Tesuque Formation Research Articles

New mud turtles (Kinosternidae,Kinosternon) from the middle–late Miocene of the United States

AbstractKinosternonSpix, 1824, was widespread in xeric to savanna associated paleowetlands across North America during the middle–late Miocene and steadily diversified following its first occurrences in the Hemingfordian. In the middle Miocene,Kinosternon rinconn. sp. occurred in the late Barstovian Cerro Conejo Formation of north central New Mexico, perhaps concurrently withKinosternon pojoaqueBourque 2012a from the Tesuque Formation. Subsequent late Miocene kinosternine fossils indicate that at least three potentially contemporaneous species existed throughout the Clarendonian. These areKinosternon pannekollopsn. sp., from the Ogallala Formation of northern Texas;Kinosternon wakeeniense, n. sp., from the Ogallala Formation of northwestern Kansas and Ash Hollow Formation of south-central Nebraska; andKinosternon notolophusn. sp., from the Alachua and Statenville formations of northern Florida.Kinosternon rinconis phylogenetically nested between theKinosternon flavescens(Agassiz, 1857) group (=PlatythyraAgassiz, 1857) and more derivedKinosternonincluding theKinosternon subrubrum(Lacépède, 1788) group (=ThyrosternumAgassiz, 1857).Kinosternon pannekollopsis recovered on the stem of theK.subrubrumgroup and is the oldest and largest member of that lineage.Kinosternon notolophusis readily differentiated from other MioceneKinosternonin possessing a distinct dorsomedial keel on the nuchal and faint dorsolateral costal carination. TheK.subrubrumgroup probably originated in the late Miocene savannas of the Great Plains and dispersed eastward via the Gulf Coastal Plain. An unnamed kinosternine taxon existed in the coastal plains of the eastern and southeastern United States during the Middle Miocene Climatic Optimum (with fossils from ~18 to 15 Ma), and disappeared from the region coincident with the end of that megathermal event.

Mylagaulid Rodents (Mammalia: Rodentia: Mylagaulidae) from the Middle Miocene (Barstovian) of New Mexico

Four species of mylagaulid rodents are described from the Tesuque Formation, Espanola Basin of New Mexico: Alphagaulus vetus (Matthew, 1924), Ceratogaulus robustus, new species, Notogaulus minor, new genus and species, and Notogauhis major, new species. Ceratogaulus robustus is distinguished from other species of the genus by its much heavier dentary and relatively wider premolar. Notogaulus is separable from other mylagaulines in its unique features of its cranium (ovate rugose areas on the nasals; shape, thickness, and porosity of bone on the postorbital processes), and relatively primitive dental morphology (no preferred separation of the branches of the parafossette on P4). The recognition of a distinct genus of mylagaulid from New Mexico demonstrates that by the middle Miocene (Barstovian) derived mylagaulines had evolved regionally into distinct genera.

A fossil mud turtle (Testudines, Kinosternidae) from the early middle Miocene (early Barstovian) of New Mexico

ABSTRACT The nearly complete skeleton of a mud turtle, Kinosternon skullridgescens, n. sp., is described from Santa Fe County, New Mexico. The specimen was collected from the early middle Miocene, early Barstovian, Skull Ridge Member of the Tesuque Formation (16.0–14.9 Ma) and is one of the oldest and most complete fossil representatives of the genus Kinosternon. Phylogenetically, the new taxon is placed on the stem of the flavescens group in conjunction with the extinct Kinosternon pojoaque from the late Barstovian of New Mexico. In addition to the flavescens group, K. skullridgescens shares morphological similarities with members of the subrubrum group (of North America), as well as with Kinosternon herrerai (from gulf drainages of eastern Mexico). Close proximity of the fossils K. skullridgescens and K. pojoaque to Mexico suggests that a small-plastroned ancestor of the extant taxa K. herrerai, Kinosternon angustipons (from lower Central America), and Kinosternon dunni (from northwestern South America) could have dispersed from North America into Central America by the middle Miocene (Barstovian). Phylogenetic results based on morphology suggest that the taxon Kinosternon steindachneri (formerly Kinosternon subrubrum steindachneri) be reinstated at the species level.

