Probably the Best Theory on Earth

2018 ◽  
Author(s):  
Roy Livermore
Keyword(s):  
Geomagnetic Field ◽  
Convincing Evidence ◽  
Ocean Floor ◽  
Bar Code ◽  
Sea Floor ◽  
Ocean Ridges ◽  
Sea Bed ◽  
The Pacific ◽  
Sea Floor Spreading

The magnetic bar-code on the ocean floor provides convincing evidence of moving continents, yet, as with the discovery of the structure of DNA, few are convinced—at first. Drilling in the deep oceans and geochemical work at mid-ocean ridges provides further evidence in support of the Vine–Matthews Hypothesis. Application of the hypothesis to data collected in the Pacific and Atlantic Oceans establishes sea-floor spreading as the process that creates new oceans and, in conjunction with reversals of the geomagnetic field, stamps the bar-code into the rocks beneath the sea bed.

The structure of the oceanic lithosphere

1971 ◽  
Vol 268 (1192) ◽  
pp. 619-619
Keyword(s):  
Oceanic Crust ◽  
Upper Mantle ◽  
Oceanic Lithosphere ◽  
Ocean Floor ◽  
Mass Motion ◽  
Sea Floor ◽  
Ocean Ridges ◽  
Velocity Gradients ◽  
The Earth ◽  
Sea Floor Spreading

Sea-floor spreading requires that new ocean floor be generated at mid-ocean ridges and that along with the underlying oceanic crust it move laterally away from its site of generation. In so far as it is unlikely that the 5 km thick oceanic crust moves independently of the underlying upper mantle, the horizontal mass motion associated with spreading extends at least some way into the mantle. The lithosphere is the crust and that part of the upper mantle to which it is mechanically coupled; together they form the brittle and relatively ‘strong’ outermost part of the Earth; velocity gradients within the lithosphere are negligible.

A Measurement of Seismic Anistropy in the Northeast Pacific

1971 ◽  
Vol 8 (9) ◽  
pp. 1056-1064 ◽  
Author(s):  
C. E. Keen ◽  
D. L. Barrett
Keyword(s):  
Seismic Refraction ◽  
Maximum Velocity ◽  
Mean Value ◽  
Ocean Basin ◽  
P Wave ◽  
Sea Floor ◽  
P Wave Velocity ◽  
The Pacific ◽  
Magnetic Lineations ◽  
Sea Floor Spreading

A seismic refraction experiment was conducted in the Pacific Ocean basin, off the coast of British Columbia, Canada. The purpose of these measurements was to obtain an estimate of the anisotropy of the mantle P-wave velocity in the area and to relate this parameter to the direction of sea floor spreading. The results show that the crustal structure is similar to that measured elsewhere in the Pacific basin. Significant anisotropy of the mantle rocks is observed; the direction in which the maximum velocity occurs being 107° and the change of velocity, about 8% of the mean value, 8.07 km/s. The direction of maximum velocity does not coincide exactly with the direction of sea floor spreading, 090°, inferred from magnetic lineations.

A. Wegener - O. Ampferer - R. Schwinner: The First Chapter of the "New Globale Tectonic"

1984 ◽  
Vol 3 (2) ◽  
pp. 178-186 ◽  
Author(s):  
Helmut Fiügel
Keyword(s):  
Pacific Plate ◽  
Benioff Zone ◽  
Sea Floor ◽  
Middle Atlantic ◽  
The Pacific ◽  
Sea Floor Spreading

Between 1906-1948, Wegener, Ampferer, and Schwinner worked out many tectonic concepts which are today parts of the New Globale Tectonic, including the idea of convection currents, the origin ofthe Middle Atlantic Ridge in connection with sea-floor spreading, the concept of the "Benioff-Zone", the subduction of parts of the Pacific plate under the continents, and the linkage of these features with volcanism. Many of these ideas were soon forgotten and had to be "rediscovered" once again.

