Author Topic: SURGE TECTONICS HIGHLIGHTS  (Read 165 times)


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« on: August 26, 2017, 10:05:53 am »
Below are excerpts from the book, Surge Tectonics

(Here's a Surge Channels Map:
- The Webpage is:
- I don't think that website is connected to Surge Tectonics science. It looks like they just use some of the science for their own religious ideas.
- That 1996 map, from the Surge Tectonics book, shows Earth's heat flow bands (55+ mW/m^2) which are said to be where surge channels are located. Regions of sparse data are the Antarctic, the south Pacific, the Himalayas and the eastern Arctic.)



SURGE TECTONICS: A New Hypothesis of Global Geodynamics, by Arthur Meyerhoff et al., 1996
3.1 Introduction
_Surge tectonics is based on the concept that the lithosphere contains a worldwide network of deformable magma chambers (surge channels) in which partial magma melt is in motion (active surge channels) or was in motion at some time in the past (inactive surge channels).
_The presence of surge channels means that all of the compressive stress in the lithosphere is oriented at right angles to their walls. As this compressive stress increases during a given geotectonic cycle, it eventually ruptures the channels that are deformed bilaterally into kobergens (Fig. 2.15).
_Thus, bilaterally deformed foldbelts in surge-tectonics terminology are called kobergens.
_Surge tectonics involves
_1. contraction or cooling of the Earth
_2. lateral flow of fluid, or semifluid, magma through a network of interconnected magma channels in the lithosphere
_3. Earth's rotation, which involves differential lag between the lithosphere and the strictosphere and its effects, i.e. eastward shifts (Table 2.3)
_the strictosphere is the hard mantle beneath the asthenosphere and lower crust
_lithosphere compression caused by cooling propels the lateral flow of magma through surge channels

_Contrary to general belief continental roots are fixed to the strictosphere [as shown] by large and increasing volumes of data, including neodymium and strontium studies of crustal rocks (..., 1979).
_the deep roots of continents are a major obstacle to any hypothesis requiring continental movements (..., 1985-1990).
_deep roots are seen beneath part of all of the Earth's ancient cratons.
_In places, however, lenses of 7.0-7.8-km/s material containing low-velocity zones (Fig. 3.5) are present (..., 1989).
_Such lenses containing low-velocity layers postdate the establishment of the deep cratonic roots, as we show in subsequent sections.

_3.3.2 Contraction Skepticism
_3.3.3 Evidence For a Differentiated, Cooled Earth
_1. The Earth includes several concentric shells, which are explicable only if the Earth differentiated efficiently and at a much higher temperature than today.
_2. The outermost of these shells may be the oceanic crust whose thickness ranges from about 4-7 km.
_This crust is characterized by relatively constant thickness and fairly uniform seismic properties.
_This uniformity is explained if the oceanic crust is the outermost of the Earth's concentric shells.
_5. A convincing evidence that huge segments of the lithosphere have been and are being engulfed by tangential compression is the existence of Verschluckungszonen (engulfment zones)
_In places along such zones, whole metamorphic and igneous belts that are characteristic of parts of a given foldbelt simply disappear for hundreds of kilometers along strike
_Although [some] considered these features to be former subduction zones, this interpretation is difficult to defend because all of these zones, regardless of age, are near-vertical bodies (1) reach only the top or middle of the asthenosphere (150 to 250 km deep) and (2) do not deviate more than 10 to 25 from the vertical (..., 1983-1984).
_6. The antipodal positions of the continents and ocean basins (unlikely a matter of chance) mean that Earth passed through a molten phase
_7. Theory (..., 1970) and laboratory experiment (..., 1956) showed that heated spheres cool by rupture along great circles. Remnants of two such great circles (as defined by hypocenters at the base of the asthenosphere) are active today: the Circum-Pacific and Tethys-Mediterranean fold systems. The importance of Bucher's (1956) experiment to contraction theory, in which he reproduced the great circles, is little appreciated.

