Crustal thickness and Moho character of the fast‐spreading East Pacific Rise from 9°42′N to 9°57′N from poststack‐migrated 3‐D MCS data

Aghaei, O.; Nedimović, M. R.; Carton, H. D.; Carbotte, S. M.; Canales, J. P.; Mutter, John C.

doi:10.1002/2013gc005069

Cited by 48 publications

(63 citation statements)

References 75 publications

(258 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the ESB and NWSB, the oceanic basement is smooth with only minor normal faults. Crustal features in these two subbasins are comparable to the typical crust created by magma-rich seafloor spreading, for example, the cases of the eastern Ogasawara Plateau and East Pacific Rise (Aghaei et al, 2014;Tsuji et al, 2007;White et al, 1992). Crustal features in these two subbasins are comparable to the typical crust created by magma-rich seafloor spreading, for example, the cases of the eastern Ogasawara Plateau and East Pacific Rise (Aghaei et al, 2014;Tsuji et al, 2007;White et al, 1992).…”

Section: Introductionmentioning

confidence: 67%

Seismic Evidence for Tectonically Dominated Seafloor Spreading in the Southwest Sub‐basin of the South China Sea

Yan

Wang

et al. 2018

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Seafloor spreading can be explained by different dynamic mechanisms, magmatically or tectonically dominated. The Southwest Sub‐basin, located at the southwest tip of the propagating seafloor spreading of the South China Sea, remains unclear for its spreading regime owing to poor and debated knowledge of the crustal structures. Here two multichannel seismic lines and one oceanic bottom seismometer line across this subbasin are reprocessed and analyzed with focus on crustal imaging. The sediments are usually 0.5–1.0 km thick over the abyssal basin and slightly thicker in the few grabens. The thickest (3.3 km) sediments are found in the fossil spreading center. The basement is fairly rough and highly faulted by ubiquitous crustal faults. The fossil spreading center is characterized by a deep median valley, similar to that of magma‐poor spreading cases. Both multichannel seismic lines show a few intermittent and diffusive reflectors at 1.5‐ to 3.6‐km depth below the fragmented basement. These reflectors, correlating well with the velocities of 6.8–7.2 km/s obtained from velocity inversion of oceanic bottom seismometer data, are interpreted as Moho reflections. Thus, the inferred crustal thickness is only 1.5–3.6 km excluding the sediments, which is much thinner than usual. The underlying mantle with velocities lower than 8.0 km/s might be serpentinized with water infiltration along these crustal faults. Therefore, it is proposed that the spreading of the Southwest Sub‐basin was tectonically dominated.

show abstract

Section: Introductionmentioning

confidence: 67%

Seismic Evidence for Tectonically Dominated Seafloor Spreading in the Southwest Sub‐basin of the South China Sea

Yan

Wang

et al. 2018

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…Finite difference modeling also indicates that a thicker Moho transition zone can result in higher amplitude Pn arrivals (Line 1), depending on the exact nature of internal layering within the Moho transition [Carbonell et al, 2002]. We speculate that the change in Moho character is associated with variability in melt supply, with melt extraction more efficient with increased magmatic input resulting in a sharper Moho [Lizarralde et al, 2004;Conley and Dunn, 2011;Aghaei et al, 2014].…”

Section: Crustal Structure Variabilitymentioning

confidence: 81%

“…If this model is correct we might expect to find thinned oceanic crust near the change in magnetic orientation associated with the initial extension, and back-arc crust in the region of northeastsouthwest lineations. Back-arc crust is observed to have structure varying from thick crust (8-10 km) with lower crustal velocities of 7.2-7.4 km/s, to crust with velocities and thicknesses indistinguishable from normal oceanic crust [e.g., Takahashi et al, 2009;Arai and Dunn, 2014]; these velocity and thickness differences are attributed to the influence of slab water enhancing melt production near the active arc [Arai and Dunn, 2014]. Since back-arc crust can have velocities and thicknesses similar to normal oceanic crust it is impossible to use velocity structure alone to distinguish crustal type.…”

