Treasure from the Earth's mantle

The origins of crude oil and natural gas are usually explained as the products of millions of years of geochemistry acting on the remains of ancient sea creatures. This hypothesis suggests that there are limited supplies of these fossil fuels. However, for many years now scientists have debated a controversial theory which suggests that hydrocarbons may form naturally from inorganic material deeper in the Earth's mantle. A team of scientists has shown for the first time that ethane and even heavier saturated hydrocarbons, such as propane and butane, can be made under the pressure and temperature conditions of the Earth's upper mantle, just below the crust. If correct, this theory hints at a way in which dwindling oil and gas reserves might be replenished.