Evidence of a recent magma dike intrusion at the slow spreading Lucky Strike segment, Mid‐Atlantic Ridge

Dziak, Robert P.

doi:10.1029/2004jb003141

Cited by 87 publications

(98 citation statements)

References 59 publications

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“…Despite this general character, small episodic and highly focused magmatic feeding to the segment center should at times occur. Recently, a seismic event recorded by an autonomous hydrophone array registered what has been interpreted as a dike emplacement episode in the Lucky Strike segment [Dziak et al, 2002].…”

Section: B04103mentioning

confidence: 99%

Identification of the magnetization low of the Lucky Strike hydrothermal vent using surface magnetic data

et al. 2005

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Two surface magnetic surveys, covering the Lucky Strike hydrothermal area, are merged into a single magnetic anomaly description, which, when inverted in the presence of topography, shows a magnetization low at the segment center, close to the central volcano, in the middle of which is located the hydrothermal vent. To test if this magnetization is in any way connected with the hydrothermal vent field, we devised a method to distinguish a “regional” field that can be attributed to the “normal” spreading geometry from the “local” field that can be attributed to the hydrothermal vent area itself. This is achieved by the computation of a three‐dimensional regional magnetic field that takes into consideration bathymetry, location of the “zero‐age” axis, asymmetry in the half spreading rates, magnetization decay with age, polarity reversals, and the transition between consecutive magnetic blocks. This model was fitted to the observed surface magnetic data, and the “magnetic residual” was inverted to allow a better definition of the magnetization anomalies. We show that as far as surface magnetic data are concerned, the magnetization low has only partial correlation with the hydrothermal field and is the signature of a relatively large area in which bulk magnetization is lower than average.

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Section: B04103mentioning

confidence: 99%

Identification of the magnetization low of the Lucky Strike hydrothermal vent using surface magnetic data

et al. 2005

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“…3-3). This polarity boundary is the Chron 2r to Chron 2An transition (age -2.581 Myrs [Ogg and Smith, 2004]) [Williams et al, in prep. ] and its presence indicates that the lithologies at this location are capable of recording a polarity reversal in a coherent manner.…”

Section: Geological Settingmentioning

confidence: 99%

“…Long term monitoring of seismicity in remote areas of the oceans using hydrophone arrays has proven to be very successful over the last decade. This is especially true at mid-ocean ridges where T-phase data are providing information on the overall seismicity of the ridge axis and are helping to constrain models of mid-ocean ridge crustal structure [e.g., Dziak andFox, 1999a, 1999b;Dziak et al, 1995Dziak et al, , 2004Schreiner et al, 1995;Fox et al, 1994Fox et al, , 1995Fox et al, , 2001Bohnenstiehl et al, 2002Bohnenstiehl et al, , 2004Smith et al, , 2003]. T-phase data are also an important source of information for studying hydroacoustic wave propagation in the oceans [Johnson et al, 1968;Pulli et al, 1999;Pulli and Upton, 2002;Harben et al, 2003].…”

Section: Introductionmentioning

confidence: 99%

Oceanic lithosphere magnetization : marine magnetic investigations of crustal accretion and tectonic processes in mid-ocean ridge environments

