Where did the carbon locked up in the crust of Earth come from? And how much carbon is locked up?

Answer 1

Carbon formed LONG before the earth and our solar system existed. In fact, all of the elements on the periodic table up to Iron (Fe), formed in very large stars. Large stars are capable of performing several different nuclear reactions that result in the production of elements like Helium, Oxygen, and Silicon. Our star (the Sun) is too small to produce anything more than He (which is really just one reaction). Thus, the carbon in the Earth's crust originally came from the universe (as did most other elements).

Carbon moves through the earth system via the carbon cycle, and by far, the largest reserve of carbon on the planet is in the lithosphere - a portion of the Earth that includes the crust. The carbon in the atmosphere and the hydroshpere (oceans and lakes) is cosiderably less than the amount found in the crust.

To put some numbers in perspective: there are approximately 80-100 million gigatons of carbon in the lithosphere. OF that, only ~4,000 gigatons are classified as fossil fuels (again, within the crust).

Answer 2

The elemental abundance of carbon, is 200 mg. per kg. of crust.

Answer 3

it came from when the earth came together, when the sun was made all this gas and stuff swirled around the sun and over time gravity pulled those stuff together to make planets, and the carbon and other stuff hardend to make earth and the gas made our atmoshpere. not sure how much carbon we have