Pliocene–Holocene deformation in the southern Rio Grande rift as inferred from topography and uplifted terraces of the Franklin Mountains, southern New Mexico and western Texas

Armour, L.K.; Langford, Richard P.; Ricketts, Jason W.

doi:10.1130/ges01572.1

Cited by 4 publications

(4 citation statements)

References 54 publications

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“…Prior to this, the Rio Grande emptied into closed basins (having no external drainage) which were formed by the opening of the Rio Grande rift 35 million years ago. Over time, the ancestral Rio Grande progressively integrated basins from north to south, eventually reaching Texas around 2 million years ago, at which time the river bifurcated and began flowing to the east side of the Franklin mountains—spilling through Fillmore Gap between the Organ and Franklin Mountains (Armour et al, 2018 ; Mack et al, 2006 ; Seager et al, 1984 ). The extent to which changes in the ancestral Rio Grande resulted in the deposition and erosion of soils habitable by G .…”

Section: Discussionmentioning

confidence: 99%

“…Within this narrow gap, the soils immediately adjacent to the river channel consist of the Delnorte-Cuntio Association-shallow gravelly loam over caliche or gravelly sandy loams (Jaco, 1971) through Fillmore Gap between the Organ and Franklin Mountains (Armour et al, 2018;Mack et al, 2006;Seager et al, 1984). The extent to which changes in the ancestral Rio Grande resulted in the deposition and erosion of soils habitable by G. arenarius (and, therefore, facilitating or blocking dispersal) is unknown, but it cannot be ruled out that the White Sands and Socorro Co. populations were once connected along the ancestral Rio Grande River valley west of the Oscura and San Andres mountains.…”

Section: Factors Impacting Distributionmentioning

confidence: 99%

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Population genetic structure of a Chihuahuan Desert endemic mammal, the desert pocket gopher,Geomys arenarius

Pfau,

Kozora,

Gatica‐Colima

et al. 2023

Ecology and Evolution

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The biogeographic history of the Chihuahuan Desert is complex, driven by numerous physiographic events and climatic changes. This dynamic history would have influenced the flora and fauna of the region including the desert pocket gopher, Geomys arenarius, a subterranean rodent endemic to the northern Chihuahuan Desert. G. arenarius is restricted to sandy soils and are considered to have a disjunct distribution. Two subspecies are recognized: G. a. arenarius and G. a. brevirostris. We used multilocus nuclear (amplified fragment length polymorphisms) and mitochondrial DNA (ND2) sequence data to uncover patterns of genetic diversity within and among populations of G. arenarius. We evaluated correspondence of genetic patterns to traditionally accepted subspecies boundaries, mapped the distribution of potentially suitable soils to identify barriers or corridors to dispersal and to guide future survey efforts, provided evidence that could be used to recognize distinct population segments, and quantified genetic diversity within populations. Both datasets were largely concordant and demonstrated hierarchical patterns of genetic divergence. The greatest divergence was consistent with the two recognized subspecies. Mapping of potentially habitable soils revealed likely barriers to dispersal contributing to the allopatric pattern of geographic distribution and areas, which may be occupied by G. arenarius but not yet documented. Because G. arenarius is restricted to soils with high sand content, and these habitable soils are disjunct within the region occupied by this species, historical factors that impacted soil deposition and deflation likely contributed to the observed patterns of genetic divergence. Genetic diversity was higher within populations of the southern subspecies (G. a. arenarius) compared to G. a. brevirostris. This may be due to a greater availability of continuous suitable soils within the range of G. a. arenarius or higher density due to greater food availability (currently or historically)—both of which could allow for a higher effective population size.

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Section: Discussionmentioning

confidence: 99%

Section: Factors Impacting Distributionmentioning

confidence: 99%

Population genetic structure of a Chihuahuan Desert endemic mammal, the desert pocket gopher,Geomys arenarius

Pfau,

Kozora,

Gatica‐Colima

et al. 2023

Ecology and Evolution

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“…Rio Grande rift-associated uplift of the Franklin Mountains is thought to have occurred in the Miocene (Harbour, 1972). Quaternary uplift is evidenced by bowed and deformed terraces that flank the east and west sides of the Franklin Mountains (Armour et al, 2018), and based on fault scarp morphology, the latest movement along the East Franklin boundary fault occurred in the Pleistocene or early Holocene (Machette, 1987).…”