3.8 Evidence for the Existence of Surge Channels
_As noted above, reflection-seismic techniques (...) have shown that the continental crust of the upper lithosphere is divisible in a very general way into an upper moderately reflective zone and a lower highly reflective zone (...). Closer scrutiny of the newly-acquired data soon revealed the presence in the lower crust of numerous cross-cutting and dipping events.
_When many of these cross-cutting events were preceived to be parts of lens-like bodies, various names sprang up: .... Strictly nongenetic names include lenses, lenticles, lozenges, and pods (...). Finlayson et al. (1989) found that the lenses have P-wave velocities of 7.0-7.8 km/s, commonly with a low-velocity zone in their middle.
_Thus we equate the lenses with the pods of "anomalous lower crust" and "anomalous upper mantle" that we discussed in a preceding section. Klemperer (1987) noted that many of the lenses are belts of high heat flow. Hyndman and Klemperer (1989) observed that the lenses generally have very high electrical conductivity.
_Meyerhoff et al. (1992b) discovered that there are two types of undeformed reflective lenses, and that many of these lenses have been severely tectonized. The first type of lens is transparent in the middle (Fig. 3.29); the second type is reflective throughout (Fig. 2.11). Tectonized lenses also may have transparent interiors, or parts of interiors; many, however, are reflective throughout (Fig. 3.21). Where transparent zones are present (Fig. 3.20), bands of high heat flow, bands of microearthquakes, belts of high conductivity, and bands of faults, fractures, and fissures are present. Where a transparent layer is not present, high heat flow and conductivity, however, are commonly still present. Meyerhoff et al. (1992b) also found that lenses with transparent interiors are younger than those without transparent interiors; moreover, there is a complete spectrum of lenses from those with wholly transparent interiors to those without.
_The best explanations of thes observations are that (1) the lenses with transparent interiors are active surge channels with a low-velocity zone sandwiched between two levels of 7.0 to 7.8 km/s material; (2) the lenses with reflective interiors are former surge channels now cooled and consisting wholly of 7.0 to 7.8 km/s material; and (3) the tectonized lenses are either active or former surge channels since converted into kobergens by tectogenesis.

_Seismotomographic data, wherever detialed studies have been made, indicate that the lenses seen in seismic-refraction and seismic-reflection studies form an interconnected, reticulate network in the lithosphere. Although only one highly detailed seismotomographic study has been made on a continental scale---this in China---it leaves no room for doubt that the 7.0-7.8-km/s lenses with transparent interiors and the seismotomographically detected low-velocity channels in the lithosphere are one and the same....
_Using seismotomographic techniques, it will be possible to map active surge channels over the world with comparative ease.

_Direct evidence for the existence of surge channels comes from tectonic belts themselves, and from one type of magma flood province. The latter include rift igneous rocks that crop out nearly continuously for their full lengths. Examples include the rhyodactic Sierra Madre Occidental-Sierra Madre del Sur extrusive and intrusive belt of Mexico and Guatemala, some 2,400 km long; the 1,600-km-long Sierra Nevada-Baja California batholith belt; the 4,000-km+ batholith and andesite belt of the Andes south of the equator; the 4,000-km-long Okhotsk-Chukotka silicic volcanic belt; the 5,800-km-long Wrangellia linear basaltic province extending from eastern Alaska to Oregon, which erupted in less than 5 Ma; and many other similar continental magma belts. The ocean basins are equally replete with them, ranging from the 60,000-km-long midocean ridge system through the 5,800-km-long Hawaiian- Emperor island and seamount chain to many similar belts of shorter lengths. Geochemical studies also show that most of these belts are interconnected. Another linear flood-basalt belt, which has been studied only relatively recently, is the subsurface Mid-Continent province that extends 2,400 km from Kansas through the Great Lakes to Ohio (Figs. 3.23, 3.24).

_Other data mentioned in the preceding sections corroborate the interconnection of active surge channels. One of these is the coincidence of the 7.0-7.8-km/s lenses of the active surge channels (Figs. 2.9, 2.31, 3.6, 3.9, 3.14, 3.20) with the belts of high heat flow (Fig. 2.26) and with belts of microseismicity. Both the presence of high heat flow and microseismicity indicate that magma is moving within active surge channels.
_However, an even more dramatic example is the June 28, 1992, Landers, California, earthquake-related activity shown on Figure 3.25. This figure shows that the 7.5- magnitude earthquake was strong enough to affect areas up to 1,250 km from the epicenter (...) and provides an exampole of Pascal's Law in action. Given the importance of Pascal's Law in surge-channel systems, the fact should be noted that the viscosity of the magma in the surge channels affected by the Landers event is sufficiently low that, when the stress was applied at a single hypocentral point (Landers), the effects could still be transmitted for 1,250 km!

