I could haggle over this for a long time, but here goes a post. The non-bold text is from:
http://www.icr.org/research/jb/largescaletectonics.htm
My comments are in bold text.
COMPUTER MODELING OF THE LARGE-SCALE TECTONICS ASSOCIATED WITH THE GENESIS FLOOD
JOHN R. BAUMGARDNER, Ph.D.
1965 Camino Redondo
Los Alamos, NM 87544
Presented at the Third International Conference on Creationism
Pittsburgh, PA, July 18-23, 1994
Copyright 1994 by Creation Science Fellowship, Inc.
Pittsburgh, PA USA - All Rights Reserved
KEYWORDS
Genesis Flood, geological catastrophism, runaway subduction, mantle dynamics, plate tectonics
ABSTRACT
Any comprehensive model for earth history consistent with the data from the Scriptures must account for the massive tectonic changes associated with the Genesis Flood. These tectonic changes include significant vertical motions of the continental surfaces to allow for the deposition of up to many thousands of meters of fossil-bearing sediments, lateral displacements of the continental blocks themselves by thousands of kilometers, formation of all of the present day ocean floor basement rocks by igneous processes, and isostatic adjustments after the catastrophe that produced today's Himalayas, Alps, Rockies, and Andes. This paper uses 3-D numerical modeling in spherical geometry of the earth's mantle and lithosphere to demonstrate that rapid plate tectonics driven by runaway subduction of the pre-Flood ocean floor is able to account for this unique pattern of large-scale tectonic change and to do so within the Biblical time frame.
INTRODUCTION
Many diverse mechanisms have been put forward to explain the dramatic and rapid geological changes connected with the Genesis Flood [6,7,13,14]. This event is here conceived to have generated the portion of the geological record beginning with the initial abrupt fossil appearance of multicellular organisms and including all of the so-called Paleozoic and Mesozoic eras and the lower part of the Cenozoic. In other words, the Flood is understood, in terms of normal usage of the words in the Genesis account, to be a global catastrophe that destroyed all the non-aquatic air-breathing life on the earth except for that preserved in the ark. Since the Scriptures indicate no large-scale destruction of life between the time of creation and the Flood, it logically follows that the initial abrupt appearance of multicellular fossils in the rock record must represent the onset of this cataclysm.
(In essence, this model is attempting to compress what is usually considered to be 500 million years of earth's history into the time of the great flood) The huge amount of energy required to accomplish such a vast amount of geological work so quickly together with the amazing order evident in the stratigraphic record
(I would term it more as "the ordered but vastly complex stratigraphic record; a great mosaic of evidence of sequences of various processes, operating in the context of a large variety of environments. Sedimentation and erosion, tectonic folding and faulting, intrusive and extrusive (volcanic) igneous activity, all these having happened in various sequences at various locations) and the smooth pattern sea floor spreading and continental drift documented in today's ocean floor obviously impose severe limitations on candidate mechanisms.
What constraints might one use to discriminate among possible mechanisms for the Flood? One is the pattern of downwarping and uplift of the earth's surface that produced the observed patterns of sedimentation. Broadly speaking, it is possible to divide the continental regions of today's earth into three general categories according to the type and amount of sedimentary cover.
(Broadly speaking? - Is that like saying "In a simplified view?) Cratonic shield areas such as the Canadian Shield, the African Shield, and the Scandinavian Shield, represent regions mostly barren of Phanerozoic
(Note: the Phanerozoic is the collective of the Paleozoic, Mesozoic, and Cenozoic), or fossil-bearing, sediment.
(OK) Surface rocks are instead pre-Phanerozoic crystalline rocks,
(There's also a lot of volcanics and sediments) frequently displaying strong metamorphism and often deeply eroded.
(Deep erosion of solid rock? Do you think that might take a long time?) Cratonic platform areas, a second category, represent broad regions of continental surface with generally
(generally?) extensive and uniform
(But not always I presume) Phanerozoic sedimentary deposits commonly a few kilometers in thickness. The third category includes Phanerozoic tectonic belts which frequently contain huge thicknesses of sediments--often up to tens of kilometers--usually with strong compressive deformations, evidence of large vertical displacements, and vast amounts of volcanism and metamorphism. These zones are mostly located along the margins of cratonic shield or platform regions and usually contain high mountains.
