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Home , Kirtland Formation, San Jose Formation

NewLate leaf locality from lower Kirtland Shalemember, Bisti area, ,

byCoteman R. Robison,U.S. Bureau ol LandManagement, Albuquerque,andAdrian Hunf, ResearchAssistant, and Donald L. Wolberg,Paleontologist, New Mexico Bureau of Minesand Mineral Resources

This preliminary report represents the first sub- stantial paleobotanic study of new Fruitland or Kirt- plant yrs. land fossils in more than 65 The florule is Rt3W Rl2W Rllw Rlow Rgw the most diverse one ever found in either the Fruir land or Kirtland, and it adds substantially to the list of taxa known from these formations. The Fruitland and Kirtland floras need more paleobotanic study; cooperation from the coal companies in the area will make this possible. More precise stratigraphic delin- eation of floras is needed in differentiatine the two formations.

The area in and around Hunter Wash. near the site of the Bisti Trading Post, in west- central San Juan Basin, has been actively in- vestigated by geologists and paleontologists for almost 70 yrs (for example, Bauer, l9l7; Bauer and Reeside, 1921; Gilmore, l9l7; Clemons, 1973; Hutchinson, 1981). Within the immediate region, rocks of the Lewis Shale (), Pictured Cliffs , , and Kirtland Shale are exposed (table l). The Bisti-Fruitland coal field, upon which this area lies, is estimated to contain 1.870 million metric tons of subbitu- minous. low-sulfur coal beneath less than 250 FIGURE 1-Gnorocrcet- MApoF AREArN vrcrNrry oF LEAFLocALITY. Also shown is Fossil Forest, a fossilifer- ft of overburden and is the greatest undevel- ous area currently being studied by the authors and others. Klmv, Lewis Shale; Kpc, Pictured Cliffs Sand- Shale; Kkl, lower shale member of Kirtland Shale; Kkf, oped reserve in the San Juan Basin (Sho- ston€; Kf, Fruitland Formation; Kk, Kirtland Farmington Sandstone Member of Kirtland Shale; TKoa, Ojo.Alamo Sandstone; Tn, Nacimiento Forma- maker, l97l). To better understand the strati- tion; Tsj, San JoseFormation. graphic record and depositional environments of the rocks containing these resources, de- tailed field investigations were made near the two large continentalareas. The San Juan member overlain by the Farmington Sand- old Bisti Trading Post (Fig. l). These involved Basinlay on the westernmargin of the seaway stone Member in turn overlain by the upper stratigraphic sedimentologic and paleontolog- and was intermittently inundated by the ad- shalemember (Bauer, l9l7; Reeside,1924). ical studies (Hunt and others, 1981). During vancesand retreatsof the sea (Fassettand The contact betweenthe lower shale member the course of these investigations a new leaf Hinds,l97l). and the Fruitland Formation is imprecise locality was found in the Fruitland-Kirtland The Pictured Cliffs Sandstonerepresents although many boundaries have been sug- sequence. delta-frontand barrierbeach deposits (Erpen- gested(Fassett and Hinds, 1971,p. l9). Lind- beck, 1979;Cumella, l98l) of the final retreat say and others (1981) suggest,rightly in our TABLE l-Uppen Cnpracrous (CavpaNraN ro of the Campanianseaway from the region. view, the presenceof a transition zone be- MeestntcHtreN)srRATtcRApHtc uNtrs IN AREA oF Coal depositsof varyingthickness and lateral tweenthe uppermostFruitland and lower Kirt- HuNrpnWasn. extent and other organic-rich sedimentswere land Shale. The leaf locality reported here is Iaid down in a variety of delta-plainand back- 8.2 m (27.1ft) abovethe highestcoal contact Stratigraphicunit Thickness barrier environments(Erpenbeck, 