The mid-ocean ridge system encompasses 70,000 kilometers of volcanic activity caused by spreading of the oceanic plates. Beneath the ridges, magma must travel through several kilometers of crust before it erupts. Due to our inability to directly observe what happens beneath the volcanoes, erupted material is regularly studied to better understand subsurface processes. Large crystals in erupted lava form at depth and preserve a chemical fingerprint of the conditions in which they grew, allowing us to have a window into the behavior of magma below the ridges. Using these crystals, Amy Lange and colleagues determined that the crystals often interact with multiple magmas beneath the ridge prior to eruption. Furthermore, the range of chemical values observed in a limited number of crystals approaches the range observed for erupted lavas at an entire ridge segment. The chemical diversity preserved in the crystals suggests that a wide range of magmas are delivered below mid-ocean ridge volcanoes on a small enough spatial and temporal time scale to be sampled by individual crystals. They observed these phenomena at the multiple ridges examined in this global study. These results suggest that magma interactions during transport are important for modulating the types of lavas that are eventually erupted.
Thick evaporites and early rifting in the Guaymas Basin, Gulf of California
Nathaniel C. Miller, Marine Geology and Geophysics, Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program, 266 Woods Hole Road, Woods Hole, Massachusetts 02543, USA; and Daniel Lizarralde, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, 266 Woods Hole Ro
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Geological Society of America