Waxing and waning volcanism along the East Pacific Rise on a millennium time scale

Cormier, Marie-Hélène; Ryan, William B. F.; Shah, Anjana K.; Jin, Weiyang; Bradley, A. M.; Yoerger, D.

doi:10.1130/0091-7613(2003)031<0633:wawvat>2.0.co;2

Cited by 39 publications

(47 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, a narrow, 40–300 m wide, 5–15 m deep trough is often present at the ridge axis and serves as the locus of most volcanic and hydrothermal activity along the ridge crest (Figure 1) [ Haymon et al , 1991; Gregg et al , 1996; Fornari et al , 1998, 2004]. Comparable troughs are common along many fast and intermediate spreading rate ridge crests [e.g., Macdonald and Fox , 1988; Cormier et al , 2003; Chadwick and Embley , 1998; White et al , 2000; Hey et al , 2004]. Detailed mapping and analysis of MOR axial trough morphology and structure provide a basis for interpreting the recent magmatic and tectonic history of the most active part of the ridge crest.…”

Section: Introductionmentioning

confidence: 99%

A record of eruption and intrusion at a fast spreading ridge axis: Axial summit trough of the East Pacific Rise at 9–10°N

Soule

Escartı́n

Fornari

2009

Geochem Geophys Geosyst

View full text Add to dashboard Cite

[1] High-resolution side-scan sonar, near-bottom multibeam bathymetry, and deep-sea photo and bathymetry traverses are used to map the axial summit trough (AST) at the East Pacific Rise between 9 and 10°N. We define three ridge axis morphologic types: no AST, narrow AST, and wide AST, which characterize distinct ridge crest domains spanning tens of kilometers along strike. Near-bottom observations, modeling of deformation above intruding dikes, and comparisons to the geologic and geophysical structure of the ridge crest are used to develop a revised model of AST genesis and evolution. This model helps constrain the record of intrusive and extrusive magmatism and styles of lava deposition along the ridge crest at time scales from hundreds to tens of thousands of years. The grabens in the narrow-AST domain (9°43 0 -53 0 N) are consistent with deformation above the most recent (<10) diking events beneath the ridge crest. Frequent high-effusion rate extrusive volcanism in this domain (several eruptions every $100 years) overprints near-axis deformation and maintains a consistent AST width. The most recent eruption at the ridge crest occurred in this area and did not significantly modify the physical characteristics of the AST. The grabens in the wide-AST domain (9°23 0 -43 0 N) originated with similar dimensions to the narrow AST. Spreading, driven primarily by the intrusion of shallow dikes within a narrow axial zone, causes the initial graben bounding faults to migrate away from the axis. Infrequent extrusive volcanism (several eruptions every $1000 years) fills a portion of the subsidence that accumulates over time but does not significantly modify the width of the AST. Outside of these domains, lower-effusion rate constructional volcanism without efficient drain-back fills and erases the signature of the AST. The relative frequency of intrusive versus extrusive magmatic events controls the morphology of the ridge crest and appears to remain constant over millennial time scales within the domains we have identified; however, over longer time scales ($10-25 ka), domain-specific intrusive-to-extrusive ratios do not appear to be fixed in space, resulting in a fairly consistent volcanic accretion over the length scale of the second-order ridge segment between 9°N and 10°N.

show abstract

Section: Introductionmentioning

confidence: 99%

A record of eruption and intrusion at a fast spreading ridge axis: Axial summit trough of the East Pacific Rise at 9–10°N

Soule

Escartı́n

Fornari

2009

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…In particular, regular episodes of summit trough collapse after periods of frequent eruptions (and associated drainage of the axial melt lens) could periodically imprint vertical offsets in seafloor bathymetry, potentially as high as~50 m (12). We consider this process more plausible than a magmatic modulation of the growth of stretching faults, which would require fluctuations in magma supply an order of magnitude greater than those expected from the effect of sea level cycles (4,8).…”

mentioning

confidence: 98%

Response to Comment on “Sensitivity of seafloor bathymetry to climate-driven fluctuations in mid-ocean ridge magma supply”