1979). The of O'Sullivan and others(1972) and Scott and Ojo Alamo Sandstone 20 rn upper portions of the Fruitland Formation others(1979) and 5.1 m (16.8ft) belowthe top Naashoibito Member 20m and the overlying Kirtland Shale lack well- of a red-browntabular sandstone, the bound- Upper shale member 30m nonmarine developedcoal depositsthat are presentin the ary of Dane (1936) and Hutchison (1981). Kirtland Shale lower Fruitland. Preliminary analyses of Pending more precise delineation of the Farmington Sandstone Fruitland and Kirtland brackish and fresh- boundarythis localityis assignedto the lower Member 120m watermolluscan faunas indicate a progressive shalemember of theKirtland Shale. Lower shale rnember 250m trend toward fresh-waterenvironments. This Locelrrv DEScRrprroN-The locality oc- Fruitland Formation 50m in sec.32, T. 24N., R. l3 Pictured Cliffs Sandstone 25 m final marine trendimplies increasing distance from the Pic- curs theSW%NE% Lewis Shale 20m regressionfrom turedCliffs shoreline(Hartman, l98l). W. (Fig. l) within a measuredsection of 19.37 SanJuan Basin Both the Fruitland and Kirtland shalewere m (63.9 ft) of channelsandstones and over- namedby Max Bauer in 1916for exposures bank depositsconsisting of carbonaceousand along the San Juan River in northwestSan noncarbonaceousmudstones and siltstones Juan County, New Mexico. Lindsay and (appendixA; Fig. 2). The localityis just below Geologic background others(1981) suggested that theKirtland Shale the shoulder of a hill and has been protected The Upper Cretaceousrocks of the Western be renamedthe as Kirt- from weathering by an overlying resistant Interior were depositedin or near an epeiric land rocks are predominantly siltstonesand siderite concretion. Although the mudstones seathat extendedfrom the Gull of Mexico to not shales.The Fruitland Formationis domi- are highly weatheredwhere not coveredby the the Arctic Ocean.This seaway,approximately nantly composedof interbeddedcoals, sand- concretion,the deposit seemsto be a lens- 3,000 mi in length and 1,000 mi in width, stones,and shales.Three members of theKirt- shapedpocket that extendslaterally about 3.5 divided the North American landmassinto land Shale are recognized:the lower shale m (l 1.6ft).

August1982 New Mexico TABLE 2-CoMpostrroN oF FLoRA. ooo o20 lg Filicophyta (ferns) or9 dq/b Polypodiaceae or8 ogg Asplenium sp. ot7 Woodwardio 2 crenata 50 cm 016 k SANDSTONE Salviniaceae ( 20 inches) 5 gg GRAYGREEN Salvinia sp. Ot ss y YELLOW Coniferophyta (conifers) ol4 lq SHALE,/MUDSTONE or3 q OOO Taxodiaceae K KHAKI Sequoia cuneata COAL/HUMATE c CREAM ot2 99 Anthophyta (fl owering plants) CA CREAMGRAY Monocotyledonae o?9 lg BRECCIA y9 YELLOWGRAY Cyperaceae 028 lg orl l9 gy GREENYELLOW Cyperacties sp. o27 k CARBONACEOUS b BLACK Dicotyledonae SHALE oro lg w WHITE Salicaceae o26 CONCRETION r RED Salix lancensis oo9 l9 S. sp. A o ORANGE oo8 d9/gg s9 br BROWN S. sp. B ooo oo7 s9 SILTSTONE Juglandaceae 99 LEAVES oo6 rg d DARK o05 Caryaantiquorum 9S 9S CLINKER I LIGHT Fagaceae oo4 dg v VERY D ry hy op I lu m subfa I ca t u m 000 coNcRETtoN Moraceae lg oo3 k Ficus baueri? o02 s F. crossii o?l ool F. planicostata FIGURE Platanaceae 2-Dllcnaruvarrc REpRESENTATToNoF MAcRosrRATrcRApHrc sEcrroN rN wHrcH LEAF LocAl-rry LIES. Platanus raynoldsii Menispermaceae Menispermites belli Fruitland and Kirtland floras are inseparable. still to be found in the Fruitland Formation Magnoliaceae The newlocality described below represents by (Tidwell and others, l98l). Three speciesof Magnolia corddolia far the largest sample of a local flora yet