Reply to comment by Shlomo P. Neuman on “Spatial correlation of permeability in cross‐stratified sediment with hierarchical architecture”

[1] We appreciate the commentary by Neuman [2006] and the opportunity for discussion and further clarification of our article [Ritzi et al., 2004]. In his commentary, Neuman expounds upon his derivation of a model for the permeability semivariogram [Neuman, 2003, equation (53)] and describes aquifer architecture that would be represented by such a model. As requested by the Associate Editor, our reply focuses on illustrating the distinctions between the types of architecture represented by Neuman [2006] and Ritzi et al. [2004]. [2] Ritzi et al. [2004] considered the structure of permeability semivariograms arising in unconsolidated sedimentary deposits, the most common type of aquifer. Sedimentologists conventionally describe such deposits using a hierarchy of stratal unit types. Each of these stratal unit types is designated based on distinguishable characteristics, such as texture and geometry. A unit type defined at one hierarchical level is composed of smaller-scale unit types defined at the next lower level. Our approach makes a link between this hierarchical stratal architecture and the structure of the permeability semivariogram. To more clearly make this point we refer to Figure 1, which illustrates stratal architecture typically found in the sedimentological literature [e.g., Bridge, 2003]. Figure 1 shows a hierarchy of unit types designated within a sedimentary deposit formed as a braid bar within a river. The braid bar is composed of smaller-scale unit types such as large-scale inclined strata and cross-bar channel fills. In this example we refer to these as level II unit types within the hierarchy. Each of these level II unit types is, in turn, composed of smaller-scale level I unit types. For example, one large-scale inclined stratum (level II) is shown to be made up of level I units including small-scale cross strata composed of fine sand, planar strata composed of medium sand, and medium-scale cross strata composed of sandy gravel. [3] An expanded hierarchy could be created by including unit types that exist at still larger or smaller scales, with any number of levels. For example, we could add a higher level in the hierarchy by representing larger-scale unit types such as point bars and major-channel fills, which occur with braid bars in channel belts. We could add a lower level in the hierarchy by representing smaller-scale stratal unit types, such as avalanche beds and interbeds, which occur within a set of cross strata [see Ritzi et al., 2004]. Dai et al. [2005] showed that hierarchies may not be unique and that a unique hierarchal designation is not required for the approach presented by Ritzi et al. [2004]. [5] Ritzi et al. [2004] studied the relative contribution of each term toward defining the composite semivariogram, along the principal directions sampled, with data representing a fluvial point-bar deposit. Dai et al. [2005] did so with data from the Skull Ridge member of the Tesuque Formation, an alluvial deposit in the Rio Grande Rift basin. In both cases, the shape and range of the composite semivariogram were mostly determined by the sum of the cross-transition terms (last three summation groups on the RHS of equation (1)), with negligible contribution from the autotransition terms (first summation group on the RHS of equation (1)). In both examples the semivariogram could be modeled by knowing just the cross-transition probabilities and the univariate statistics for permeability, further underscoring the importance of the cross-transition terms. [7] The issue from our article upon which Neuman [2006] has focused concerns the dropping of the cross-transition terms, as done by Neuman [2003] and as in other approaches in the literature [e.g. Davis et al., 1997]. The context was that when stratal hierarchies are delineated in sedimentary deposits based, in part, on differences in sediment texture (mean grain size and grain size sorting), the stratal unit types can give rise to a hierarchy of multiple permeability modes. If so, Ritzi et al. [2004] and Dai et al. [2005] have shown that in directions in which lags will cross stratal boundaries (which is true for all directions in Figure 1), the permeability semivariogram can be almost entirely defined by the sum of cross-transition terms (last three summation groups on the RHS of equation (1)). Indeed, in both examples presented in these articles, it was the autotransition terms rather than the cross-transition terms that could be assumed negligible when modeling the permeability semivariogram.

