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Home , Galisteo Basin, Galisteo Formation, Menefee Formation

Stratigraphy and tectonic implications of Paleogene strata in the Laramide Galisteo Basin, north-central

by Spencer G. Lucas, New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, New Mexico 87104; Steven M. Cath er, New Mexico Bureau of Mines and Mineral Resources, Socorro, New Mexico 87801; John C. Abbott, Department of Geosciences, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801; and Thomas E. Williamson, New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, New Mexico 87104

Abstract Mexico has long been identified as the Formation, however, are green andred. base of the Galisteo Formation. This Although the Mesaverde-Galisteo con- We exclude the lower 0-442 m from boundary is a profound regional uncon- tact locally appears to be the Galisteo Formation and identify it as a formity between rocks of Late conformable, regionally the contact is new, -bounded and putative early age that has a major unconformity representing stratigraphic unit, the Diamond Tail been interpreted to reflect a major pulse in much of the and Formation. The Diamond Tail Formation Laramide tectonism. This pulse estab- probably some of the early Tertiary (Stearns, 1943; Gorham, 1979; is dominantly coarse-grained subarkosic lished the Laramide Galisteo Basin as a Beaumont, 1979). to arkosic sandstone and con- depocenter during Paleogene time. Here, we glomeratic sandstone with lesser reinterpret the stratigraphic relationships These criteria of Stearns (1943) for se- amounts of drab, green, gray, and lecting the Mesaverde-Galisteo contact maroon mudstone. It crops out in of the lower part of the Galisteo Formation are well accepted and have provided the north-central New Mexico in the Hagan and modify previous concepts of the late basis for most subsequent mapping (e.g., Basin and the Madrid-Cerrillos- Laramide evolution of the Galisteo Basin. Galisteo area where it unconformably Disbrow and Stoll, 1957; Bachman, 1975; overlies Upper Cretaceous strata of Picha, 1982) and interpretation of the La- the and is Previous studies ramide depositional and tectonic history unconformably overlain by lower of the Galisteo Basin (Baltz, 1978; Chapin Stearns (1943) established the criteria Eoce ne re d-bed strata of the and Cather, 1981; Gorham, 1979; Gorham used by subsequent workers to recognize Galisteo Formation. The index Hyra- and Ingersoll, 1979; Lucas and Ingersoll, cotherium sp. establishes the and map the base of the Galiste o 1981; Lucas, 1984; Smith et al., 1985; (late -early Formation in north-central New Mexico. Cather, 1992; Lucas and Williamson, 1993; Eocene) age of the upper part of the As noted by Stearns (1943), there is a dis- Abbott et al., 1995). In this paper, we Diamond Tail Formation. The Diamond conformable contact between the Eocene demonstrate that the Galisteo Formation Tail Formation is tentatively correlated Galisteo Formation and the Upper Creta- as currently construed consists of two tec- with the Cuba Mesa and Regina Mem- ceous Mesaverde Group. As summarized tonosequences, i.e., two lithologically dis- bers of the and by Lucas (1982, p. 9): tinctive, unconformity-bounded units appears to record an early phase of Mesaverde sandstones below the contact deposited as responses to separate tectonic Laramide trans-tensional subsidence in are fine to medium grained and thinly events. We eliminate the lower tectono- the Galisteo Basin. laminated. In contrast, Galisteo sequence from the Galisteo Formation and Introduction sandstones above the contact are coarse grained to conglomeratic and are more identify it as a lithologically distinct, map- thickly laminated. Most Mesaverde pable unit—the Diamond Tail Formation. The boundary between Cretaceous and mudstones are gray and black (organic We also briefly discuss the tectonic impli- Paleogene rocks in north-central New rich). Most mudstones of the Galisteo cations of this revised stratigraphy.

