Publications by authors named "Jeffrey C Alt"
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 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.