Nelia W. Dunbar

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[1] Air mass trajectories in the Southern Hemisphere provide a mechanism for transport to and deposition of volcanic products on the Antarctic ice sheet from local volcanoes and from tropical and subtropical volcanic centers. This study extends the detailed record of Antarctic, South American, and equatorial volcanism over the last 12,000 years using(More)
A total of 24 tephra-bearing volcanic layers have been recognized between 550 and 987 m depth in the Siple Dome A (SDM-A) ice core, in addition to a number already recognized tephra in the upper 550 m (Dunbar et al., 2003; Kurbatov et al., 2006). The uniform composition and distinctive morphological of the particles composing these tephra layers suggest(More)
[1] We present a new method for inferring the relative location (lowversus high-southern latitude), and therefore the potential climatic impact, of past eruptions based on the particle size distribution (PSD) of micrometer-sized ash measured continuously in the West Antarctic Ice Sheet (WAIS) Divide ice core. We find that particles from a high-southern(More)
We present a new surface-balance and ice-motion dataset derived from high-precision GPS measurements from a network of steel poles within three icefields of the Allan Hills blue-ice area, Antarctica. The surveys were conducted over a 14 year time period. Ice-flow velocities and massbalance estimates for the main icefield (MIF) are consistent with those from(More)
High-resolution Fourier transform infrared (FTIR) spectroscopy has been used to document the presence of hydrogen, to estimate its concentration, and to document its oxygen speciation in anorthoclase crystals and associated melt inclusions from Mount Erebus, Antarctica. Synchrotron-generated infrared radiation, 100 to 1000 times brighter than(More)
A mammoth jaw found as a large clast in the channel of Matanza Arroyo near Socorro, New Mexico, is here termed the Matanza mammoth. Cemented pebbly sandstone attached to the jaw shows that it was reworked from partially cemented ancestral Rio Grande sediments exposed in the channel 50–90 m upstream. This jaw is from one of the geologically oldest and most(More)
Since 2000, significant collections of Latest Miocene hominin fossils have been recovered from Chad, Kenya, and Ethiopia. These fossils have provided a better understanding of earliest hominin biology and context. Here, we describe five hominin teeth from two periods (ca. 5.4 Million-years-ago and ca. 6.3 Ma) that were recovered from the Adu-Asa Formation(More)
The West Antarctic ice sheet (WAIS) is highly vulnerable to collapsing because of increased ocean and surface temperatures. New evidence from ice core tephra shows that subglacial volcanism can breach the surface of the ice sheet and may pose a great threat to WAIS stability. Micro-CT analyses on englacial ice core tephra along with detailed shard(More)
In situ recovery (ISR) operations have been proposed to recover uranium from sandstone-hosted uranium deposits in New Mexico. ISR (also known as in situ leaching, solution mining, solution-leach mining, leach mining) is conducted by wells that circulate native groundwater, amended with oxygen (or other forms of oxidant) to dissolve the uranium and gaseous(More)