figs (Family Moraceae)occur in the florule: Lauraceae described. Ficus vaueri, F. crossii, and F. planicostata. Laurophyllum coloradensis Ficus planicostata (figs.7 and 8) is by far the L. wardiana Floral composition L. salicifolium most frequentlyencountered species in the col- Leguminosae The plant taxa identifiedare listedin table Iection, with specimensranging in size from Leguminosites 2. Only a few ferns occur in Fruitland-Kirt- 1.5x 2.5 cm (.6 x I .0 inches)to 6.2 x 9.3 cm Rhamnaceae land floras(Tidwell and others,l98l), and the (2.5 x 3.7 inches).Menispermites belli (fig. 9) Rhamnus sp. florule discussedhere containsonly three gen- is the only member of the moonseedfamily Zizyphus sp. era: Asplenium, Woodwardia, and Salvinia. (Menispermaceae)in the florule. The laurela Vitaceae Salvinia (plate 1, fig. 1; all further references (Fauraceae)are represented,by Laurophyllum Cissus marginata to plate figures will be made by the notation coloradensis,L. wardiana (fig. Dilleniaceae l0), and L. fig. and the number)is interestingbecause it is (fig. Dillenites cleburni salicifolium l1). Of the family Dilleni- Myrtaceae an aquatic, floating fern that requires open aceae,only Dillenites cleburni (fig. l2) is pre- Myrtophyllum toneyi water. sent.The buckthorn family (Rhamnaceaeltras Taxonomic Position Uncertain The only conifer in the florule is Sequoia one specieseach from the genera(Rhamnus\ Carpites baueri cuneata,which bears short, Iancelike leaves on and Zizyphusin the florule, but the exactspe- C. Iancensis young branchesand scalelikeleaves on older ciesaffinity for the specimensis yet to be de- c. sp. branches.Sequoio cuneata is thoughtto have termined. The remaining dicot families in the Ficus? trineruis been a dominant element of late Cretaceous florule are eachrepresented by a singlespecies Rhamnusminutus peat swampsin the Rocky Mountain region and include: Carya antiquorum unidentifiedinfl uorescence of the Jug- (Parker,1976). This florule is severelyimpov- landaceae (walnut family), Platanus ray- erishedin conifers,which represent only 3.20/o noldsii of the Platanaceae(sycamore family), of the assemblageas opposed to 12.3V0for the Magnolia cordifolia of the Magnoliaceae, Fossil leavesare preservedin light-brown entireFruitland-Kirtland flora (table3). Leguminositessp. of the Leguminosae(pea compressionsthat vary in quality of preserva- The anthophyta(angiosperms or flowering family), Cissus marginato of the Vitaceae tion from fair to good. Rare, small, poorly plants) are the dominant element of the flo- (grape family), and Myrtophyllum torreyi of preservedgastropods and bivalvesare found rule, comprising87.l9o of theidentical species the Myrtaceae(myrtle family). in associationwith the leaves and these (table2). Monocotsare representedby a few In termsof numbersof specimens,the most specimenswill be studiedby J. Hartman,Uni- specimensassignable to the genusCypercites. frequentlyencountered dicot generain the flo- versity of Minnesota. The environmentof In general,monocots are lesscommon in this ruleare, in decreasingorder of abundance: deposition was a meandering stream that florule than elsewherein the Fruitland-Kirt- Ficus periodically flooded interchannel areas, land. On the other hand,26 speciesof dicots, Laurophyllum creatingtransient swamps and ponds. representing15 generaand 13 families, are Dryophyllum PREvroussruDrEs-Although the Fruitland presentin the florule. The willow family (Sali- Salix Formation and, to a much lesserextent, the caceae)is representedby Salix loncensis(fig. Myrtophyllum Kirtland Shale are rich in plant