I just read a post on Substack by a geologist named Richard Gibson. In his “Geologic Column” (https://richardigibson.substack.com/p/the-irkutsk-amphitheater) he wrote about the Arkutsk Amphitheater in Siberia. These rocks are very old and contain some very old oil. A thin layer of Paleozoic rocks from the Cambrian to the Ordovician (540-450 mya) overlays older and thicker Precambrian rocks (1200-570 mya). Significant hydrocarbon deposits from 4-8 % TOC are present. Some of the rocks are so old that the organic material has been completely converted to methane.
Wow! Got me thinking …
If we buy the proposition that higher rates of bio-organic material were deposited during the geologic Hothouse periods where all that warmth drove ancient algae, bacteria and plants to massively proliferate and to be accumulated under anoxic conditions, trapped and capped, then higher yield petroleum source rocks might be found during these Hothouse periods. From my 675-million-year climate cycle (see model below, Fig. 6) we can trace the physical hydrocarbon source rocks back to their proxy temperature Hothouse origins (http://thestoryofclimatechange.substack.com). We can see the Cretaceous Hothouse from about 125 mya to about 50 mya. The Cretaceous rocks contain around 40% of our active oil deposits with another 20-30% of our petroleum coming from Mesozoic rocks of 275 to 120 mya. We can see in the proxy temperature model that the Mesozoic oil-rich rock depositions might be punctuated in time with periodic and lesser Hothouse periods every 30 million years or so. Remember, the hypothesis places the Mesozoic climate of the Triassic and Jurassic in a highly modulated (variable) and diminutive Icehouse (Scutum-Crux spiral arm crossing). The out-of-plane modulation, driven by our planetary system’s 30 million year out-of-plane galactic orbital oscillation, forces the lesser hot peaks into the “Hot” climate zone while the Cretaceous Hothouse was driven mostly by the 50-million-year inter-arm space transit with it’s significantly lower cosmic radiation flux, less ionization and aerosol formation, fewer clouds, and much hotter temperatures.
Further back in time to about 275 million years ago, the Permian Hothouse rocks are yielding hydrocarbons. Further back, the Devonian Hothouse at about 375 mya also provides us hydrocarbons. The Cambrian Hothouse around 500 mya also yields petroleum source rocks.
Our model allows us to go further back in time to the Precambrian and into the Neoproterozoic where, around 775 mya we find Tonian Hothouse source rocks (replayed by the Cretaceous). Further back we can trace the Irkutsk rocks to the Hothouse at 950 mya (replayed by the Permian), to 1050 mya (replayed by the Devonian), and finally to the Hothouse at 1175 (replayed by the Cambrian). This analysis shows us why the older Irkutsk rocks are so rich – the sediments span four Hothouse periods while the thinner surface layers only contain one Hothouse.
I suppose this thesis might hold to at least 2.3 billion years ago when the Great Oxygenation Event signaled the abundance of life necessary for significant bio-accumulation to occur. The galactic hypothesis cannot be proven yet (if ever) but high resolution data, revealing rock age and hydrocarbon profiles, might confirm or falsify my overarching hypothesis.
regards,
Kirby