OBSERVATIONS OF THE CARBON SEQUESTRATION POTENTIAL OF THE COAST RANGE OPHIOLITE, CALIFORNIA

Global warming and the environmental repercussions that follow present a threat to a considerable portion of the global population and biological communities. With populous countries like China and India growing and developing their transportation infrastructure, greenhouse gas levels show no sign of decreasing. One way to suppress global warming is to reduce the concentration of CO₂ in the atmosphere.

Carbon sequestration via mineralization is one of the primary methods of carbon dioxide capture available. Mafic and ultramafic rocks are ideal for this purpose as they react readily with carbon dioxide to form carbonate minerals in which the carbon is stable. Many ultramafic rocks contain olivine and pyroxines, which react with carbon-rich fluids via

Mg₂SiO₄(Mg-olivine) + CaMgSi₂O₆ (CaMg-pyroxene) + 2CO₂ + 2H₂O → Mg₃Si₂O₅(OH)₄ (serpentine) + CaCO₃(calcite) + (MgCO₃)(magnesite) (Kellemen and Matter 2008)

Serpentinite, another ultramafic rock, contains serpentine minerals, which also react with CO₂ via

Mg₃Si₂O₅(OH)₄ (serpentine) + 3CO₂ → 3MgCO₃(magnesite) + 2SiO₂(silica) + 2H₂O (O'Connor et al. 2001)

In both cases, the CO₂ is stabilized in carbonates. Additionally, the products calcite, magnesite and silica all have industrial uses that could offset the cost of sequestration.

The Coast Range Ophiolite (CRO) in Northern California is assemblage of ultramafic, mafic, and minor felsic igneous rocks located in Northern California (Shervais et al. 1985 and Bailey 1971). The CRO is comprised of largely serpentinized ultramafic. These rocks are in close proximity to cities with high populations--San Francisco, Oakland, etc. -- locations that demand resources such as electricity, fuel, and cement, all of which are CO₂ emitters. Given the large quantity of serpentinites near areas of dense population, there is an excellent opportunity for close proximity in situ carbon sequestration. I present field observations for CRO outcrops and selected subsurface cored intervals with a computation framework for estimating the volume of serpentinites in the area, and their carbon storage potential.