks Concealed fault MAP OF WESTERN PART OF DURANGO-GALLUP COAL 'FIELD, COLORADO AND NEW MEXICO. DURAtfGO-GALLtTP COAL FIELD, COLORADO-NEW MEXICO. Grancle Railroad. In New Mexico Gallup, McKinley County, situated on the Atchison,- Topeka and Santa Fe Railway, is. the only important town in the area. The coal beds occur in the Upper Cretaceous, and have a maximum thickness of nearly 80 feet, with an average for the workable beds of about 10 feet. The better coals occur in the northern part of the area in the Mesaverde formation.0 The thicker coal beds occur in the Laramie formation, but they are of poorer quality than those of the Mesaverde. Coal beds also occur in the Mancos and Dakota for mations. The character of the coals varies from subbituminous 6 to a good grade of bituminous. The field work on which this report is based was of a rapid reconnais sance nature throughout and was done mainly during the autumn of 1906. For assistance in the preparation of the report, the writer wishes to acknowledge his indebtedness to Mr. James H. Gardner, who rendered valuable services in both field and office. GENERAL GEOLOGY. STRATIGRAPHY. Fossils collected by this party in 1906 and by Schrader's party during the previous year, which were studied by Stanton and Knowl- ton, indicate that the several formations observed and mapped in the field have the time values shown in the accompanying table. In classifying the Cretaceous sediments the formation names of Cross 0 are followed as nearly as their limits could be interpreted; aCross, Whitman, Geologic Atlas U. S., La Plata folio (No. 60), U. S. Geol. Survey, 1899. 6 The term subbituminous has been adopted by the Geological Survey for that class of coal com monly known as " black lignite." - <=0p. cit. Stratigraphic succession, age of beds, and tentative correlations in Durango-Gallup coalfield, Colorado-New Mexico. CO-^ Forma tionor group." System. Character of strata. Where exposed. Thickness. GO 'E2 Economic value. North area. Central North area. Central area- South area. North Central South «2 area. South area. area. area. area. Terrace gravel, alluvial wash, 'and flood-plain Feet. Feet. Feet. Residual clays used deposits, with chert fragments in central Variably throughout field. 0-200 (?) (?) *I area and hot-spring deposits in south area. for brickmaking. Quaternary. Unconformity. cene(?). Conglomerate; Well developed Pleisto- sandy matrix, along La Plata angular, fine River between 4-40 gravels of red Lap lat a and quartzite. Fruitland.N.Mex. Unconformity. 1-3 Occupies large O Eoceneor Eocene. Basic lavas local post- Rhyolite, rhyolitic tuff, and ly amygdaloid- areas between Dikes, flows, and isolated necks as in Zuni and In 200+ 0-100+ O e dikes of biotite monchi- al; amygdules Ship Rock. scription Rock (") O quite. filled with sec and f a rt h e r ondary calcite. south. Unconformity. Q isatch(?). Unconsolid a t e d Locally present Sand stones, pinkish sand, south, of Gal- conglomer drabmud shale, East of Animas lup, occupying Shales might be ates, and clay and conglomer River and in Can top of mesa 1,200+ 0-500 used for b rick- shales. ate with r>ink yon Largo. north of Salt making. Unconformity. i Coarse con- g 1 o in e r ate, t-Larami g From Carbon Junc -« pink sandy tion east and C1 matrix, peb- west, and. east of 0-300 b 1 e s and McDermott Ar- P bowlders of o quartzite and PU < volcanic rock. Unconformity. Contains workable 3 coal beds, above C Basin Mountains; basal massive & Massive gray sandstone at east of McDer- sandstone. Sand <u ao base, above which are mott Arroyo in East and north" of 500- 200- stone excellent SS coal beds and alternating Colorado; east of Rio Chaco. 1,000 800 for building a sandstone and shale beds. The Meadows in and some of shale u New Mexico. beds might be C3 utilized in brick- hJ. making. K Forms base of Basin Mountains, covers " <B Dark-drab clay shale con Could be used, in £"3 Fort Lewis Mesa and The Meadows, 250- taining limy concretions and crosses San Juan River below Fruit- 1,600 part, for manu OJ= and thin lenses of lime land ; outcrops in narrow band east and 2,000 facture of clay stone. north of Rio Chaco. products. « Contains valuable ra C coal beds, espe Occurs in Great cially in upper Cretaceous.. UpperCretaceoi Consists of two massive Caps Mesa Verde Hogback; covered and lower parts formatioisaverde sandstones between which Massive sand and prominent by Tertiary in of formation. stones and in- high lands east, In -Zuni Basin c'750- C o m m e r c i ally occur thin sandstone and terbedded drab west, and south Choiskai Moun north of lati 1,500+ 1,000+ valuable beds o"f shale beds, interstratifled shales and coal of Durango; is a- tains; surfacerock tude of Nutria. d 1,450 fire clay are m ined , and including workable beds. prominent escarp inGallupBasm.in from formation coal beds. ment maker. Nutria monocline near Gallup. and eastward. Sandstone excel- - lent for building S purposes. Parts used for brick- making at Du ea Dark-drab clay Dark-drab clay shale, slightly East and west of rango. Is ap Mancosshal shale, slightly arenaceous; contains limy Durango: occu Encircles Zuni parently adapted arenaceous; concretions and lenses irreg pies base of es Underlies hogback Basin on east, 1,000- 750- to manufacture of contains limy ularly. Transitional sand carpments and and borders field south, and 1,400 1,000 750+ Portland cement. concretions stone and shale beds inter- valleys; forms throughout area. west sides. Concains valua and lenses ir stratified at top, containing base "of Mesa ble coal beds in regularly. a few coal beds. Verde. southern part of area. d-san Dakota Massive hard quartzose sandstone at top; same Caps Animas City Mountain; outcrops BordersZuni Ba Sandstones are stone. sin; outcrops 100- 150- 150- good building at base, locally conglomeratic; dark bitumin east and west from Durango; occurs north of Santa stones; coal beds ous shale, containing coal bed, locally work at mouth of Mancos River; underlies Fe Railway 300 300 300 locally mined, but able, between sandstones. Great Hogback, or is contained in it. east of Gallup. generally dirty. aFormation names follow Cross, W., Geologic Atlas U. S.,La Plata folio (No. 60), as nearly as possible. c Vicinity of Porter, Colo. b Surface flows up to 200feet. <* San J uan River. OS 380 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1906, PART II. The Dakota is the basal formation of the Cretaceous in this region. Below it occur the Jurassic-Triassic rocks, whose upper beds range in character from the typical "variegated marl series" of Newberry to massive vermilion or white saccharoidal sandstone.