Middle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications

Ruleman, Chester A.; Hudson, Adam M.; Thompson, Ren A.; Miggins, Daniel P.; Paces, James B.; Goehring, Brent M.

doi:10.1016/j.quascirev.2019.07.028

Cited by 24 publications

(10 citation statements)

References 31 publications

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“…Clustering of dates suggests that carbonate at this site formed during a period of ∼6 kyrs. In contrast, data for three clast rinds from the GM site, previously reported by Ruleman et al (2019), yielded a wider range of ages, from 44.2 ± 0.3 to 72.2 ± 2.0 ka, indicating an older age and longer period of carbonate accumulation within this well-developed soil profile. For the ZP and GM sites, δ 13 C values range 5.5‰ to 3.3‰ (Figure 7b), and ∆ 47 values range 0.630‰-0.690‰ (Table 3).…”

Section: Soil Carbonate Dating and Stable Isotope Resultsmentioning

confidence: 56%

“…Dense, crystalline carbonate was also targeted specifically to minimize the incorporation of dust-size detrital carbonate and silicate material in the authigenic soil carbonate, in order to reduce their contribution to the measured carbon, oxygen, and U-series isotope ratios used for paleoenvironmental reconstruction and geochronology. Previous studies showed that soil carbonates sampled this way in the SLV are relatively low in detritus component, evidenced by successful U-series dating with low detrital 232 Th for many of the exact samples used in this study (Johnstone et al, 2018;Ruleman et al, 2019). Specific depths for each sample zone were not carefully recorded.…”

Section: Field and Laboratory Samplingmentioning

confidence: 93%

“…Alluvial deposits of the SLV are typically coarse grained, consisting of paleofan or river gravels abandoned by incision in response to tectonic uplift along range fronts and/or base-level fall caused by Rio Grande incision (Ruleman et al, 2013(Ruleman et al, , 2019. These deposits are dominated by clasts of Proterozoic gneiss and schist in drainages issuing from the Sangre de Cristo Mountains, and by Neogene volcanic rocks from the San Juan Mountains.…”

Section: Study Area Climate and Soil Monitoring Sitesmentioning

confidence: 99%

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Clumped Isotopes Record a Glacial‐Interglacial Shift in Seasonality of Soil Carbonate Accumulation in the San Luis Valley, Southern Rocky Mountains, USA

Hudson,

Kelson,

Paces

et al. 2024

Geochem Geophys Geosyst

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Clumped isotope paleothermometry using pedogenic carbonates is a powerful tool for investigating past climate changes. However, location‐specific seasonal patterns of precipitation and soil moisture cause systematic biases in the temperatures they record, hampering comparison of data across large areas or differing climate states. To account for biases, more systematic studies of carbonate forming processes are needed. We measured modern soil temperatures within the San Luis Valley of the Rocky Mountains and compared them to paleotemperatures determined using clumped isotopes. For Holocene‐age samples, clumped isotope results indicate carbonate accumulated at a range of temperatures with site averages similar to the annual mean. Paleotemperatures for late Pleistocene‐age samples (ranging 19–72 ka in age) yielded site averages only 2°C lower, despite evidence that annual temperatures during glacial periods were 5–9°C colder than modern. We use a 1D numerical model of soil physics to support the idea that differences in hydrologic conditions in interglacial versus glacial periods promote differences in the seasonal distribution of soil carbonate accumulation. Model simulations of modern (Holocene) conditions suggest that soil drying under low soil pCO2 favors year‐round carbonate accumulation in this region but peaking during post‐monsoon soil drying. During a “glacial” simulation with lowered temperatures and added snowpack, more carbonate accumulation shifted to the summer season. These experiments show that changing hydrologic regimes could change the seasonality of carbonate accumulation, which in this study blunts the use of clumped isotopes to quantify glacial‐interglacial temperature changes. This highlights the importance of understanding seasonal biases of climate proxies for accurate paleoenvironmental reconstruction.

