[meteorite-list] vast geoablation in Argentina, craters from SW to NE -- Cox re Boslough bursts: Rich Murray 2011.07.31
From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Sun, 31 Jul 2011 18:11:56 -0500 Message-ID: <47F5F303CF2A42AA860AD3B7875A2337_at_ATARIENGINE2> While no one is going to address all of these points from this long post, I'll tackle one --- the Libyan Desert Glass: > Low Altitude Airburst... from a ~100 meter diameter > NEO melted sand into glass across a region about 10 km > in diameter during Libyan Desert Glass impact... > 35 million years ago. The problem is that when walks the incredible inferno of this part of the Sahara and its vast sands, one thinks: how could this sand have been fused in glass? And that is a DEAD WRONG question. 35 to 28 million years ago this area, and tens of thousands of square miles around it, were UNDERWATER. These low desert basins were a lacrustine environment -- shallow waters, with an occasional patch of swampy ground (on what are now hilltops). When I say "shallow," I mean 100 meters more or less. Underlying the LDG area is sandstone, the upper layers of which is younger than the LDG, sandstone that formed at those lake bottoms. The LDG is found along the former shoreline in one area of the SW shore of the Depression. There's a nice Google map of those lacrustine basins at: http://www.inognidove.it/egypt/ If the LDG formed from dry desert sand by incredible heat from an airburst or an impact, it had to have happened somewhere else and the LDG was moved here, or they are yellow tektites from the same event as other tektites their age or another event of similar age elsewhere. If the Belize tektites are "australites" in age, they were tossed a long way. The LDG could have been tossed from Chesapeake Bay, which BTW was a lot closer to Egypt in the Oligocene than it is now, as the Atlantic was narrower, not that great distances matter much to tektites. I would give a bunch of references, but since I've posted about this twice over the last ten years and put lots of citations in them, just check the List Archives if you want references. Here's one, though. "The 1981 expedition... established that the present mass of glass exceeds 14,000,000 tons; the original mass of glass may have been 10,000 times greater, or 140,000,000,000 tons." [units converted] http://www.sciencedirect.com/science/article/pii/0022309384901777 140 billion tons of glass is one heck of a lot of glass for one little 100-meter NEO to whip up a batch of. Let's see. First you have to boil 10-100 meters of water off, then dry out the wet bottoms and all the sand, then you have to melt 140,000,000,000 tons of it. I think you need a bigger bang... even to toss it there. Sterling K. Webb ---------------------------------------------------------------------------- ----- Original Message ----- From: "Rich Murray" <rmforall at gmail.com> To: <meteorite-list at meteoritecentral.com>; "Rich Murray" <rmforall at gmail.com>; "Rich Murray" <rmforall at comcast.net> Sent: Sunday, July 31, 2011 2:11 PM Subject: [meteorite-list] vast geoablation in Argentina, craters from SW to NE -- Cox re Boslough bursts: Rich Murray 2011.07.31 vast geoablation in Argentina, craters from SW to NE -- Cox re Boslough bursts: Rich Murray 2011.07.31 http://rmforall.blogspot.com/2011_07_01_archive.htm Sunday, July 31, 2011 [ at end of each long page, click on Older Posts ] http://groups.yahoo.com/group/astrodeep/message/91 [ you may have to Copy and Paste URLs into your browser ] http://www.bibliotecapleyades.net/ciencia/ciencia_asteroids_comets27.htm Something Wicked This Way Comes Meteor A New Kind of Catastrophe by Dennis Cox 09 April 2011 from SOTT Website "...At Sandia Labs, Mark Boslough used their 'Red Storm' supercomputer to simulate the airburst and impact of a 120-meter diameter stony asteroid. [ http://www.space.com/2295-supercomputer-takes-cosmic-threat.html ] The colors in the simulation we see in the below video, are graded by temperature. White = 5800?K - 5527?C Red = 2000?K - 1727?C http://www.youtube.com/watch?v=Gr7i33UhmC8&feature=player_embedded Simulation of an asteroid exploding in Earth's atmosphere, taking into account the momentum. [ 21 second video ] Dr Boslough tells us that, in it, we see the ablated meteoritic vapor mixes with the atmosphere to form an opaque fireball with a temperature of thousands of degrees. As it hits the ground, the hot vapor cloud expands to a diameter of 10 km within seconds, remaining in contact with the surface, with velocities of several 100m/s. And at temperatures exceeding the melting temperature of quartz for more than 20 seconds. Moreover, the air speed behind the blast wave exceeds several hundred meters per second during this time. For comparison, an ordinary oxy-acetylene cutting torch in a steel shop uses a thin stream of hot gases at only about 900?C. and 40 psi to cut steel. The speed of that stream of hot gasses is only a little bit more than a stiff breeze. But that's all it takes to turn solid iron into a melted, aerosol, spray. And to blow it away in runnels of melt into heaps of slag. Dr Boslough tells us that: "Simulations suggest strong coupling of thermal radiation to the ground, and efficient ablation of the resulting melt by