Scaphohippus, A New Genus of Horse (Mammalia: Equidae) from the Barstow Formation of California

A new genus of hypsodont equid, Scaphohippus, is recognized from the Green Hills Division (Ba1), Second Division (Ba1), and Barstow Faunas (Ba2) of the medial Miocene Barstow Formation, as well as from Ba1 and Ba2 faunas in the Punchbowl Formation of California, the Tesuque Formation of New Mexico, the Pawnee Creek Formation of Colorado, and the Olcott Formation of Nebraska. The genus includes two species, Scaphohippus sumani n. sp. and Scaphohippus intermontanus n. sp. Scaphohippus is a member of the “protohippine” clade, but is differentiated from its more derived sister taxon, Protohippus, by an arc-shaped incisor battery, a shorter I3-P1 diastema, and a more rounded protocone. The upper cheek teeth of S. sumani n. sp. have an unworn crown height of 40 mm. The protocone remains isolated until as much as 60% of wear, and the enamel fossettes are more complex than those of S. intermontanus n. sp. S. intermontanus n. sp. has an unworn crown height of 48–50 mm, the protocone opens by 30% of wear, and the enamel fossettes are simpler than those of S. sumani n. sp. Phyletic analysis shows S. sumani n. sp. to be the more primitive species. Similar facial and dental characteristics reveal a likely common ancestor with Merychippus insignis. The wider geographic and temporal range of S. sumani n. sp. reported here allows for useful phyletic and biogeographic interpretations. S. sumani n. sp. and M. insignis diverged during the late Hemingfordian (He2) of the Great Plains and both taxa dispersed throughout the western United States. S. intermontanus n. sp. is only recognized from the Barstow Formation, where it was likely directly descended from S. sumani n. sp.

Bassariscus and Probassariscus (Mammalia, Carnivora, Procyonidae) from the early Barstovian (middle Miocene)

ABSTRACT The mesocarnivorous procyonine genera Bassariscus and Probassariscus first appear in the early Barstovian, when they are represented by four species. Bassariscus antiquus is known from the Olcott Formation of Nebraska, B. cf. parvus from the Skull Ridge Member of the Tesuque Formation of New Mexico, and B. minimus, sp. nov., from the Olcott Formation and Observation Quarry in Nebraska. Probassariscus is restricted to the single species P. matlhewi from the Virgin Valley Formation of Nevada, Observation Quarry of Nebraska, and possibly the Flemming Formation of Texas. The subfamily Procyoninae is divided into two tribes, Potosini and Procyonini. The procyonin Probassariscus is more closely related to Procyon and Nasua than to Bassariscus. Based on dental characteristics, Bassariscus is the most primitive genus of the Procyonini.

A Partial Skeleton of Pseudaelurus (Carnivora: Felidae) from the Nambé Member of the Tesuque Formation, Española Basin, New Mexico

Abstract I describe a partial felid skeleton of Pseudaelurus validus new species, from the early Miocene, late Hemingfordian of New Mexico. This is the earliest known felid from North America having cranial, upper, and lower dentition as well as postcranial information. A nearly complete set of limb bones provides the first insight into the morphometry of this lynx to puma-sized cat. The skull, similar to that of the earlier European Proailurus lemanensis displays a high and thin sagittal crest with prominent nuchal crests. In the auditory region, the tympanic bulla architecture resembles that of Proailurus and relates to modern felids. The skeleton includes an articulated manus and pes with an apparently functional first metatarsal bone, hitherto unknown in the genus Pseudaelurus Log-ratio diagrams are used to compare this skeleton with various extinct and modern felids. Dental morphology, as well as the new postcranial information revealed by this skeleton, is contrasted with that of other felids.

Alluvial-slope deposition of the Skull Ridge Member of the Tesuque Formation, Espanola Basin, New Mexico

Alluvial-slope deposition of the Skull Ridge Member of the Tesuque Formation, Espanola Basin, New Mexico

Recognition and significance of streamflow‐dominated piedmont facies in extensional basins