("Broadly speaking", I accept this)
These three categories, in the context of the Flood, respectively represent broadly uplifted and eroded areas, broadly downwarped areas that accumulated moderate thicknesses of sediment
(Apparently from the erosion of the pre-Phanerozoic cratonic shields.), and localized belts where downwarping and deformation were extreme and where huge thicknesses of sediment accumulated
(This sediment being proposed as having been scraped off of the top of the oceanic crust). The evidence indicates that when the forces responsible for the extreme downwarping in these tectonic belts abated, high mountains appeared as the deep, narrow, sediment-filled trenches rebounded isostatically.
(Is this isostatic rebound really theoretically expected? Also I note that the sediments miraculously now solid rock, to be uplifted into mountains!) The sedimentary patterns therefore suggest that transient processes, almost certainly operating in the earth's mantle, caused dynamical subsidence and uplift within craton interiors and intense localized downwarping at craton edges. In the context of the Flood, these observational data speak of large and rapid vertical motions of the earth's surface. Such vertical motions represent distinctive patterns of internal stress and mechanical work that must be accounted for by any successful mechanism.
(Yes, more or less this has happened, just not recently, and probably not over a very restricted time period)
A second major geological constraint concerns the large lateral displacements of the cratonic blocks
(Recognizing the "continental drift" of plate tectonic theory) that also occurred during the Flood. From a stress distribution standpoint this requirement of translating continental blocks by thousands of kilometers in a short period of time severely constrains candidate mechanisms because it involves the solid-state deformation of rock in the mantle below. That craton interiors display so little Phanerozoic deformation
(Is there really so little?)despite the fact the cratons traversed such vast distances so rapidly means that stress levels within the cratons never approached the fracture or yield limits and that the forces responsible for moving these huge bodies of rock were diffuse and relatively uniform over the area of the block.
(Or maybe it was a slow process) Mechanisms that move the plates by applying forces at their edges cannot produce this general absence of deformation in the craton interiors. The only conceivable mechanisms able to move plates so far and so rapidly
(This presumes they were moved rapidly; Again, maybe it was a slow process) with hardly any internal deformation are those that involve large scale flow in the earth's mantle and that apply relatively mild and uniform tractions on the base of the plates.
(Large convection cells in the oceanic mantle is scientifically accepted; Under the continental crust - I personally don't know. There is a failed oceanic rift in the North American mid-continent, that happened in the late pre-Cambrian (pre-Phanerozoic). This failed rift includes the Lake Superior basin.) This constraint as well as the previous one both point to catastrophic overturning of the mantle
(Yes indeed, if you're going to compress 500 million years down that much) driven by gravitational potential energy in large volumes of cold rock at the earth's surface and/or in the upper mantle and assisted by a runaway instability resulting from a temperature and stress dependent deformation law for silicate rock. The thrust of this paper is to report advances in numerical modeling of such a mechanism for the Flood. Results from this effort have been presented in papers at the two previous ICC meetings in 1986 and 1990 [4,5]. In the 1990 paper it was shown how subducting ocean floor along the Pangean margins leads to a pulling apart of the supercontinent in a manner generally consistent with the pattern of seafloor spreading recorded in the rocks of today's ocean floor [16]. This paper describes a number of improvements in the model. One is the use of a much more detailed reference state for the earth that includes compressibility and phase changes. Another is the addition of depth variation in the mantle's viscosity structure that provides for a low viscosity upper mantle and a higher viscosity lower mantle. Another is a much improved plate treatment that includes the oceans. The plates are now tracked using a highly accurate particle-in-cell method. Dynamic surface topography and sea level are now also computed as part of a time dependent calculation. This yields maps of the continental flooding that occurs in response to the mantle's internal dynamics. In addition there are several numerical improvements that allow larger time steps and provide increased accuracy.
