AI Article 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.
Article Abstract
Sampling an intact sequence of oceanic crust through lavas, dikes, and gabbros is necessary to advance the understanding of the formation and evolution of crust formed at mid-ocean ridges, but it has been an elusive goal of scientific ocean drilling for decades. Recent drilling in the eastern Pacific Ocean in Hole 1256D reached gabbro within seismic layer 2, 1157 meters into crust formed at a superfast spreading rate. The gabbros are the crystallized melt lenses that formed beneath a mid-ocean ridge. The depth at which gabbro was reached confirms predictions extrapolated from seismic experiments at modern mid-ocean ridges: Melt lenses occur at shallower depths at faster spreading rates. The gabbros intrude metamorphosed sheeted dikes and have compositions similar to the overlying lavas, precluding formation of the cumulate lower oceanic crust from melt lenses so far penetrated by Hole 1256D.
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| http://dx.doi.org/10.1126/science.1126090 | DOI Listing |
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