New Mexico Geology November 1997 89 Diamond Tail Formation

Name and type section

We recognize strata previously included in the lower part of the Galisteo as a separate stratigraphic unit, the Diamond Tail Formation (Fig. 1). The formation takes its name from the Diamond Tail Ranch in the Hagan Basin of Sandoval County. The type section of the Diamond Tail Formation and most of its Hagan Basin outcrops are on lands owned by the ranch. The type section of the Diamond Tail Formation is 1.0 km north of the ghost town of Hagan in the NE¼NW¼SW¼ sec. 28 T13N R6E. This is essentially the same section as Gorham's (1979, appendix I, plate 5; Gorham and Ingersoll, 1979, fig. 2) Hagan section. Strata in this section that Gorham (1979) assigned to the lower part of the Galisteo Formation—his "lower buff-pebbly sandstone" through "lower buff-sandstone and mudstone" informal members—compose the type section of the Diamond Tail Formation. These strata also correspond to the informally designated "lower unit of the strata of the Galisteo basin" of Abbott et al. (1995). At its type section (Fig. 2), the Diamond Tail Formation is 442 m thick. It discon- formably overlies -bearing strata of the Menefee Formation (Picha, 1982) and is disconformably overlain by the Galisteo Formation. Here, three informal members of the Diamond Tail Formation can be recognized. The lower member is 165 m thick and is mostly grayish-orange and yellowish -gray, medium- to coarse- grained, troughcrossbedded sandstone and conglomeratic sandstone. The sandstone is subarkosic to arkosic, and conglomerate clasts are dominantly quartzite and chert up to 0.5 cm in diameter, although a few larger (up to 4 cm diameter) clasts are present. Thin beds and lenses of olive-gray mudstone are a minor constituent. Ironstone cannonball concretions are common (Fig. 3B,C); logs and fragments of silicified wood are locally present. This lower member of the Diamond Tail Formation at its type section forms a prominent hogback between strike valleys formed by Menefee , lignites, carbonaceous shales and lenticular sandstones below and variegated mudstones of the middle member of the Diamond Tail Formation above. The basal contact is marked by a pronounced disconformity, with conglomeratic sandstone of the basal Diamond Tail overlying fine-grained sandstone and contain abundant sideritic concretions, trough cross-bedded. Some sandstone carbonaceous shale of the Mesaverde many of which are cannonball shaped. beds are pebbly, with numerous clasts of (Fig. 3A). The upper member of the Diamond Tail gray-to-white quartzite up to 0.5 cm in The middle member is 176 m thick and Formation at the type section is 101 m of diameter. Mud-stone is a subordinate forms a northwest-striking valley at sandstone and mudstone similar in part of the unit and is greenish gray. The the type section. It consists of variegated many features to the lower member. upper member forms a hogback together light-olive to maroon mudstone and Sandstones are mostly subarkoses that with overlying basal minor sandstone (Fig. 3D). Mudstones are yellowish gray to grayish orange and New Mexico Geology November 1997 91 conglomerate and sandstone of the The Diamond Tail Formation has a dis- our Fig. 1. Galisteo Formation (Fig. 3D). The base of tribution similar to that of the overlying the Galisteo Formation is readily selected Galisteo Formation. Major outcrop belts of Thickness and lithology above the upper member at the base of a the Diamond Tail Formation (Fig. 1) are: (1) the Hagan Basin, where it crops out in laterally continuous conglomerate The maximum thicknes s o f t h e that has a coarse-grained, subarkosic, a north–south belt encompassing the type section in T13-14N R6E [Stearns (1953), Diamond Tail Formation is 442 m at its very pale orange to pale yellowish- type section. In the Cerrillos area, a more brown matrix (Fig. 3E). Clasts are up to Kelley and Northrop (1975), Gorham (1979), and Picha (1982) are among the typical thickness is 100-150 m. Dramatic 4 cm in diameter and consist mostly of changes in thickness of the Diamond Tail chert, quartzite, and numerous workers who mapped as Galisteo Formation strata in the Formation take place laterally over short and sandstone. Paleozoic clasts become distances. For example, in the Hagan much more abundant higher in the Hagan Basin that we assign to the Diamond Tail Formation]; (2) southwest of Basin, the Diamond Tail Formation is 442 section. m thick at