HOW LIVING ORGANISMS BECOME ORGANIC MATTER

Do you know that the production,accumulation and preservation of undegraded organic matters are perquisites for the existence of petroleum source rocks..Organic matter can be defined as material comprised of organic molecules in monomeric or polymeric form which are derived or inherited directly or indirectly from the organic parts of organisms,this definition excludes the skeletal parts like shell,bone and teeth  of course which are inorganic..

Organism dies,decay begins,complex molecules break down rapidly..A large part of living organisms are polymers such as cellulose,chitin,protein,sporopollenin....from bio-ploymers they all 
become geo-monomers..

organic matteris is also synthesized during the process of photosynthesis

Only a very small amount of these organic materials are ultimately transformed to petroleum,there are three stages in the evolution of organic matter in sediments ''DIAGENESIS----CATAGENESIS----METAGENESIS''

DIAGENESIS is a process that involves biological,physical and chemical alteration of organic matter prior to significant changes caused by heat,it has to do with recent sediments that have subsided to shallow depths where temperature is less than 50degree celsius,during diagenesis,methane,carbondioxide and water are given off by the organic matter,the end product here is kerogen which is a direct precursor of PETRROLEUM

CATAGENESIS
At this stage,organic matter and sediments have subsided to depth where temperature is greater than 50 but less than 150 degree C..temperature is the main driving force for changes in organic matter at this stage,this corresponds to the principal zone of petroleum generation or threshold of hydrocarbon generataion or oil kitchen,organic matter experiences major changes as kerogen produces first liquid petroleum

METAGENESIS is reached at great depth and it occurs at high temperatures and pressure verging on metamorphism,it occurs at temperature range of 150-200degree C,in this stage DRY GAS[100% METHANE} is formed...

After the above three processes,the petroleum  and gases gotten are then subjected to different refining processes where they are broken down to form the oils we use in our everyday life...

so living organisms becomes organic matter,organic matter becomes crude oil,crude oil is the main source of the oils we use in our everyday life such as petrol,diesel,lubricating oils..e.t.c..