Heat flow from the Mid-Ocean Ridges and sea-floor spreading

1969 ◽  
Vol 8 (4-6) ◽  
pp. 319-344 ◽  
Author(s):  
X. Lepichon ◽  
M.G. Langseth
Keyword(s):  
Heat Flow ◽  
Sea Floor ◽  
Ocean Ridges ◽  
Sea Floor Spreading

Icelandia

2021 ◽  
Author(s):  
Gillian Foulger ◽  
Laurent Gernigon ◽  
Laurent Geoffroy
Keyword(s):  
Continental Crust ◽  
Structural Complexity ◽  
Ne Atlantic ◽  
Sea Floor ◽  
Passive Margins ◽  
The North ◽  
The Pacific ◽  
Ne Atlantic Ocean ◽  
Sea Floor Spreading ◽  
North And South

<p>The NE Atlantic formed by complex, piecemeal breakup of Pangea in an environment of structural complexity. North of the present-day latitude of Iceland the ocean opened by southward propagation of the Aegir ridge. South of the present-day latitude of Iceland breakup occurred along the proto-Reykjanes ridge which formed laterally offset by ~ 100 km from the Aegir ridge to the north. Neither of these new breakup axes were able to propagate across the east-westerly striking Caledonian frontal thrust region which formed a strong barrier ~ 400 km wide. As a result, while sea-floor spreading widened the NE Atlantic, the Caledonian front region could only keep pace by diffuse stretching of the continental crust, which formed the aseismic Greenland-Iceland-Faroe ridge. The magmatic rate there was similar to that of the ridges to the north and south and so the stretched continental crust is now blanketed by thick mafic flows and intrusions. The NE Atlantic also contains a magma-inflated microcontinent – the Jan Mayen Microplate Complex, and an unknown but probably large amount of stretched continental crust blanketed by seaward-dipping reflectors in the passive margins of Norway and Greenland. The NE Atlantic thus contains voluminous continental crust in diverse forms and settings. If even a small portion of the sunken continental material contiguous with the Greenland-Iceland-Faroe ridge is included the area exceeds a million square kilometers, an arbitrary threshold suggested to designate a sunken continent. We have called this region Icelandia. The conditions and processes that funneled large quantities of continental crust into the NE Atlantic ocean are common elsewhere. This includes much of the North and South Atlantic oceans including both the seaboards and the deep oceans. Nor are such processes and outcomes confined to oceans bordered by passive margins. They are also found around the Pacific rims where subduction is in progress. Indeed, these conditions and processes likely are generic to essentially all the world's oceans and are potentially also informed by observations from intracontinental extensional regions and land-locked seas.</p>

2. Seafloor spreading and magnetic anomalies

2015 ◽  
pp. 17-35
Author(s):  
Peter Molnar
Keyword(s):  
Sea Level ◽  
Deep Sea ◽  
Magnetic Anomalies ◽  
Seafloor Spreading ◽  
Ocean Floor ◽  
Sea Level Changes ◽  
Ocean Ridges ◽  
The Pacific ◽  
History Of ◽  
The Difference

‘Seafloor spreading and magnetic anomalies’ begins with the Vine–Matthews Hypothesis, which proposed that strips of seafloor parallel to the mid-ocean ridges, where two plates diverge from one another, were magnetized in opposite directions because the Earth’s field had reversed itself many times. A test of the Vine–Matthews Hypothesis, which required determining the age of the seafloor, became a test of seafloor spreading. Dating the ocean floor using magnetic anomalies detected by magnetometers towed behind ships and core samples extracted during the Deep-Sea Drilling Project confirmed the hypothesis. With magnetic anomalies to date the seafloor and a curve relating seafloor depth and age, the difference between the Atlantic, with its ‘ridge’, and the Pacific and its ‘rise’ became comprehensible. With a theory for predicting the depths of oceans, it was also possible to understand the history of sea-level changes.

A Decade of Challenge the Future of Biogeography

1985 ◽  
Vol 4 (2) ◽  
pp. 187-196 ◽  
Author(s):  
Gareth Nelson
Keyword(s):  
Critical Evaluation ◽  
Pacific Basin ◽  
Main Task ◽  
Radial Expansion ◽  
Sea Floor ◽  
Biogeographic Patterns ◽  
The Pacific ◽  
The Difference ◽  
Sea Floor Spreading ◽  
East West

According to Croizat's global synthesis, the main biogeographic patterns include trans-Atlantic, trans-Pacific, trans-Indoceanic, Boreal, and Austral. Geological and geophysical theories vary, but agree that sea-floor spreading in the Pacific is different in its effect from that in other ocean basins. The difference allows for radial expansion of the basin and not merely east-west displacement of continental areas. Biogeographic data suggest that bipolar (boreal + austral) distributions are to be reckoned among the results of sea-floor spreading in the Pacific. Data from one group of inshore fishes (family Engraulidae) exemplify this notion and add, as terminal parts of the differentiation of the Pacific Basin, trans-Panama marine vicariance and a collateral occurrence in freshwater of tropical South America. These findings corroborate Croizat's synthesis. They suggest that the critical evaluation of that synthesis will be the main task of biogeography over the next decade. They indicate that within the area of systematics, evaluation will require a cladistic approach and the elimination of paraphyletic groups from classification.

