Very true. The collision of the Indian plate left a trail of deformation all the way from Iraq, through Russia, to Mongolia, and into Vietnam, spanning almost all of Asia. Really incredible to think about.
Ah yes. Precambrian hydrocarbons. Back when I worked in western Montana (minerals exploration) I remember there being some interest in possible Belt rocks having some, although little, possibility for hydrocarbon potential. I never kept up with the interest and it seems that it was one of those geo- optimistic ideas. Based on this post I wonder if the Belt rocks were just too old. There is no lack of section, but too early for hydrocarbons to be preserved or even deposited. I am sure that the Irkutsk Amphitheater oil/gas occurrences probably figured into the discussion. I haven't thought about Belt rocks in some time so thanks for the post. Happy Lipalian Interlude!
The Belt play I was slightly involved with in the early-mid 1980s did not anticipate Belt-age source rocks or generation (I think you are right, they are too old), but potentially to find reservoirs in the Belt in which Cretaceous-sourced oil might have accumulated. The idea was that Belt rocks had been thrust (in the style of the Lewis Overthrust) many kilometers over the Cretaceous black shales. I think the Arco-Gibbs well in 1984, west of Kalispell, decided that question after they drilled about 18,000 feet of Belt. The vague anticlinal trap they may have seen on seismic data turned out the be some of the Purcell Sills within the Belt, not Phanerozoic sediments.
I do remember Arco drilling on some overthrust acreage in western Wyoming and drilled to 20K feet (I think) on a target below several thrust sheets. The hole never hit the target due to very difficult drilling conditions. So another "win" for Arco :)
At least those were mostly Phanerozoic sediments :) . A company I know of drilled about 17,000 feet of rhyolite and basalt in the Snake River Plain, to test the idea of possible sediments beneath thin surficial lavas.
Hope does spring eternal. I would think the hot-spot volcanism would have obliterated any hydrocarbons. Just looking at the removal of fault-block mountains across the plain makes the argument that, although scientifically interesting, the hole would have little hope of any payoff.
Yes, I forgot about ARCO's work. I was "transitioning" from employment to unemployment (coincidentally from Anaconda, which was under the Arco) around that time. Still what a pile of rocks. The Precambrian is continually fascinating.
Interesting notes Richard. I agree some heliodors and more greenish that I care for, but that's me. And I found some cool micro pholgopite in the desert around Caballo, NM. Yes, i'd assume they are hexagonal. Take one look, duhh! But no-.
Do you remember a lecture given by an Israeli geochemist about the origin of petroleum? I think Meinschein brought him in. He found that petroleum looked a lot like bee honey comb wax or plant cuticule and that water draining off continents contained a lot of this waxy material. He concluded that petroleum was formed by the heating and recombinations of those waxes. It's been nearly 60 years so don't be too hard on me.
Here was me thinking oil was basically Jurassic... But of course something in the Precambrian (stromatolite type algae ) photosynthesised enough oxygen to rust up all the iron and then "poison" the atmosphere with O2
You're correct that the majority of oil (estimates typically range from 60% to 75% of the total) was generated in source rocks of Mesozoic age, and of that mostly Jurassic and Cretaceous. But there's plenty of odds and ends lying around, and given the insatiable demand for it, and its irregular distribution geopolitically, the other random sources, even if smaller, are important.
The thought of the collision of India with Asia forming mountains 2500 km away really speaks to the force involved in that tectonic motion!
Agreed. Not to mention that the same collision also produced the trough that holds Baikal, the deepest lake.
Very true. The collision of the Indian plate left a trail of deformation all the way from Iraq, through Russia, to Mongolia, and into Vietnam, spanning almost all of Asia. Really incredible to think about.
Bikal is a fascinating structural story. A pull-apart basin along a major fault zone between the Eurasian and Amur Plates It's around 6 to 10 KM deep. This from Earthquake Insights https://earthquakeinsights.substack.com/p/m54-earthquake-below-lake-baikal
I hope it's not paywalled.
Ah yes. Precambrian hydrocarbons. Back when I worked in western Montana (minerals exploration) I remember there being some interest in possible Belt rocks having some, although little, possibility for hydrocarbon potential. I never kept up with the interest and it seems that it was one of those geo- optimistic ideas. Based on this post I wonder if the Belt rocks were just too old. There is no lack of section, but too early for hydrocarbons to be preserved or even deposited. I am sure that the Irkutsk Amphitheater oil/gas occurrences probably figured into the discussion. I haven't thought about Belt rocks in some time so thanks for the post. Happy Lipalian Interlude!
The Belt play I was slightly involved with in the early-mid 1980s did not anticipate Belt-age source rocks or generation (I think you are right, they are too old), but potentially to find reservoirs in the Belt in which Cretaceous-sourced oil might have accumulated. The idea was that Belt rocks had been thrust (in the style of the Lewis Overthrust) many kilometers over the Cretaceous black shales. I think the Arco-Gibbs well in 1984, west of Kalispell, decided that question after they drilled about 18,000 feet of Belt. The vague anticlinal trap they may have seen on seismic data turned out the be some of the Purcell Sills within the Belt, not Phanerozoic sediments.
I do remember Arco drilling on some overthrust acreage in western Wyoming and drilled to 20K feet (I think) on a target below several thrust sheets. The hole never hit the target due to very difficult drilling conditions. So another "win" for Arco :)
At least those were mostly Phanerozoic sediments :) . A company I know of drilled about 17,000 feet of rhyolite and basalt in the Snake River Plain, to test the idea of possible sediments beneath thin surficial lavas.
Hope does spring eternal. I would think the hot-spot volcanism would have obliterated any hydrocarbons. Just looking at the removal of fault-block mountains across the plain makes the argument that, although scientifically interesting, the hole would have little hope of any payoff.
Yes, I forgot about ARCO's work. I was "transitioning" from employment to unemployment (coincidentally from Anaconda, which was under the Arco) around that time. Still what a pile of rocks. The Precambrian is continually fascinating.
Interesting notes Richard. I agree some heliodors and more greenish that I care for, but that's me. And I found some cool micro pholgopite in the desert around Caballo, NM. Yes, i'd assume they are hexagonal. Take one look, duhh! But no-.
Do you remember a lecture given by an Israeli geochemist about the origin of petroleum? I think Meinschein brought him in. He found that petroleum looked a lot like bee honey comb wax or plant cuticule and that water draining off continents contained a lot of this waxy material. He concluded that petroleum was formed by the heating and recombinations of those waxes. It's been nearly 60 years so don't be too hard on me.
Very very vaguely I might recall that.
Here was me thinking oil was basically Jurassic... But of course something in the Precambrian (stromatolite type algae ) photosynthesised enough oxygen to rust up all the iron and then "poison" the atmosphere with O2
You're correct that the majority of oil (estimates typically range from 60% to 75% of the total) was generated in source rocks of Mesozoic age, and of that mostly Jurassic and Cretaceous. But there's plenty of odds and ends lying around, and given the insatiable demand for it, and its irregular distribution geopolitically, the other random sources, even if smaller, are important.