Olive¹,

Behn²,

Ito³

et al. 2016

Science

View full text Add to dashboard Cite

Tolstoy reports the existence of a characteristic 100 thousand year (ky) period in the bathymetry of fast-spreading seafloor but does not argue that sea level change is a first-order control on seafloor morphology worldwide. Upon evaluating the overlap between tectonic and Milankovitch periodicities across spreading rates, we reemphasize that fast-spreading ridges are the best potential recorders of a sea level signature in seafloor bathymetry. We acknowledge the clear distinction made by Tolstoy (1) between the ideas put forward in (2) and the hypothesis central to (3). In (3), it is proposed that seafloor relief is caused primarily by changes in the height of volcanic constructions on Milankovich time scales, which reflect a control of sea level cycles on mid-ocean ridge (MOR) magma supply. Meanwhile, (1, 2) point out that seafloor eruption rates may be extremely sensitive to small external perturbations such as orbital stresses. In particular, they suggest that-in addition to sea level cycles modulating overall MOR magma supplyeccentricity cycles may modulate rates of volcanic extrusion on the seafloor. A 100-thousand-year (ky) characteristic periodicity in the bathymetry of the fast-spreading Southern East Pacific Rise (SEPR) is presented to support this idea. In (2), however, Tolstoy does not imply that such processes are the primary cause for the abyssal hill fabric of global seafloor, which was the focus of our initial study (4).A characteristic periodicity of 100 ky at the SEPR, with a full spreading rate of 14.7 cm/year, translates into a seafloor length scale of 7.4 km, which is considerably larger than the characteristic 1-to 3-km spacing of normal faults measured at fast-spreading ridges (5, 6). The biggest tectonic scarps (~50 m) in such settings correspond to axis facing faults that accommodate the small fraction of plate separation not taken up by crustal emplacement (7,8). Additional, more closely spaced faults form in response to flexural stresses as the lithosphere migrates away from the axial high, but these generally produce smaller scarps (≤20 m) (5, 9-11). Overall, the spectral signature of the tectonic fabric of fast-spreading seafloor should consist of several distributed peaks at periodicities near and below~40 ky (Fig. 1). Such peaks are present in the bathymetric spectrum of the SEPR but are much less energetic than the 100-ky peak (2). This 100-ky peak could therefore be the signature of a periodic (but nontectonic) process capable of creating coherent relief on top of the fault-induced fabric.Based on these observations of fault geometry and distribution, our models suggest that topography-building processes at MORs act as low-pass filters-they only record fluctuations in melt supply on time scales longer than the cutoff period set by intrinsic properties of the lithosphere and magmatic accretion zone. Tolstoy rightfully points out that this cutoff period generally decreases with spreading rate, making fastspreading ridges the best candidates to efficiently record a climatic modulati...

show abstract

“…[2] High-resolution mapping of the seafloor started at fast spreading ridges during the last decade, with the help of submersible-borne scanning sonars [Kurras et al, 1998;Chadwick et al, 2001;Cormier et al, 2003;Tanaka et al, 2007]. These studies allow resolutions of the order of a few decimeters, over areas of a few thousand square meters.…”

Section: Introductionmentioning

confidence: 99%

Recent volcanic events and the distribution of hydrothermal venting at the Lucky Strike hydrothermal field, Mid‐Atlantic Ridge

Ondréas

Cannat

Fouquet

et al. 2009

Geochem Geophys Geosyst

128

View full text Add to dashboard Cite

[1] We present new high-resolution bathymetry and backscatter data acquired in 2006 with the ROV Victor 6000 over the Lucky Strike hydrothermal field, Mid-Atlantic Ridge. As long-term monitoring of the Lucky Strike area (MoMAR project) is being implemented, these new high-resolution data offer an unprecedented view of the distribution of hydrothermal edifices, eruptive facies, and small-scale tectonic features in the Lucky Strike vent field. We show that vents located in the NW and NE correspond with wide expanses of lumpy seafloor which we interpret as primarily made of broken chimneys and sulfide edifices. They are found above scarps with relief >50 m or on associated mass wasting deposits. By contrast, the SE and SW vents correspond with small expanses of lumpy seafloor and are located near smaller scarps which we interpret as more recent faults. Hydrothermal edifices in the SW venting area appear very recent, postdating the emplacement and faulting of the most recent lava. We propose that this difference in the age of hydrothermal edifices does not mean that hydrothermal venting itself is more recent in the southern part of the Lucky Strike field because preexisting sulfide deposits there may have been buried by recent volcanic deposits. Instead, the older edifices in the northern part of the hydrothermal field may have been allowed more time to grow because they are set above the level of recent lava flows. The formation of a lava lake is the most recent eruptive event detected at Lucky Strike. Lava drainback is evidenced by benches and lava pillars, suggesting a close connection with an underlying magma reservoir, which probably corresponds to the melt body imaged by Singh et al. (2006). We have found no evidence that this lake was active for months to decades, as lava lakes at terrestrial volcanoes. It may instead have formed as a lava pond, with successive lava flows covering the eruptive vents, as proposed for similar features at the EPR. The horizontal surface of the lake is deformed only near its southwestern shore, along a NNEtrending set of faults and fissures, which appear to control the distribution of hydrothermal chimneys.

show abstract

Waxing and waning volcanism along the East Pacific Rise on a millennium time scale

Cited by 39 publications

References 14 publications

A record of eruption and intrusion at a fast spreading ridge axis: Axial summit trough of the East Pacific Rise at 9–10°N

A record of eruption and intrusion at a fast spreading ridge axis: Axial summit trough of the East Pacific Rise at 9–10°N

Response to Comment on “Sensitivity of seafloor bathymetry to climate-driven fluctuations in mid-ocean ridge magma supply”

Recent volcanic events and the distribution of hydrothermal venting at the Lucky Strike hydrothermal field, Mid‐Atlantic Ridge

Contact Info

Product

Resources

About