Summary of Water Origins
The origins of water on the earth is a mystery in science. One theory is that comets containing ice brought water to earth. That origin is not likely, because there would still be a lot of such comets, and there are very few. Therefore, the water would have originate on the earth. The fact that there are some watery comets means that the planet which exploded had water on it.
A few decades ago, scientists assumed the earth began with a reducing atmosphere. (Recent science is deteriorating into irrationality; so it's necessary to go back a few decades to view real science.) The reducing atmosphere would have contained methane and similar hydrocarbons. Ammonia was also assumed to be prevalent, since DNA and proteins would have needed such nitrogen.
Recently, evidence was found to indicate the water of the oceans goes back about 4.5 billion years. This amount of time does not eliminate the possibility of a reducing atmosphere at the origins. The reduced molecules could have been oxidized quite rapidly. The oxidation products would have been carbon dioxide and water.
Most of the nitrogen would have been in the form of N2 gas, since that molecule is very stable and pervasive. Oxygen must have existed as O2 gas. These gasses were apparently buried with the minerals during the formation of the earth. Since these gasses are quite light, they would have percolated to the surface and into the atmosphere quite rapidly. Oxygen might have started as perchlorate which broke down into sodium chloride and oxygen gas.
As the oxygen escaped into the atmosphere, it would have oxidized the volatile hydrocarbons to carbon dioxide and water. But there were also non-volatile hydrocarbons which were buried in the minerals, and they were not exposed to the oxygen. There is no other logical origin for existing hydrocarbons as oil and coal. The claim that hydrocarbons originated with biological material is ridiculous. There is no source of chemical energy to reduce biological materials. heat and pressure will not do it. There is no way to get chemical energy out of heat and pressure.
What this means is that oil and coal have more energy than biological materials. This is because oil and coal have hydrogen attached to carbon without oxygen. The hydrogen is in a higher energy state than the oxygen containing molecules of biological materials. Therefore, if biological materials were the source of oil and coal, there would need to be some means of increasing the energy level of the molecules.
Commentators speak of heat and pressure changing molecules, as if the energy state of the molecules could be increased through heat and pressure. They don't seem to realize that chemical energy cannot be derived from kinetic and thermal energy, which means heat and pressure.
Chemical energy is in the motion of electrons. The motion of electrons cannot be changed significantly through heat and pressure, because heat and pressure act upon nuclei, not electrons. The motion of nuclei cannot influence the motion of electrons significantly.
Therefore, the hydrocarbons would have been created when pure hydrogen came into contact with some form of carbon during the formation of planets. The result was a reducing atmosphere. As oxygen escaped from the minerals (probably originating with sodium perchlorate), it oxidized the hydrocarbons creating the oceans.
However, if all of the water in the oceans originated with the oxidation of hydrocarbons, there probably would have been more carbon dioxide, and if the oxygen originated with sodium perchlorate, there would have been more salt. What this adds up to is that most of the water formed very early in planet formation, and sometime later, hydrocarbons were oxidized creating additional water, carbon dioxide and sodium chloride.
A large amount of carbon dioxide would have resulted from oxygen combining with hydrocarbons. Calcium would have attached to the carbon dioxide creating calcium carbonate as chalk. Some of the carbonate would have been gradually replaced with oxygen creating dolomite and limestone. Slowly, the oceans would absorb the remaining carbon dioxide converting it into more calcium carbonate and limestone.
The amount of carbon dioxide in the air has been continually decreasing because of the oceans absorbing and mineralizing it. There was twenty times as much carbon dioxide in the air when terrestrial life began 543 million years ago as now. During the dinosaur years, it was down to five times as much. Now there is so little carbon dioxide in the air that all of biological life is on the verge of becoming extinct due to the difficulty plants have in producing photosynthesis with a deficiency of carbon dioxide. CO2 Graph