its type section, but in Arroyo Cerrillos in T14N R7-8E and at the Galisteo Formation type section east of del Tuerto, 6.5 km to the north, it is only Modification of Galisteo Formation Cerrillos in secs. 16, 20, 21 T14N R8E 210 m thick. A further 5 km to the north, it type section where strata mapped as the lower part of is less than 20 m thick. the Galisteo Formation by Disbrow and The thickness distribution of the Diamond Tail is similar to that of the Recognition of the Diamond Tail Stoll (1957), Bachman (1975), and Lucas Formation restricts the Galisteo Formation (1982), among others, belong to the overlying Galisteo Formation in the and therefore alters the content of the Diamond Tail Formation; (3) farther Hagan Basin (see Gorham, 1979). Both Galisteo Formation type section. Lucas east, outcrops south of Galisteo units thin to the northwest and exhibit (1982, p. 9-10) described this type section Creek along and around Arroyo Choro their maximum thicknesses near the east of Cerrillos in secs. 15, 16, 21, 22 (T13N R8-9E) and to the northeast in the ghost town of Hagan. The basal T14N R8E. Units 10-21 of this section vicinity of (mostly west of) Galisteo in T13- unconformity of the Galisteo Formation, (120 m thick) are assigned by us to the 14N R9-10E, include strata mapped which we select at the base of Gorham's (1979) "lower white conglomeratic Diamond Tail Formation. This limits the as the lower part of the Galisteo Galisteo Formation at its type section to Formation by Bachman (1975) and sandstone" near Hagan, appears to climb northwestward in paleoelevation. units 22-83 of Lucas's (1982, fig. 4) Johnson (1975) that we assign to the section, for a total thickness of 979 m. Diamond Tail Formation. This is shown by the northwesterly onlap East of Cerrillos, the Diamond Tail It is important to note that the Diamond of progressively younger units within Formation is exposed north of Galisteo Tail Formation is not present at the Wind- the Galisteo against the basal Creek in secs. 16, 20, 21 T14N R8E. The mill Hill area south of San Ysidro (T14N unconformity (see Gorham, 1979, plate 5). basal bed of the formation is a locally con- R1E; Fig. 1) where the basal Galisteo For- The northwestward thinning of the glomeratic brown sandstone; clasts are mation rests directly on the Menefee For- Diamond Tail Formation appears to be the gray and white quartzite and chert as mation (Galusha, 1966; Slack, 1973; Lucas, result of both greater pre-Galisteo erosion to the northwest and syndepositional much as 0.5 cm in diameter. This conglo- 1982). The Diamond Tail Formation is not meratic sandstone rests with prominent exposed in the St. Peter's Dome area near thickening of the Diamond Tail to the scour on fine- to medium-grained Los Alamos (Cather, 1992) or in the La southeast near Hagan. quartzose sandstone of the Mesaverde Bajada or La Cienega areas southwest of Most of the Diamond Tail Formation is Group. Overlying Diamond Tail Formation Santa Fe (Sun and Baldwin, 1958), yellow, orange and gray, medium- to coarse-grained arkose and subarkose (see mud-stones are brown and gray, as are although it is possible the Diamond Tail sandstones, which make up most of the exists in the subsurface in these areas. Gorham, 1979, for petrographic descrip- Diamond Tail section. The sandstones are Outcrops of Galisteo Formation have tions). Trough-crossbedding is the domi- mostly medium- to coarse-grained, con- been mapped near Placitas by Stearns nant bedform of these sandstones, and glomeratic, trough-crossbedded subarkos- (1953), Kelley (1977), Kelley and Northrop locally they contain abundant petrified es. Ironstone concretions are abundant. (1975), and Menne (1989). These rocks are wood and ironstone cannonball The base of the overlying Galisteo Forma- sandstone, drab mudstone, and rare, concretions. tion is a polymodal conglomerate of Pre- slightly pebbly sandstone that have been Conglomeratic sandstone (and, more rarely, conglomerate) also is a common quartzite and granite with sub- variably oxidized beneath the basal ordinate Paleozoic limestone, sandstone, unconformity of the . We rock-type in the Diamond Tail Formation. These conglomeratic units contain mostly and chert clasts similar to beds in the regard these beds as probably belonging lower part of the Galisteo Formation at the to the Mesaverde Group. It is possible, small (<0.5 cm diameter), well-sorted type section of the Diamond Tail however, that these strata belong to