-Materials trapped in diamonds offer clues to life’s origin; point to oceans’ worth of water hidden in Deep Earth
Secretariat: Carnegie Institution for Science, Washington, DC
Thousands of diamonds formed hundreds of kilometers deep within the planet paved the way to many of the most historic discoveries about Deep Earth, to be shared and celebrated by more than 250 international scientists Oct. 24-26 at the US National Academy of Sciences, Washington DC
Scientists with the Deep Carbon Observatory, a 10-year collaboration involving 1,200 experts from 55 nations, produced 1,400 peer-reviewed papers — one of the largest international Earth science projects ever undertaken.
Multi-disciplinary teams of researchers explored how carbon moves between Earth’s interior, surface and atmosphere; where carbon came from; how much carbon the planet contains and in what forms (including bacteria and microbes in a subterranean ecosystem twice the size of Earth’s oceans); the limits of life on Earth, and how life began.
DCO’s discoveries have many applications, including inter-planetary research, the development of new materials, and potential carbon capture and storage strategies.
Deep Carbon Observatory highlights 10 top discoveries to celebrate first 10 years of a global investigation of Earth’s largest, least-known ecosystem
Washington DC – Thousands of diamonds, formed hundreds of kilometers deep inside the planet, paved the road to some of the 10-year Deep Carbon Observatory program’s most historic accomplishments and discoveries, being celebrated Oct. 24-26 at the US National Academy of Sciences.
Unsightly black, red, green, and brown specks of minerals, and microscopic pockets of fluid and gas encapsulated by diamonds as they form in Deep Earth, record the elemental surroundings and reactions taking place within Earth at a specific depth and time, divulging some of the planet’s innermost secrets.
Hydrogen and oxygen, for example, trapped inside diamonds from a layer 410 to 660 kilometers below Earth’s surface, reveal the subterranean existence of oceans’ worth of H2O — far more in mass than all the water in every ocean in the surface world.
This massive amount of water may have been brought to Deep Earth from the surface by the movement of the great continental and oceanic plates which, as they separate and move, collide with one another and overlap.
This subduction of slabs also buries carbon from the surface back into the depths, a process fundamental to Earth’s natural carbon balance, and therefore to life.
Knowledge of Deep Earth’s water content is critical to understanding the diversity and melting behaviors of materials at the planet’s different depths, the creation and flows of hydrocarbons (e.g. petroleum and natural gas) and other materials, as well as the planet’s deep subterranean electrical conductivity.
By dating the pristine fragments of material trapped inside other super-deep diamond “inclusions,” DCO researchers could put an approximate time stamp on the start of plate tectonics — “one of the planet’s greatest innovations,” in the words of DCO Executive Director Robert Hazen of the Carnegie Institution for Science. It started roughly 3 billion years ago, when the Earth was a mere 1.5 billion years old.
Diamond research accelerated dramatically thanks to the creation of DCO’s global network of researchers and led to some of the program’s most intriguing discoveries and achievements.
Diamonds from the deepest depths, often small with poor clarity, are not generally used as gemstones by Tiffany’s but are amazingly complex, robust and priceless in research. Inclusions offered DCO scientists samples of minerals that exist only at extreme high subterranean pressure, suggested three ways in which diamonds form, and put a rough time stamp on the beginning of plate tectonics on Earth.
While as many as 90% of analyzed diamonds were composed of carbon scientists expected in the mantle, some “relatively young” diamonds (up to a few hundred million years old) appear to include carbon from once-living sources; in other words, they are made of carbon returned to Deep Earth from the surface world.
Diamonds also revealed unambiguous evidence that, hundreds of miles down — well beyond the realm of living cells — “abiotic” methane forms.
Unravelling the mystery of deep abiotic energy helps explain how deep life in the form of microbes and bacteria is nourished, and fuels the proposition that life first originated and evolved far below (rather than migrating down from) the surface world.
Diamonds also enabled DCO scientists to simulate the extreme conditions of Earth’s interior.
DCO’s Extreme Physics and Chemistry community scientists used diamond anvil cells — a tool that can squeeze a sample tremendously between the tips of two diamonds, coupled with lasers that heat the compressed crystals — to simulate deep Earth’s almost unimaginable extreme temperatures and pressures.
Using a variety of advanced techniques, they analyzed the compressed samples, identified 100 new carbon-bearing crystal structures, and documented their intriguing properties and behaviors.
The work provides insights into how carbon atoms in Deep Earth “find one another,” aggregate, and assemble to form diamonds and other material.
Development of new materials; potential carbon capture and storage strategies
DCO’s discoveries and research are important and applicable in many ways, including the development of new materials and potential carbon capture and storage strategies.
DCO scientists are studying, for example, how the natural timescale for sequestration of carbon might be shortened.
The weathering of and microbial life inside Oman’s Samail Ophiolite — an unusual, large slab pushed up from Earth’s upper mantle long ago — offers a tutorial in nature’s carbon sequestration techniques, knowledge that might help offset carbon emissions caused by humans.
In Iceland, another DCO natural sequestration project, CarbFix, involves injecting carbon-bearing fluids into basalt and observing their conversion to solids.
A Decade of Discovery
Hundreds of scientists from around the world meet in Washington DC Oct. 24 to 26 to share and celebrate results of the wide-ranging, decade-long Deep Carbon Observatory — one of the largest global research collaborations in Earth sciences ever undertaken (venue, program: Deep Carbon 2019: Launching the Next Decade of Deep Carbon Science, https://deepcarbon.net/deep-carbon-2019).
With its Secretariat at the Carnegie Institution for Science in Washington DC, and $50 million in core support from the Alfred P. Sloan Foundation, multiplied many times by investments worldwide, a multidisciplinary group of 1,200 researchers from 55 nations worked for 10 years in four interconnected scientific “communities” to explore Earth’s fundamental workings, including:
* How carbon moves between Earth’s interior, surface and atmosphere
* Where Earth’s deep carbon came from, how much exists and in what forms
* How life began, and the limits — such as temperature and pressure — to Earth’s deep microbial life
They met the challenge of investigating Earth’s interior in several ways, producing 1,400 peer-reviewed papers while pursuing 268 projects that involved, for example:
* Studying diamonds, volcanoes, and core samples obtained by drilling on land and at sea
* Conducting lab experiments to mimic the extreme temperatures and pressures of Earth’s interior, and through theoretical modeling of carbon’s evolution and movements over deep time, and
* Developing new high tech instruments
DCO scientists conducted field measurements in remote and inhospitable regions of the world: ocean floors, on top of active volcanoes, and in the deserts of the Middle East.
Where instrumentation and models were lacking,
DCO scientists developed new tools and models to meet the challenge. Throughout
these studies, DCO invested in the next generation of deep carbon researchers,
students and early career scientists, who will carry on the tradition of
exploration and discovery for decades to come.