Pyrolysis of Early Pre-Cambrian Onverwacht Organic Matter (> 3 × 109 yr old)

Abstract

CARBONACEOUS matter and microstructures of unknown origin in the oldest known sedimentary rocks (part of the Onverwacht Series in South Africa; <3.0 × 109 yr old) have created considerable interest (unpublished work of B. N., L. A. Nagy, C. G. Engel, A. E. J. Engel, G. O. W. Kremp and C. M. Drew (1967), and refs. 1–5). Because these rocks may be as old as ∼ 3.5 × 109 yr, while the generally accepted age of the Earth is 4.5 × 109 yr, carbon compounds in the Onverwacht Sediments may be derived from some of the first living matter on Earth or perhaps from prebiological substances. Most sedimentary rocks are porous, and even the Onverwacht carbonaceous and argillaceous chert has been found to exhibit a small degree of liquid permeability6. Part of the soluble organic compounds could therefore have been brought in and deposited in the Onverwacht by percolating solutions at a later geological age. But, on the other hand, the insoluble organic polymeric substance, or kerogen, seems to be basically indigenous and most of it, if not all, was deposited with the rocks in Onverwacht times. We have therefore analysed the Onverwacht kerogen, hoping that this might elucidate the nature of the carbon compounds that were present on the Earth ∼ 3.5 × 109 yr ago.