Rocks In New Mexico Research Articles

Early Paleocene landbird supports rapid phylogenetic and morphological diversification of crown birds after the K–Pg mass extinction

Evidence is accumulating for a rapid diversification of birds following the K-Pg extinction. Recent molecular divergence dating studies suggest that birds radiated explosively during the first few million years of the Paleocene; however, fossils from this interval remain poorly represented, hindering our understanding of morphological and ecological specialization in early neoavian birds. Here we report a small fossil bird from the Nacimiento Formation of New Mexico, constrained to 62.221-62.517 Ma. This partial skeleton represents the oldest arboreal crown group bird known. Phylogenetic analyses recovered Tsidiiyazhi abini gen. et sp. nov. as a member of the Sandcoleidae, an extinct basal clade of stem mousebirds (Coliiformes). The discovery of Tsidiiyazhi pushes the minimum divergence ages of as many as nine additional major neoavian lineages into the earliest Paleocene, compressing the duration of the proposed explosive post-K-Pg radiation of modern birds into a very narrow temporal window parallel to that suggested for placental mammals. Simultaneously, Tsidiiyazhi provides evidence for the rapid morphological (and likely ecological) diversification of crown birds. Features of the foot indicate semizygodactyly (the ability to facultatively reverse the fourth pedal digit), and the arcuate arrangement of the pedal trochleae bears a striking resemblance to the conformation in owls (Strigiformes). Inclusion of fossil taxa and branch length estimates impacts ancestral state reconstructions, revealing support for the independent evolution of semizygodactyly in Coliiformes, Leptosomiformes, and Strigiformes, none of which is closely related to extant clades exhibiting full zygodactyly.

Update of industrial minerals and rocks of New Mexico

Update of industrial minerals and rocks of New Mexico

Detrital zircon geochronology from the Cambrian-Ordovician Bliss Sandstone, New Mexico: Evidence for contrasting Grenville-age and Cambrian sources on opposite sides of the Transcontinental Arch

Cambrian sandstones of the western United States and northern Mexico record deposition above a major unconformity on the rift margin of Laurentia. Detrital zircon ages from the Cambrian-Ordovician Bliss Sandstone in southern New Mexico are used to test models for the influence and significance of the Transcontinental Arch during the early Paleozoic. We obtained U-Pb zircon ages of basement rocks to test potential local source rocks in New Mexico. An orthogneiss in the Florida Mountains has an age of 1627 ± 18 Ma (all errors 2σ). The San Diego Mountain granite underlying the Bliss Sandstone is ∼1400 Ma. A rapakivi granite in the Little Hatchet Mountains has a U-Pb Concordia age of 1077 ± 4 Ma, coeval with the Pikes Peak granite and several granites in Sonora, Mexico. Three samples of the Florida Mountains granite underlying the Bliss Sandstone yield an average age of 510 ± 5 Ma; this is a rare and distinctive age of magmatism in western Laurentia. Zircons with these ages can be used as tracers for understanding transportation paths of sediment. The Bliss Sandstone was studied from eight localities in southern New Mexico; one overlies the Cambrian Florida Mountains granite, and three lie to the west. The sandstones are quartzarenite, subarkose, and arkose. The most abundant detrital zircon population included Grenville ages with a main peak at 1250 Ma. Other significant peaks are at 1465 Ma, 1625 Ma, 1710 Ma, and 1850 Ma, and these populations generally decrease in abundance with increasing age. Only five Archean zircons (out of 845) were discovered. Cambrian detrital zircons are present in the Florida Mountains Bliss Sandstone locality, directly overlying the Cambrian granite. They are also present in two localities 60–80 km southwest and northwest of the Florida Mountains. Maximum depositional ages from sandstones with Cambrian zircons range from 509 ± 7 Ma to 504 ± 12 Ma, overlapping with the age of the Florida Mountains granite. The four localities east of the Florida Mountains did not have any Cambrian detrital zircons. We interpret these data as indicating that the Cambrian intrusions of the Oklahoma-Colorado rift were not a source for the Cambrian zircons in the Bliss Sandstone. The Tapeats Sandstone in the Grand Canyon does not have Cambrian zircons and has a minor Grenville peak at 1070 Ma (Gehrels et al., 2011), significantly younger than the 1250 Ma Grenville peak in the Bliss Sandstone. We interpret these differences as being related to different source areas on opposite sides of the Transcontinental Arch. The differences in the specific ages of Cambrian plutons between the Oklahoma rift and the Florida Mountains granite can be used to test depositional models for other Cambrian sandstones of the southwest U.S. and in Mexico, where the presence of Cambrian zircons in the Caborca Block has implications for the Mojave-Sonora megashear hypothesis.