Alluvial slopes are piedmonts characterized by parallel steam channels rather than alluvial fans. They are common landforms in extensional basins of the south‐western United States but have received little attention from geomorphologists or sedimentologists. Persistence of channellized flow across piedmonts, as opposed to sheetflooding due to loss of flow confinement on alluvial‐fan surfaces, distinguishes alluvial‐slope and alluvial‐fan facies. Miocene strata of the Tesuque Formation (Española basin, New Mexico) and Pliocene strata of the St. David Formation (San Pedro Valley, Arizona) provide examples of extensional basin–piedmont successions constructed by discrete gravel and sand bedload channels and aggrading interfluve floodplains and aeolian sand sheets. Distinction of alluvial‐fan and alluvial‐slope piedmont deposits has several important implications. The contrasting facies geometries associated with the two landforms produce distinctly different aquifer and reservoir properties. It is hypothesized that alluvial slopes are more likely to form than alluvial fans where mountain fronts lack abrupt structural and topographic definition. This circumstance will most likely be met (a) along tectonically inactive and embayed mountain fronts and (b) on the hangingwall ramp side of half grabens.

Stratigraphic and tectonic evolution of the northern Española basin, Rio Grande rift, New Mexico

New K-Ar radiometric dates from Miocene volcanic rocks in the northern Espanola basin and northeastern Jemez Mountains of north-central New Mexico help constrain the late Tertiary depositional and tectonic history of the area. Stratigraphic relationships and radiometric ages from lava flows and dikes show that the Santa Fe Group, which is the dominant fill of the Rio Grande rift in the Espanola basin, consists of two Miocene alluvial fans separated stratigraphically by eolian deposits. The older (>12.4 Ma) fan, the Chama-EI Rito Member of the Tesuque Formation, was derived mainly from the north and northeast; it consists of volcaniclastic silty sandstone and gravel. The younger (<12 Ma) fan, the Chamita Formation, was built to the southwest and contains rock material from the Sangre de Cristo Mountains and from northern New Mexico in gravel channels cut into sandstone. These fans overlap in the study area and interfinger with the 14 Ma to 12 Ma northeast-transported eolian deposits of the Ojo Caliente Sandstone Member of the Tesuque Formation. Between about 15 Ma and 14 Ma, during deposition of the Tesuque Formation, Jemez volcanism began with eruption of Lobato Basalt in an area that is now the northern Jemez Mountains. Basaltic volcanism became wide-spread only during a brief period ca. 10 Ma, when flows spread out across much of the study area. This episode of basaltic volcanism largely shut off ca. 9 Ma, approximately coeval with a regional clockwise rotation of the extension direction. This suggests a causal connection between the tectonic activity and basaltic volcanism. Minor Lobato volcanism continued until ca. 7 Ma. Stratigraphic evidence suggests that the stream that formed Santa Clara Canyon, the largest east-trending drainage in the north-east Jemez Mountains, has been located near its present position since at least middle Miocene time. The channel has meandered and shifted laterally, resulting in markedly different stratigraphic sections on either wall of the canyon in the vicinity of the western boundary (Pajarito) fault of the Espanola basin. Two major north-trending faults (the Guaje Mountain and Canada del Amagre) have significantly larger strike-slip components than dip-slip components. The large horizontal component of displacement on these faults is probably related to counterclockwise rotation of the intra-rift blocks. Approximate slip rates for the faults, calculated using a radiometrically dated basalt dike and dacite dome, are virtually identical, yielding a slip rate of 0.1 mm/yr during the past 5 m.y.

Sedimentation pattern of a rift-filling unit, Tesuque Formation (Miocene), Espanola Basin, Rio Grande Rift, New Mexico; discussion and reply

Sedimentation pattern of a rift-filling unit, Tesuque Formation (Miocene), Espanola Basin, Rio Grande Rift, New Mexico; discussion and reply

Sedimentation Pattern of a Rift-filling Unit, Tesuque Formation (Miocene), Espanola Basin, Rio Grande Rift, New Mexico

