The Deep Carbon Observatory is “a broadly interdisciplinary, international effort to characterize Earth’s carbon—crust to core, at scales from nano to global.” This program was initiated two years ago and is run by the geophysical laboratory at the Carnegie Institution in Washington, D.C.
Areas of investigation:
The presence of microbial life in solid rock miles below the surface and its possible relationship to production of hydrocarbons.
Abiotic production of methane, natural gas. Russian scientists have long maintained that hydrocarbons are produced deep within the mantle by inorganic processes. If so, abiotic methane could greatly expand our supply of natural gas and petroleum.
The properties of carbon under high pressure and temperature.
What happened to the primordial carbon? “The nature and extent of carbon reservoirs and fluxes in Earth’s deep interior are not well known. The primitive chondritic meteorites that formed our planet average ~3.2% carbon, yet estimates of Earth’s total carbon inventory are much lower, ranging from 0.07 to 1.5 wt% (an uncertainty of more than 20-fold). Earth appears to be significantly depleted in highly volatile elements compared to chondrites, but we do not know for sure because large reservoirs of carbon may be hidden in the mantle and core.”
Diamonds, pure carbon, underwent a change about 3 billion years ago. Diamonds “provide age and chemical information for a span of more than 3.5 billion years and include clues to the evolution of the atmosphere, the growth of the continental crust, and the beginning of plate tectonics.”
This site seems worthy of checking from time to time. The News tab brings up press release of the research and links to scientific papers. The Science tab provides more detailed explanation of the areas of investigation.