fossils, re- 2) and two undeterminedspecies (figs. 3 and Rhamnus markably little paleobotanicwork has been 4). For the oak family (Fagaceae),the only Menispermites done.The only studiesare by Knowlton(1917) speciespresent is the extinctD ryophyllum sub- Three kinds of seedshave beenrecovered Lee (1917). and Subsequentpublications only falcatum (figs. 5 and 6). This is the first report from the locality. They are Carpites baueri have listed additional taxa (O'Sullivan and of Dryophyllum ftom the Kirtland Shale.The (fig. l3), C. loncensis,and C. sp. (fig. 14). 1972; others, Kuesand others,1977; Tidwell genusDryophyllum is common in Late Creta- Two speciesof dicotyledonousleaves and an and others,l98l). Basedon publishedstudies, ceousfloras of the Rockv Mountains but has F

New Mexico Geology August1982 TABLE 3-PBncnNr or FLoRAspEclES rN sruDy AREAcovERED rN THrssruDy coMpARED inflorescence(fig. l5) cannotbe assignedwith ro roreL F nurrr-r.N>K rnrlexo (Tidwell and others, I 98 I ). certaintyto anyknown taxon. Clearly, the remainsof dicots are the pre- Species for Species Percent dominateelement in the florule. They make total this this Percent of total up 83.990of the florule as comparedwith Fruitland-Kirtland report report Fruitland-Kirtland 60.20/ofor the known Fruitland-Kirtland flora (table3). Filicophyta 9 9.7 12.3 Osmundaceae 2 2.7 Depositional environment 2 2.'.7 Schizaeaceae gastropods Cyathaceae I 1.3 Basedon the presenceof aquatic the fine- Polypodiaceae J 2 6.5 4.1 and bivalves. the fern Salvinia, and Salvinaceae I I ).L 1.3 grained texture of the sedimentscontaining the fossils,the depositionprobably took place J.Z 12.3 Coniferophyta 9 I standingwater (Fig. 3). Presumably 2 2.',| in open, Araucariaceae pondsexisted on the floodplains Cupressaceae I 1.3 smalllakes or in the rock Taxodiaceae 5 5-Z 6.8 betweenstream channels. Lower Incertae sedis I 1.3 sequence,Fruitland interchannelareas were '75.3 occupiedby coal swamps.In contrast,in the Anthophyta 55 2'.7 87.1 Kirtland, swampswere far less well repre- ).2 15.0 Monocotyledonae 1l I suggestingbetter drained conditions I 1.3 sented, Sparganiaceae time. The standingwater or Cyperaceae I 3.2 1.3 during Kirtland Palmae 6 8.2 pond in which the leaveswere deposited must Araceae I 1.3 havehad a high sedimentationrate to retain Pontederiaceae I l.J compressionsof suchcomplete and well pre- Cannaceae 1 l -J served leaves. The higher energy, coarser grainedsediments (see B and G of appendixB) 44 26 83.9 60.2 Dicotyledonae significantly contain only poorly sorted, Salicaceae 2 36 9.7 2.7 brokenplant fragmentsand no leaves.Ninety- Juglandaceae I I J -Z 1.3 of the long axesof leaves Fagaceae 2 I J -Z 2.7 threemeasurements Moraceae 9 J 9.7 12.3 and stems were made and indicate current Lauraceae 4 J 9.7 5.5 directionswith a northeast-southwesttrend Platanaceae 2 I J.Z 2.'7 Gie. a). Nymphaeceae I 1.3 The abundanceof medium-sizedangiosper- Cercidiphyllaceae I 1.3 mous leaveswith entireor nearlyentire mar- Menispermaceae I 3.2 t.J gins and drip points may indicate a warm- J -Z 2.7 Magnoliaceae 2 subtropicalclimate during late I 1.3 temperateto Saxifragaceae Kirtland time. Leguminosae 2 I 3.2 2.'.7 Fruitlandand early Rhamnaceae 2 2 6.5 2.'7 Vitaceae 2 I 3.2 2.'.l Dillenaceae I I J.L 1.3 Myrtaceae 2 I J.a 2.7 Cornaceae 1 1.3 Bignoniaceae I l.J Caprifoliaceae 1 1.3 Incertae sedis 6 6 19.4 8.2 TOTAL t) JI 100 100

ANT L ITHOLOGY TERIAL '/,

KEY lmm=lcm A 'r/, t80" ,'z Concretion n=93 IO READINGS Mudstones B FIGURE 4-Rosp DTAGRAM op onrrNranroN on 93 SiI tslone s STEMAND LEAF FRAGMENTSFROM LOCALITY.