_3.9 Geometry of Surge Channels
_Corry (1988) published the "Christmas Tree" model shown in Figure 2.8; Bridgwater et al. (1974) published the more complex model shown in Figure 3.26. Either of these could be cross sections of surge channels. Both are multitiered with one or more magma chambers above the main chamber.

_Study of Figures 2.8, 2.9, 2.11, 2.31, 3.6, 3.9, 3.13, 3.14, 3.20, 3.23 and 3.24 might lead one to believe that surge channels are everywhere fairly simple structures expressed at the surface by a single belt of earthquake foci, high heat flow, bands of faults-fractures-fissures (streamlines), and related phenomena which, during tectogenesis, deform into a single kobergen. Although this simple picture is true of many kobergens, it is not true of all. Study of Figures 3.26 and 3.27 suggests that, during tectogenesis of the surge-channel complexes shown on these figures, two or more parallel kobergens may exist at the surface. Such a complex surface expression is in fact quite common. Well-documented examples are found in the Western Cordillera of North America, the Mediterranean-Tethys orogenic belt (including the Qinghai-Tibet Plateau), and the Andes, inter alia. Within the Western Cordillera, the Qinghai-Tibet Plateau, and the Andes, we have found four or more parallel kobergens side by side at the surface as documented and illustrated by Meyerhoff et al. (1992b).

_The principal forces acting on the lithosphere are compression, rotation, and gravity.
_Thus, when the postulated tholeiitic picrite magma reachs the Moho- (i.e., the zone between 8.0-km/s mantle below and 6.6-km/s above), it has reached its level of neutral buoyancy and spreads laterally. Under the proper conditions---abundant magma supply and favorable crustal structure---a surge channel can form. We suggest the possibility that the entire 7.0-7.8-km/s layer may have formed in this way. In support of this suggestion, we note that the main channel of every surge channel studied, from the Archean to the Cenozoic, is located precisely at the surface of the Moho-. This indicates that the discontinuity is very ancient, perhaps as old as the Earth itself. This fact and the great difference in P-wave ==velicities above and below the Moho- surface suggest in turn that the discontinuity originated during the initial cooling of the Earth. Hence, Mooney and Meissner's (1992) "transition zone" was the level of neutral buoyancy at the time the 7.0-7.8-km/s material was emplaced.
_The formation of the Christmas-tree-like structures (Figs. 2.8, 3.26) at the Moho- is simply an extension of the larger scale process of magma transfer from the asthenosphere to the discontinuity. Once surge channels are established at the discontinuity, the same processes take over that brought the magma to the discontinuity in the first place, specifically, magma differentiation in the channels and the Peach-Kohler climb force (...). After lighter magmas have formed by differentiation and related processes, they rise to their own neutral buoyancy levels, forming channels above the main surge channel (Figs. 3.23, 3.27).



Chapter 6 Magma Floods, Flood Basalts, and Surge Tectonics
_Some 63% of the ocean basins are covered with flood basalts. At least 5% of the continents are likewise covered with flood basalts. Thus 68%---a minimum figure--- of the Earth's surface is covered with these basaltic rocks. Flood basalts, then, are not the oddities that many suppose them to be. In spite of this, they receive little attention among the scientific community.
_Engel et al. (1965) long ago demonstrated that deep ocean-floor tholeiitic basalts are the oceanic equivalent of the continental flood basalts. The Basalt Volcanism Study Project (1981) differentiated between the continental flood basalts and "ocean-floor basalts," while recognizing that the principal differences were the abundance of minor and rare-earth elements. Press and Siever (1974...) recognized the fact that the ocean-floor basalts and continental flood basalts are nearly the same, and that their differences are explained readily by contamination in the continental crustal setting.

