Rhyolitic volcanism of the central Snake River Plain: a review

The central Snake River Plain (CSRP) of southern Idaho and northern Nevada, USA, forms part of the Columbia River-Yellowstone large igneous province. Volcanic rocks of the province are compositionally bimodal (basalt-rhyolite), and the rhyolites produce a broadly time-transgressive record of a hotspot which is currently located under Yellowstone. Snake River Plain rhyolites represent hot (>850°C), dry magmas and have field characteristics consistent with high emplacement temperatures. Individual ignimbrite sheets reach 1,000km3 and exhibit little to no compositional zonation on a large scale but reveal considerable complexity on a crystal scale, particularly with regard to pyroxene compositions. Multiple pyroxene compositions may exist in a single ignimbrite which, along with multiple glass compositions in widely dispersed fallout tephra, suggests complex storage of rhyolite prior to eruption. Unlike most igneous rocks, the mineral cargo of the CSRP rhyolites exhibits little isotopic variability, with unimodal 87Sr/86Sr values returned from plagioclase grains inferred to represent the combination of strong crystal-melt coupling and rapid diffusional re-equilibriation. All the rhyolites within the CSRP have a characteristic low-δ 18O signature; with >20,000km3 of rhyolite exhibiting this depletion, the CSRP represents the largest low-δ 18O province on Earth. The low-18O nature of the rhyolites requires assimilation of hydrothermally altered materials which may be from altered Eocene batholithic rocks or from down-dropped intra-caldera tuffs. The wide range of crustal assimilants, with highly variable radiogenic isotope characteristics, available in the CSRP is permissive of a variety of petrogenetic models based on radiogenic isotopic dat

SNAKE: The Plain and Its People

Idaho\u27s longest river curves west through desert landscapes, cutting deep through ancient formations, flowing through space and time. How have humans dealt with the desert? How have we been shaped by the land? SNAKE: The Plain and Its People explores the physical and ecological roots of Idaho civilization through science, social science, photography and art.https://scholarworks.boisestate.edu/fac_books/1371/thumbnail.jp

Scrapheap Challenge: A novel bulk-bone metabarcoding method to investigate ancient DNA in faunal assemblages

Highly fragmented and morphologically indistinct fossil bone is common in archaeological and paleontological deposits but unfortunately it is of little use in compiling faunal assemblages. The development of a cost-effective methodology to taxonomically identify bulk bone is therefore a key challenge. Here, an ancient DNA methodology using high-throughput sequencing is developed to survey and analyse thousands of archaeological bones from southwest Australia. Fossils were collectively ground together depending on which of fifteen stratigraphical layers they were excavated from. By generating fifteen synthetic blends of bulk bone powder, each corresponding to a chronologically distinct layer, samples could be collectively analysed in an efficient manner. A diverse range of taxa, including endemic, extirpated and hitherto unrecorded taxa, dating back to c.46,000 years BP was characterized. The method is a novel, cost-effective use for unidentifiable bone fragments and a powerful molecular tool for surveying fossils that otherwise end up on the taxonomic “scrapheap”

Geology of the Ely-Hoyt Lakes District, northeastern Minnesota

Description of the bedrock geology in the Ely-Hoyt Lakes area, northeastern Minnesot

M-011 Outcrop map of southern part of Duluth Complex and associated Keweenawan rocks, St. Louis and Lake Counties, Minnesota

Scale 1:250,000