Multiple intrusions, 2147′

Today we finally saw our first clear intrusion in the rock core, in fact we saw multiple intrusions.  These intrusions are dikes that fed magma to surface eruptions in the distant past, and the magma that cooled into solid rock at depth and never reached the surface is what we’re able to sample by drilling now. Encountering dikes by drilling at the rim of the Lāna‘i caldera was expected, the surprise was that we drilled about 600 feet before finding some! In the picture below, you can see a high-angle dike that intruded into the overlying rock in the far left column of the core box, and some of the features of the dike rock itself like vesicle banding and a slight coarsening of the groundmass (indicated by the gradation to lighter gray color) in the rest of the box. As of this evening, we’ve processed rock core to a depth of 2147 ft below the surface.

A high angle intrusive contact (far left column) and the dike rock associated with it.
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