_Continental flood-basalt provinces are geometrically of two types. The first is broadly ovate, or even round, with the maximum diameter ranging from about 500 km (Columbia River Basalt) to more than 2,500 km (Siberian Traps). The second is distinctly linear, with a width of 100 to 200 km and lengths up to and even exceeding 3,000 km.
_Tectonism and metamorphism can severely disrupt any flood-basalt province after its formation. For example, ... the Antrim Plateau Volcanics of northern Australia ... parts ... have been removed by erosion. ... Similarly, only very scattered, strongly flooded, and metamorphosed remains of the Willouran Mafic rocks are preserved in ... South Australia, but their distribution shows that [it] is a linear flood-basalt province.

_6.6 Flood-Basalt Provinces and Frequency in Geologic Time
As we observed near the beginning of this chapter, the commonly used textbooks of physical geology, structural geology, and geotectonics rarely list more than 10 to 20 flood-basalt provinces. However, the magnificent review of basalts by the participants in the Basalt Volcanism Study Project (1981) mentions or figures not less than 56 flood-basalt provinces and 45 additional provinces of dike swarms which the project participants thought might have fed flood-basalt provinces that have since been removed by erosion.
_Yoder (1988, ...) wrote that "Great basaltic 'floods' have appeared on the continents throughout geologic time (Table 1)," but showed on his Table 1 none older than 1,200+/- 50 Ma. He also ... made it clear that he regards midocean-ridge and other oceanic basalts as flood basalts, as have a number of earlier workers (..., 1974). We concur absolutely with their interpretation. We also concur with the participants of the Basalt Volcanism Study Project (1981) that evidence of the existence of flood provinces extends back in time to at least 3,760 Ma, and very likely to the Earth's earliest (but nowhere preserved) history.

_6.7 Non-Basalt Flood Volcanism in Flood-Basalt Provinces
The bimodal nature of many flood-basalt provinces has been known and stressed for many years (..., 1981). Time seems not to be a major factor (the idea being that, the longer an underlying magma chamber is present, the more the magma will interact with the continental crust above it). The most important factor may be the crustal stress state.
_We believe that the evidence from these examples demonstrates convincingly that there is a complete gradation from all-basalt and basaltic andesite flood provinces to bimodal provinces containing mainly rhyolite and ignimbrite. Hence, there are basalt floods and rhyolite floods.
_... The volumetric predominance of these ash-flow tuffs has led to recognition of the [Sierra Madre Occidental] as the world's largest rhyolite-dominated volcanic province" (Fig. 6.28).
_Thus, from 38 Ma until 17 Ma, a truly bimodal column of extrusive rocks accumulated in northern Mexico and adjoining parts of the United States, with rhyolite at one end, basaltic andesite at the other, and very little rock of intermediate compositions. ... [Skipping remainder of paragraph]
_We believe that these basalts of the "southern cordilleran basaltic andesite" suite are flood basalts. And if they are flood basalts, then we have demonstrated that the same mechanism that leads to continental and oceanic basalt outpourings also produces the "orogenic andesite suite".
_The Okhotsk-Chukotka Volcanic Belt, a linear belt of Cretaceous volcanics, is similar to the Sierra Madre Occidental. It extends 3,000 km from the mouth of Uda Bay (northwestern Sea of Okhotsk) to the Bering Sea almost at St. Lawrence Island. It seems to have every type of volcanic from andesitic through rhyolite. Basalts are scarce. Soviet geologists either ignore it or say that it is the remnant of a volcanic arc.

