Tracing the subducted oceanic crust beneath the Central California Continental Margin: Results from ocean bottom seismometers deployed during the 1986 Pacific Gas and Electric EDGE Experiment

1991 ◽  
Vol 96 (B4) ◽  
pp. 6493-6506 ◽  
Author(s):  
Anne Tréhu
Keyword(s):  
Oceanic Crust ◽  
Continental Margin ◽  
Ocean Bottom ◽  
Central California ◽  
Ocean Bottom Seismometers ◽  
Subducted Oceanic Crust

Comparison of the S/N ratios of low-frequency hydrophones and geophones as a function of ocean depth

1981 ◽  
Vol 71 (5) ◽  
pp. 1649-1659
Author(s):  
Thomas M. Brocher ◽  
Brian T. Iwatake ◽  
Joseph F. Gettrust ◽  
George H. Sutton ◽  
L. Neil Frazer
Keyword(s):  
Nova Scotia ◽  
Continental Margin ◽  
Low Frequency ◽  
Weather Conditions ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Scotian Shelf ◽  
Ocean Bottom Seismometers ◽  
Particle Velocities ◽  
Refraction Data

abstract The pressures and particle velocities of sediment-borne signals were recorded over a 9-day period by an array of telemetered ocean-bottom seismometers positioned on the continental margin off Nova Scotia. The telemetered ocean-bottom seismometer packages, which appear to have been very well coupled to the sediments, contained three orthogonal geophones and a hydrophone. The bandwidth of all sensors was 1 to 30 Hz. Analysis of the refraction data shows that the vertical geophones have the best S/N ratio for the sediment-borne signals at all recording depths (67, 140, and 1301 m) and nearly all ranges. The S/N ratio increases with increasing sensor depth for equivalent weather conditions. Stoneley and Love waves detected on the Scotian shelf (67-m depth) are efficient modes for the propagation of noise.

Geophysical measurements in the region of the Explorer ridge off western Canada

1978 ◽  
Vol 15 (9) ◽  
pp. 1508-1525 ◽  
Author(s):  
R. D. Hyndman ◽  
G. C. Rogers ◽  
M. N. Bone ◽  
C. R. B. Lister ◽  
U. S. Wade ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Seismic Refraction ◽  
Ocean Bottom ◽  
Low Velocity ◽  
Geothermal Heat ◽  
Juan De Fuca Plate ◽  
The North ◽  
The Pacific ◽  
Ocean Bottom Seismometers ◽  
Seismic Reflection Profiles

The region of the Explorer spreading centre off Vancouver Island, British Columbia, has been studied through a marine geophysical survey. Earthquake epicentres located by three ocean bottom seismometers confirm that the boundary between the Pacific plate and the Explorer plate (the northern extension of the Juan de Fuca plate) at present lies along the Sovanco fracture zone, the Explorer ridge, and the Dellwood Knolls. The epicentres of earthquakes in this area as determined by the onshore seismic network are found to be subject to significant errors. The ocean bottom seismometers also have been used for a detailed seismic refraction line just to the north of the Explorer spreading centre employing explosives and a large airgun as sources. A preliminary analysis of the data indicates a fairly typical crustal structure but a shallow and low velocity mantle near the ridge crest, and illustrates the value of ocean bottom seismometers in oceanic refraction studies. A new geothermal heat flux probe was employed in this study that permitted repeated 'pogostick' penetrations without raising the instrument to the surface. Six profiles with a total of 112 penetrations provided valuable data on the nature of hydrothermal circulation in the oceanic crust. Eleven standard heat probe stations provided some restraints on the poorly known age of the oceanic crust along the margin. Seismic reflection profiles using a 3.5 kHz system, a high resolution pulser profiler, and a large airgun were used as aids in the interpretation of the seismic and heat flow data.

