First Results from HOTSPOT: The Snake River Plain Scientific Drilling Project, Idaho, U.S.A.

J W Shervais,K E Potter,D R Schmitt,J P Evans,L Morgan,T Lachmar,D Nielson,L D Champion,A A Prokopenko,J M Glen,J A Kessler,D D Blackwell,L M Liberty,E H Christiansen,W C Pat Shanks

doi:10.5194/sd-15-36-2013

Abstract

HOTSPOT is an international collaborative effort to understand the volcanic history of the Snake River Plain (SRP). The SRP overlies a thermal anomaly, the Yellowstone-Snake River hotspot, that is thought to represent a deep-seated mantle plume under North America. The primary goal of this project is to document the volcanic and stratigraphic history of the SRP, which represents the surface expression of this hotspot, and to understand how it affected the evolution of continental crust and mantle. An additional goal is to evaluate the geothermal potential of southern Idaho. Project HOTSPOT has completed three drill holes. (1) The Kimama site is located along the central volcanic axis of the SRP; our goal here was to sample a long-term record of basaltic volcanism in the wake of the SRP hotspot. (2) The Kimberly site is located near the margin of the plain; our goal here was to sample a record of high-temperature rhyolite volcanism associated with the underlying plume. This site was chosen to form a nominally continuous record of volcanism when paired with the Kimama site. (3) The Mountain Home site is located in the western plain; our goal here was to sample the Pliocene-Pleistocene transition in lake sediments at this site and to sample older basalts that underlie the sediments. We report here on our initial results for each site, and on some of the geophysical logging studies carried out as part of this project. doi:<a href="http://dx.doi.org/10.2204/iodp.sd.15.06.2013" target="_blank">10.2204/iodp.sd.15.06.2013</a>

Highlights

Mantle plumes are thought to play a crucial role in the Earth’s thermal and tectonic evolution
We report here on our initial results for each site, and on some of the geophysical logging studies carried out as part of this project
The central questions addressed by Project HOTSPOT are as follows: how do mantle hotspots interact with continental lithosphere, and how does this interaction affect the geochemical evolution of mantle-derived magmas and of the continental lithosphere?

Summary

Introduction

Mantle plumes are thought to play a crucial role in the Earth’s thermal and tectonic evolution. They have long been implicated in the rifting and breakup of continents, and plume-derived melts play a significant role in the creation and modification of the continental crust and mantle lithosphere (DePaolo and Manga, 2003; DePaolo and Weis, 2007). Much of our understanding of mantle plumes comes from plume tracks in oceanic lithosphere, but oceanic lithosphere is recycled back into the mantle by subduction, and evidence for mantle plumes in the oceanic realm is destroyed. If we are to understand plume-related volcanism prior to 200 Ma, we must learn how plume-derived magmas inter-.

Objectives

Results

Conclusion