ABSTRACT The Miocene Tesuque Formation is a > 2,000m-thick sedimentary unit filling most of the Espanola basin, an asymmetrical basin which is part of the Rio Grande continental rift in north-central New Mexico (U.S.A.). It is composed of conglomerate, sandstone, mudrock, and limestone of nonmarine origin, with numerous interbedded ashfall-tuff layers. The sedimentation pattern of the Tesuque Formation was determined by the interaction of two distinct paleodrainage systems deriving from the eastern and northeastern margins of the Espanola basin during the rifting process. The two systems generated two lithosomes, which can be discriminated in outcrop by means of paleocurrent study, sandstone and conglomerate petrology, and sedimentary facies analysis. Their surficial expressions are called rovinces A and B. Province A has westward paleocurrents and a mixed plutonic and medium-to-high-grade metamorphic provenance. Province B has SSW-directed paleocurrents and significant volcanic and sedimentary detrital inputs. Both provinces represent deposition in a dynamic alluvial-fluvial-lacustrine environment. Nevertheless, sedimentary facies of province A are representative of an ephemeral environmental regime, whereas those of province B seem to represent a more perennial regime. The basin fill, as a whole, is organized in upward fining megasequences averaging about 200 m in thickness. The gradual passage from proximal to more distal environments of deposition is documented within several megasequences. The lower part of these megasequences is composed of braidplain deposits, whereas the upper (and finer) part is characterized by sandflat deposits, lacustrine carbonates and nodular calcretes. Although the eastern margin of the Espanola basin (contributing the detritus of the Tesuque Formation) represents the relatively unfaulted side of a half graben, the documented upward fining megasequences are comparable to similar megasequences derived from tectonically active basin margins. This suggests that sedimentation style on a shallow ramp along the tectonically inactive side of a half graben can be determined by tectonism of the master fault system along the opposite (deeper) side of the basin.

Miocene sediment dispersal in the central Española basin, Rio Grande rift, New Mexico, U.S.A.

The central Española basin in north-central New Mexico represents one of the best opportunities to examine deposits related to the development of the Rio Grande rift. The Miocene Tesuque Formation represents the bulk of the Española basin fill. It is composed of a 2000–2500 m thick sequence of alluvial-fluvial and, subordinately, lacustrine deposits with numerous interbedded ash-fall tuff layers. The overall detrital composition of the Tesuque Formation is very similar throughout the central Española basin. Provenance is primarily from basement uplifts composed of Precambrian igneous and high-grade metamorphic rocks. Nevertheless, the combined use of paleocurrent analysis, and sandstone and conglomerate petrology allows a detailed reconstruction of the sediment paleodispersal system. Two sedimentary provinces are present within the Tesuque Formation: Province A, present in the eastern, central and southern portions of the study area, has a predominantly plutoniclastic and metamorphiclastic composition, and shows systematic paleocurrents toward the west. The sediments were derived from the Precambrian-cored Santa Fe block of the Sangre de Cristo Mountains, located directly to the east of the study area. Province B, present only in the northwestern portion of the study area, is characterized by a minor but significant amount of volcaniclastic and sedimentaclastic detritus, and shows consistent SSW-directed paleocurrents. The source area was possibly located in the area of the Taos Plateau and Latir volcanic fields. An intermediate narrow and discontinuous belt (province A + B) represents a hybrid province, where directional and compositional parameters are gradational.

Sedimentology and stratigraphy of the Miocene Zia sand of New Mexico

The Zia Sand was named and described by Galusha (1966), who presented a summary of field work in the Zia Sand by Frick Laboratory parties under his direction. Rocks included in the formation are partly, but not entirely, the same as those included in the Lower Gray Member of the Santa Fe Formation by Bryce and McCann (1937). Galusha and Blick (1971) summarized previous publications on rocks assigned to the Zia Sand. On biostratigraphic evidence, they excluded from the formation several exposures Bryan and McCann (1936) and Spiegel (1961) included in or correlated with the Lower Gray Member. Manley (1978) redefined the Zia Sand to. include the overlying rocks Galusha regarded as an unnamed unit or units equivalent in age to, but lithologically distinct from, the Tesuque Formation of the Santa Fe Group, in the Espanola basin. Kelley (1977) likewise combined the Zia Sand with the overlying units, retaining the name Zia for eolian sands. These revisions are rejected here; the limits of the Zia Sand used are very nearly those set by Galusha, in publications (1966; Galusha and Blick, 1971) and in the records of the Frick Laboratory. The rocks equivalent in age to the Tesuque Formation should receive further study and separate names. The Zia Sand as used here is a distinct depositional sequence. Galusha excluded the Zia Sand from the Santa Fe Group; other authors have included it. This paper does not attempt to resolve the question.