Section: Nature Of Aleutian Basin Crustmentioning

confidence: 99%

Aleutian basin oceanic crust

Christeson

Barth

2015

Earth and Planetary Science Letters

View full text Add to dashboard Cite

Editor: P. Shearer Keywords:Aleutian basin Bering Sea oceanic crust wide-angle seismic ocean bottom seismometer We present two-dimensional P-wave velocity structure along two wide-angle ocean bottom seismometer profiles from the Aleutian basin in the Bering Sea. The basement here is commonly considered to be trapped oceanic crust, yet there is a change in orientation of magnetic lineations and gravity features within the basin that might reflect later processes. Line 1 extends ∼225 km from southwest to northeast, while Line 2 extends ∼225 km from northwest to southeast and crosses the observed change in magnetic lineation orientation. Velocities of the sediment layer increase from 2.0 km/s at the seafloor to 3.0-3.4 km/s just above basement, crustal velocities increase from 5.1-5.6 km/s at the top of basement to 7.0-7.1 km/s at the base of the crust, and upper mantle velocities are 8.1-8.2 km/s. Average sediment thickness is 3.8-3.9 km for both profiles. Crustal thickness varies from 6.2 to 9.6 km, with average thickness of 7.2 km on Line 1 and 8.8 km on Line 2. There is no clear change in crustal structure associated with a change in orientation of magnetic lineations and gravity features. The velocity structure is consistent with that of normal or thickened oceanic crust. The observed increase in crustal thickness from west to east is interpreted as reflecting an increase in melt supply during crustal formation.

show abstract

“…At the EPR, the cross-axis offset between a centre of mantle melt delivery and the rise axis also correlates with the intensity of rise crest volcanic, hydrothermal and tectonic activity 9 , and the distal ends of third-order segments may be associated with a decrease in the efficiency of mantle melt extraction 49 .…”

Section: Magmatic Segmentation Of Mid-ocean Ridgesmentioning

confidence: 98%

Segmentation of mid-ocean ridges attributed to oblique mantle divergence

et al. 2016

View full text Add to dashboard Cite

The origin of mid-ocean ridge segmentation-the systematic along-axis variation in tectonic and magmatic processesremains controversial. It is commonly assumed that mantle flow is a passive response to plate divergence and that between transform faults magma supply controls segmentation. Using seismic tomography, we constrain the geometry of mantle flow and the distribution of mantle melt beneath the intermediate-spreading Endeavour segment of the Juan de Fuca Ridge. Our results, in combination with prior studies, establish a systematic skew between the mantle-divergence and plate-spreading directions. In all three cases studied, mantle divergence is advanced with respect to recent changes in the plate-spreading direction and the extent to which the flow field is advanced increases with decreasing spreading rate. Furthermore, seismic images show that large-o set, non-transform discontinuities are regions of enhanced mantle melt retention. We propose that oblique mantle flow beneath mid-ocean ridges is a driving force for the reorientation of spreading segments and the formation of ridge-axis discontinuities. The resulting tectonic discontinuities decrease the e ciency of upward melt transport, thus defining segment-scale variations in magmatic processes. We predict that across spreading rates mid-ocean ridge segmentation is controlled by evolving patterns in asthenospheric flow and the dynamics of lithospheric rifting.S ince the discovery that Earth's mid-ocean ridge system is divided into segments 1-3 a wealth of observations have shown that there are systematic, along-axis variations in tectonic and magmatic processes 2,4-6 . Between transform faults, the boundaries of ridge segments are defined by long-lived, non-transform tectonic offsets or second-order ridge crest discontinuities 2,3 ( Fig. 1) that often occur at axial depth maxima and that migrate along the plate boundary. These second-order discontinuities include overlapping spreading centres (OSCs) at fast-and intermediate-spreading rates, and oblique shear zones at slow-spreading rates. The origin of non-transform tectonic offsets and their relations to segment-scale magmatic processes remains actively debated 1,2,5-9 .The prevailing hypothesis for segmentation of spreading centres attributes second-order offsets to variations in magma supply from the upwelling mantle. In this view, segment centres overlie sites of increased melt supply and magma is redistributed along axis at crustal or mantle depths toward magma-starved segment ends 1,2,8,10 . Alternatively, competing hypotheses suggest that changes in the plate-spreading direction are related to the formation of tectonic offsets 7 and to a misalignment between sub-ridge mantle and crustal processes 9 . Here, we seismically image the geometry of mantle flow and the distribution of shallow mantle melt beneath the intermediate-spreading Endeavour segment of the Juan de Fuca Ridge (JdFR). We synthesize our results with observations from other spreading environments to identify the mechanisms responsible ...

show abstract

Crustal thickness and Moho character of the fast‐spreading East Pacific Rise from 9°42′N to 9°57′N from poststack‐migrated 3‐D MCS data

Cited by 48 publications

References 75 publications

Seismic Evidence for Tectonically Dominated Seafloor Spreading in the Southwest Sub‐basin of the South China Sea

Seismic Evidence for Tectonically Dominated Seafloor Spreading in the Southwest Sub‐basin of the South China Sea

Aleutian basin oceanic crust

Segmentation of mid-ocean ridges attributed to oblique mantle divergence

Contact Info

Product

Resources

About