_6.9 Surge-Tectonics Origin of Magma Floods
In the preceding pages we have referred to the presence of several flood-basalt provinces around the world, and have shown that some flood provinces include large volumes of silicic rocks, usually rhyolite and/or dacite. We have also shown by the northern Mexican example that flood basalts can interfinger with the andesite orogenic suite.
_The available evidence has led us to the conclusion that the same mechanism causes volcanism in the midocean ridges, linear island and seamount chains, oceanic plateaus, island arcs, and continental interiors. We next attempt an explanation of our conclusion.
_Many attempts have been made to explain flood volcanism in the framework of the plate-tectonics hypothesis. The two principal explanations involve (1) hot spots, or mantle plumes and (2) an extraterrestrial cause (e.g., an asteroid impact).
_Extraterrestrial causes have been proposed by Alt et al. (1988), who applied this hypothesis to the Columbia River flood-basalt province. A major problem with this concept is that it does not explain linear flood-basalt provinces such as the Keweenawan (Mid-Continent) rift and Wrangellia. Furthermore, Mitchell and Widdowson (1991) pointed out that impact and shock phenomena should be present in the area surrounding the Columbia River province if it resulted from extraterrestrial action, but they are entirley absent.
_As we noted in Chapters 3 and 4, Mooney et al. (1983) observed that all active rifts studied by them have an anomalous lower crust with P-wave velocities in the 7.0 to 7.7 km/s range (Fig. 6.36). [Others] obtained the identical result.... Fuchs (1974) believed that this pod of anomalous lower crustal material houses the mechanism that causes rifting. It is interesting to note that all midocean ridges have a pod of 7.0-7.7 km/s as well (..., 1959-1965). (Furthermore, each island arc and foldbelt also has a pod of 7.0-7.7 km/s material that pinches out from the center of the arc or foldbelt (..., 1987-1989 ... for the Japan arc ... [and] for the Appalachians.)
_Figure 3.6 is a cross section across the Baykal rift, from Krylov et al. (1979) and Sychev (1985). Years of refraction work have shown [that] Lake Baykal is underlain at about 32 km by a pod that is connected to the deeper asthenosphere. The shallow pod contains a low-velocity zone that presumably is a partial melt. The pod extends the full length of the rift. It is, in short, a channel containing partly molten magma and an excellent example of one of our surge channels. Were it to burst, we believe that it would produce another linear flood-basalt province.
_According to our surge tectonic hypothesis, magma in surge channels moves both vertically and horizontally. When two surge channels come in contact, their magmas join together. If they are oriented at an appreciable angle to one another, we believe that the result is a "collision". These5 "collisions" are responsible for the eruption of round or ovate flood-basalt provinces worldwide.