Proterozoic Tectonic Evolution of the Picuris Mountains, Northern New Mexico

The gross structure of the Picuris Range, defined by the buckled and imbricated km-thick Ortega Formation quartzite, is that of a tight synclinorium bounded by limb-parallel ductile shear zones. Folds are moderately inclined, horizontal, and are locally refolded, cleavage-transected, and cut by ductile faults. Three boundaries separate lithostratigraphic successions: (1) the south-dipping Pilar shear zone, which separates the Glenwoody Formation from overlying Hondo Group, shows both reverse and normal motion; (2) the Plomo fault is a south-dipping, ductile reverse fault, which separates the Hondo Group from the structurally overlying, but older, Vadito Group; and (3) the north-striking Picuris-Pecos fault, which truncates both of the other boundaries, separates supracrustal rocks from an eastern plutonic terrane. Granitoids (1680-1450 Ma) intrude Vadito Group rocks only. The first two boundaries do not juxtapose different tectonometamorphic terranes, even though they are major shear zones. Although the Picuris Range has common characteristics with adjacent ranges, several features mark it as unusual (cleavage-transected folds, a problematic distribution of plutons, and a map-scale anticline). These features may be manifestations of the strain heterogeneity characteristic of the Proterozoic rocks of New Mexico, rather than evidence of diverse tectonic histories. Folding and top-to-the-north shearing occurred during a progressive shortening event, perhaps related to the ca. 1650 Ma Mazatzal orogeny of Arizona and central New Mexico.

Albian ophiuroids from Cerro de Cristo Rey, Dona Ana County, New Mexico

Fossil ophiuroids (Echinodermata) have been recovered from rocks of the Comanche Series (Albian, Early Cretaceous) at Cerro de Cristo Rey, New Mexico. This is the first report of fossil ophiuroids from Mesozoic rocks in New Mexico.

Fracture Swarms in Low-Permeability-Sandstone Gas Reservoir Rocks in New Mexico, Colorado, and Wyoming: Implications for Exploration and Development

Fracture permeability is of primary importance to producibility of gas from many low-permeability sandstone gas reservoirs in the western US; but the location, orientation, spacing, and connectedness of fractures in the subsurface are difficult to measure directly. Maps of fractures provide the most accurate representation of fracture spatial distribution, trace length, connectivity, and size and shape of fracture-bounded blocks. In this study, fracture patterns were characterized by mapping five large exposures of Pictured Cliffs and Frontier sandstone along the margins of the San Juan and Green River basins. A set of fractures, interpreted as having formed in flat rocks prior to local Tertiary folding and uplift, is recognized in both formations. In contrast to the conventional model of regional fractures in which fractures are arranged in regularly spaced, orthogonal arrays, these fractures occur in discrete swarms separated laterally by domains that either lack fractures or have only rare fractures. These less fractured domains may be as much as several hundred meters wide. Within swarms, fractures are well interconnected along the length of the swarm but poorly interconnected across the width of the swarm. Fractures between swarms are commonly isolated. For the Pictured Cliffs and Frontier outcrops that were studied, themore » fracture pattern is self-similar over scales ranging from outcrop to interwell scale with fractal dimension D {approximately}1.2. In low-permeability sandstones of the Rocky Mountain region, irregularly spaced fracture swarms are potential targets for gas exploration and should be incorporated into fractured-reservoir models.« less

Metamorphic evolution of Proterozoic rocks in New Mexico

Metamorphic evolution of Proterozoic rocks in New Mexico

Proterozoic crustal history of the western United States as determined by neodymium isotopic mapping