the clasts dominantly of white and gray Formation (Fig. 3F). Red and green Diamond Tail Formation, although no quartzite and chert. Diamond Tail mudstone immediately overlie the basal unconformity is apparent between them Formation conglomeratic sandstones and Galisteo conglomerate near Cerrillos. and the carbonaceous Cretaceous rocks conglomerates are thus easily beneath. distinguished from Galisteo Formation Contacts, distribution, mappability Conglomeratic sandstone and drab conglomerates, which are commonly coarser-grained (>2 cm diameter) and mudstone exposed near the towns of The upper and lower contacts of the Galisteo and Lamy (Fig. 1) appear to be contain a greater variety of clast Diamond Tail Formation are regional Diamond Tail Formation. The geographic lithologies (quartzite, chert, limestone, . Coarse -grained distribution and the nature of the upper granite, sandstone). Clast compositions sandstones and conglomerates at the and lower contacts of the Diamond Tail in suggest that coarse detritus in the Diamond Tail was recycled primarily from base of the Diamond Tail Formation are these areas, however, are in need of scoured into finer-grained sandstones and further study. texturally and mineralogically mature coal-bearing shales of the Upper Mappability of the Diamond Tail clasts derived largely from Mesozoic Cretaceous Mesaverde Group (generally Formation can readily be strata. In contrast, clasts in the Galisteo Menefee Formation). Conglomerate at demonstrated at various scales. In Formation in the Hagan area undergo an the base of the Galisteo Formation most areas it can be easily mapped abrupt upsection evolution from a disconformably overlies locally pebbly at a scale of 1:24,000, and it can be Diamond Tail-like suite in the basal sandstone of the Diamond Tail Formation. separated from the Galisteo Formation conglomerate to a more litho-logically diverse, texturally and miner- on broader regional-scale maps such as

92 November 1997 New Mexico Geology alogically less mature suite above. In other areas, such as near Cerrillos, the basal Diamond Tail-like suite is missing, and the polymodal suite comprises the basal conglomerate. These relationships indicate that sediments above the basal Galisteo unconformity were largely supplied by rising basement uplifts that exposed Paleozoic and rocks except in local areas, such as near Hagan, where scouring and resedimentation of Diamond Tail deposits was initially dominant. The detrital record of apparent unroofing shown by the Diamond Tail /Galisteo sequence is broadly similar to the unroofing of late Laramide uplifts described elsewhere in New Mexico (Seager and Mack, 1986; Gather, 1991, 1992). Except in the vicinity of the type section, Diamond Tail mudstones are green or gray; no red-bed mudstones are present. Mudstone in the upper part of the Diamond Tail Formation in the area of its type section, however, is maroon (dark reddish brown and grayish red) and contains numerous sideritic nodules. In contrast, red mudstones of the Galisteo Formation are brick red (moderate reddish brown) and lack sideritic nodules.

Age and correlation Until this study, no other than were known from the Diamond Tail Formation, so no known before the Wasatchian lma (late Williamson and Lucas, 1992). direct evidence ,of its age was Paleocene–early Eocene) but ranges Lithologic similarities between the available. All previously reported into the Bridgerian Ima (Krishtalka et al., Diamond Tail and Cuba Mesa–Regina fossils from the strata of the Galisteo 1987). Members include basal sandstone- Basin were found in the restricted dominated sequences, subarkosic Galisteo Formation, above the Diamond The above specimen was sandstones with numerous Tail. recovered from the upper part of the cannonball concretions and silicified NMMNH (New Mexico Museum of middle member of the Diamond Tail, ¼ wood, generally drab mudstones with Natural History and Science) P-25046 from 1.1 km northeast of Hagan (NE SE¼ numerous sideritic concretions, and NMMNH locality 3043 in the Diamond sec. 28 T13N R6E). The youngest dated conglomerate dominated by well-rounded Tail Formation is a left dentary fragment Cretaceous unit it overlies, the clasts of quartzite and chert. These Menefee Formation, is of early with a partial P2 P3- 4, and partial M1 (Fig. 4). similarities, as well as comparable The dentition is highly worn, indicating a age. The oldest age-diagnostic fo s s i l s stratigraphic position