scholarly journals Supplemental Material: Major reorganization of the Snake River modulated by passage of the Yellowstone Hotspot

2021 ◽  
Author(s):  
Lydia M. Staisch ◽  
et al.
Keyword(s):  
Detrital Zircon ◽  
River Sediments ◽  
Snake River ◽  
Zircon Age ◽  
Yellowstone Hotspot ◽  
Dimensional Scaling ◽  
Relative Contribution ◽  
Location Map ◽  
River Plain ◽  
Best Fit

Figure S1: Detrital zircon age spectra from modern rivers.; Figure S2: Detrital zircon age spectra from fluvial and lacustrine sandstones; Figure S3: Shepard plots from Multi-Dimensional scaling (MDS) analysis comparing distance and disparity for four metrics of detrital zircon similarity; Figure S4: DZmix results for three hypothesized river networks; Figure S5: SRP sample location map and detrital unmixing results; Table S1: Modern and ancestral river detrital zircon sample locations, ages, and references; Table S2: U-Pb zircon age results for new modern and ancestral river sands; Table S3: Intercomparison results between modern and ancestral river sediments; Table S4: Best-fit DZmix results estimating the relative contribution of hypothesized sources to measured detrital zircon age spectra of ancestral river sands; Table S5: Best-fit DZMix results that estimate the relative contribution of Snake River Plain tributaries to Miocene-Pliocene Lake Idaho strata.

scholarly journals Supplemental Material: Major reorganization of the Snake River modulated by passage of the Yellowstone Hotspot

2021 ◽  
Author(s):  
Lydia M. Staisch ◽  
et al.
Keyword(s):  
Detrital Zircon ◽  
River Sediments ◽  
Snake River ◽  
Zircon Age ◽  
Yellowstone Hotspot ◽  
Dimensional Scaling ◽  
Relative Contribution ◽  
Location Map ◽  
River Plain ◽  
Best Fit

Figure S1: Detrital zircon age spectra from modern rivers.; Figure S2: Detrital zircon age spectra from fluvial and lacustrine sandstones; Figure S3: Shepard plots from Multi-Dimensional scaling (MDS) analysis comparing distance and disparity for four metrics of detrital zircon similarity; Figure S4: DZmix results for three hypothesized river networks; Figure S5: SRP sample location map and detrital unmixing results; Table S1: Modern and ancestral river detrital zircon sample locations, ages, and references; Table S2: U-Pb zircon age results for new modern and ancestral river sands; Table S3: Intercomparison results between modern and ancestral river sediments; Table S4: Best-fit DZmix results estimating the relative contribution of hypothesized sources to measured detrital zircon age spectra of ancestral river sands; Table S5: Best-fit DZMix results that estimate the relative contribution of Snake River Plain tributaries to Miocene-Pliocene Lake Idaho strata.

scholarly journals Major reorganization of the Snake River modulated by passage of the Yellowstone Hotspot

2021 ◽  
Author(s):  
Lydia M. Staisch ◽  
Jim E. O’Connor ◽  
Charles M. Cannon ◽  
Chris Holm-Denoma ◽  
Paul K. Link ◽  
...  
Keyword(s):  
Rocky Mountains ◽  
Detrital Zircon ◽  
Columbia River ◽  
Snake River Plain ◽  
Snake River ◽  
Columbia Basin ◽  
Northern Rocky Mountains ◽  
Yellowstone Hotspot ◽  
River Plain ◽  
Hells Canyon

The details and mechanisms for Neogene river reorganization in the U.S. Pacific Northwest and northern Rocky Mountains have been debated for over a century with key implications for how tectonic and volcanic systems modulate topographic development. To evaluate paleo-drainage networks, we produced an expansive data set and provenance analysis of detrital zircon U-Pb ages from Miocene to Pleistocene fluvial strata along proposed proto-Snake and Columbia River pathways. Statistical comparisons of Miocene-Pliocene detrital zircon spectra do not support previously hypothesized drainage routes of the Snake River. We use detrital zircon unmixing models to test prior Snake River routes against a newly hypothesized route, in which the Snake River circumnavigated the northern Rocky Mountains and entered the Columbia Basin from the northeast prior to incision of Hells Canyon. Our proposed ancestral Snake River route best matches detrital zircon age spectra throughout the region. Furthermore, this northerly Snake River route satisfies and provides context for shifts in the sedimentology and fish faunal assemblages of the western Snake River Plain and Columbia Basin through Miocene−Pliocene time. We posit that eastward migration of the Yellowstone Hotspot and its effect on thermally induced buoyancy and topographic uplift, coupled with volcanic densification of the eastern Snake River Plain lithosphere, are the primary mechanisms for drainage reorganization and that the eastern and western Snake River Plain were isolated from one another until the early Pliocene. Following this basin integration, the substantial increase in drainage area to the western Snake River Plain likely overtopped a bedrock threshold that previously contained Lake Idaho, which led to incision of Hells Canyon and establishment of the modern Snake and Columbia River drainage network.

