catagensiirtymävaiheeseen

Catagensiirtymävaiheeseen is a Finnish term that translates roughly to "transition phase of catagenesis" or "catagenetic transition phase" in English. It refers to a specific stage within the process of organic matter transformation in sedimentary rocks, particularly concerning the generation of hydrocarbons. This phase is situated between the diagenesis (early stage of alteration) and metagenesis (late stage of alteration) of organic matter.

During catagenesis, organic matter undergoes significant thermal maturation. The catagensiirtymävaiheeseen represents a period where the organic matter is transitioning from being primarily capable of generating oil to becoming increasingly capable of generating gas. This means that the complex organic molecules (kerogen) within the source rock are breaking down under increasing temperature and pressure, and the type of hydrocarbons produced is shifting.

In this transition phase, both oil and wet gas (gas containing heavier hydrocarbon components like ethane and propane) are typically generated. As temperatures continue to rise beyond this phase, the remaining organic matter will increasingly produce dry gas (methane). Understanding the catagensiirtymävaiheeseen is crucial in petroleum geology for evaluating the hydrocarbon potential of sedimentary basins and predicting the type of hydrocarbons that might be present. It helps geoscientists estimate the timing and extent of hydrocarbon generation and migration.