[Rockhounds] Geologists' Record-Breaking Drill Into Earth's Crust Reveals Mantle Secrets

[Kreigh Tomaszewski]

Like a mosquito tunneling into the skin to get at the rich feast within,
geologists poked a long, narrow drill into Earth's crust last year, pulling
out a treasury of geological goodness.

The result is a long cylinder of rock, known as a core sample, measuring a
record-shattering
<https://www.guinnessworldrecords.com/world-records/762820-longest-mantle-rock-core-sample>
1,268
meters (4,160 feet) in length. Made up of igneous rock that has been
chemically altered by seawater in a process known as serpentinization, the
cylinder has now been analyzed and its secrets revealed.

This thread of Earth-skin, extracted from the ocean depths, is a repository
of information that can be used to plumb Earth's mysterious mantle, the
layer of solid volcanic rock that separates the crust from the core.

"We recovered a 1268-meter-long section of serpentinized oceanic mantle
peridotite," writes a team
<http://www.science.org/doi/10.1126/science.adp1058> led by petrologist and
geochemist Johan Lissenberg of Cardiff University in the UK.

"The nearly continuous recovery provides an opportunity to obtain a robust
and quantitative lithological, mineralogical, structural, and alteration
inventory of the upper mantle."

Earth's mantle, to we surface-crawlers, is frustratingly out of reach. At
its thinnest, Earth's crust is 6 kilometers (3.7 miles) thick.

We do have the tools to drill down pretty deep
<https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole> from the
continental surface – as evidenced by the mind-blowing 12,262-metre deep
Kola borehole in Russia – but the continental crust is a lot thicker
<https://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuity> than
the oceanic crust.

https://www.sciencealert.com/geologists-record-breaking-drill-into-earths-crust-reveals-mantle-secrets