Fine-scale segmentation of the crustal magma reservoir beneath the East Pacific Rise

Carbotte, S. M.; Marjanović, M.; Carton, H. D.; Mutter, John C.; Canales, J. P.; Nedimović, M. R.; Han, S.; Perfit, Michael R.

doi:10.1038/ngeo1933

Cited by 88 publications

(169 citation statements)

References 26 publications

Supporting

Mentioning

159

Contrasting

Order By: Relevance

“…The discontinuity interpreted at 9828 ′ N is not evident in modern GPS navigation bathymetry data from the region (e.g. White et al 2002; or in the crustal magma lens (Detrick et al 1987;Kent et al 1993;Carbotte et al 2013), and the apparent pinching of the axial low velocity zone evident in the seismic tomography study occurs near the edge of the survey box where resolution is limited (Dunn et al 2000). Furthermore, the geometry of the region of low velocities and presumed high melt content within the uppermost mantle resolved in this study is inconsistent with that found in the recent, more comprehensive, regional study of Toomey et al (2007).…”

Section: Geophysical Properties Of Discontinuities and Ridge Segmentsmentioning

confidence: 99%

“…North of Clipperton, evidence supporting this hypothesis includes the finding that no axial magma lens (AML) has been detected within c. 70 km north of the TF, although seismic reflection studies image an AML 1-2 km beneath the seafloor along much of the EPR between 8830 ′ 178N (Fig. 2g, Detrick et al 1987, 1993;Kent et al 1993Kent et al , 2000Babcock et al 1998;Carbotte et al 2000Carbotte et al , 2013. Further, lavas erupted over the past c. 1 Ma at the segment north of Clipperton have lower Mg#s than those from the south (Mg# of 5-7 compared with 7 -9), indicating lower eruption temperatures and less melt replenishment or greater cooling for the northern segment ( Fig.…”

Section: Geophysical Properties Of Discontinuities and Ridge Segmentsmentioning

confidence: 99%

“…In one of the few studies of sufficient sampling density to explore detailed geochemical systematics associated with fourth-order offsets, Goss et al (2010) report subtle differences in the compositions of lavas sampled along the fourth-order segments north and south of the 9853 ′ N deval resulting from differences in extents of melting and fractionation. Carbotte et al (2013) showed that the boundaries between these small-scale geochemical and tectonic segments in this region correlate with disruptions in the continuity and characteristics of the underlying melt lens. Based on these relationships, they argued that the fourth-order tectonic segmentation is inherited from partitioning of the crustal magma lens, and that the chemical differences along adjacent segments result from dominantly vertical transport of melt from these chemically distinct melt lens segments.…”

Section: Geochemical Properties At Discontinuities and Along Ridge Sementioning

confidence: 99%

“…Recent seismic reflection observations of the EPR between the Siqueiros and Clipperton TFs reveal disruptions in the crustal magma lens coincident with third-, as well as the finer-scale fourthorder seafloor discontinuities (Carbotte et al 2013;Marjanovic 2013;Han et al 2014). The nature of magma lens disruptions varies, but in some locations offset and overlapping melt lenses are imaged that in plan view display a geometry similar to that of OSCs (at 9836 ′ -39 ′ N, Han et al 2014).…”

Section: Geophysical Properties Of Discontinuities and Ridge Segmentsmentioning

confidence: 99%

“…Fourth-order offsets are not associated with anomalies in the axial MBA or with changes in the cross-sectional area of the ridge as measured in regional-scale bathymetry studies (Scheirer & Macdonald 1993). However, they often coincide with breaks and local deep points (on the order of 50 m) in the AML and are attributed to fine-scale (5-15 km) segmentation of this melt reservoir (Carbotte et al 2000(Carbotte et al , 2013Marjanovic 2013).…”

Section: Geophysical Properties Of Discontinuities and Ridge Segmentsmentioning

confidence: 99%

See 4 more Smart Citations

Tectonic and magmatic segmentation of the Global Ocean Ridge System: a synthesis of observations

Carbotte

Smith

Cannat

et al. 2015

Self Cite

View full text Add to dashboard Cite

Mid-ocean ridges display tectonic segmentation defined by discontinuities of the axial zone, and geophysical and geochemical observations suggest segmentation of the underlying magmatic plumbing system. Here, observations of tectonic and magmatic segmentation at ridges spreading from fast to ultraslow rates are reviewed in light of influential concepts of ridge segmentation, including the notion of hierarchical segmentation, spreading cells and centralized v. multiple supply of mantle melts. The observations support the concept of quasi-regularly spaced principal magmatic segments, which are 30-50 km long on average at fast-to slow-spreading ridges and fed by melt accumulations in the shallow asthenosphere. Changes in ridge properties approaching or crossing transform faults are often comparable with those observed at smaller offsets, and even very small discontinuities can be major boundaries in ridge properties. Thus, hierarchical segmentation models that suggest large-scale transform fault-bounded segmentation arises from deeper level processes in the asthenosphere than the finer-scale segmentation are not generally supported. The boundaries between some but not all principal magmatic segments defined by ridge axis geophysical properties coincide with geochemical boundaries reflecting changes in source composition or melting processes. Where geochemical boundaries occur, they can coincide with discontinuities of a wide range of scales.Discovery and interpretations of mid-ocean ridge (MOR) segmentation: historical review