(The numeric theory is beyond me; I'll concede it's validity. Heads must have really been spinning when the author presented this math at a creationist conference. This is the stuff of high level structural geology and geophysics)
MATHEMATICAL FORMULATION
(Omitted, see original paper if you wish)
THE REFERENCE STATE
(Omitted, see original paper if you wish)
PHASE CHANGES
(Omitted, see original paper if you wish)
NUMERICAL APPROACH
(Omitted, see original paper if you wish)
TREATMENT OF THE RUNAWAY INSTABILITY
(Omitted, see original paper if you wish)
INITIAL CONDITIONS
(Omitted, see original paper if you wish)
RESULTS
Starting with these initial conditions, the numerical model is advanced in time by solving the momentum, mass, and energy conservation equations at every mesh point on each time step. Tractions on the base of the surface plates produced by flow in the mantle below causes the plates to move and their geometry to change. Fig. 4 contains a sequence of snapshots at times of 10, 30, 50, and 70 days showing the locations of the continental blocks and the velocities and temperatures at a depth of 100 km. A notable feature in the velocity fields of Fig. 4 is the motion of the nonsubducting continental blocks toward the adjacent zones of downwelling flow. This motion is primarily a consequence of the drag exerted on a nonsubducting block by the material below it as this material moves toward the downwelling zone. Such a general pattern of flow is evident in the cross-sectional slices of Fig 5. The translation of the nonsubducting blocks in this manner leads to a backward, or oceanward, migration of the zones of the downwelling. This oceanward translation of the continental blocks as well as the subduction zones therefore acts to pull the supercontinent apart. This behavior is a basic fluid mechanical result and not the consequence of any special initial conditions or unusual geometrical specifications other than the asymmetrical downwelling at the edges of nonsubducting portions of the surface. That the continental blocks move apart without colliding and overrunning one another, on the other hand, depends in a sensitive way on the initial distribution of thermal perturbations, the shapes of the blocks, and timing of their breakup. A moderate amount of trial and error was involved in finding the special set of conditions that leads to the results shown in Fig. 4 and 5.
OK, maybe it could happens in theory (hypothesis?), but did it ever really happen at that fast of a rate? Did it happen at the time proposed for the "great flood? Documentation of the evidence is called for. I don't think the evidence exists)
An important output from the calculations is the height of the surface relative to sea level. Fig. 6 shows global topography relative to sea level at a time of 30 days. Several features are noteworthy. One is the broad belt of depression and flooding of the continental surface adjacent to subduction zones, as evident, for example, along the western margins of North and South America. This depression of the surface is mostly due to the stresses produced by the cold slab of lithosphere sinking into the mantle below these regions. Narrow trenches several kilometers in depth lie inside these zones. A second feature is the elevation of the topography above the oceanic spreading ridges. This effect is so strong that some portions of the ridge are above sea level.
(OK, this helps in boiling water into the atmosphere) Since the volume occupied by the ridges displaces sea water, a result is to raise the global sea level and to flood significant portions of the continent interiors.
(A mainstream accepted hypothesis) A third effect is the elevation of continent areas flanking zones of continental rifting. This is a consequence of the intrusion of a significant volume of hot buoyant rock from deeper in the mantle beneath these zones. This produces a belt of mountains several kilometers high on either side of the rift zone between North America and Africa, for example. It is worth emphasizing that the topography dynamically changes with time and that Fig. 6 is but a snapshot. It illustrates, however, that what is occurring in the mantle below has a strong and complex effect on the height relative to sea level of a given point at the earth's surface. Although this calculation is crude and merely illustrative, it shows that this mechanism produces the general type of vertical surface motions required to create key aspects of the global stratigraphic record. It produces broad scale continental flooding; it creates belts of thick sediments at the edges of cratons; it uplifts portions of the continents where broad scale erosion and scouring would be expected to occur.
CONCLUSIONS
This calculation illustrates that with relatively modest initial perturbations, gravitational potential energy stored in the earth's upper thermal boundary layer drives an overturning of the mantle that pulls the Pangean supercontinent apart, moves the continental blocks by thousands of kilometers, elevates much of the newly formed seafloor above sea level, floods essential all of the continental surface, and produces dramatic downwarpings of the continent margins that lie adjacent to zones of subduction.
