Australia: The Land Where Time Began
The Permian Extinction Debate
A cluster of asteroid/comet impacts caused a cataclysm that ended the Permian Period over a short geological time frame, 5-8 Ma. Marusek hypothesised that several of the impacts were large enough to rupture the crust of the Earth which produced deep impact effects that included large fractures in the floor of the ocean along the joins of the tectonic plates. The undersea vulcanisation that resulted released vast quantities of acidic gases. Acidification of the ocean resulted from gas scrubbing of the ocean. Fractures at continent/ocean seams were produced by the impacts also focussing on the opposite side of the Earth. The Emeishan Traps and the Siberian Traps which generated surface vulcanisation over prolonged periods were the results which led to extensive acid rain. Evolutionary weaknesses within marine and terrestrial life forms were targeted by these 2 processes which culminated in a massive die-off at the end of the Permian.
A cataclysmic mass extinction occurred at about 250 Ma. At this time the cataclysm that brought the Permian Period to an end was caused by a cluster of comet/asteroid impacts over a short geological timeframe, 5-8 million years.96 % of all marine species, as well as 70 % of all land vertebrate species went extinct (Raup, 1979; Bowring et al., 1998). There was also a rapid die-off of rooted plant species (Ward et al., 2000). At this time there was also the only mass extinction of insect species. The Permian Extinction is the greatest die-off in the history of life on Earth.
The Permian Extinction was a cluster of mass extinctions that are constrained tightly in geological time (Kaiho et al., 2003):
1. The Gaudalupian-Lapingian Boundary (GLB)
2. The Wuchiapingian-Changshingian Boundary (WCB)
3. The Permian-Triassic Boundary (PTB).
These 3 major mass extinctions occurred clustered within a period of 5-8 Myr (Kaiho et al., 2003).
In this paper the hypothesis is presented that:
· A cluster of extinctions events were caused by a cluster of impact events.
· That of these impactors several had sufficient kinetic energy to break through the crust of the Earth.
· That massive flood vulcanisation was produced by these deep impactors.
· And that the leading cause of extinctions in the oceans and on the land was acidic gases that were released from magma.
Following the completion of a study of the mortality effects that was triggered by impacts of large asteroids or comets, the analysis showed that these effects are too localised to explain adequately the global nature of the extinctions that occurred at the end of the Cretaceous and the Permian. Several effects have been postulated, such as global firestorm, impact winter that was induced by ejecta debris and megatsunami that penetrated great distances over landmasses, but none of these are supported (Marusek, Impact, http//Personals.galaxyinternet.net/tunga/17.htm).
The effects of impact by an asteroid or comet have been compared to that of a large nuclear weapon. According to Marusek although the comparison may be a good approximation, there is a significant difference. The kinetic energy produced by a nuclear weapon blast is released spherically in all directions, while the kinetic energy released by an impact is focused along the line of the impact vector. In this paper the hypothesis is presented that a large impactor is capable of penetrating the crust of the Earth and releasing most of its energy deep in the mantle by a process called acoustic fluidisation (Collins et al., 2002), a process by which the solid crust of the Earth is caused by the energy of impact to be converted to liquid. In a fraction of a second the impactor passes through the atmosphere and the crust in a manner similar to the way a shaped-charge projectile penetrates the armour of a tank. Surface impacts leave a large crater and throw a worldwide debris field, whereas these deep impactors generate large scars or crustal uplifts that bury much of the impact debris.
The energy of the impact can be thought of as the sum of the energy released at the surface and the energy that is released deep within the earth. According to Marusek the surface component can be approximated to the blast and thermal radiation effects from a comparable sized thermonuclear weapon. The effects of the energy of the impact that is released in the mantle are obscure being observable only as massive flood vulcanisation, the formation of a deep magma hotspot and interior structure anomalies, such as magnetic pole reversals. In this paper Marusek also theorises that the energy that is released deep in the Earth may be an order of magnitude greater than the surface component. E.g. a Long Period Comet (LPC) that is 20 miles in diameter and travelling at 110,000 miles per hour (50 kps) that has a density of 0.75 gm/cc would release kinetic energy that is equivalent to 39 x 108 megatons of TNT (1.6 x 1025 joules). Of this, about 6 x 108 megatons of TNT might be released at the surface which would produce an impact structure about 200 miles across. The scar formed by a deep impactor might appear to have been made by a much smaller impactor, as the surface component is all that is visible. A deep impactor will break through the crust and release most of its impact energy (in this example, 32 x 108 megatons of TNT) as the transfer of heat and momentum deep within the shell of the Earth.
The joints of tectonic plates will be flexed by the interior shock wave from a deep impactor, which will produce large fractures in the floor of the ocean and massive undersea flood vulcanisation at these seams around the world. Most of the destructive energy of the shock wave will be focused on the exit vector, which will in turn devastate a large area of crust on the opposite side of the globe. Damage is generally greater if the exit vector is close to the seam between continental and oceanic crust because a hinged joint is a weak flex joint. The function of tectonic plates is similar to a slow moving engine. Its delicate balance can be upset by the force of the impact which causes the plate to be fractured and derailed, and extensive long-term crustal damage will result.
The focused shock wave in the GLB impact ruptured the crustal surface to produce the Emeishan Traps. An acidic tuff bed, that was about 2 metres thick, was produced by the GLB impact with extensive distribution of airborne ash over thousands of kilometres (Isozaki, 2001). The oceans were also driven into a state of anoxia by the GLB impact.
Another deep impactor that produced a magnetic pole reversal caused the WCB (Erwin, 1994). The oceans were thrown into a superanoxic state, which persisted for more than 10 Myr, by the WCB.
The Siberian Traps, which are terrestrial flood vulcanisation, formed when the focused shock wave from the PTB impact damaged the crust near Eastern Russia. Between 3 and 5 million km3 of lava was generated by this surface wound (Bowring et al., 1999). A magnetic pole reversal was also produced by the PTB impact (Erwin, 2994).
The vulcanisation from the Emeishan and Siberian Traps lasted more than 10 million years. A marine ecological disaster was produced by the undersea vulcanisation. A terrestrial ecological disaster was also produced by the terrestrial flood vulcanisation, and the terrestrial disaster also contributed to the marine disaster. The release of the compressed gases in the magma was the primary cause of the extinctions; with the actual die-offs taking place very rapidly. The collapse of the marine and terrestrial ecosystems occurred very rapidly, is just a few 10s of thousands of years in the PTB (Twitchett, 2001).
A detailed discussion of the marine extinction mechanism, the terrestrial extinction mechanism, the physical evidence that supports the extinctions pathways, and the evidence of the impact events are included in the full paper.
|Author: M.H.Monroe Email: firstname.lastname@example.org Sources & Further reading|