scholarly journals Three-dimensional inversion of marine magnetic anomalies on the equatorial Atlantic Ridge (St. Paul Fracture Zone): Delayed magnetization in a magmatically starved spreading center?

2002 ◽  
Vol 107 (B12) ◽  
pp. EPM 7-1-EPM 7-14 ◽  
Author(s):  
Bertrand Sichler ◽  
Roger Hékinian
Keyword(s):  
Fracture Zone ◽  
Three Dimensional ◽  
Magnetic Anomalies ◽  
Spreading Center ◽  
Equatorial Atlantic ◽  
Marine Magnetic Anomalies

Termination of a fossil continent-ocean fracture zone imaged with three-dimensional seismic data: The Chain Fracture Zone, eastern equatorial Atlantic

Geology ◽  
2005 ◽  
Vol 33 (8) ◽  
pp. 641-644 ◽  
Author(s):  
Richard J. Davies ◽  
Christopher J. MacLeod ◽  
Richard Morgan ◽  
Sepribo E. Briggs
Keyword(s):  
Oceanic Crust ◽  
Fracture Zone ◽  
Niger Delta ◽  
Three Dimensional ◽  
Seafloor Spreading ◽  
Spreading Center ◽  
Equatorial Atlantic ◽  
Half Graben ◽  
History Of ◽  
Subsequent Phase

Abstract We describe the first three-dimensional imaging of the termination of a continent-ocean fracture zone (COFZ), the Chain Fracture Zone, located offshore of the Niger Delta. The COFZ marks the abrupt transition between extended continental crust, comprising multiple half-graben, and oceanic crust that has a pervasive seafloor-spreading fabric. It preserves a history of continent-continent shearing followed by oceanic crust accretion and continent-ocean shearing during the inception of Atlantic rifting. The termination is marked by steeply dipping faults with sigmoidal planform and thrusts that probably formed as a result of continent-continent or continent-ocean shearing. These are crosscut by the seafloor-spreading fabric that formed during the subsequent phase of oceanic crust accretion. The accreted oceanic crust is cut by listric and planar faults that curve in the direction of the COFZ, where they terminate. The transition from continental to oceanic crust across the COFZ is sharp and resolvable to ∼100–200 m. Complexes of lava flows emanate from volcanoes along the COFZ, bifurcating and trifurcating down the volcano flanks. The volcanoes are 2–5.5 km wide and 1.4 km in height relative to adjacent oceanic crust and were injected at the COFZ, probably as the spreading center migrated along it.

Termination of a fossil continent-ocean fracture zone imaged with three-dimensional seismic data: The Chain Fracture Zone, eastern equatorial Atlantic

Geology ◽  
2005 ◽  
Vol 33 (8) ◽  
pp. 641 ◽  
Author(s):  
Richard J. Davies ◽  
Christopher J. MacLeod ◽  
Richard Morgan ◽  
Sepribo E. Briggs
Keyword(s):  
Fracture Zone ◽  
Seismic Data ◽  
Three Dimensional ◽  
Equatorial Atlantic

Metamorphism in the Troodos ophiolite: implications for marine magnetic anomalies

Nature ◽  
1980 ◽  
Vol 285 (5766) ◽  
pp. 563-564 ◽  
Author(s):  
Suzanne Beske-Diehl ◽  
Subir K. Banerjee
Keyword(s):  
Magnetic Anomalies ◽  
Troodos Ophiolite ◽  
Marine Magnetic Anomalies

A PRELIMINARY REPORT ON MODEL STUDIES OF MAGNETIC ANOMALIES OF THREE‐DIMENSIONAL BODIES

Geophysics ◽  
1956 ◽  
Vol 21 (3) ◽  
pp. 794-814 ◽  
Author(s):  
Isidore Zietz ◽  
Roland G. Henderson
Keyword(s):  
Magnetic Fields ◽  
Rapid Method ◽  
Preliminary Report ◽  
Three Dimensional ◽  
Magnetic Anomalies ◽  
Constant Thickness ◽  
Laboratory Methods ◽  
Model Experiments ◽  
Model Studies ◽  
Different Depths

Model experiments were made to devise a rapid method for calculating magnetic anomalies of three‐dimensional structures. The magnetic fields of the models were determined using the equipment at the Naval Ordnance Laboratory, White Oaks, Md. An irregularly shaped mass was approximated by an array of prismatic rectangular slabs of constant thickness and varying horizontal dimensions. Contoured maps are being prepared for these magnetic models at different depths and for several magnetic inclinations. The fields of these three‐dimensional structures are obtained by super‐imposing the appropriate contoured maps and adding numerically the effects at each point. The equipment and laboratory methods are described. Theoretical and practical examples are given.

Sign in / Sign up

Export Citation Format

Share Document