The continent–ocean boundary south of Flemish Cap: constraints from seismic refraction and gravity

1989 ◽  
Vol 26 (7) ◽  
pp. 1392-1407 ◽  
Author(s):  
B. J. Todd ◽  
I. Reid
Keyword(s):  
Oceanic Crust ◽  
Structural Information ◽  
Seismic Refraction ◽  
P Wave ◽  
Ocean Bottom ◽  
Crustal Layer ◽  
Air Gun ◽  
Ocean Bottom Seismometers ◽  
Plate Reconstructions ◽  
Ocean Boundary

A seismic-refraction survey providing deep crustal structural information on the continent–ocean boundary south of Flemish Cap on the east coast of Canada was carried out using large air-gun sources and ocean-bottom seismometers. The seismic-refraction results and gravity modelling suggest that thinned continental crust extends 25 km seaward of the shelf break. The transition from continental to oceanic crust with a main crustal layer p-wave velocity of 7.3 km/s extends seaward over 100 km to the south. One refraction profile with thin (~4 km) oceanic crust was probably shot on, or very near, the trace of a fracture zone. Previous plate reconstructions have suggested that Cretaceous-age sea-floor spreading south of Flemish Cap occurred as a series of short spreading segments offset by transform fauits, or by asymmetric rifting between Iberia and Flemish Cap. This study suggests that an oblique shear margin may have formed south of Flemish Cap. possibly as a result of transcurrent motion between Flemish Cap and Iberia.

NOBLE GASES TRACE DEHYDRATION OF SUBDUCTED OCEANIC CRUST

2016 ◽  
Author(s):  
Andrew J. Smye ◽  
◽  
Colin R.M. Jackson ◽  
Matthias Konrad-Schmolke ◽  
Stephen Parman ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Noble Gases ◽  
Subducted Oceanic Crust

The role of sulfides in the chalcophile and siderophile element budget of the subducted oceanic crust

2021 ◽  
Author(s):  
Jesse B. Walters ◽  
Alicia M. Cruz-Uribe ◽  
Horst R. Marschall ◽  
Brandon Boucher
Keyword(s):  
Oceanic Crust ◽  
Subducted Oceanic Crust ◽  
Element Budget

scholarly journals Microearthquake seismicity and focal mechanisms at the Rodriguez Triple Junction in the Indian Ocean using ocean bottom seismometers

2001 ◽  
Vol 106 (B12) ◽  
pp. 30689-30699 ◽  
Author(s):  
Kei Katsumata ◽  
Toshinori Sato ◽  
Junzo Kasahara ◽  
Naoshi Hirata ◽  
Ryota Hino ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Triple Junction ◽  
Focal Mechanisms ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometers ◽  
The Indian Ocean

A suite of alkali basalts and gabbros associated with the Hare Bay Allochthon of western Newfoundland

1977 ◽  
Vol 14 (3) ◽  
pp. 346-356 ◽  
Author(s):  
R. A. Jamieson
Keyword(s):  
Oceanic Crust ◽  
Continental Margin ◽  
Upper Mantle ◽  
Ultramafic Rocks ◽  
Alkali Basalts ◽  
Crust And Upper Mantle ◽  
Bay Area ◽  
Close Proximity ◽  
Thrust Sheets

The Hare Bay Allochthon of northwestern Newfoundland consists of a series of sedimentary, volcanic, metamorphic, and ultramafic rocks which was emplaced over a Cambro-Ordovician continental margin as several thrust sheets. It probably represents a continental margin sequence overridden by oceanic crust and upper mantle. The Partridge Point gabbro, Cape Onion volcanics, and Ireland Point Volcanics, which now occur in the Maiden Point, Cape Onion, and St. Anthony tectonic slices respectively, appear to be closely related on petrographic and chemical grounds. Olivine, titanaugite, kaersutite, and plagioclase indicate that these rocks formed as a single suite of hydrous alkali basalts, possibly as part of a seamount near a continental margin. This relationship provides a link between the lower sedimentary and the upper igneous-metamorphic structural slices of the allochthon and implies that most of the transported rocks in the Hare Bay area evolved in close proximity to each other.

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