0 Leovespresenf References U Bauer, C. M., 1917, Contributions to the geology and 00 Leoveson lominoe paleontology of San Juan County, New Mexico; l) Slrat- igraphy of a part of the Chaco River valley: U.S. m Leoves overlopping Geological Survey, Prof. Paper 98Q, p. 27 l-218 E Bauer, C. M., and Reeside,J. B., Jr., 1921, Coal in the Lorge omountof nonleof middle and easternparts of San Juan County, New Mex- F I moleriol Survey, Bull. 716, p. 155-248 o ico: U.S. Geological Smoll omounlof nonleof W. 1973, The role of fossil vertebrates in in- u Clemens, A., moteriol terpretation of Late Cretaceous stratigraphy of the San 'bF Juan Basin, New Mexico, in Cretaceous and Tertiary H 24 rocks of the southern Plateau, J. E. Fassett, ed.: Four Corners Geological Society, Mem.,224 p. I 23 Cumella, S. P., 1981, Sedimentary history and diogenes of the Pictured Cliffs Sandstone, San Juan Basin, New Mexico and Colorado: Austin, Texas, Texas Petroleum FIGURE 3-MrcnosrnnucRApHy oF PLANTLocALrry ResearchCommittee, Rept. No. UT 8l-1, 219 p.

August1982 New Mexico Geology Dane, C. H., 1936,The La Ventana-ChacraMesa coal field:U.S. GeologicalSurvey, Bull.860-C, p. 8l-l6l Erpenbeck,M. F., 1979,Stratigraphic relationships and depositionalenvironments of the Upper Cretaceouspic- turedCliffs Sandstoneand FruitlandFormation, south- westernSan Juan Basin, New Mexico: M.S. thesis,Texas TechUniversity, T8 p. Fassett,J. E., and Hinds,J. S., 197t,Geology and fuel re- sourcesof the Fruitland Formation and Kirtland Shateof the San Juan Basin,New Mexico:U.S. GeologicalSur- vey,Prof. Paper6768, 75 p. Gilmore,C. W., 1917,Contributions ro the geologyand paleontologyof SanJuan County, New Mexico; 2) Verte- brate faunasof Ojo Alamo, Kirtland, and Fruitland for- mations:U.S. GeologicalSurvey, Prof. Paper98e, p. 279-308 Hartman, J H., 1981,Mollusca from Upper Crelaceous Fruitland and Kirtland Formations,western San Juan Basin, New Mexico: American Associationof Petroleum Geologists,Bull.65, p. 560 Hunt, A , Wolberg,D. L., and Menack,J., 1981,Late Cre- taceousstratigraphy in the area of Hunter Wash, San Juan Basin, New Mexico: American Associationof PetroleumGeologists, Bull. 65,p. 56t Hutchinson,P. J., 1981,Stratigraphy and paleontologyof the Bisti badlandsarea, San Juan County, New Mexico: M.S. thesis,University of NewMexico, 219 p. Knowlton,F. H., 1917,Contributions to rhe geologyand paleontologyof San Juan County, New Mexico; 4) Flora of the Fruirlandand Kirtland Formations: U.S. Geoloei- calSurvey, Prof. Paper98Q. p. 327-353 Kues,B. S , Froehlich,J. W., Schiebout,J. A., and Lucas. S. G., 197?,Paleontological survey, resource assessment, and mitigation plan for the Bisti-Star Lake area, north- westernNew Mexico: U.S. Bureauof Land Management, rept to Albuquerqueoffice, 399p. Lee,W. T., 1917,Geology of rheRaton Mesa and otherre- gionsin Coloradoand New Mexico: U.S. GeologicalSur- vey,Prof. Paper l0l, p.9-221 Lindsay,E. H., Butler,R. F., and Johnson,N. M., 1981, Magnetic polarity zonation and biostratigraphyof Late Cretaceousand Paleocenedeposits, San Juan Basin,New Mexico:American Journal ofScience, v.281, p. 390-435 O'Sullivan,R. B., Repenning,C. A., Beaumont,E. C , and Page,H. G., 1972,Stratigraphy of the Cretaceousrocks and the Tertiary Ojo Alamo Sandstone,Navajo and Hopi Indian Reservations,Arizona, New Mexico, and Utah:U S.Geological