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Section: Soil Carbonate Dating and Stable Isotope Resultsmentioning

confidence: 56%

Section: Field and Laboratory Samplingmentioning

confidence: 93%

Section: Study Area Climate and Soil Monitoring Sitesmentioning

confidence: 99%

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Clumped Isotopes Record a Glacial‐Interglacial Shift in Seasonality of Soil Carbonate Accumulation in the San Luis Valley, Southern Rocky Mountains, USA

Hudson,

Kelson,

Paces

et al. 2024

Geochem Geophys Geosyst

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“…The range of the central population extends from the river networks of the Mississippi Watershed into the northern and western extents of the Interior Plains and encompasses a large east–west shift in habitat type from eastern temperate mixed forest to arid prairie grassland. The inferred assignment of the disjunct Rio Grande subpopulation of the southwestern United States to the central population can be explained by previously hypothesized Pleistocene connectivity between the Upper Arkansas River and the head of the Rio Grande at the San Luis Drainage Basin (Repasch et al, 2017; Rogers et al, 1992; Ruleman et al, 2019).…”

Section: Discussionmentioning

confidence: 87%

“…Similar to patterns found in numerous taxa (Conant & Collins, 1998;Peterson, 1999;Soltis et al, 2006) and snakes in particular (Burbrink et al, 2008;Burbrink, Bernstein, et al, 2021;Burbrink & Guiher, 2015;Fontanella et al, 2008;Myers et al, 2020), the deepest phylogenetic split within T. sirtalis is between a clade largely restricted to this region and all other clades, reflecting the shared effects of potential fidelity to the low elevation subtropical climate and the historic glacial cycles that repeatedly isolated the region from the mainland (Webb, 1990). Rio Grande at the San Luis Drainage Basin (Repasch et al, 2017;Rogers et al, 1992;Ruleman et al, 2019).…”

Section: Phylogeographymentioning

confidence: 99%

Biogeographic barriers and historic climate shape the phylogeography and demography of the common gartersnake

Jones,

Leaché,

Burbrink

2023

Journal of Biogeography

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AimCurrent distributions of widespread North American (NA) species have been shaped by Pleistocene glacial cycles, latitudinal temperature gradients, sharp longitudinal habitat transitions and the vicariant effects of major mountain and river systems that subdivide the continent. Within these transcontinental species, genetic diversity patterns might not conform to established biogeographic breaks compared to more spatially restricted taxa due to intrinsic differences or spatiotemporal differences. In this study, we highlight the effects of these extrinsic variables on genetic structuring by investigating the phylogeographic history of a widespread generalist squamate found throughout NA.LocationNorth America.TaxonCommon gartersnake, Thamnophis sirtalis.MethodsWe evaluate the effects of major river basins and the forest‐grassland transition into the Interior Plains on genetic structure patterns using phylogenetic, spatially informed population structure and demographic analyses of single nucleotide polymorphism data and address range expansion history with ecological niche modelling using locality and historic climate data.ResultsWe identify four phylogeographic lineages with varying degrees of connectivity between them. We find discordant population structure patterns between sex‐linked and autosomal loci with respect to the relationship between the central NA lineage relative to coastal lineages. We find support for southeast Pleistocene refugia where recent secondary contact occurred during the Last Glacial Maximum and evidence for both northern and southern refugia in western NA.Main ConclusionOur results provide strong evidence for a Pliocene origin for T. sirtalis in central‐southeastern NA preceding its rapid expansion across the continent prior to middle Pleistocene climate‐mediated lineage formation. We implicate major riverine networks within the Mississippi watershed in likely repeated westward expansion events across the Interior Plains. Finally, we corroborate prior conclusions that phenotypic differences between subspecies do not reflect shared evolutionary history and note that the degree of separation between inferred lineages warrants further investigation before any taxonomic revisions are proposed.

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Paleohydrologic history of pluvial lake San Agustin, New Mexico: Tracking changing effective moisture in southwest North America through the last glacial transition

Hudson

Quade

Holliday

et al. 2023

Quaternary Science Reviews

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Middle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications

Cited by 24 publications

References 31 publications

Clumped Isotopes Record a Glacial‐Interglacial Shift in Seasonality of Soil Carbonate Accumulation in the San Luis Valley, Southern Rocky Mountains, USA

Clumped Isotopes Record a Glacial‐Interglacial Shift in Seasonality of Soil Carbonate Accumulation in the San Luis Valley, Southern Rocky Mountains, USA

Biogeographic barriers and historic climate shape the phylogeography and demography of the common gartersnake

Paleohydrologic history of pluvial lake San Agustin, New Mexico: Tracking changing effective moisture in southwest North America through the last glacial transition

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