Hydrocarbon Related Diagensis

Imagine that you are a tiny microfossil trapped in sediment and buried in a sedimentary basin with kilometres of sediment weighing down on you. You are trapped in a symbiotic watery fluid, warm and rich in silica, which you can’t resist. If you have quartz grains in your skeleton, you slowly accept silica bit by bit and small crystals of quartz form inside your skeleton. These sediments also have fossil organic matter, and they produce fluids of their own. With increasing temperature and time, this fossil organic matter converts to hydrocarbons and you have more fluids to deal with. Depending on your site of burial, this may or may not affect you. If you’re unlucky and reside above a petroleum reservoir, and the earth moves, and fractures, those hydrocarbons are released through fractures and migrate to the earth’s surface. If you are caught by this upward migrating oil, this is what you might look like, assuming you are a microfossil:

For more information on the alteration of foraminifera from hydrocarbon migration see the following publication:

McNeil, D.H., Dietrich, J.R., Issler, D.R., Grasby, S.E., and Dixon, J. (2011)