show abstract

Section: Geophysical Properties Of Discontinuities and Ridge Segmentsmentioning

confidence: 99%

Section: Geophysical Properties Of Discontinuities and Ridge Segmentsmentioning

confidence: 99%

Section: Geochemical Properties At Discontinuities and Along Ridge Sementioning

confidence: 99%

Section: Geophysical Properties Of Discontinuities and Ridge Segmentsmentioning

confidence: 99%

Section: Geophysical Properties Of Discontinuities and Ridge Segmentsmentioning

confidence: 99%

See 3 more Smart Citations

Tectonic and magmatic segmentation of the Global Ocean Ridge System: a synthesis of observations

Carbotte

Smith

Cannat

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

Seafloor photo‐geology and sonar terrain modeling at the 9°N overlapping spreading center, East Pacific Rise

Klein

White

Nunnery

et al. 2013

Geochem Geophys Geosyst

Self Cite

View full text Add to dashboard Cite

[1] A fundamental goal in the study of mid-ocean ridges is to understand the relationship between the distribution of melt at depth and seafloor features. Building on geophysical information on subsurface melt at the 9 N overlapping spreading center on the East Pacific Rise, we use terrain modeling (DSL-120A side scan and bathymetry), photo-geology (Jason II and WHOI TowCam), and geochemical data to explore this relationship. Terrain modeling identified four distinct geomorphic provinces with common seafloor characteristics that correspond well to changes in subsurface melt distribution. Visual observations were used to interpret terrain modeling results and to establish a relative seafloor age scale, calibrated with radiometric age dates, to identify areas of recent volcanism. On the east limb, recent eruptions in the north are localized over the margins of the 4 km wide asymmetric melt sill, forming a prominent off-axis pillow ridge. Along the southern east limb, recent eruptions occur along a neovolcanic ridge that hugs the overlap basin and lies several kilometers west of the plunging melt sill. Our results suggest that long-term southward migration of the east limb occurs through a series of diking events with a net southward propagation direction. Examining sites of recent eruptions in the context of geophysical data on melt distribution in the crust and upper mantle suggests melt may follow complex paths from depth to the surface. Overall, our findings emphasize the value of integrating information obtained from photo-geology, terrain modeling, lava geochemistry and petrography, and geophysics to constrain the nature of melt delivery at mid-ocean ridges.Components: 13,950 words, 12 figures.

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

Aghaei

Nedimović

Carton

et al. 2014

Geochem Geophys Geosyst

Self Cite

View full text Add to dashboard Cite

We computed crustal thickness (5740 6 270 m) and mapped Moho reflection character using 3-D seismic data covering 658 km 2 of the fast-spreading East Pacific Rise (EPR) from 9 42 0 N to 9 57 0 N. Moho reflections are imaged within 87% of the study area. Average crustal thickness varies little between large sections of the study area suggesting regionally uniform crustal production in the last 180 Ka. However, individual crustal thickness measurements differ by as much as 1.75 km indicating that the mantle melt delivery has not been uniform. Third-order, but not fourth-order ridge discontinuities are associated with changes in the Moho reflection character and/or near-axis crustal thickness. This suggests that the thirdorder segmentation is governed by melt distribution processes within the uppermost mantle while the fourth-order ridge segmentation arises from midcrustal to upper-crustal processes. In this light, we assign fourth-order ridge discontinuity status to the debated ridge segment boundary at 9 45 0 N and third-order status at 9 51.5 0 N to the ridge segment boundary previously interpreted as a fourth-order discontinuity.Our seismic results also suggest that the mechanism of lower-crustal accretion varies along the investigated section of the EPR but that the volume of melt delivered to the crust is mostly uniform. More efficient mantle melt extraction is inferred within the southern half of our survey area with greater proportion of the lower crust accreted from the axial magma lens than that for the northern half. This south-to-north variation in the crustal accretion style may be caused by interaction between the melt sources for the ridge and the Lamont seamounts.

show abstract

Fine-scale segmentation of the crustal magma reservoir beneath the East Pacific Rise

Cited by 88 publications

References 26 publications

Tectonic and magmatic segmentation of the Global Ocean Ridge System: a synthesis of observations

Tectonic and magmatic segmentation of the Global Ocean Ridge System: a synthesis of observations

Seafloor photo‐geology and sonar terrain modeling at the 9°N overlapping spreading center, East Pacific Rise

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

Contact Info

Product

Resources

About