Williams¹

2007

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The origin of symmetric alternating magnetic polarity stripes on the seafloor is investigated in two marine environments; along the ridge axis of the fast spreading East Pacific Rise (EPR) (90 25'-90 55'N) and at Kane Megamullion (KMM) (230 40'N), near the intersection of the slow-spreading Mid Atlantic Ridge with Kane Transform Fault. Marine magnetic anomalies and magnetic properties of seafloor samples are combined to characterize the magnetic source layer in both locations. The EPR study suggests that along-axis variations in the observed axial magnetic anomaly result from changing source layer thickness alone, consistent with observed changes in seismic Layer 2a. The extrusive basalts of the upper crust therefore constitute the magnetic source layer along the ridge axis and long term crustal accretion patterns are reflected in the appearance of the axial anomaly. At KMM the C2r.2r/C2An. In (-2.581 Ma) polarity reversal boundary cuts through lower crust (gabbro) and upper mantle (serpentinized peridotites) rocks exposed by a detachment fault on the seafloor, indicating that these lithologies can systematically record a magnetic signal. Both lithologies have stable remanent magnetization, capable of contributing to the magnetic source layer. The geometry of the polarity boundary changes from the northern to the central regions of KMM and is believed to be related to changing lithology. In the northern region, interpreted to be a gabbro pluton, the boundary dips away from the ridge axis and is consistent with a rotated conductively cooled isotherm. In the central region the gabbros have been removed and the polarity boundary, which resides in serpentinized peridotite, dips towards the ridge axis and is thought to represent an alteration front. The linear appearance of the polarity boundary across both regions indicates that the two lithologies acquired their magnetic remanence during approximately the same time interval. Seismic events caused by detachment faulting at Kane and Atlantis Transform Faults are investigated using hydroacoustic waves (T-phases) recorded by a hydrophone array. Observations and ray trace models of event propagation show bathymetric blockage along propagation paths, but suggest current models of T-phase excitation and propagation need to be improved to explain observed characteristics of T-phase data. AcknowledgementsA thesis may have your name on the title page, but it is truly the joint effort of many people that gets you through to the end of a Ph.D.. I am very grateful to my main thesis advisor Maurice Tivey, who taught me so much about magnetics and always had time to talk about my research when I knocked on his door. Learning to write a scientific paper has been a long learning curve and I really appreciate Maurice's editing skills and stamina for reading drafts of my papers. I have been lucky enough to be in the right place at the right time to work on some excellent datasets, particularly the Kane Megamullion data that makes up the majority of my thesis, and I thank Mau...

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“…Typical oceanic earthquake swarms at volcanic ridge areas normally reach their highest magnitude somewhere around a maximum magnitude of 5 or higher (Fox and Dziak 1998;Dziak et al 2004); however, the amount of such earthquakes is unique at Gakkel Ridge. Making a crude but empirically supported estimate (Utsu 2002) by equating body wave magnitude with moment magnitude scale following Kanamori (1977):…”

Section: Magnitudesmentioning

confidence: 99%

Did the 1999 earthquake swarm on Gakkel Ridge open a volcanic conduit? A detailed teleseismic data analysis

Riedel¹,

Schlindwein²

2009

J Seismol

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In 1999, a seismic swarm of 237 teleseismically recorded events marked a submarine eruption along the Arctic Gakkel Ridge, later on also analyzed by sonar, bathymetric, hydrothermal, and local seismic studies. We relocated the swarm with the global location algorithm HY-POSAT and analyzed the waveforms of the stations closest to the events by cross-correlation. We find event locations scattered around 85 • 35 N and 85 • E at the southern rift wall and inside the rift valley of the Gakkel Ridge. Waveforms of three highly correlating events indicate a volumetric moment tensor component and highly precise referenced double-difference arrival times lead us to believe that they occur at the same geographical position and mark the conduit located further southeast close to a chain of recently imaged volcanic cones. This result is supported by station residual anomalies in the direction of the potential conduit. Seismicity is focused at the crust-mantle boundary at 16-20 km depth, but C. Riedel (B) · V. Schlindwein

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Evidence of a recent magma dike intrusion at the slow spreading Lucky Strike segment, Mid‐Atlantic Ridge

Cited by 87 publications

References 59 publications

Identification of the magnetization low of the Lucky Strike hydrothermal vent using surface magnetic data

Identification of the magnetization low of the Lucky Strike hydrothermal vent using surface magnetic data

Oceanic lithosphere magnetization : marine magnetic investigations of crustal accretion and tectonic processes in mid-ocean ridge environments

Did the 1999 earthquake swarm on Gakkel Ridge open a volcanic conduit? A detailed teleseismic data analysis

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