and age, relatively mature individual. The specimen from the overlying Galisteo allow a tentative correlation of the is referred to Hyracotherium sp. based on Formation are middle Wasatchian (earliest Diamond Tail Formation with the its size and premolar morphology. The Eocene) mammals found 248-303 m Cuba Mesa and Regina Members of above the Diamond Tail–Galisteo P2 is narrow (width = 2.5 mm) but the San Jose Formation in the San possesses a small talonid. The posterior contact near Cerrillos (Lucas, 1982; Juan Basin (Fig. 5). Correlation with Lucas and Williamson, 1993). The premolars (P3 -4 ) are molariform and the Paleocene possess prominent metaconids in a Hyracotherium fossil from the Diamond (see Baltz, 1967, p. 57) can probably lingual position and large hypoconids in a Tail Formation must be older than the be ruled out because of the labial position. Both lack distinct Lysitean mammals from the lower generally fine grained nature of the paraconids but have weak paracristids part of the overlying Galisteo For- Nacimiento and the fact that it has at the anterior of the tooth. The labial mation, but is not older than earliest Wa- not yielded any fossils as young as faces of both teeth are marked by a satchian (Graybullian). The data Wasatchian (Williamson and Lucas, discontinuous basal cingulid. provided by adjacent stratigraphic 1992; Williamson, 1996). A more complete units are consistent with a late The tooth size (P3 length = 6.5 mm, understanding of the temporal Paleocene–early Eocene age for the width = 3.5 mm; P4 length = 6.7 mm, correlation between strata of the San width = 4.4 mm; M, anterior width = upper part of the Diamond Tail Formation. Juan and Galisteo Basins must 5.3 mm) falls within the range of H. We tentatively correlate the Galisteo- await better constraints on the age of angustidens and H. vasacciense (Kitts, Diamond Tail unconformity with the the lower part of the Diamond Tail 1956). Unfortunately, the characters base of the upper persistent Formation and of the upper used to distinguish these species sandstone of the Llaves Member of the Nacimiento and lower San Jose (e.g., presence/absence of diastema San Jose Formation in the San Juan (Cuba Mesa Member) Formations. between P1 and P2 , P3 morphology: Basin. The underlying Regina Member (and correlative Ditch Canyon and Kitts, 1956) are not present in this Tectonic significance specimen. The Wasatchian land-mammal lower Llaves Members, see Smith, 1988) is dominantly drab, variegated "age" (lma) is typified by the occurrence of The Galisteo Basin is one of several Hyracotherium. Hyracotherium is not mudstones and subarkosic sandstones(Baltz, 1967; Smith, 1988; wrench-related basins of late Laramide

New Mexico Geology November 1997 93 Tijeras—Cañoncito fault zone was right-oblique normal during the Laramide (Abbott, 1995), which lends support to the half-graben model for the Galisteo Basin proposed by Cather (1992). We cannot demonstrate that the unconformity that intervenes between the Diamond Tail and Galisteo Formations is tectonic in origin. It is possible, for example, that this unconformity was the result of sedimentary offlap and subsequent onlap driven by climatically influenced rates of sediment supply in a uniformly subsiding half graben. We feel, however, that the abrupt influx of locally derived Precambrian and Paleozoic clasts at or slightly above this unconformity argues for a tectonic origin. The upper Galisteo Formation tectono- sequence of early to late Eocene age in the Galisteo Basin is lithologically similar to the fill of other Echo Park-type basins in New Mexico, which consist of variegated red-bed sequences that contain polymodal conglomerates dominated by locally derived Paleozoic and Precambrian lithologies. Although not well constrained everywhere, the age of the fill in these other basins is middle to late Eocene (see summary in Lucas and Williamson, 1993), coeval with the upper part of the Galisteo Formation. topographic relief in the otherwise high- In contrast, the upper Paleocene—lower age (Echo Park-type basins of Chapin and standing transpressional welt that Cather, 1981) in New Mexico. The Galisteo Eocene tectonosequence in the Galisteo formed along the eastern margin of the Basin (i.e., Diamond Tail Formation) differs from these other basins in at Plateau during late Laramide has no lithologic or temporal equivalent least three major ways: (1) the time. Low relief in the Galisteo Basin in the Echo