At http://phys.org/print332685617.html … there is apparently a mid continent Rift across the Mid West, some 2000 miles in length, running from Lake Superior south as far as Oklahoma and Alabama. However, it is unseen – as it is now underground. Geologists say it began as a narrow crack in the crust which was subsequently enlarged by the welling up of volcanic rock, and somewhat later, further intrusions of igneous rocks buried the feature.
The geologists now say they have modelled what happened. The Rift was caused by rocks pulling apart to create a rift valley feature – but it is not disclosed exactly why rocks should choose to open a gap. They did. That is it. Further, as the crust was being pulled apart magma flowed into the crack. However, when the crack ceased to expand the magma flow did not stop. Older magma layers sank under the weight of more and more magma out pouring onto the surface and left behind a 20 mile thick layer of volcanic rock. So far, all very good and a reasonable explanation. However, underlying all this is Plate Tectonics theory – which is used to explain the reality of the crack and the oozing out of the Mantle of lots and lots of magma. Then, we are informed that millions of years later, a super-continent reassembled itself – a bit like lego pieces moving round a computer screen. In the process the Rift was squeezed, very tightly. It is now underlain by rock that is extremely thick. Finally, it is worth pointing out that the extent of the Rift, a subterranean feature, is determined by variations in the gravity field. It seems they don't really know if a Rift actually exists as it is based on the assumption the magma is dense and the rift is delineated, from one end to the other, by the pull of gravity on the volcanic rock that has been laid down over the Rift.
At http://phys.org/print332757626.html … there is just one major volcanic area in Australia – in the SE. It stretches from Melbourne to Mount Gambier is S Australia, a dormant volcano that last blew around 3000BC. The research then sets about exploring why volcanoes here differ to those volcanoes on the so called Pacific Rim of Fire. They claim it is all due to plate movement, the get out clause of all geological oddities. The Australian plate is moving against the Indonesian plate. However, you may note New Guinea was part of the Australian land mass not so long ago (and so on).
At http://phys.org/print332665683.html … a massive mountain chain, comparable in height and extent to the modern Himalayas, once spanned 2500km from West Africa to NE Brazil – when the two continents were joined at the hip. This mountain chain has since eroded away – and the sediments washed into the ocean. These provided the neutrients necessary for life to flourish.
We are then informed that scientists have actually speculated something along these lines for many a long year – 'scientists have speculated that such a large mountain range must have been feeding the oceans because of the way life thrived and ocean chemistry changed at this time (600 million years ago) …'. They go on to say they have actually found the elusive mountain chain – even though it has long since disappeared. Gradually of course. The 'rocks' with an origin in the roots of the mountain chain are able to tell the story, it is alleged. Needless to say it involves the consensus view of Plate Tectonics. The mountains were formed in the first place by continents colliding (another hark back to a previous situation prior to Pangaea). As such, and using the mouse of a computer, rocks at the surface were pushed 100km deep into the Mantle by subduction. Later, the roots popped back out of the Mantle and re-emerged at the surface. They now exist in Togoland, Mali, and in NE Brazil (it is claimed).