Geomagnetic Polarity Stratigraphy of Type Tesuque Formation, Santa Fe Group, in Espanola Valley, New Mexico: ABSTRACT

Sampling of the several type sections of the Tesuque Formation, lower Santa Fe Group, exposed near Espanola, New Mexico, has yielded a composite magnetic-polarity stratigraphy in which the 760-ft (230 m), fine-grained, tuffaceous middle (Skull Ridge) Member is characterized by a long, uninterrupted interval of reversed polarity; approximately 900 ft (275 m) of the coarser grained upper (Pojoaque) member is characterized by rocks predominantly of normal polarity. Laboratory results from AF demagnetization in fields up to 200 oe, and from the acquisition and removal of IRM (often of multiple specimens cut from single samples), indicate that the magnetic signals in these rocks, probably borne by detrital magnetite, are a record of the geomagnetic field at or near the time of deposition. The stratigraphic utility of the results is confirmed by replication in geographically separate, lithostratigraphically equivalent sections in different fault blocks. Within the context of the medial to late Miocene time span long acknowledged for this part of the Santa Fe Group, this composite polarity stratigraphy appears to correlate best with the standard Tertiary polarity time scale as follows: fossiliferous Nambe Member: early Epoch 16; Skull Ridge Member: late Epoch 16 and early Epoch 15; Pojoaque Member: mid-Epoch 15 and younger. These results indicate an age for at least the Pojoaque Member significantly younger (by about 3 to 4 m.y.) than fission-track ages recently reported for ash beds in the type Pojoaque section. End_of_Article - Last_Page 555------------

Magnetic-polarity stratigraphy of the Miocene type Tesuque Formation, Santa Fe Group, in the Española Valley, New Mexico

Several of the type sections of the Tesuque Formation, lower Santa Fe Group, exposed near Espanola, New Mexico, have yielded a composite magnetic-polarity stratigraphy in which the 230-m, fine-grained, tuffaceous middle (Skull Ridge) member is characterized by a long zone of uninterrupted reversed polarity; approximately 300 m of the coarser-grained, upper (Pojoaque) member is characterized by rocks predominantly of normal polarity. Results from AF demagnetization in fields up to 300 oe and from the acquisition and removal of IRM indicate that the more stable magnetic remanence in these rocks is probably borne by detrital magnetite and therefore can be taken as a record of the geomagnetic field at or near the time of deposition. The stratigraphic utility of the results is confirmed by replication in geographically separate, lithostratigraphically equivalent sections in different fault blocks. Within the constraints of a middle to late Miocene age long acknowledged for this part of the Santa Fe Group, this composite polarity stratigraphy appears best to correlate with the standard Tertiary polarity time scale as follows: fossiliferous Nambe Member, early Epoch 16; Skull Ridge Member, late Epoch 16 to early Epoch 15; Pojoaque Member, mid Epoch 15 to as young as early Epoch 12. The results indicate an age for at least part of the Pojoaque Member significantly older (by about 1.5 to 3.5 m.y.) than fission-track ages recently reported for ash beds in its type section. They are, however, more consistent with age assignments of these sediments based on placement of their contained mammalian faunas in the North American Land Mammal Age chronology.

Playa Deposit in the Bishop's Lodge Member of the Tesuque Formation, Santa Fe County, New Mexico

ABSTRACT The examination of samples collected at two locations, one in the northern part of the Santa Fe Quadrangle and the other about 4 miles north, in the Tesuque Quadrangle, discloses the presence of amorphous gypsum in amounts ranging from 55 percent to 88 percent in the silts and sands of the upper beds of the Bishop's Lodge Member of the Tesuque Formation. Intense chemical weathering was noted in the volcanic and granitic components of the playa beds and the theory is offered that frequent wetting and dessication during deposition were responsible for mildly acidic solutions which could have caused the chemical weathering observed. The discovery of a marked disconformity at the top of the playa beds separating them from the overlying Tesuque Formation, coupled with changes in lithology, mode of sedimentation, and nature of terrain supplying the sediments, suggests that the Bishop's Lodge Member and beds underlying it should be separated from the Tesuque Formation.