Park-type basins of New Galisteo Basin has a transtensional, area would have facilitated the Mexico. The Cuba Mesa—Regina section in rather than a transpressional, origin integration of paleodrainage across the the , however, is (Cather, 1992; Abbott et al., 1995); (2) Plateau margin and may explain the lithologically similar to the Diamond the late Laramide strata of the Galisteo external paleodrainage of the San Tail Formation, being dominated by a Basin contain two distinct Juan Basin (Smith, 1988, 1992a). In drab sequence of mudrock, tectonosequences, whereas other contrast, other late Laramide basins sandstone, and minor conglomerate Echo Park-type basins in New Mexico on the eastern part of the Colorado characterized by well-rounded clasts of appear to contain only one; and (3) Plateau [Baca Basin (Cather and quartzite and chert (Smith, 1988; the Galisteo Basin contains a thick Johnson, 1986); Piceance Creek Williamson and Lucas, 1992). sequence of late Laramide clastic Basin (Johnson, 1988)] were bounded Although the Cuba Mesa Member is deposits that were derived in large on the east by transpressional uplifts undated pale-ontologically, its upper part from an extensive catchment in and show evidence for paleohydrographic part intertongues with the Regina the San Juan Basin area of the closure. Member, which has yielded Wasatchian eastern Colorado Plateau (Cather, fossils. The Regina Member (and 1992, fig. 7). In contrast, sediments in In the Hagan area, the Diamond laterally equivalent lower Llaves and wrench-related basins to the north Tail and Galisteo Formations both Ditch Canyon Members) is overlain by and south (El Rito, Carthage—La Joya, display their maximum thicknesses the upper persistent sandstone of the and Cutter Sag —Love Ranch basins; to the south east, adjacent to the Llaves Member and the red beds of see Chapin and Cather, 1981) appear Tijeras—Cañoncito fault zone. Both the Tapicitos Member of middle to have been locally derived from units thin markedly to the northwest, and Wasatchian (Lysite) age. We have shown a smaller catchments on the basal beds of the Galisteo appear possible unconformity at the base of the to lap northwestward across the upper persistent sandstone of the transpressional uplifts along the east- Llaves Member in Fig. 5, although this ern boundary of the Colorado Plateau. eroded top of the Diamond Tail. The Tijeras—Cañoncito fault zone was an active is speculative. Smith (1988, 1992b) The three attributes of the Galisteo argued that an increased contribution of Basin described above may be intrabasin structure in the Galisteo Basin during the Eocene, as shown by coarse, basement-derived detritus to interrelated and share a common mudrocks of the Tapicitos Member origin. The extensional aspect of the preservation of Upper Cretaceous rocks and beds of the Diamond Tail may have allowed greater oxidation Galisteo Basin appears to have been and reddening during Eocene pedo - related to transtensional deformation Formation on the up-thrown, southeast block (Abbott et al., 1995). These genesis than in the finer grained, along the Tijeras—Cañoncito fault zone, more poorly drained paleosols of which acted as a releasing bend in the relationships suggest that the Diamond the drab Regina Member. A similar right-lateral wrench system of the Tail and Galisteo Formations explanation may apply to deposits Laramide southern Rocky represent two distinct tectonosequences of the Galisteo Basin, where an Mountains (Cather, 1992). This in part of a basin that was subsiding increase in basement -derived extensional aspect of deformation would and tilting southeastward along the detritus at or near the base of the tend to produce alocal gap of low Ti je ras- Cañoncito fault zone. The Galisteo Formation (as shown by clast

94 November 1997 New Mexico Geology lithology) coincides approximately with L. (eds.), Santa Fe Country: New Mexico dridge, W. S., Dickerson, P. W., Riecker, R. E., and the change from drab to red coloration. Geological Society, Guidebook 30, pp. 259-274. Zidek, J. (eds.), rift: northern New The probable tectonic origin of the uncon- Cather, S. M., 1991, Stratigraphy and provenance Mexico: New Mexico Geological Society, Guide- of Upper Cretaceous and Paleogene strata of the book 35, pp. 123 -128. formity beneath the Galisteo Formation wester n Sierra Blanca basin, New Mexico; in suggests that an episode of middle Wasat- Lucas, S. G., and Ingersoll, R. V., 1981, Cenozoic