Initial Nd isotopic ratios of crystalline rocks from an area of ∼ 1.5 × 10 6 km 2 of the western United States have been determined in order to map Precambrian age province boundaries and thus document the growth and modification of the North American continent in the Proterozoic. The use of three representative rock suites of different ages— Mesozoic and Tertiary peraluminous granitic rocks, middle Proterozoic (ca. 1.4 Ga) “an-orogenic” granitic rocks, and lower Proterozoic (ca. 1.7 Ga) igneous and metamorphic rocks—allows the ages of the provinces to be distinguished on the basis of different Nd isotopic evolution paths rather than solely on the basis of model ages. Three age provinces have been delineated, each generally northeast-southwest trending, having decreasing crystallization ages and increasing initial e Nd values with increasing distance southeastward from the Archean craton. Province 1 is composed of crustal rocks of central Utah and northeastern Nevada, which are characterized by average values of e Nd (1.7 Ga) ≈ 0 and T DM ≈ 2.0–2.3 Ga. Province 2 covers Colorado, southern Utah, and northwestern Arizona and has e Nd (1.7 Ga) ≈ +3 and T DM ≈ 1.8–2.0 Ga. Province 3, which comprises the basement rocks of New Mexico and southern Arizona, has e Nd (1.7 Ga) ≈ +5 and T DM ≈ 1.7–1.8 Ga. An additional region of province 1-type isotopic characteristics, herein named “Mojavia,” is found in eastern California and western Nevada. Crust formation in each province involved a large component of mantle-derived material plus a moderate amount (∼20%) of pre-existing crust. As the new crust was built outward from the Archean nucleus, however, contributions of Archean material to the newly forming crust were more effectively screened, so that the most distal province (3) is derived almost entirely from Proterozoic mantle. The province boundaries are subparallel to the crystallization age trends determined by other workers. An exception to this is the Mojavia region of province 1, which crosscuts and truncates the other provinces in the region of the lower Colorado River. This region appears to be displaced relative to other areas of the North American basement that have similar isotopic characteristics. This suggests the presence of a previously unrecognized large-scale, left-lateral, north-south–trending basement offset of Proterozoic age in the vicinity of the California-Arizona border.

The rugose coralTabulophyllum traversensisfrom the Oñate Formation (Middle Devonian) of the Mud Springs Mountains, New Mexico

The Oñate Formation of Middle Devonian (Givetian) age is exposed in the Mud Springs Mountains of New Mexico, where it is represented by an unusually shaly and extremely fossiliferous facies.Tabulophyllum traversensis(Winchell) found here is the only rugose coral species known thus far from Middle Devonian rocks of New Mexico and is of special interest as evidence of migration between the area of the Oñate occurrence and those in the Cedar Valley Limestone in Iowa and the Traverse Group of Michigan. The occurrence is also of interest because of the association of the Oñate coral with the receptaculitidSphaerospongiasp. cf.S. tessellata(also known from Canada, Australia, and New York). The corals apparently utilized receptaculitids as a solid substrate for post-larval growth and developed an extremely broad flat base, fixed to the upper surface ofSphaerospongia.

The first Oligocene mammal from New Mexico

Oligocene landscapes of New Mexico were dominated by andesite stratovolcanoes and resurgent domes of ash-flow tuff (ignimbrite) cauldrons (Smith et al., 1985). This pervasive volcanism produced volcanic and volcaniclastic rocks that have been neglected by vertebrate paleontologists, so that, until now, no Oligocene vertebrate fossils have been discovered in New Mexico. This documents the initial results of vertebrate paleontological investigations of Oligocene rocks in New Mexico, a lower jaw of the oromerycid artiodactylMontanatylopus matthewi, the first Oligocene mammal from the state. In this paper, CM = Carnegie Museum of Natural History and UNM = University of New Mexico.

Arnoldia kuesii, a New Juvenile Fernlike Plant from the Lower Permian of New Mexico

A nearly complete juvenile fernlike plant is described here from Lower Permian rocks of New Mexico. The fossil consists of a horizontal rhizome with roots, a short thick upright aerial branch, and a tuft of dimorphic leaves. It is assigned to Arnoldia kuesii gen. et sp. n. and appears to be the first juvenile fernlike plant known from the Upper Paleozoic. Abundant palynomorphs and other plant fossils associated with the fossil indicate that it is Early Permian in age.