In the Wake of the Yellowstone Hotspot

2000 ◽  
Author(s):  
Robert B. Smith ◽  
Lee J. Siegel
Keyword(s):  
National Park ◽  
Lava Flows ◽  
Snake River Plain ◽  
Snake River ◽  
Earthquake Activity ◽  
Basalt Lava ◽  
Mountain Ranges ◽  
Yellowstone Hotspot ◽  
A Chain ◽  
River Plain

Anyone who drives through southern Idaho on Interstates 84 or 15 must endure hours and hundreds of miles of monotonous scenery: the vast, flat landscape of the Snake River Plain. In many areas, sagebrush and solidified basalt lava flows extend toward distant mountain ranges, while in other places, farmers have cultivated large expanses of volcanic soil to grow Idaho’s famous potatoes. Southern Idaho’s topography was not always so dull. Mountain ranges once ran through the region. Thanks to the Yellowstone hotspot, however, the pre-existing scenery was destroyed by several dozen of the largest kind of volcanic eruption on Earth—eruptions that formed gigantic craters, known as calderas, measuring a few tens of miles wide. Some 16.5 million years ago, the hotspot was beneath the area where Oregon, Nevada, and Idaho meet. It produced its first big caldera-forming eruptions there. As the North American plate of Earth’s surface drifted southwest over the hotspot, about 100 giant eruptions punched through the drifting plate, forming a chain of giant calderas stretching almost coo miles from the Oregon—Nevada—Idaho border, northeast across Idaho to Yellowstone National Park in northwest Wyoming. Yellowstone has been perched atop the hotspot for the past 2 million years, and a 45-by-30-mile-wide caldera now forms the heart of the national park. After the ancient landscape of southern and eastern Idaho was obliterated by the eruptions, the swath of calderas in the hotspot’s wake formed the eastern two-thirds of the vast, 50-mile-wide valley now known as the Snake River Plain. The calderas eventually were buried by basalt lava flows and sediments from the Snake River and its tributaries, concealing the incredibly violent volcanic history of the Yellowstone hotspot. Yet we now know that the hotspot created much of the flat expanse of the Snake River Plain. Like a boat speeding through water and creating an arc-shaped wave in its wake, the hotspot also left in its wake a parabola-shaped pattern of high mountains and earthquake activity flanking both sides of the Snake River Plain.

scholarly journals Experimental Melting of Hydrothermally Altered Rocks: Constraints for the Generation of Low-δ18O Rhyolites in the Central Snake River Plain

2019 ◽  
Vol 60 (10) ◽  
pp. 1881-1902 ◽  
Author(s):  
Juliana Troch ◽  
Ben S Ellis ◽  
Chris Harris ◽  
Peter Ulmer ◽  
Anne-Sophie Bouvier ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Large Scale ◽  
Country Rock ◽  
Isotope Composition ◽  
Snake River Plain ◽  
Snake River ◽  
Crustal Material ◽  
Yellowstone Hotspot ◽  
River Plain ◽  
Source Materials

Abstract Quantifying the relative contributions of crustal versus mantle-derived melt is important for understanding how silicic magmas are generated, stored, and interact with country rock in trans-crustal magmatic systems. Low-δ18O rhyolitic ignimbrites and lavas erupted during Miocene volcanic activity in the central Snake River Plain (14–6 Ma) have been inferred to be the result of large-scale partial or bulk melting of pre-existing hydrothermally altered lithologies of the Idaho batholith and Challis volcanic field. In this study, we assess the melting behaviour of heterogeneously altered source materials via partial melting experiments over a range of run times at conditions of 750–1000°C and 1–2 kbar, and apply our observations to current models for the petrogenesis of low-δ18O rhyolites along the Yellowstone hotspot track. Partial melt produced in the experiments inherits the bulk oxygen isotope composition from hydrothermally altered peraluminous source materials independent of the melt fraction, excluding the possibility for preferential, disequilibrium melting of 18O-depleted mineral phases during incipient melting. We propose a new model to explain the generation of low-δ18O rhyolites in the central Snake River Plain, whereby mantle-derived magmas assimilate ∼30–40% of crustal material that was hydrothermally altered at high temperatures in two stages: (1) a preceding episode of hydrothermal alteration during intrusion of Eocene plutons (‘pre-existing source’); (2) syn-magmatic hydrothermal alteration within a nested caldera complex. During assimilation, dilution of peraluminous crustal lithologies with mantle-derived magma maintains the metaluminous character of rhyolites erupted along the Yellowstone hotspot track. These results link previous models favouring melting of either pre-existing or syn-magmatically altered lithologies for the generation of low-δ18O rhyolites along the Yellowstone hotspot track and provide direct experimental observation of the chemical processes occurring during assimilation processes in magmatic environments.

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