Cretaceous volcanic activity has a great influence on the formation of coal. This period is one of the warmest periods in the history of the earth, and volcanic activity released a lot of carbon dioxide into the atmosphere. Nowadays, it is found that many strata rich in coal resources were mostly formed in this period.

These Cretaceous volcanic activities released a lot of carbon dioxide into the atmosphere. It can be inferred that the crustal movement was active at that time, and volcanic eruptions were intense, frequent and wide. Therefore, a large amount of carbon dioxide will be released into the atmosphere. These carbon dioxide promoted the growth and reproduction of plants, and formed a large number of plant debris. These plant debris, together with volcanic ash and other substances, finally formed coal after a long period of pressure and high temperature.

The above information is for reference only. For more detailed information, please refer to the books related to geology and coal science.