Publications

Options for selecting a high Na concentration mineral for instrument calibration that are suitably stable under the electron beam are limited [1]. NaCl (approximately a mass fraction of 39 % Na) is not practical for use alongside other embedded and polished materials in a mounted block of standards. While albite (NaAlSi3O8; approximately a mass fraction of 8 % Na) represents a typical...

Cultures throughout history have valued jadeite jade (hereinafter jade), a natural material assemblage composed predominately of the NaAl endmember pyroxene, jadeite (NaAlSi2O6) that is prized for its mechanical properties and enticing coloration [1, 2]. The geological setting for the formation of jadeite-rich rocks and associated complex geochemical phenomena is well documented in the...

Angrite meteorites represent interesting sampling of planetary crustal environments. Quench-textured angrites with strong crystal zoning originated from the shallow surface region, with evidence of reducing conditions during solidification. Plutonic angrites have more coarse-grained igneous and metamorphic textures with comparatively less zoning and are interpreted as having equilibrated...

Planet Earth has evolved over the past 4.5 billion years from an entirely anoxic planet with possibly a different tectonic regime to the oxygenated world with horizontal plate tectonics that we know today. For most of this time, Earth has been inhabited by a purely microbial biosphere albeit with seemingly increasing complexity over time. A rich record of this geobiological evolution...

The East Anatolian Fault Zone (EAFZ) is a plate-bounding strike-slip fault capable of hosting large earthquakes, as demonstrated by the extremely damaging February 2023 Mw 7.8 and Mw 7.7 mainshocks of the Kahramanmaraş earthquake sequence. Deformation related to this boundary, part of the Anatolia-Arabia-Africa (A3) Triple Junction, is diffuse, as was shown by part of this earthquake...

High-grade ores in low-sulfidation epithermal deposits commonly consist of banded veins containing quartz as the most abundant gangue mineral. Previous studies suggested that at least some of the quartz has formed as a product of recrystallization from a noncrystalline silica precursor. Detailed petrographic studies confirm that high-grade veins from the

No abstract available.

Sulfur (S) is a central element in global biogeochemical cycling and Earth’s redox evolution. Minerals that contain S are an important record of local environmental conditions at the time of their formation based on chemical speciation and redox. However, the oxidation state of S for hundreds of different S-containing minerals and thousands of S-containing mineral localities is unknown...

Deformation in southeastern Alaska and southwest Yukon is governed by the subduction and translation of the Pacific-Yakutat plates relative to the North American plate in the St. Elias region. Despite notable historical seismicity and major regional faults, studies of the region between the Fairweather and Denali faults are complicated by glacial coverage and the remote setting. In the...

No abstract available.

The 1.1 Ga Midcontinent Rift System (MRS) has been investigated in the Lake Superior region for more than a century. The most influential geophysical data for modern paradigms has come from seismic-reflection profiles collected by the Great Lakes International Multidisciplinary Program on Crustal Evolution (GLIMPCE) in the late 1980s. We are revisiting seismic-reflection GLIMPCE line C...

The Sangre de Cristo Mountains of southern Colorado and northern New Mexico, USA, contain an unusual combination of thick- and thin-skinned contractional structures involving both basement and cover rocks in the Laramide Rocky Mountain foreland. These structures are truncated by down-faulted extensional basins to the east and west. Together with synorogenic sediments, these structures...