Oil shales have been deposited across the globe in a variety of lacustrine and marine settings for more than a billion years. These finely laminated rocks originated as some of the most kerogen-rich clastic sedimentary sequences in the world and are therefore of great interest and importance as petroleum source rocks. Paleolatitude, paleoclimate, and tectonic setting were all important factors in the distribution of lakes and their organic-rich sedimentary facies, but major lakes most commonly were associated with rift, intracratonic, or intermontane basins.

Precambrian and early Paleozoic lacustrine petroleum source rocks contain mostly type I algal kerogen, but because the development of vascular plants during the Silurian provided additional types of vegetation, younger organic shales also can produce gas and waxy crude oils. Large lacustrine oil shale accumulations of late Paleozoic age are found in South America, eastern Canada, Greenland, Great Britain, western China, and east Africa.

Lacustrine oil shales continued to accumulate along continental margins in rift basins associated with the breakup of Pangaea during the Mesozoic. Large long-lived lakes formed in southeastern Africa and western Australia, as well as in many Newark Supergroup basins in eastern North America and the conjugate African margin. During the Early Cretaceous, lacustrine deposits were associated with rifting between South America and Africa. Thick late Mesozoic and Cenozoic lacustrine sequences with extensive oil shales are prevalent throughout China, southeastern Asia, and western United States.

The distribution of lacustrine oil shales through geologic time reflects deposition in both shallow and deep lakes in all types of continental sedimentary basins. Therefore, one finds no shortage of productive analogs for lacustrine systems around the world. Through improved understanding of geologic controls on deposition and preservation of source and reservoir facies, petroleum exploration in lacustrine basins also will become more effective.