The geological record of oceanic crustal accretion and tectonism at slow-spreading ridges

Jaroslow, Gary E.

doi:10.1575/1912/5693

Cited by 12 publications

(16 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From detailed mapping of sediment thickness [Jaroslow, 1997] Table 1). Average slopes on the seamount flanks range from 10 ø to 16 ø.…”

Section: Study Areamentioning

confidence: 99%

See 1 more Smart Citation

Record of seamount production and off‐axis evolution in the western North Atlantic Ocean, 25°25′–27°10′N

Jaroslow¹,

Smith²,

Tucholke³

2000

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

Beyond the crest of the rift mountains (>4 Ma crust) faulting is no longer active, and changes in the off-axis seamount population reflect crustal aging processes as well as temporal changes in seamount production that occurred at the ridge axis. Estimates of population density for off-axis seamounts show a positive correlation to crustal thickness inferred from analysis of gravity data, suggesting that increased seamount production accompanies increased magma input at the ridge axis. We find no systematic variations in seamount population density along isochron within individual ridge segments. Possible explanations are that along-axis production of seamounts is uniform or that seamount production is enhanced in some regions (e.g., segment centers), but many seamounts do not meet our counting criteria because they are masked by younger volcanic eruptions and low-relief flows.

show abstract

“…From detailed mapping of sediment thickness [Jaroslow, 1997] Table 1). Average slopes on the seamount flanks range from 10 ø to 16 ø.…”

Section: Study Areamentioning

confidence: 99%

“…$clater and Wixon, 1986]. There is little, if any, faulting beyond the crest of the rift mountains [Jaroslow, 1997].…”

Section: Geological Backgroundmentioning

confidence: 99%

Record of seamount production and off‐axis evolution in the western North Atlantic Ocean, 25°25′–27°10′N

Jaroslow¹,

Smith²,

Tucholke³

2000

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Within the bounding walls, however, both the greater size of faults [Jaroslow, 1996;McAllister and Cann, 1996;Searle et al, 1998], as well as observed hypocenter depths and focal mechanisms [Kong et al, 1992;Wolfe et al, 1995], implies that inward dipping bounding wall faults may be constrained at the depth of the brittle-plastic transition [cf. Harper, 1985].…”

Section: Inward Versus Outward Dipping Faultsmentioning

confidence: 99%

“…Estimates of brittle extension suggest that these faults accommodate---1.5 + 1% brittle extension (assuming fault dips of 60ø-90ø), nearly an order of magnitude less than that accommodated beyond the valley floor on the TAG [e.g., Jaroslow, 1996] …”

Section: Summary and Conclusionmentioning

confidence: 99%

“…We find no positive correlation between dip direction and orientation, and dip direction shows little symmetry about the axis of the FFZ or any other ridge-parallel line(Figures 4 and 6). Fault spacings range from tens to hundreds of meters, in contrast with much larger spacings (4-15 kin) typical in off-axis MAR abyssal hill fault populations [e.g.,Shaw and Lin, 1993;Jaroslow, 1996].Figure 7a illustrates the roughly linear relationship between maximum fault displacement (reported as maximum throw d) and fault length L within the FFZ population. The d/oe ratio (¾) of individual faults ranges from 0.017 to 0.085, with a mean value of 0.030 for the population (consistent with the terrestrial mean [e.g., Schlische et al, 1996]).…”

mentioning

confidence: 96%

See 1 more Smart Citation

Faulting and fault scaling on the median valley floor of the trans‐Atlantic geotraverse (TAG) segment, ∼26°N on the Mid‐Atlantic Ridge

Bohnenstiehl¹,

Kleinrock²

1999

J. Geophys. Res.

View full text Add to dashboard Cite

Abstract. A quantitative assessment of faulting on the median valley floor of a slow spreading ridge is accomplished through the analysis of high-resolution DSL-120 sidescan sonar and coregistered bathymetric data from the TAG segment near 26øN on the MidAtlantic Ridge. At this location, faulting is exposed within a 3-5 km wide ridge-parallel zone lying asymmetrically on the eastern half of the median valley floor. Mapped faults have a normal sense of displacement, are < 2 km in length, and accommodate ~ 1.5% brittle extension. Evidence of fault linkage within the fault population includes kinked and bent fault traces in map view, the development of overlapping fault segments or relay ramps, and the presence of multiple local maxima in the displacement-distance profiles of some faults. Faults have a slight tendency to dip to the east, or outward relative to the valley axis, and exhibit little symmetry of fault dip about the axis of the faulted zone or any other ridgeparallel line. Faults exhibit a roughly linear relationship between maximum fault throw and fault length, with a mean ratio of 0.030 for the population. Regression of length-frequency data indicates a power-law distribution, with an exponent of 1.64-1.96, demonstrating that fractal populations can exist in the mid-ocean ridge environment. The fractal nature of this length-frequency distribution and the ratio of maximum fault throw to fault length differ significantly from those described previously for populations of larger abyssal hill faults in the fast spreading environment, where the distribution is exponential and the throw-to-length ratio is ~5 times lower. These results suggest that the scaling of fault populations in the midocean ridge setting may vary as a function of spreading rate and/or fault size.

show abstract

Spatial and temporal variations in crustal production at the Mid‐Atlantic Ridge, 25°N–27°30′N and 0–27 Ma

2015

View full text Add to dashboard Cite

We use high-resolution multibeam bathymetry, shipboard gravity, side-scan sonar images, and magnetic anomaly data collected on conjugate flanks of the Mid-Atlantic Ridge at 25°N-27°30′N and out tõ 27 Ma crust to investigate the crustal evolution of the ridge. Substantial variations in crustal structure and thickness are observed both along and across isochrons. Along isochrons within spreading segments, there are distinct differences in seafloor morphology and gravity-derived crustal thickness between inside and outside corners. Inside corners are associated with shallow depths, thin crust, and enhanced normal faulting while outside corners have greater depths, thicker crust, and more limited faulting. Across-isochrons, systematic variations in crustal thickness are observed at two different timescales, one at~2-3 Myr and another at >10 Myr, and these are attributed to temporal changes in melt supply at the ridge axis. The shorter-term variations mostly are in-phase between conjugate ridge flanks, although the actual crustal thickness can be significantly different on the two flanks at any given time. We observe no correlation between crustal thickness and spreading rate. Thus, during periods of low melt supply, tectonic extension must increase to accommodate the full plate separation rate. This extension commonly is concentrated in long-lived faults on only one side of the axial valley, resulting in strong across-axis asymmetries in crustal thickness and seafloor morphology. The thin-crust flank has few volcanic features and exhibits elevated, blocky topography with large-offset, often irregular faults, while the conjugate thicker-crust flank shows shorter-offset, regular faulting, and common volcanic features. The variations in melt supply at the ridge axis most likely are caused either by episodic convection in the subaxial mantle or by variable melting of chemically heterogeneous mantle.

show abstract

The geological record of oceanic crustal accretion and tectonism at slow-spreading ridges

Cited by 12 publications

References 55 publications

Record of seamount production and off‐axis evolution in the western North Atlantic Ocean, 25°25′–27°10′N

Record of seamount production and off‐axis evolution in the western North Atlantic Ocean, 25°25′–27°10′N

Faulting and fault scaling on the median valley floor of the trans‐Atlantic geotraverse (TAG) segment, ∼26°N on the Mid‐Atlantic Ridge

Spatial and temporal variations in crustal production at the Mid‐Atlantic Ridge, 25°N–27°30′N and 0–27 Ma

Contact Info

Product

Resources

About