Stress history and tectonic development of the Rio Grande Rift, New Mexico

Paleostress determinations from radiometrically dated dikes indicate ENE‐WSW regional extension began by about 32 Ma in New Mexico, and perhaps earlier in the southern part of the state. The extension direction maintained this orientation until sometime after 23 Ma when it rotated clockwise to an E‐W or WNW‐ESE direction, which is the present orientation. The spreading direction in the Rio Grande rift, however, has been E‐W since the beginning of rifting about 31 Ma and reflects control of spreading by preexisting structural grain. NE‐SW extension occurred in the Grants‐Pie Town area of the Colorado Plateau and in the roofs of batholiths in the Socorro and Questa areas concurrently with E‐W spreading in the Rio Grande rift. Nearly orthogonal orientations of late Eocene‐Oligocene (38–32 Ma) paleostress indicators in southern New Mexico indicate a nearly isotropic middle Tertiary stress field. Both the western and eastern boundaries of the zone of E‐W spreading along the Rio Grande rift in northern New Mexico shifted 60–200 km eastward sometime between 23 and 16 Ma, perhaps coeval with rotation of the direction of regional extension. This eastward shift also coincided approximately with the renewal of volcanism following an early Miocene (22–17 Ma) lull. During the late Miocene (9–5 Ma), the eastern boundary of E‐W spreading shifted back to the present eastern margin of the Rio Grande rift. The N‐S to NNE‐SSW orientation of the least principal horizontal stress in the southern Great Plains province has persisted since at least 28 Ma. Stress province boundaries can be remarkably sharp with stress orientations changing by 90° within 30 km or less. The NE trending Jemez lineament transects the Colorado Plateau, Rio Grande rift (Basin and Range), and southern Great Plains stress provinces, but except for a transition zone along the present southeastern boundary of the Colorado Plateau, both paleostress and contemporary stress reflect the respective stress provinces, not the lineament. Chemical analyses of dated dikes reveal highly variable compositions but indicate that true basalts are more common among early rift (>20 Ma) volcanic rocks than is generally recognized. A histogram constructed from nearly 200 radiometric ages of igneous rocks in New Mexico between 104°W and 108°W longitude indicates that volcanism along the Rio Grande rift has been episodic with peaks at 37–34, 31–27, 26–22, 17–13,12–6, and 5–0 Ma.

Cenozoic continental deposits of New Mexico: An overview

Cenozoic rocks of New Mexico are wholly continental in origin and contrast markedly with most pre-Cenozoic deposits. Extensive stratigraphic and paleontologic work facilitates correlations and paleoenvironmental reconstructions; less extensive sedimentologic and petrologic studies allow detailed reconstructions of dispersal patterns and provenance locally. The accompanying papers summarizing recent research on the Cenozoic of New Mexico provide many new insights concerning paleontology, sedimentology, stratigraphy, and tectonics. The Cenozoic history of New Mexico can be divided into three phases on the basis of plate-tectonic events affecting the southwestern United States and styles of deformation, magmatism, and sedimentation in local areas. The Paleocene and Eocene were characterized by amagmatic basement deformation (Laramide orogeny), resulting in complex uplifts and basins, followed by widespread beveling. Massive outpourings of intermediate to silicic volcanics characterized much of the state during the Oligocene. The Neogene (Miocene to Holocene) has been characterized by extensional tectonics and bimodal volcanism, best expressed by the Rio Grande rift. Local sedimentary and paleontologic histories of the numerous Cenozoic basins of New Mexico reflect these regional tectonic processes.

The Mississippian System of New Mexico and Southern Arizona: ABSTRACT

Lower Mississippian rocks of New Mexico and southern Arizona (pre-zone 7 Tournaisian age) are unconformable on rocks of Late Devonian to Precambrian age. Mississippian rocks were deposited during transgression on a surface of low relief. Tournaisian transgression began in southern Arizona, depositing the Escabrosa Limestone and, in southwestern New Mexico, the Keating (207 m), Caballero (18 m), and Lake Valley (180 m) Formations. At the end of Tournaisian time, epicontinental seas flooded southern and central Arizona, depositing the younger parts of the Escabrosa and Redwall Limestones. Osagean seaways extended to central and northern New Mexico depositing Kelly (35 m) and Espiritu Santo (35 m) Formations. The Espiritu Santo consists of subtidal to supratidal quartz sands one and carbonate rocks. Zuni Highlands and Pedernal Highlands formed two low islands. The end of the Tournaisian is marked by marine regression, regional uplift, and erosion. Major regional marine transgression in early Visean is represented by parts of Escabrosa Limestone of southern Arizona, massive encrinites of the Hachita Formation (107 m) in southwestern New Mexico, basin carbonate rocks of the lower part of the Rancheria Formation (46 m) in south-central New Mexico, and the subtidal Tererro Formation (18 m) in north-central New Mexico. The Cowles Member (10 m) of the Tererro Formation indicates that sedimentation ceased in northern and central New Mexico in late Visean time. In southwestern New Mexico, the Paradise Formation (134 m) represents shallow-marine sediments and ranges rom zone 15 into zone 19 (late Visean and Namurian). The Rancheria Formation (69 m) and the Helms Formation (50 m) of south-central New Mexico are deep-water facies of the Paradise Formation. Pennsylvanian sedimentary rocks in southern Arizona and in New Mexico truncate Mississippian sedimentary rocks of Namurian, Visean, and Tournaisian age. End_of_Article - Last_Page 671------------