the high-velocity shear flow." We have its existence predicted in peer reviewed literature. But so far I haven't heard anyone attempt to describe the form that such geo-ablative melt might take as it is emplaced. While in motion, any ablated materials from a large, geo-ablative, airburst like that would be in atmospheric suspension, in a density current similar to a pyroclastic flow. And when everything comes to rest, the resulting rock form might be visually indistinguishable from ordinary volcanic tuff, or ignimbrite. If so, we face a conundrum in the Earth sciences. Because it has always been assumed without question that only terrestrial volcanism can melt the rocks of the Earth, or produce 'Tuff'. If very large airbursts can produce formations of geo-ablative melt, instead of craters, then almost every last pebble of airburst melt on this fair world of ours has been mis-defined as volcanogenic. Astronomers Victor Clube, and William Napier, had been talking about the giant comet they described as the progenitor of the Taurid Complex since 1982, in their book The Cosmic Serpent. But no one had connected the dots, and put the Younger Dryas comet, and the Taurid Progenitor together. Except in private, speculative, emails, and letters. And to the best of my knowledge there was nothing in refereed literature. http://dl.dropbox.com/u/2268163/Paleolithic%20extinctions.pdf 7 page Then, in early 2010 Professor Napier published a paper in the Journal Monthly Notices of the Royal Astronomical Society titled, "Paleolithic extinctions and the Taurid Complex," -- in it we read: "The proposition that an exceptionally large comet has been undergoing disintegration in the inner planetary system goes back over 40 years (Whipple 1967), and the evidence for the hypothesis has accumulated to the point where it seems compelling. Radio and visual meteor data show that the zodiacal cloud is dominated by a broad stream of largely cometary material which incorporates an ancient, dispersed system of related meteor streams. Embedded within this system are significant numbers of large NEOs, including Comet Encke. Replenishment of the zodiacal cloud is sporadic, with the current cloud being substantially over-massive in relation to current sources. The system is most easily understood as due to the injection and continuing disintegration of a comet 50-100 km in diameter. The fragmentation of comets is now recognized as a major route of their disintegration, and this is consistent with the numerous sub-streams and co-moving observed in the Taurid complex. The probable epoch of injection of this large comet, ~20-30 kyr ago, comfortably straddles the 12.9 kyr date of the Younger Dryas Boundary. The hypothesis that terrestrial catastrophes may happen on timescales ~0.1 Myr, due to the Earth running through swarms of debris from disintegrating large comets, is likewise not new (Clube & Napier, 1984). However the accumulation of observations has allowed us to build an astronomical model, closely based on the contemporary environment, which can plausibly yield the postulated YDB (Younger Dryas Boundary) catastrophe. The interception of ~10E15 gm of material during the course of disintegration is shown here to have been a reasonably probable event, capable of yielding destruction on a continental scale. The object of this paper is not to claim that such an encounter took place at 12,900 BP -- that is a matter for Earth scientists -- but to show that a convincing astronomical scenario can be constructed which seems to give a satisfactory match to the major geophysical features of the Younger Dryas Boundary data. If indeed the YDB event was an astronomical catastrophe, its occurrence bears little relation to current impact hazard assessments derived from NEO surveys." It was indeed an astronomical catastrophe. And the nature of the event bears no resemblance whatsoever to anything in any NEO hazard assessments, or anything in current impact theory. With Professor Napier's work specifically proposing in refereed literature that the Taurid Progenitor was the Younger Dryas comet, he changed the game completely. Because he didn't just give us a convincing astronomical model of the event. We also have a pretty good picture of the physical properties of the thing that did the disastrous deed. And if you can describe a beast, you can predict its footprints. It is important to note here that the astronomical model of the Taurids implies that most catastrophic impact events are probably the result of a very large cluster of smaller fragments, and cometary debris. And not a single, large bolide. Mark Boslough's simulations predict the temps, pressures, flow directions, and rotation speeds, of a single impact down-blast vortex. And since we are working from postulate that the events of the YDB were caused by the impact storms, of the debris streams, of the fragmented Taurid progenitor. The YD impact hypothesis as it stands, describes tens of thousands of such airbursts in a little over an hour. And accompanied by clouds of particles down to the size dust grains falling into the atmosphere at something like 30 km/per second, as the Earth crossed through the orbital path of the giant fragmented comet's debris stream. Firestone, and friends proposed destructive forces equivalent to as much as 10E9 megatons of TNT. And at temps hotter than the surface of the sun. (a half pound of TNT will blow a hole in the ground you could lose a small car in) Professor Napier states, "The interception of ~10E15 gm of material during the course of disintegration is shown here to have been a reasonably probable event, capable of yielding destruction on a continental scale."