Survey, Prof. Paper521, 65 p. Parker, L., 19?6,The paleoecology of the fluvial coal- PLATE l-RnpnEspurnrlvE SpECTMENS:l) Salvinia sp., x 4.62t 2) Salix lancensis,x 0.99; 3) Salrx forming swamps and associated plain sp. A, x fluvial environ- 1.32; 4')Salix sp. B, x 1.32; ments in the Blackhawk Formation (Upper 5, 6) Dryophyllum subfelcatum,S-base, 6-apex, both x 0.33; 7, 8) Ficusplani- Cretaceous) costata,T-x0.53,8-x1.65;9)Menispermitesbelli,xl.32:'10)Laurophyllumwardiana,x0.40tll) of central Utah: Brigham Young University, Geology Lauro- Studies,v. 22,p. 99-ll8 phtllum salicifolium, x0.99; 12)Dillenites cleburni, x 1.98; l3) Carpitesbaueri, x 9.24; 14)Csrpites sp.,x Reeside,J. 8., Jr., 1924,Upper Cretaceousand Tertiary 2.64;and l5) unidentifiedinfluorescence, x 3.63. formationsof the westernpart of the SanJuan Basin of Colorado and New Mexico: U.S. GeologicalSurvey, Prof. Paper134,70 p. Total thickness-16.E4m (55.9ft) Total thickness-16.84m (55.9ft) scott, G. R , O'Sullivan,R., Mytton, J. w., 1g79,Recon_ Unit Thickness Unil Thickness naissancegeologic map of the Alamo MesaWest ouad- No. Description (cm, inches) No. Description (cm, inches) rangle,San Juan County, New Mexico:U.S. Geoloeical Survey,Misc. FieldSrudy Map MF-1074,I sheet,Jcale 026 White sandstone, medium-grained; amber blebs l-2 mm in diameter: l:24.000 about l0q0 organic clasts overall but dull coal l8 with plant-rich laminae; grades Shomaker,J. W., 1971,Bisti Fruitlandarea in strippable up- 018 Dark-gray-green shale; rich in plant ward into 027 low-sulfur coal resourcesof the San Juan Basin in New 96 debris (20-3090) 20 Mexico and Colorado: New Mexico Bureauof Mines and 02s Gray-green mudstone: 5-1090 017 Dark-gray mudstone; lacks plant MineralResources, Mem. 25,p. I l0-l l6 organlc matter; very rare occur- debris or carbonaceous material, Tidwell,W.D., Ash, S R., andParker, L. R., 1981,Crera- rences of leaf fragments 148 59 gradesupwards into 018 66 26 ceousand Tertiary floras of the San Juan Basin. in Ad- 024 Gray-green mudstone; with 016 Olive sandstone, fine-grained 40 I6 vancesin San paleontology, JuanBasin S. G. Lucas,J. abundantly preserved leaves just be- 015 Gray-green mudstone; occasional K. Rigby, Jr., and B. S. Kues,eds.: University of New low a sideritic concretionary layer occurrences of plant debris in carbo- MexicoPress, p. 394 forming a protective cap; leaf-bear- naceouspockets 64 26 ing horizon laterally discontinuous 148 014 White sandstone, medium-grained; well indurated and prominent ledge 023 Sandy mudstone, gray-green; little former 36 14 organic material present 48 t9 APPENDIX A-Mresunso SECTToN;MEAsuRED By 013 Gray mudstone; with about l59o 022 White sandstone. fine- to A. HuNr AND J. MENAcK, JuLy 1980, usrNc e organic debris 18 7 medium-grained; crossbedded lami- BnuNtott coupAss ANDJAcoB's srAFF 012 Gray-green mudstone, very nae; less than lOqo plant debris but carbonaceous (50-6090); very deep, locally more carbonaceous; locally Total thickness-16.84m (55.9ft) deep weathering developed (45 cm); red-brown color developed: iron Unil Thickness characterized by development of staining in some laminae; fines up- No. Description (cm, inches\ ward inro 023 l8 vegetation along the outcrop of this unit 147 59 029 White sandstone, medium-grained; 021 White sandstone, fine-grained; 5- 011 White sandstone, fine- about l5qo organic clasts 4l