Correlation of some igneous rocks of New Mexico by the fusion method

Thirty‐six samples of igneous rocks and ten of metamorphic rocks, for which complete chemical analyses have been obtained, were powdered and fused into artificial glasses in the carbon arc of a spectrograph. Curves showing the relation between the indices of refraction of such glasses and the composition of the rock samples may be used to estimate the approximate composition and may aid in the correlation of igneous rocks. By this method, the SiO2 content of an unknown rock sample may be estimated to within three per cent of accuracy, whereas MgO, CaO, and the combined Fe2O3 + FeO may be estimated to within two per cent of accuracy. The method is not so satisfactorily applied to rhyolite and quartz latite, because these rocks do not readily form homogeneous glasses in the carbon arc.Aside from the effect of changing proportions of SiO2, the indices of refraction of the artificial glasses are determined, in decreasing order, by the oxides Fe3O2, TiO2, FeO, MgO, CaO, Na20, and K20.From comparative studies of variation diagrams, it can be shown why the method is particularly effective for volcanic rocks of intermediate composition, but may not be applied satisfactorily to altered, metamorphic, or other igneous rocks.

Correlation of Pennsylvanian Rocks of New Mexico

A typical section of Pennsylvanian rocks in central New Mexico is 1,500-1,800 feet thick. The lowest beds lie below the zone of Fusulina and contain Chaetetes milleporaceous, Spirifer rockymontanus, Spirifer occidentalis, Cleiothyridina orbicularis, and Mesolobus mesolobus. These beds are considered to be younger than Bend, Morrow, or lower Pottsville, and are believed to be correlative with the lower Cherokee, lower Atoka, upper Dornick Hills, lower Deese, lower Millsap Lake, lower Hartville, upper Pottsville, and lower Allegheny. The zone above this contains Fusulina euryteines, Wedekindellina euthysepta, W. excentrica, Chaetetes milleporaceous, Cleiothyrodina orbicularis, and Mesolobus mesolobus. These beds are correlated with the upper Cherokee, McCoy, upper Hermosa, middle Hartville, upper Millsap Lake, Haymond, upper Atoka, middle Deese, Boggy, Wetumka, Carbondale, and upper Allegheny. The equivalent of the Marmaton and Wewoka has not been recognized but is believed to be present. The succeeding zone is the equivalent of the Kansas City and Lansing, upper Hartville, middle Gaptank, middle Canyon, middle Hoxbar, and lower Conemaugh. It is characterized by Triticites nebraskensis, Echinoconchus semipunctatus, and Neospirifer latus. Next above is a zone containing numerous advanced species of Triticites, Enteletes hemiplicatus, Marginifera hystricula, and Chonetes transversalis. This zone is the equivalent of the lower Virgil, lower Cisco, upper Gaptank, and Vamoosa. Finally, the highest beds contain Triticites ventricosus and are probably the equivalent of a part of the Wabaunsee and the upper part of the Cisco (restricted).

Correlation of the Pennsylvanian Rocks of New Mexico: ABSTRACT

A typical section of Pennsylvanian rocks in central New Mexico is 1,500-1,800 feet thick. The lowest beds lie below the zone of Triticites and Wedekindellina and contain Chaetetes milleporaceous, Spirifer rockymontanus, Spirifer occidentalis, Cleiothyridina orbicularis, and Mesolobus mesolobus. These beds are considered to be younger than Bend, Morrow, or lower Pottsville, and are believed to correlate with the lower Cherokee, lower Atoka, upper Dornick Hills, lower Deese, lower Millsap Lake, lower Hartville, upper Pottsville, and lower Allegheny. The zone above contains Fusulina euryteines, Wedekindellina euthysepta, Wedekindellina excentrica, Chaetetes milleporaceous, Cleiothyridina orbicularis, and Mesolobus mesolobus. These beds are correlated with the upper Cherokee, McCoy, upper Hermosa, middle Hartville, upper Millsap Lake, middle Haymond, upper Atoka, middle Deese, Boggy, Wetumka, Carbondale, and upper Allegheny. The equivalent of the Marmaton and Wewoka has not been recognized but is believed to be present. The succeeding zone is the equivalent of the Kansas City and Lansing, upper Hartville, middle Canyon, middle Gaptank, middle Hoxbar, and lower Conemaugh. It is characterized by Triticites nebraskensis, Echinoconchus semipunctatus, and Neospirifer latus. Next above is a zone containing numerous advanced species of Triticites, Enteletes hemiplicatus, Marginifera hystricula, and Chonetes transversalis. This zone is the equivalent of the lower Virgil, lower Cisco, upper Gaptank, and Vamoosa. Finally, the highest Pennsylvanian beds in New Mexico contain Triticites ventricosus and are probably the equivalent of at least a part of the Wabaunsee and the upper part of the lower Cisco. End_of_Article - Last_Page 1705------------