Publications by authors named "Jeffrey Alt"
Article Synopsis
- The subseafloor igneous basement contains a vast microbial habitat, but little is known about the life that exists there, especially in older sections over 65 million years old.
- Recent research tested this by analyzing samples from the Louisville Seamount Chain, finding varied cell biomass indicating the presence of microbial life in rocks older than 65 million years.
- The dominant bacterial genes found suggest active microbial processes related to nitrogen, sulfur, metal transformations, and hydrocarbon breakdown, highlighting a much broader range of subseafloor life than previously recognized.
Sediment-covered basalt on the flanks of mid-ocean ridges constitutes most of Earth's oceanic crust, but the composition and metabolic function of its microbial ecosystem are largely unknown. By drilling into 3.5-million-year-old subseafloor basalt, we demonstrated the presence of methane- and sulfur-cycling microbes on the eastern flank of the Juan de Fuca Ridge.
View Article and Find Full Text PDFSubstantial stall waste is generated from horses on softwood bedding. The methane potential (G(pot)) of horse manure and constructed mixtures of stall waste with softwood bedding was determined at 35°C. G(pot) of 68, 191 and 273 mL/g volatile solids (VS) were estimated for three separate batches of horse manure, indicating variability in the material.
View Article and Find Full Text PDFProxies for past seawater chemistry, such as Mg/Ca and Sr/Ca ratios, provide a record of the dynamic exchanges of elements between the solid Earth, the atmosphere, and the hydrosphere and the evolving influence of life. We estimated past oceanic Mg/Ca and Sr/Ca ratios from suites of 1.6- to 170-million-year-old calcium carbonate veins that had precipitated from seawater-derived fluids in ocean ridge flank basalts.
View Article and Find Full Text PDFArticle Synopsis
- Sampling intact oceanic crust through various geological layers is crucial for understanding mid-ocean ridge formation, yet remains a scientific challenge.
- Recent drilling at Hole 1256D in the eastern Pacific Ocean successfully accessed gabbro at a depth of 1157 meters, providing insight into crust formed at superfast spreading rates.
- The discovery of gabbros, which reflect crystallized melt lenses, aligns with seismic predictions that suggest shallower melt lenses occur faster spreading rates and suggests a complex interaction with the surrounding metamorphosed dikes and lavas.