Geological and geophysical characteristics of the Tuzo Wilson Seamounts: implications for plate geometry in the vicinity of the Pacific – North America – Explorer triple junction

1989 ◽  
Vol 26 (11) ◽  
pp. 2365-2384 ◽  
Author(s):  
S. M. Carbotte ◽  
J. M. Dixon ◽  
E. Farrar ◽  
E. E. Davis ◽  
R. P. Riddihough
Keyword(s):  
North America ◽  
Triple Junction ◽  
Fault System ◽  
Magnetic Data ◽  
Transform Fault ◽  
Seismic Profiles ◽  
Sea Floor ◽  
Sea Bed ◽  
Seamarc Ii ◽  
The Pacific

SeaMARC II imagery, SEABEAM bathymetry, seismic reflection profiles, and gravity and magnetic data are used to establish the tectonic significance of the Tuzo Wilson Seamounts, two submarine volcanic edifices located southwest of the southern end of the Queen Charlotte transform fault. SeaMARC II imagery reveals a parallel transform fault, an extension of the Revere–Dellwood Fault, bordering the southwest end of the Dell wood Knolls and terminating at the southwest end of the Tuzo Wilson Seamounts. This transform-fault system links spreading at the north end of Explorer Ridge to extension at the Tuzo Wilson Seamounts. An inactive continuation of this transform 50 km to the northwest of Tuzo Wilson Seamounts is inferred from seismic profiles. Between Dellwood Knolls and Tuzo Wilson Seamounts, this transform fault has offset Pleistocene (ca. 10 000 a) sea-bed features in a right-lateral sense by 250 m and has offset part of the Dellwood Knolls volcanic edifice by 6–8 km. Numerous normal faults at the Tuzo Wilson Seamounts and Dellwood Knolls are roughly orthogonal to the Queen Charlotte and Revere–Dellwood transforms and indicate rifting in an extensional jog between the transforms. Seismic profiles reveal sediments and basement back-tilted northwest and southeast away from the Tuzo Wilson Seamounts, also consistent with extension. Acoustic imagery indicates that the Tuzo Wilson Seamounts are surrounded by basalt flows that are largely free of sediment cover and thus postdate recent rapid sedimentation (< 10 000 a). In contrast, few of the flows around Dellwood Knolls are free of sediment. Basalts from the Tuzo Wilson Seamounts have high magnetizations (average 35 A/m) and are free of manganese encrustation. Tuzo Wilson Seamounts have a + 1000 nT magnetic anomaly, which can be modelled with normal, high-intensity (up to 40 A/m) magnetization and with geometry and depth matching the topography of the seamounts and surficial basalt flows. Their small, positive free-air gravity is largely accounted for by their topography; no appreciable local density contrast exists below the surrounding sea floor.The Tuzo Wilson Seamounts and Dellwood Knolls are separate sites of sea-floor spreading, although the partition of spreading between them is indeterminate. The 50 km inactive continuation of the Revere–Dellwood transform requires that a total of at least 100 km of sea floor has been created at the Tuzo Wilson and Dellwood spreading centres, probably within the last 2.5 Ma. The sea floor between the Tuzo Wilson Seamounts and Dellwood Knolls either is a separate microplate or is under going distributed strain. The triple junction of the Pacific, North America, and Explorer plates is not a discrete point; rather it occupies the strained and seismically active region between the northern Explorer Ridge and the Tuzo Wilson Seamounts.

Magnetic anomalies in the Pacific and sea floor spreading

1968 ◽  
Vol 73 (6) ◽  
pp. 2069-2085 ◽  
Author(s):  
W. C. Pitman ◽  
E. M. Herron ◽  
J. R. Heirtzler
Keyword(s):  
Magnetic Anomalies ◽  
Sea Floor ◽  
The Pacific ◽  
Sea Floor Spreading
Sign in / Sign up

Export Citation Format

Share Document