Comment on "A new class of plumes"

50th anniversary of recovery of the first basalt core by means of scientific ocean drilling

Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149

5th April, 2011

April 1, 2011, April Fools' Day, was the 50th anniversary of recovery of the first basalt core by means of scientific ocean drilling. This was at the Experimental Mohole test site off Guadalupe Island, Mexico, southeast of San Diego. The drilling took place on a barge, CUSS I (Figure 1), with dynamic positioning in relation to a beacon on the seafloor sustained by 4 large outboard motors.

Participating scientists (Figure 2) included chief scientist and radiolarian paleontologist William R. Riedel (with glasses and hands to mouth), Gustav Arrhenius (far right), and the Director of Scripps Institution of Oceanography, Roger Revelle (to Riedel's left). This was the first successful scientific ocean drilling in deep water, and was the necessary precursor to design and construction of drilling vessels such as Glomar Challenger, used by the Deep Sea Drilling Project, and JOIDES Resolution. Among other luminaries, John Steinbeck was aboard CUSS I and he wrote an article that appeared in Life Magazine a week or so later. In the photograph, Steinbeck is the man with his back to the camera on the left.

Figure 1: The barge CUSS I.

Figure 2: Participating scientists: A photograph taken in the galley. William R. Riedel (with glasses and hands to mouth). Next to him, facing the camera, from left to right, are Fritz Goro, Roger Revelle, and Gustav Arrhenius.

Some of this information was recently featured in an article by Damon Teagle and Benoit Isledefonse, published in Nature. Next week they will head out as co-chief scientists on IODP Expedition 335 aboard JOIDES Resolution to deepen Hole 1256. This is an open hole that thus far reaches all the way through sheeted dikes, just into the top of the gabbroic layer in the eastern Pacific. Further deepening of the hole should penetrate rock that once was at the level of the seismically detected melt lens of the East Pacific Rise. This is expected to provide a complete section for in situ evaluation of the important Layer 2 - Layer 3 transition.

Figure 3 shows a mounted and polished basalt chip from the Experimental Mohole drilling. Recent Cr-spinel analysis of this chip, which is fairly primitive basalt, somewhat figuratively represents the closest we have come to the mantle, by drilling directly through basalts in a Mohole venture.

Figure 3: Polished chip of basalt from the Experimental Mohole drilling core.

Reference

Teagle, D. & B. Ildefonse, Journey to the mantle of the Earth, Nature, 47, 437-439, 2011.