To form an oil shale deposit two conditions need to be met:
1) part of a lake or marine basin that is ‘far’ from a supply of coarse clastics, and 2) anoxic conditions need to exist in the lower part of the water column so that organic material that
Ctnd: lack of oxygen will prevent the destruction of organic material . This will ultimately give rise to an oil shale. Modern examples: the Black Sea and the Great Rift lakes in Africa
Oil shale rocks are created by organic matter and terrigenous sediment buildup. Bacterial activity causes organic matter to deposit on sediments, forming an anoxic environment in the seawater column
also, one aspect of organic matter buildup in sediments is the Sapropel, and black shale contains fine to moderately-grained terrigenous particles, including quartz, clay minerals, sandstone, and shale.
The detritus of plants or the remnants of extinct phytoplankton and zooplankton that accumulated with sediments could be the source of OM (Organic Matter).
Black shale is formed physically by the pressure and high temperature of clay and terrigenous sediment layers following the formation of lithification (becomes sedimentary rock), which forms organic shale and, in the end, kerogen, which is a waxy substance. The oils eventually emerge from the water through the shale pores, containing rocks that are a substantial oil shale reserve.
References :
1-Schulz., D.H., Zabel ., M., Marine Geochemistry
2nd revised, updated and extended edition, 4.2 Organic Matter Accumulation
in Sediments, (2006) , printed in Germany by Springer-Verlag Berlin Heidelberg , Page: 127 .
2- Speight., G.J ., Fuel Flexible Energy Generation, 1 - Introduction to fuel flexible energy, (2016) , published on Elsevier website : https://www.sciencedirect.com/science/article/abs/pii/B9781782423782000018
3- Li., H., Misra., S., Machine Learning for Subsurface Characterization, Index construction , dimensionally reduction , and clustering techniques for the identification of flow units in shale formations suitable for enhanced oil recovery using light –hydrocarbon injection , 1.1 Geology of the shale formation, (2020) , published on Elsevier website , Page: 158 .
4- Bai., Y.Y., Xie., Q. W., Liu., J.Z., Xu., B.Y., Formation and evolution mechanisms of coal and oil shale from the Middle
Jurassic Shimengou Formation, northern Qaidam Basin, China, 1. Introduction, (2022), Published on Elsevier website : https://www.sciencedirect.com/science/article/pii/S0169136822005145?via%3Dihub
Pages : 1 , 2 .
5- Dyni., R.J ., Geology and Resources of Some World Oil-Shale
Deposits, Abstract , Introduction, (2006) , published on U.S. Geological Survey Scientific Investigations Report 2005–5294, Virginia , USA , Page : 1 .
6- Oil formation, a topic from website : https://energyeducation.ca/encyclopedia/Oil_formation
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