We have proposed a new hypothesis of global tectonics in this book, one that is different and will be considered unorthodox by many scientists and non-scientists alike. However, we believe that current tectonic hypotheses cannot adequately explain the increasing volume of data being collected by both old and new technologies. We believe that the hypothesis of surge tectonics does explain these data sets, in a way that is simple and more accurate.
_The major points of the surge-tectonics hypothesis can be summarized as follows:
_1. All linear to curvilinear mesoscopic and megascopic structures and landforms observed on Earth (and similar features seen on Mars, Venus, and the moons of Jupiter, Saturn and Uranus), and all magmatic phenomena are generated, directly or indirectly, by surge channels. The surge channel is the common denominator of geology, geophysics, and geochemistry.
_2. Surge channels formed and continue to form an interconnected worldwide network in the lithosphere. They contain fluid to semifluid magma, or mush, differentiated from the Earth's asthenosphere by the cooling of the Earth. All newly differentiated magma in the asthenosphere must rise into the lithosphere. The newly formed magma has a lower density and therefore, is gravitationally unstable in the asthenosphere. It rises in response to the Peach-Kohler climb force to its level of neutral buoyancy (that is, to form a surge channel).
_3. Lateral movements in the Earth's upper layers are a response to the Earth's rotation. Differential lag between the more rigid lithosphere above and the (more) fluid asthenosphere below causes the fluid, or mushy, materials to move relatively eastward.
_4. Surge channels are alternately filled and emptied. A complete cycle of filling and emptying is a geotectonic cycle.
_The geotectonic cycle takes place along this sequence of events:
_a. Contraction of the strictosphere is always underway, because the Earth is cooling;
_b. The overlying lithosphere, which is already cool, does not contract, but adjusts its basal circumference to the upper surface of the shrinking strictosphere by large-scale thrusting along lithosphere Benioff zones and normal-type faulting along the strictosphere Benioff zones.
_c. Thrusting of the lithosphere is not a continuous process, but occurs when the lithosphere's underlying dynamic support fails. When the weight of the lithosphere overcomes combined resistance of the asthenosphere and Benioff zone friction, lithosphere collapse begins in a episodic fashion. Hence, tectogenesis is episodic.
_d. During anorogenic intervals between lithosphere collapses, the asthenosphere volume increases slowly as the strictosphere radius decreases and decompression of the asthenosphere begins.
_e. Decompression is accompanied by rising temperature, increased magma generation, and lowered viscosity in the asthenosphere, which gradually weakens during the time intervals between collapses.
_f. During lithosphere collapse into the asthenosphere, the continentward (hanging wall) sides of the lithosphere Benioff zones override (obduct) the ocean floor. The entire lithosphere buckles, fractures, and founders. Enormous compressive stresses are created in the lithosphere.
_g. When the lithosphere collapses into the asthenosphere, the asthenosphere- derived magma in the surge channels begins to surge intensely. Where volume of magma in the channels exceeds volumetric capacity, and when compression in the lithosphere exceeds the strength of the lithosphere that directly overlies the surge channels, the surge-channel roofs rupture along the cracks that comprise the fault-fracture-fissure system generated before the rupture. Rupture is bivergent and forms continental rifts, foldbelts, strike-slip zones, and midocean rifts. We call such bilaterally deformed belts kobergens.
_h. Once tectogenesis is completed, another geotectonic cycle or subcycle sets in, commonly within the same belt.
_5. Movement in the surge channel during the taphrogenic phase of the geotectonic cycle is parallel with the channel. It is also very slow, not exceeding a few centimeters per year. Flow at the surge-channel walls is laminar as evidenced by the channel-parallel faults, fractures, and fissures observed at the Earth's surface (Stoke's Law). Such flow also produced the more or less regular segmentation observed in tectonic belts.
_6. Tectogenesis has many styles. Each reflects the rigidity and thickness of the overlying lithosphere. In opcean basins where the lithosphere is thinnest, massive basalt flooding occurs. At ocean-continent transitions, eugeosynclines with alpinotype tectogenesis form. In continental interiors where the lithosphere is thicker, either germanotype foldbelts or continental rifts are created.
_7. During the geotectonic cycle, and within the eugeosynclinal regime, the central core (crest of the surge channel) evolves from a rift basin to a tightly compressed slpinotype foldbelt. Thus a rift basin up to several hundred kilometers wide narrows through time until it is a zone no more than a few kilometers wide that is occupied by a streamline (strike-slip) fault zone (e.g. the San Andreas fault). Then as compression takes over and dominates the full width of the surge-channel crest, the streamline fault zone is distorted, surge channel still contains any void spaces, the overlying rocks may collapse into it, and through this process of Verschluckung (engulgment) become a Verschluckungzone.
_8. The Earth above the strictosphere resembles a giant hydraulic press that behaves according to Pascal's Law. A hydraulic press consists of a containment vessel, fluid in that vessel, and a switch or trigger mechanism. In the case of the Earth, the containment vessel is the interconnected surge-channel system; the fluid is the magma in the channels; and the trigger mechanism is worldwide lithosphere collapse into the asthenosphere when that body becomes too weak to sustain the lithosphere dynamically. Thus tectogenesis may be regarded as surge-channel response to Pascal's Law.
_9. Surge channels, active or inactive, underlie nearly every major feature of the Earth's surface, including all rifts, foldbelts, metamorphic belts, and strike-slip zones. These belts are roughly bisymmetrical, have linear surface swaths of faults, fractures, and fissures, and belt-parallel stretching lineations. Aligned plutons, ophiolites, melange belts, volcanic centers, kimberlite dikes, diatremes, ring structures and mineral belts are characteristic. Zoned metamorphic belts are also characteristic. In some areas, linear river valleys, flood basalts, and/or vortex structures may be present. A lens of 7.8-7.0 km/s material always underlies the belt.
_10. Active surge channels are most easily recognized by the presence of high heat flow (Fig. 2.26), microseismicity, lines of thermal springs, small negative Bouguer gravity anomalies, and a 7.8-7.0 km/s lens of material that is transparent in the center or throughout.
_11. Inactive surge channels possess a linear positive magnetic anomaly, a linear Bouguer positive gravity anomaly, and a linear, lens-shaped pod of 7.8-7.0 km/s material that is reflective throughout.
_12. A surge-tectonics approach to geodynamics provides a new means for determining the origin of the Earth's features and their evolution through time, for analyzing regions prone to earthquakes and volcanism, and for predicting the location and formation of mineral deposits throughout the globe.
« Last Edit: August 28, 2017, 02:35:34 pm by Admin »

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