The key to the short time scale is the phenomenon of power-law creep that, for parameter values measured experimentally and for strain rates observed in the calculation, yields more than eight orders of magnitude reduction in effective viscosity relative to a condition of zero strain rate. Indeed maximum strain rates implied by the calculated velocities are on the order of 10-4 s-1 --precisely in the range for which laboratory measurements have been made [10,11]. As discussed in more detail in the companion paper, the combination of the effect of the endothermic phase transition at 660 km depth to act as a barrier to vertical flow [12,15,19,20] with the tendency of thermal runaway of regions of cold material from the upper thermal boundary layer, makes a sudden catastrophic avalanche event a genuine possibility. Thermal runaway behavior is a direct consequence of the positive feedback associated with viscous heating and temperature dependent rheology [1,9] and amplified by an extreme sensitivity to strain rate. A notable outcome of the recent high resolution mapping of the surface of Venus by the Magellan spacecraft is the conclusion that there was a tectonic catastrophe on Venus that completely resurfaced the planet in a brief span of time [18]. This event in terms of radiometric time
(Using isotopic dating methods?! They had access to rocks of Venus?), accounting for the uncertainties in the cratering rate estimates, coincides almost precisely with the Flood event on earth. A mechanism internal to Venus was almost certainly the cause of that catastrophe. It is reasonable to suspect that simultaneous catastrophes on both the earth and Venus likely were due to the same phenomenon of runaway avalanche in their silicate mantles.
(God decided to purge Venus of life, at the same time?)
This mechanism of runaway subduction then appears to satisfy most of the critical requirements imposed by the observational data to successfully account for the Biblical Flood. It leads to a generally correct pattern of large scale tectonic change; it produces flooding of the continents; it causes broad uplifts and downwarpings of craton interiors with intense downwarpings at portions of craton margins to yield the types of sediment distributions observed. It also transports huge volumes of marine sediments to craton edges as ocean floor, in conveyor belt fashion, plunges into the mantle and most of the sediment is scraped off and left behind.
(Conceivable, but the evidence isn't there) It plausibly leads to intense global rain as hot magma erupted in zones of plate divergence, in direct contact with ocean water, creates bubbles of high pressure steam that emerge from the ocean, rise rapidly through the atmosphere, radiate their heat to space, and precipitate their water as rain.
(Again, conceivable, but note that this is not introducing any new water into the biosphere; It's just cycling water out of the ocean, to be re-precipitated and ultimately returned to the ocean. If the mid-ocean ridge was deep in the ocean, I would expect that the heat would dissipate into the ocean water; If it was close or at the water surface, perhaps the water would boil, to become vapor in the atmosphere) That no air-breathing life could survive such a catastrophe and that most marine life also perished is readily believable.
(My impression is, that relative to the effects of the truly massive seismic and volcanic events also happening, the water might be a relatively small problem. Indeed, a vast amount of volcanism is a prime candidate for the poorly understood massive extinctions at the end of the Paleozoic) Finally, numerical modeling appears to be the most practical means for reconstructing a comprehensive picture of such an event and for creating a conceptual framework into which the geological observational data can be correctly integrated and understood.
(Sure, you have a mathematical model, but did it really happen?) This calculation, it is hoped, is a modest step in that direction.
REFERENCES
(Omitted, see original paper if you wish)
FIGURES
(Omitted, see original paper for link, if you wish)
This paper assumes that the "great flood" happened, and then tries to fit the evidence into that model. The more conventional approach would be to look at the evidence, and then try to deduce what caused the evidence.
An increase in the rate of mid-ocean ridge spreading does have mainstream scientific acceptance (personal communication with geology professor, on line references have been tough to come by). Whether there was also "runaway" subduction, is something I don't personally know. Also, the cause-effect relationship between mid-ocean ridge spreading and plate subduction is uncertain to me.
Comments on sedimentary processes: Essentially, the size of the sediment particles are a reflection of the energy of the depositional environment. In a high energy environment, the coarse fragments are deposited, while the finer fragments are carries away, until they are deposited in a lower energy environment. Limestones are essentially indicative of a lack of coarser clastic material being deposited - the coarse clastics have settled out before arriving at that location. The geologic records shows multiple transgressions and regressions of the seas up onto the continents. Were there a series of "mini-great floods", that comprised the total "great flood"? This "great flood" scenario is essentially part of that of that God created a young earth, but such that it appears to be much older. As miracles go, this is certainly one of God's "greatest hits" and/or greatest deceptions.
What would I expect the current earth to look like, had this flood and other events happened (what is it, 4500 years ago)? First of all, I wouldn't expect the sedimentary rock deposits to exist as they do. I would expect to still see prominent evidence of great erosion and great deposition. Perhaps gullies everywhere, and great deltas where the sediment was dumped into the elevated seas.
In summary, the professional term for a paper of this nature is "Arm Waving".
Moose
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Old Earth evolution - Yes
Godly creation - Maybe
[This message has been edited by minnemooseus, 12-23-2001]
[This message has been edited by minnemooseus, 12-23-2001]
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