Random crustal magnetization and its effect on coherence of short-wavelength marine magnetic anomalies

Blakely, Richard J.

doi:10.1016/0012-821x(79)90064-5

Cited by 6 publications

(4 citation statements)

References 23 publications

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“…Instead, results from the North Atlantic [Hall and Ryall, 1977;Levi, 1979] show magnetic units containing both polarities, intermediate directions, and large differences in intensity. Moreover, some of these units extend laterally for at least 100 m [Hall and Ryall, 1977]• and these units can produce short-wavelength anomalies at the ocegi• surface [Schouten and Denham, 1979;Blakely, 1979]. Unfortunately, the DSDP has yet to perform the first-order experiment: to drill into crust within a region of rapid spreading rate and orderly magnetic anomalies, such as the areas of Figure 2.…”

Section: The Depth To the Magnetic Source Z Is Equal To The Depth To supporting

confidence: 83%

Statistical averaging of marine magnetic anomalies and the aging of oceanic crust

Blakely¹

1983

J. Geophys. Res.

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Visual comparison of Mesozoic and Cenozoic magnetic anomalies in the North Pacific suggests that older anomalies contain less short‐wavelength information than younger anomalies in this area. To test this observation, magnetic profiles from the North Pacific are examined from crust of three ages: 0–2.1, 29.3–33.1, and 64.9–70.3 m.y, B.P. For each time period, at least nine profiles were analyzed by (1) calculating the power density spectrum of each profile, (2) averaging the spectra together, and (3) computing a ‘recording filter’ for each time period by assuming a hypothetical seafloor model. The model assumes that the top of the source is acoustic basement, the source thickness is 0.5 km, and the time scale of geomagnetic reversals is according to Ness et al. (1980). The calculated power density spectra of the three recording filters are complex in shape but show an increase of attenuation of short‐wavelength information as the crust ages. These results are interpreted using a multilayer model for marine magnetic anomalies in which the upper layer, corresponding to pillow basalt of seismic layer 2A, acts as a source of noise to the magnetic anomalies. As the ocean crust ages, this noisy contribution by the pillow basalts becomes less significant to the anomalies. Consequently, magnetic sources below layer 2A must be faithful recorders of geomagnetic reversals.

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Section: The Depth To the Magnetic Source Z Is Equal To The Depth To supporting

confidence: 83%

Statistical averaging of marine magnetic anomalies and the aging of oceanic crust

Blakely¹

1983

J. Geophys. Res.

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“…Likewise, it remains to be an open question on the mechanisms of lower crust and upper mantle magnetization as well as their contribution to surface magnetic anomalies [38]. In fact, these types of questions and arguments have existed ever since the early buildup of the Vine-Matthews model [39][40][41][42][43][44][45]. Earlier, magnetic sources causing seafloor spreading magnetic anomalies are thought to be confined within the shallow part of the oceanic crust, but satellite magnetic anomalies and ODP drilling confirm that these magnetic sources can be deep seated, and the gabbro layer of the lower crust can also contribute appreciably to surface magnetic anomalies.…”

Section: Deep Magnetic Layer Structure and Thermal Evolutionmentioning

confidence: 99%

Magnetic recording of the Cenozoic oceanic crustal accretion and evolution of the South China Sea basin

Song

2012

Chin. Sci. Bull.

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“…The smoothing of the geomagnetic field reversal signal which provides information on the width of the emplacement zone has been modelled with discrete random and highfrequency emplacement of the magnetic source (Matthews & Bath 1967;Harrison 1968;Blakely & Cox 1972;Schouten & McCamy 1972;Atwater & Mudie 1973;Blakely 1974;. The random noise which affects the coherence of marine magnetic anomalies and which provides information on the size and number of discrete magnetic units in the magnetic source layer has been modelled with discrete random but low-frequency emplacement (Matthews & Bath 1967;Blakely 1979).…”

Section: Stochastic Models For the Marine Magnetic Anomaly Sourcementioning

confidence: 99%

“…Low-frequency emplacement of the extrusive flows is the most likely contributor to the noise observed in marine magnetic anomalies because it generates a laterally inhomogeneous extrusive source layer (Blakely 1979) of variable thickness .…”

Section: Stochastic Models For the Marine Magnetic Anomaly Sourcementioning

confidence: 99%

On the quality of marine magnetic anomaly sources and sea-floor topography

Schouten

Denham

Smith

1982

Geophysical Journal International

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The quality of marine magnetic anomaly sources is described with the power-density representation of a stochastic model of random temporal and spatial emplacement of the marine magnetic anomaly source in the oceanic crust. Typical values of sea-floor spreading and emplacement parameters define a high-fidelity process of recording and sea-surface detection of the palaeomagnetic field reversals for spreading rates over 20mmyr-'. An analogous stochastic model is developed for the formation of sea-floor topography by normal faulting. It is shown that the random process of normal faulting observed in the inner walls of the FAMOUS rift valley can account for the quality of the adjacent West Rift Mountains topography.

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Random crustal magnetization and its effect on coherence of short-wavelength marine magnetic anomalies

Cited by 6 publications

References 23 publications

Statistical averaging of marine magnetic anomalies and the aging of oceanic crust

Statistical averaging of marine magnetic anomalies and the aging of oceanic crust

Magnetic recording of the Cenozoic oceanic crustal accretion and evolution of the South China Sea basin

On the quality of marine magnetic anomaly sources and sea-floor topography

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