..." Cochrane/Pueyrredon Lake, Lago Posades on SW of dark plateau -47.299381 -71.980131 .151 km el Lago Ghio -47.304100 -71.533653 .376 km el 1 km crater, 3 ground views -47.323359 -70.786983 .725 km low Guadal Grande white low -46.725080 -69.835423 .299 km el low SW edge of NE rim of black plateau -45.844801 -69.674997 .506 km el highest of 3 .2 km size round lakes on E edge of large dark melted plateau -45.710081 -69.435403 1.087 km el white lake in 15 km wide basin -45.595170 -69.536351 .674 km el low, 337 m under 1.011 km high SW past edge -44.674044 -68.059731 .740 km el -45.139829 -68.360533 1.36X.41 km size NNW, .472 km el low at NNW bottom, 112 m below .482 km el plateau W of low point, shows as usual no high rim, confirming the formation by erosion within a few seconds of high density very hot directed blast from air burst of ice comet fragment arriving at perhaps 35 km/sec at low angle, maybe 10-45 deg to ground -- common white minerals may arrive from impactor. -45.207627 -68.384444 2 km size crater on plateau, with many fractal craters close together, .378 km el low, 94 m below .452 km el plateau to NE, with .2 km size crater on SE rim, .419 km low, 29 m below .448 km el plateau -- while the very similar rim slope in angle and height, that is the outer boundary of this long NS plateau, is evidence that a much vaster plateau surface was ablated away by the barrage of air burst comet fragments, not by previous or subsequent massive water floods. The plateau surface in general must have been partially melted and levelled during the geoablative process. Four fine ground photos on Google Earth N of this location show some of the flat dark and red layers in this region: Los Altares, Chubut Argentina, ground view, -44.725178 -68.611603 .322 km el Laguna de Agnia with many concave arc ridges uphill E -43.807717 -69.690869 .603 km el low ~5X2 km pond size within 12 km basin, impact features may extend E for 52 km. white pond, fairly in line E of Laguna de Agria, Chubut -43.903411 -69.200781 .471 km el ~.8X.2 km long pond, within 6 km wide basin -- the length of the whole feature is 52 km. one crater within a fractal horde, -42.960219 -68.310961 .977 km el low, 3 km size Impact melt formation by low-altitude airburst processes, evidence from small terrestrial craters and numerical modeling, H E Newsom & MBE Boslough 2008 Mar 2p abstract: Rich Murray 2010.11.17 http://rmforall.blogspot.com/2010_11_01_archive.htm Wednesday, November 17, 2010 [ at end of each long page, click on Older Posts ] http://groups.yahoo.com/group/astrodeep/message/73 [ you may have to Copy and Paste URLs into your browser ] 3 times more downward energy from directed force of meteor airburst in 3D simulations by Mark B. E. Boslough, Sandia Lab 2007.12.17: Rich Murray 2010.08.30 http://rmforall.blogspot.com/2010_08_01_archive.htm Monday, August 30, 2010 [ at end of each long page, click on Older Posts ] http://groups.yahoo.com/group/astrodeep/message/63 [you may have to Copy and Paste URLs into your browser] [Extract] http://74.125.155.132/scholar?q=cache:YY6MFUns_CkJ:scholar.google.com/+%22Mark+B\ oslough%22,+impacts&hl=en&as_sdt=10000000000 [ Extracts ] "Dr. Boslough has also shown that an LAA [ Low Altitude Airburst ] from a ~100 meter diameter NEO melted sand into glass across a region about 10 km in diameter during Libyan Desert Glass impact ~35 million years ago. During this event the LAA's fireball settled onto parts of Egypt and Libya for about a minute with temperatures approaching 5,000 K. Its hypersonic blast wave extended radially for about 100 kilometers." ground views of over 100 .1-.5 km shallow (ice comet fragment bursts) craters, Bajada del Diablo, Argentina (.78-.13 Ma BP) [42.87 S 67.47 W] Rogelio D Acevedo et al, Geomorphology 2009 Sept: Rich Murray 2010.03.28 http://rmforall.blogspot.com/2010_03_01_archive.htm Saturday, March 27, 2010 http://groups.yahoo.com/group/astrodeep/message/47 ______________________________________________ Rich Murray, MA Boston University Graduate School 1967 psychology, BS MIT 1964, history and physics, 1943 Otowi Road, Santa Fe, New Mexico 87505 505-819-7388 rmforall at gmail.com http://groups.yahoo.com/group/AstroDeep/messages http://RMForAll.blogspot.com new primary archive http://groups.yahoo.com/group/aspartameNM/messages group with 118 members, 1,625 posts in a public archive http://groups.yahoo.com/group/aspartame/messages group with 1223 members, 24,362 posts in a public archive http://groups.yahoo.com/group/rmforall/messages ______________________________________________ ______________________________________________ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list at meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list Received on Sun 31 Jul 2011 07:11:56 PM PDT |
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