Barker, J. M., Kues, B. S., Austin, G. S., and Lucas, continental deposits of New Mexico: an over- chian (-53 Ma) tectonism caused wide- S. G. (eds.), Geology of the Sierra Blanca, Sacra- view: Geological Society of America, Bulletin, spread unroofing of basement terranes in mento, and Capitan Ranges, New Mexico: New Part I, v. 92, pp. 917-932. the Laramide Brazos-Sangre de Cristo up- Mexico Geological Society, Guidebook 42, pp. Lucas, S. G., and Williamson, T. E., 1993, Eocene lift, which contributed detritus to both the 265-275. vertebrates and late Laramide stratigraphy of Galisteo Formation and the Tapicitos Cather, S. M., 1992, Suggested revisions to the New Mexico: New Mexico Museum of Natural Member of the San Jose Formation. Tertiary tectonic history of north -central New History and Science, Bulletin 2, pp. 145 -158. The lower (Diamond Tail) tectonose - Mexico; in Lucas, S. G., Kues, B. S., Williamson, Menne, B., 1989, Structure of the Placitas area, quence of the Galisteo Basin is unique S. E., and Hunt, A. P. (eds.), San Juan Basin IV: northern Sandia uplift, Sandoval County, New New Mexico Geological Society, Guidebook 43, Mexico: Unpublished MS thesis, University of among the Echo Park-type basins of New pp. 109-122. New Mexico, Albuquerque, 163 pp. Mexico, both lithologically and chronolog- Cather, S. M., and Johnson, B. D., 1986, Eocene Picha, M. G., 1982, Structure and stratigraphy of ically. Although we can only speculate depositional systems and tectonic framework of the Montezuma salient-Hagan Basin area, San- about the origin of this early tectonose- west-central New Mexico and eastern Arizona; in doval County, New Mexico: Unpublished MS quence, it is possible that the unique trans- Peterson, J. A. (ed.), Paleotectonics and sedi- thesis, University of New Mexico, Albuquerque, tensional nature of the Galisteo Basin mentation in the Rocky Mountain region, United 248 pp. caused sediments to be trapped sooner States: American Association of Petroleum Geol- Seager, W. R., and Mack, G. H., 1986, Laramide ogists, Memoir 41, pp. 623-652. than in basins along the high-standing, paleotectonics of southern New Mexico; in transpressional regions to the north and Chapin, C. E., and Gather, S. M., 1981, Eocene tec- Peterson, J. A. (ed.), Paleotectonics and sedimen- tation in the Rocky Mountain region, United south. Additionally, the extensive San tonics and sedimentation in the Colorado Pla- teau-Rocky Mountain area: Arizona Geological States: American Association of Petroleum Geol- Juan Basin catchment that apparently exit- Society, Digest, v. 14, pp. 173-198. ogists, Memoir 41, pp. 669-685. ed through the Galisteo Basin (Cather, Disbrow, A. E., and Stoll, W. C., 1957, Geology of Slack, P. B., 1973, Structural geology of the north- 1992) would have supplied voluminous the Cerrillos area, Santa Fe County, New Mexico: east part of the Rio Puerco fault zone, Sandoval sediments to provide a stratigraphic New Mexico Bureau of Mines and Mineral County, New Mexico: Unpublished MS thesis, record of any subsidence events within the Resources, Bulletin 48,73 pp. University of New Mexico, Albuquerque, 74 pp. basin. Galusha, T., 1966, The Zia Sand Formation, new Smith, L. N., 1988, Basin analysis of the lower early to medial beds in New Mexico: Eocene San Jose Formation, San Juan Basin, New American Museum Novitates, no. 2271,12 pp. Mexico and Colorado: Unpublished PhD disser- ACKNOWLEDGMENTS- The New Mexico Gorham, T. W., 1979, Geology of the Galisteo tation, University of New Mexico, Albuquerque, Bureau of Mines and Mineral Resources Formation, Hagan basin, New Mexico: Unpub- 166 pp. (C. E. Chapin, Director) and New Mexico lished MS thesis, University of New Mexico, Smith, L. N., 1992a, Stratigraphy, sediment disper- Albuquerque, 136 pp. Museum of Natural History and Science sal and paleogeography of the lower Eocene San supported this research. The owners of the Gorham, T. W., and Ingersoll, R. V., 1979, Evolution Jose Formation, San Juan Basin, New Mexico Diamond Tail Ranch allowed access to of the Eocene Galisteo basin, north-central New and Colorado; in Lucas, S. G., Kues, B. S., Wil- their property, and Gary Morgan assisted Mexico; in Ingersoll, R. V., Woodward, L. A., and liamson, T. E., and Hunt, A. P. (eds.), San Juan in the field. Earlier versions of the manu- James, H. L. (eds.), Santa Fe Country: New Basin IV: New Mexico Geological Society, Guide- Mexico Geological Society, Guidebook 30, pp. book 43, pp. 