CAMBRIAN AND PRECAMBRIAN PETROLEUM AN APPRAISAL

Abstract

Accumulated evidence indicates that (1) the major portion of chemical and organic evolution occurred during the 3-5 x 109 years of the earth's history preceding the Paleozoic; (2) the basic elements constituting petroleum existed in the early phases of the earth's history; (3) unmetamorphosed Precambrian and Cambrian lithic types are similar to younger ones; and (4) the population of the later Precambrian and early Paleozoic seas was relatively rich and varied, though hard skeletal parts are notably absent in the Precambrian rocks and, in all probability, were not widely developed.

As petroleum is now generally considered of organic origin and is a widely disseminated and integral part of most sedimentary rocks, unmetamorphosed Precambrian and Cambrian strata should be prospective for petroleum. Discoveries of large reserves of oil in the Cambrian in parts of North Africa, Russia and the United States support this asserted prospectivity. Shows of indigenous gas in the late Proterozoic of the Amadeus Basin, Northern Territory, Australia, indicate that unmetamorphosed Precambrian strata may also yield commercial amounts of hydrocarbons.