Section: Franklin Mountainsmentioning

confidence: 99%

Thermochronological transect across the Basin and Range/Rio Grande rift transition: Contrasting cooling histories in contiguous extensional provinces

et al. 2021

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The Basin and Range and Rio Grande rift (RGR) are regions of crustal extension in southwestern North America that developed after Laramide-age shortening, but it has not been clear whether onset and duration of extension in these contiguous extensional provinces were the same. We conducted a study of exhumation of fault blocks along a transect from the southeastern Basin and Range to across the RGR in southern New Mexico. A suite of 128 apatite and 63 zircon (U-Th)/He dates (AHe and ZHe), as well as 27 apatite fission-track (AFT) dates, was collected to investigate the cooling and exhumation histories of this region. Collectively, AHe dates range from 3 to 46 Ma, ZHe dates range from 2 to 288 Ma, and AFT dates range from 10 to 34 Ma with average track lengths of 10.8–14.1 µm. First-order spatiotemporal trends in the combined data set suggest that Basin and Range extension was either contemporaneous with Eocene–Oligocene Mogollon-Datil volcanism or occurred before volcanism ended ca. 28 Ma, as shown by trends in ZHe data that suggest reheating to above 240 °C at that time. AHe and ZHe dates from the southern RGR represent a wider range in dates that suggest the main phase of cooling occurred after 25 Ma, and these blocks were not reheated after exhumation. Time-temperature models created by combining AHe, AFT, and ZHe data in the modeling software HeFTy were used to interpret patterns in cooling rate across the study area and further constrain magmatic and/or volcanic versus faulting related cooling. The Chiricahua Mountains and Burro Mountains have an onset of rapid extension, defined as cooling rates in excess of >15 °C/m.y., at ca. 29–17 Ma. In the Cookes Range, a period of rapid extension occurred at ca. 19–7 Ma. In the San Andres Mountains, Franklin Mountains, Caballo Mountains, and Fra Cristobal range, rapid extension occurred from ca. 23 to 9 Ma. Measured average track lengths are longer in Rio Grande rift samples, and ZHe dates of >40 Ma are mostly present east of the Cookes Range, suggesting different levels of exhumation for the zircon partial retention zone and the AFT partial annealing zone. The main phase of fault-block uplift in the southern RGR occurred ca. 25–7 Ma, similar to what has been documented in the northern and central sections of the rift. Although rapid cooling occurred throughout southern New Mexico, thermochronological data from this study with magmatic and volcanic ages suggest rapid cooling was coeval with magmatism in the Basin and Range, whereas in the Rio Grande rift cooling occurred during an amagmatic gap. These observations support a model where an early phase of extension was facilitated by widespread ignimbrite magmatism in the southeastern Basin and Range, whereas in the southern Rio Grande rift, extension started later and continues today and may have occurred between local episodes of basaltic magmatism. These differences in cooling history make the Rio Grande rift tectonically distinct from the Basin and Range. We infer based on geologic and thermochronological evidence that the onset of extension in the southern Rio Grande rift occurred at ca. 27–25 Ma, significantly later than earlier estimates of ca. 35 Ma.

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“…The basins surrounding the Franklin Mountains not only preserve sediment sourced from the range but also sediment that was carried by the ancestral Rio Grande river (e.g. Armour et al, 2018).…”

Section: Franklin Mountainsmentioning

confidence: 99%

Fault Kinematics of the Southern Rio Grande Rift: Exploring the Possibility of Fault Reactivation

Gonzalez¹

2019

Geological Society of America Abstracts With Programs

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The region in and around the southern Rio Grande rift has experienced a long and complex tectonic history since the Precambrian era. In addition to recording extension directions due to the opening of the Rio Grande rift, faults can also possibly record contractional deformation related to the Laramide orogeny, extension along the boundary of the Mesozoic Chihuahua Trough, and possibly strike-slip movement since the Precambrian related to the Texas Lineament. The northern and central segments of the Rio Grande rift preserve mostly N-S-trending faults, whereas the southern segment preserves NW-SE-trending faults. The main hypothesis to test is that although both fault sets were active during extension of the rift, the NW-SE trending faults may preserve evidence for underlying reactivated older faults, possibly dating back to the Precambrian. Using exposed faults in the southern rift, a paleostrain analysis was performed to determine maximum extension (S₁) and maximum shortening (S₃) directions. Fault kinematic data was collected from six mountain ranges in southern New Mexico and western Texas. Results support a model where the entire Rio Grande rift evolved within a general EWdirected extensional stress field. This resulted in extension along NS-trending dip-slip faults in the northern and central segments of the rift. In contrast, in the southern rift EW-directed extension may have been accomplished through reactivation of much older underlying structures in the crust, resulting in NW-trending dip-slip and oblique-slip faults. This observation could help explain the geometric "bend" in the Rio Grande rift as it continues south into Texas and northern Mexico. Further investigation of the kinematics is underway and is critical to understanding the importance of reactivation during continued extension within the southern Rio Grande rift. vi

show abstract

Pliocene–Holocene deformation in the southern Rio Grande rift as inferred from topography and uplifted terraces of the Franklin Mountains, southern New Mexico and western Texas

Cited by 4 publications

References 54 publications

Population genetic structure of a Chihuahuan Desert endemic mammal, the desert pocket gopher,Geomys arenarius

Population genetic structure of a Chihuahuan Desert endemic mammal, the desert pocket gopher,Geomys arenarius

Thermochronological transect across the Basin and Range/Rio Grande rift transition: Contrasting cooling histories in contiguous extensional provinces

Fault Kinematics of the Southern Rio Grande Rift: Exploring the Possibility of Fault Reactivation

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