297 -309. script were kindly reviewed by C. E. 219-224. Stearns, B. S. Brister, G. A. Smith, and L. N. Smith, L. N., 1992b, Mudrock sedimentology and Johnson, R. B., 1975, Geologic map of the Galisteo paleopedology of the San Jose Formation; in Smith. quadrangle, Santa Fe County, New Mexico: U.S. Lucas, S. G., Kues, B. S., Williamson, T. E., and Geological Survey, Geologic Quadrangle Map Hunt, A. P. (eds.), San Juan Basin IV: New Mexi- 1234, scale 1:24,000. References co Geological Society, Guidebook 43, pp. 56-58. Johnson, R. C., 1988, Early Cenozoic history of the Smith, L. N., Lucas, S. G., and Elston, W. E., 1985, Uinta and Piceance Creek Basins, Colorado and Paleogene stratigraphy, sedimentation and vol- Abbott, J. C., 1995, Constraints on the deforma- Utah, in Sloss, L. L. (ed.), Sedimentary Cover- canism of New Mexico; in Flores, R. M., and tional history of the Tijeras- Cañoncito fault sys- North American Craton: U.S.; The Geology of Kaplan, S. S. (eds.), Cenozoic paleogeography of tem, north-central New Mexico: Unpublished MS North America: Geological Society of America, v. D- west-central United States: Society of Economic thesis, New Mexico Institute of Mining and 2, pp. 144 -154. Paleontologists and Mineralogists, Rocky Moun- Technology, Socorro, 161 pp. Kelley, V. C., 1977, Geology of the Albuquerque tain Section, Denver, pp. 293-315. Abbott, J. C., Gather, S. M., and Goodwin, L. B., Basin, New Mexico: New Mexico Bureau of Stearns, C. E., 1943, The Galisteo Formation of 1995, Paleogene synorogenic sedimentation in Mines and Mineral Resources, Memoir 33,59 pp. the Galisteo basin related to the Tijeras-Cañoncito north-central New Mexico: Journal of Geology, v. Kelley, V. C., and Northrop, S. A., 1975, Geology of 5, pp. 301 -319. fault system; in Bauer, P. W., Kues, B. S., the area, New Mexico: New Dunbar, N. W., Karlstrom, K. E., and Harrison, B. Stearns, C. E., 1953, Tertiary geology of the Mexico Bureau of Mines and Mineral Resources, Galisteo-Tonque area, New Mexico: Geological (eds.), Geology of the Santa Fe Region: New Memoir 29,136 pp. Mexico Geological Society, Guidebook 46, pp. Society of America, Bulletin, v. 64, pp. 459-507. Kitts, D. B., 1956, American Hyracotherium 271-278. Sun, M.-S. and Baldwin, B., 1958, Volcanic rocks of (Perissodactyla, ): Bulletin of the the Cienega area, Santa Fe County, New Mexico: Bachman, G. 0., 1975, Geologic map of the Madrid American Museum of Natural History, v. 110, pp. New Mexico Bureau of Mines and Mineral Re- quadrangle, Santa Fe and Sandoval Counties, 1-60. New Mexico: U.S. Geological Survey, Geologic sources, Bulletin 54,80 pp. Krishtalka, L., West, R. M., Black, C. C., Dawson, Quadrangle Map GQ-1268, scale 1:62,500. Williamson, T. E., 1996, The beginning of the age of Baltz, E. H., 1967, Stratigraphy and regional tec- M. R., Flynn, J. J., Turnbull, W. D., Stucky, R. K., McKenna, M. C., Bown, T. M., Golz, D. J. and mammals in the San Juan Basin: biostratigraphy tonic implications of part of Upper Cretaceous Lillegraven, J. A., 1987, Eocene (Wasatchian and evolution of Paleocene mammals of the and Tertiary rocks, east-central San Juan Basin, through Duchesnean) biochronology of North Nacimiento Formation: New Mexico Museum of New Mexico: U.S. Geological Survey, Profes- Natural History and Science, Bulletin 8,141 pp. sional Paper 552,101 pp. America; in Woodburne, M. 0. (ed.), Cenozoic mammals of North America: University of Cali- Williamson, T. E., and Lucas, S. G., 1992, Baltz, E. H., 1978, Résumé of Rio Grande depres- fornia Press, Berkeley, pp. 77-117. Stratigraphy and mammalian biostratigraphy of sion in north-central New Mexico: New Mexico the Paleocene Nacimiento Formation, southern Bureau of Mines and Mineral Resources, Circular Lucas, S. G., 1982, Vertebrate paleontology, stratig- raphy, and biostratigraphy of Eocene Galisteo San Juan Basin, New Mexico; in Lucas, S. G., 163, pp. 210-228. Kues, B. S., Williamson, T. E., and Hunt, A. P. Beaumont, E. C., 1979, Geology of the Cerrillos Formation, north -central New Mexico: New Mexico Bureau of Mines and Mineral Resources, (eds.), San Juan Basin IV: New Mexico coal field, Santa Fe County, New Mexico; in Geological Society, Guidebook 43, pp. 265-296. Ingersoll, R. V., Woodward, L. A., and James, H. Circular 186,34 pp. Lucas, S. G., 1984, Correlation of Eocene rocks of the northern and adjacent areas: implications for Laramide tectonics; in Bal-

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