Formation of oceanic crust at slow spreading rates: New constraints from an extinct spreading center in the Labrador Sea

Geology ◽  
1996 ◽  
Vol 24 (9) ◽  
pp. 771 ◽  
Author(s):  
K. E. Louden ◽  
J. C. Osler ◽  
S. P. Srivastava ◽  
C. E. Keen
Keyword(s):  
Oceanic Crust ◽  
Spreading Center ◽  
Labrador Sea ◽  
Slow Spreading ◽  
Spreading Rates

Geophysical Studies in Baffin Bay and some Tectonic Implications

1972 ◽  
Vol 9 (3) ◽  
pp. 239-256 ◽  
Author(s):  
C. E. Keen ◽  
D. L. Barrett ◽  
K. S. Manchester ◽  
D. I. Ross
Keyword(s):  
Oceanic Crust ◽  
Seismic Reflection ◽  
Seismic Refraction ◽  
The Arctic ◽  
Spreading Center ◽  
Labrador Sea ◽  
Baffin Bay ◽  
Definitive Evidence ◽  
Nares Strait ◽  
The North

A recent seismic refraction experiment in the deep central region of Baffin Bay showed that it is underlain by oceanic crust. This paper describes the results of gravity, magnetic, and seismic reflection profiling measurements in the bay. There is no definitive evidence for a buried ridge or for magnetic lineations in the center of the area. The magnetic and gravity anomaly fields have been used to define the boundary between the oceanic and continental crust around the bay and therefore the extent of oceanic crust presumed to have been formed by sea-floor spreading. Some of the characteristics of the seismic reflection lines across the continental margins, perhaps typical of this area, are also discussed. The results have been used to reconstruct the history of opening of Baffin Bay in conjuction with geophysical measurements in the Labrador Sea to the south and over the Alpha Ridge in the Arctic Ocean to the north. An attempt has been made to reconcile the geometry of opening with continental geology. Two phases of spreading are suggested. The first involves openings, in both the Labrador Sea and in Baffin Bay, about a pole in the Canadian Arctic Islands. The second, most recent stage of opening, requires that the Nares Strait was once a transform fault, perhaps connecting a Baffin Bay spreading center to the Alpha Ridge to the north.

Extremely asymmetric magmatic accretion of oceanic crust at the ends of slow-spreading ridge segments

Geology ◽  
2000 ◽  
Vol 28 (2) ◽  
pp. 179-182 ◽  
Author(s):  
Simon Allerton ◽  
Javier Escartín ◽  
Roger C. Searle
Keyword(s):  
Oceanic Crust ◽  
Spreading Ridge ◽  
Slow Spreading

scholarly journals Assessing the impact of sedimentation on fault spacing at the Andaman Sea spreading center

Geology ◽  
2020 ◽  
Author(s):  
Clément de Sagazan ◽  
Jean-Arthur Olive
Keyword(s):  
Active Faults ◽  
Spreading Rate ◽  
Andaman Sea ◽  
Spreading Center ◽  
Normal Faults ◽  
Mid Ocean Ridge ◽  
Plate Separation ◽  
Slow Spreading ◽  
Ocean Ridge ◽  
The Impact

The stabilizing effect of surface processes on strain localization, albeit predicted by several decades of geodynamic modeling, remains difficult to document in real tectonic settings. Here we assess whether intense sedimentation can explain the longevity of the normal faults bounding the Andaman Sea spreading center (ASSC). The structure of the ASSC is analogous to a slow-spreading mid-ocean ridge (MOR), with symmetric, evenly spaced axis-facing faults. The average spacing of faults with throws ≥100 m (8.8 km) is however large compared to unsedimented MORs of commensurate spreading rate, suggesting that sedimentation helps focus tectonic strain onto a smaller number of longer-lived faults. We test this idea by simulating a MOR with a specified fraction of magmatic plate separation (M), subjected to a sedimentation rate (s) ranging from 0 to 1 mm/yr. We find that for a given M ≥ 0.7, increasing s increases fault lifespan by ~50%, and the effect plateaus for s > 0.5 mm/yr. Sedimentation prolongs slip on active faults by leveling seafloor relief and raising the threshold for breaking new faults. The effect is more pronounced for faults with a slower throw rate, which is favored by a greater M. These results suggest that sedimentation-enhanced fault lifespan is a viable explanation for the large spacing of ASSC faults if magmatic input is sufficiently robust. By contrast, longer-lived faults that form under low M are not strongly influenced by sedimentation.

Reflective oceanic crust formed at a fast-spreading center in the Pacific

Geology ◽  
1997 ◽  
Vol 25 (6) ◽  
pp. 499 ◽  
Author(s):  
C. R. Ranero ◽  
T. J. Reston ◽  
I. Belykh ◽  
H. Gnibidenko
Keyword(s):  
Oceanic Crust ◽  
Spreading Center ◽  
The Pacific ◽  
Fast Spreading

scholarly journals The tectonic and volcanic evolution of the Mangatolu Triple Junction

2020 ◽  
Author(s):  
Rebecca Mensing ◽  
Margaret Stewart ◽  
Mark Hannington ◽  
Alan Baxter ◽  
Dorothee Mertmann
Keyword(s):  
Triple Junction ◽  
Hydrothermal Systems ◽  
Spreading Center ◽  
Valuable Insight ◽  
Triple Junctions ◽  
Lau Basin ◽  
The North ◽  
Spreading Centers ◽  
Spreading Rates ◽  
Back Arc

<p>The Mangatolu Triple Junction (MTJ) is an intraoceanic back-arc spreading center that is host to at least 3 distinct hydrothermal systems. It is located in the NE Lau Basin, which opened due to rollback of the Pacific plate along the Tonga-Kermadec trench. At the MTJ, three spreading centers meet in a ridge-ridge-ridge (RRR)-type triple junction separating the Tonga plate in the east, the Niuafo’ou microplate in the southwest, and an unnamed microplate in the north. The MTJ is directly linked to the formation and evolution of the Northeast Lau microplate mosaic, as plate fragmentation inevitably results in the formation of triple junctions, but it remains unclear whether the spreading centers are the drivers of plate fragmentation or a consequence of stress relocation related to microplate rotation. Detailed investigation of the geology and structural setting of the MTJ therefore provides valuable insight into the development in the northeast Lau Basin. Here we present the first comprehensive 1:200,000 geological map of the MTJ, based on a compilation of marine geophysical data (hydroacoustics, magnetics, and gravity) derived from 7 research cruises that have investigated the region between 2004 and 2018. Analysis of the mapped geological formations at the MTJ shows the importance of relict arc crust originating from the Tofua Arc in the architecture of the triple junction, which includes three stages of back-arc crust development and extensive off-axis volcanism. The spreading centers along each arm of the MTJ exploit pre-existing crustal weaknesses, interpreted to have formed during initial Lau Basin opening. A reconstruction of the basin opening, based on the mapped features and published spreading rates, revealed that initiation of the MTJ commenced approximately 180,000 years ago, consistent with the very recent and ongoing dynamic evolution of the NE Lau Basin and emerging microplate mosaic. Intersecting fabrics indicate sequential evolution of the 3 arms of the triple junction, with extension along the northeast arm dominant in the early history and more recent extension along the southern and western arms. The results of this study contribute to our growing understanding of the tectonic framework of the northeast Lau Basin and the role of triple junctions in microplate formation.</p>

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