Genesis of the Continents and their Mineralisation. Bob Watchorn’s AusIMM talk Bunbury 3rd October 2019
Robert Watchorn
Genesis of the Continents and their Mineralisation. World craton tomography showing continents studied by Bob Watchorn in 2019
Tomographic image of the Earth showing the remaining pre 4 billion year lithosphere as blue areas. The Australian craton has been researched in detail from 70 to 300 km depth. The North American and North China cratons have had preliminary research.
Genesis of the Continents and their Mineralisation.
The following images are a selection from the talk I will be giving on the Genesis of the Continents and their Mineralisation at Bunbury Mercure Sanctuary Resort For the AusIMM South West Branch on 3rd October 2019.
If you want to register for the talk the link is below.
The slides are self explanatory and I will be following up the talk with new papers on this website.
Geology plan of Australia showing the remaining Archaean rocks as brown areas. The rings seen in Tomography at the 75 km level (yellow) show that the pre Archaean (Hadean) rocks of the Lithosphere continue unbroken under all of Australia.Australian Tomography at 75 km depth. The brown younger lithology in the centre of Australia occupies the centre of the Central Australian giant ring structure (impact) similar to the younger lavas filling the centres of the largest moon impact mares.The stacked plans of Australian tomography from 75 – 300 km depth indicate that during the Late Heavy Bombardment from 4.1 – 3.8 Ga very large rings were formed in the lower half of the lithosphere and also at the end with smaller impacts in the middle lithosphere.The main rings have been traced from the 75 km surface (just below the Moho right to the base at 300 km without loss of diameter. This indicates they originally penetrated much deeper.This is an attempt to capture the destruction of the Late Heavy Bombardment in top left inset, and its affect on Australia is seen at the 150 km level. The great similarity between the giant ring structures on Earth and the moon mares makes it a certainty that both formed by giant impacts. During the Late Heavy Bombardment it is suggested the lithosphere built up by extrusion of lavas in ‘earth mares’ similar to those on the moon. This is perfectly feasible even at the rate corals grow. 300 km in 300 million years is only 10 mm a year!. The lithosphere was rigid at this time and has essentially remained rigid as evidenced by the still nearly circular giant ring structures. When the LHB ceased surface deposition slowed down and the Moho unconformity formed. Then the crust formed more slowly but with more active tectonics because of the start of Plate Tectonics sometime between 2.6 and 1.5 billion years ago. The cratons remain relatively intact because of their buoyancy and thus isostatic uplift.
Come to the talk, or if that is impossible for 99.9% of you then see it on the AusIMM website when it is published. I guarantee it will change the paradigm by which you view the Genesis of the Continents and their Mineralisation and how to target your exploration for minerals.