I6 lOqo plant debris in thin lamina- to medium-grained; about 20qo plant 028 Lighrgray mudstone; finely divided tions; grades upwa:d into 022 20 fragments in matrix; approximately sand-sized plant fragments t8 020 Light-gray mudstone with less than l09o clay in thin laminae less than I 027 Olive sandstone, fine-grained; with 590 organic matter; dark-brown sid- mm thick and clay pebbles up to 2 about 5q0 organic eritic concretions present matter; olive lam- 82 33 cm x I cm; poorly developed ripple inae alternate with light-gray fine- 019 Dark-gray (weathered) to black, marks 78 31 grained laminae 92 J/ lignitic horizon; very friable with (continued on p. 48)

New Mexico Geology August1982 45 Palarlto fault zone LateCretaceous leaflocality Unit Thlckness (continuedfrom p.4I) (continuedfrom p. 45) No. Description (cm,lnches) APPENDIX A (continuefi References Siltstone, gray-green; scattered Bailey,R. A., Smith,R. L., and Ross,C. S., 1969,Strati- subrounded plant fragments; well- Totrl thickness-16.t4 n (55.9ft) graphic nomenclatureof volcanic rocks in the Jemez sorted,averaging 5 mm (.2 inches)in Unit Thickness Mountains, New Mexico: diameter 15.2 6,1 U,S. GeologicalSurvey, Bull. No. Description (cm, iaches) r274-P,p. l-19 c Mudstone, gray-green; a few Cordell, L., 1979,Gravimetric expressionof grabenfault- 010 White sandstone,medium-grained; scattered stem fragments; poorly ing in Santa Fe country and the Espafiola Basin, New with large plant fragments up to 5 sortedup to 3 x 5 cm (1.2 x 2 inches) 3.8 t.5 Mexico: New Mexico Geological Society, Guidebook cm'!;well induratedand forms char- D Mudstone, gray-green; occasional 3fth field conference,p. 59-64 acteristic popcorn surface texture horizons with leaves 3 cm (1.2 Dalrymple,G. 8., Cox, A., Doell,R. R., and Gromme.C. upon weathering;some hoodoo (col- inches)in length and also horizons geomagnetic S., 1967, polarity epochs:Earth umnsor pinnacles)development 89 36 of poorly sortedstems up to 1.3 x 2 and PlanetaryScience Letters, v. 2, p. 163-173 009 White sandstone, fine-grained; cm (.5x.8 inchesl 22.8 9.t Doell, R. R., Dalrymple,c. B., Smith,R. L., and Bailey, about 590 plant debris concentrated gray-green; R. A., 1968, Paleomagnetism,potassium-argon ages, Mudstone, many in laminae. Undulating bedding jumbled many which over- and geology of rhyolites and associatedrocks of the leaves, of finely dcveloped; well indurated 2-5 cm (.8-2 Valles caldera, New Mexico: Geological Society of lap; leavessubcomplete with fine laminationsand mud America,Mem. l16, p.2ll-248 Dart- inches)in length,small fragmentsup lngs 60 24 (.2 inches)in length; poorly Galusha,T., and Blick, J. C., 1971,Stratigraphy of the to 5 mm sorted stem fragments l-5 cm (.+2 SantaFe Group, New Mexico: AmericanMuseum of Na- 008 Dark gray-greenmudstone with 15- (.3 tural History,Bull., v. 144,art. l, 128p. 2090 plant debris up to 3.5 cm'; inches)in lengthand up to .75 cm Golombek, M. P., 1981,Ceometry and rate of extension coarsensupward 30 I2 inches) wide; slickensidesup to 39 (16 in length, leaves across the Pajarito fault zone, Espanola Basin, Rio 00? Gray-green mudstone with about cm inches) on (.12 Grande rift, northern New Mexico: Geology, v. 9, p. 590 plant fragments and stems; laminaeaveraging .3 cm inches) 2l-24 gradesupward into 008 28 apan 17.8 7.1 -,1982, paja- gray-green; Geology,structure, and rectonicsof the 006 Sandstone,white, medium-grained; Mudstone, scattered (a), a) 7.5 3.0 rito fault zone in the EspaflolaBasin of the Rio Grande with large fragmentsof plants up to Ieavesfew in number: lens of grades rift, New Mexico: GeologicalSociety of America, Bull., 5 cm'?;about l0qo plant content 25 few scatteredcomplete leaves ln revlew laterally into stems and poorly 005 Mudstone, gray-green; with Griggs, R. L., 196/.,Geology and ground water resources sortedsmall plant fragments,but no approximately l09o carbonaceous of the Los Alamos area, New Mexico: U.S. Geological leav€s;stems 5-10 cm (2-4 inches) debris;coarsens upwards into 006 6l Survey,Water-supply Paper 1753, 107 p. long and up to I cm (.4 inches)wide, Jiracek, G. R., 1974, Geophysicalstudies in the Jemez 004 Carbonaceousmudstone, dark-gray; fragmentsare subrounded2-.25 mm Mountains region, New Mexico: New Mexico Geological up to 40qoplant debrisis up to 2 cm' (.08-.01 inches) in diameter; (b) b) 5.0 2.0 Society,Guidebook 25th field conference,p. 137-144 poorly sorted;coarsens upwards; be- sameas lateral, stem-richportion of Kelley, V. C., 1979, T€ctonics, middle Rio Grande rift, comesmuch lesscarbonaceous later- (a), sharp contact with plant-rich New Mexico, in Rio Granderift-tectonics and magma- ally (aboutl09o) 28 l1 portion of (a) tism, R. E. Riecker,ed.: Washington,D.C., American 003 Olive sandstone, medium-grained; Lateral from (a) and (b) siltstone, GeophysicalUnion, p. 57-70 with some iron staining along bed- yellow-green;few broken plant frag- Manley, K., l9?9, Stratigraphyand structureof the Espa- dingplanes; 5-1090 plant debris ll7 ments (no leaves);lens-shaped cross flola Basin, Rio Granderift, New Mexico, in Rio Grande 002 Gray siltstone;590 plant debris;iron section7 x 60 x 15 cm (2.8 x24 x 6 rift-tectonics and magmatism, R. E. Riecker, ed.: stainingin fractures l8 inches) 7,0 2.8 Washington, D.C., American p. Geophysical Union, Mudstone, gray-green; full of 7l-86 001 White sandstone;fine-grained lenses of sand rich in carbonizedplant de- overlapping complete leaves that Reilinger,R. E., and York, J. E., 1979,Relative crustal bris and silt lacking plant debris; cover l0o9o of surface on laminae subsidencefrom levelingdata in a seismicallyactive part lensessubparallel to bedding; fines about every .5 cm (.2 inches);inter- of the Rio Grande rift, New Mexico: Geology, v. 7, p. upward into 002; much lateral varia- vening layers produce complete 139-143 tion in plant debriscontent (5-20q0) 30 t2 leavesnot overlapping 7.7 3.1 Smith, R. L., Bailey,R. A., and Ross,C. S., 1970,Geo- gray-green; logic map of the JemezMountains, New Mexico: U.S. Mudstone, large stems (2-4 GeologicalSurvey, Misc. Inv. Map I-571 APPENDIX B-Msnsun so sEcrrott. 5-10 cm inches)long and I cm (.4 wide, Stearns,C. E., 1943, The of north- inches) also many small Unit Thickness pieces, centralNew Mexico:Journal of Geology,v. p. stem subroundedfrom 3 to 8 51, 301- No. Description {tr'm.inchesl 319 o mm (.12to.32 inches)in diameter 15.2 3.1 Concretion, dark-brown; siderite J Grades down with less stem to with veins of barite; rare, poorly subrounded fragments less than 2 preserved leaf impressions extend mm (.08 inches)in diameter to un- laterally1.8 m (5.9ft) 35.6 fossiliferousgray-green mudstone 45.9 18.4 tr

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