Dating the Growth of Oceanic Crust at a Slow-Spreading Ridge

Schwartz, Joshua; John, Barbara E.; Cheadle, M. J.; Miranda, Elena A.; Grimes, C. B.; Wooden, Joseph L.; Dick, H. J.

doi:10.1126/science.1116349

Cited by 94 publications

(79 citation statements)

References 22 publications

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“…1A), adjacent to the Atlantis II Transform (57ЊE; Dick et al 1991bDick et al , 2000Matsumoto et al 2002;Baines et al 2003;Hosford et al 2003;Schwartz et al 2005). Its detachment-fault system (∼300 km 2 in area) developed initially by dipping toward the axial valley to the north, accommodating at least 15 km of slip parallel to the spreading direction Matsumoto et al 2002).…”

Section: Atlantis Bank 32њs Swir: "Gabbro-localized" Detachment Cormentioning

confidence: 99%

“…In situ rock samples collected with submersibles span roughly 3 m.yr. of crustal accretion (Schwartz et al 2005) and are derived from structural depths between the uppermost 400 m of the footwall and the detachment-fault surface (Arai et al 2000;Kinoshita et al 2001;Matsumoto et al 2002;Miranda 2006;E. A. Miranda and B. E. John, submitted).…”

Section: Atlantis Bank 32њs Swir: "Gabbro-localized" Detachment Cormentioning

confidence: 99%

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Oceanic Core Complex Development in Modern and Ancient Oceanic Lithosphere: Gabbro‐Localized versus Peridotite‐Localized Detachment Models

Miranda¹,

Dilek²

2010

The Journal of Geology

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A B S T R A C TDrilling and submersible studies of the Atlantis Bank (Southwest Indian Ridge) and the Atlantis Massif (Mid-Atlantic Ridge) oceanic core complexes reveal "gabbro-localized" and "peridotite-localized" end-member models of strain localization and deformation during core complex development, in which the gabbroic fault rocks exhibit extensive and rare high-temperature ductile-deformation fabrics, respectively. Both models emphasize a footwall cored by gabbroic intrusions, therefore precluding an amagmatic origin of core complex formation. We test these models by using relict oceanic core complexes preserved in the western Mirdita Ophiolite in Albania. The Puka and Krabbi massifs display traits of the peridotite-localized detachment model, whereby amagmatic tectonic extension is not required for the formation of this category of core complexes.

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Section: Atlantis Bank 32њs Swir: "Gabbro-localized" Detachment Cormentioning

confidence: 99%

Section: Atlantis Bank 32њs Swir: "Gabbro-localized" Detachment Cormentioning

confidence: 99%

Oceanic Core Complex Development in Modern and Ancient Oceanic Lithosphere: Gabbro‐Localized versus Peridotite‐Localized Detachment Models

Miranda¹,

Dilek²

2010

The Journal of Geology

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“…There is a considerable body of evidence that indicates it occurs in lava flows and shallow level magma chambers that solidify as dikes and sills [O'Hara, 1968]. However, it can also occur in the mantle below oceanic ridges Niu, 1997;Coogan et al, 2001;Herzberg, 2004b;Schwartz et al, 2005], Réunion [Albarède et al, 1997], and west Greenland [Larsen and Pedersen, 2000].…”

Section: Introductionmentioning

confidence: 99%

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Herzberg

Asimow

Arndt

et al. 2007

Geochem Geophys Geosyst

627

449

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International audienceSeveral methods have been developed to assess the thermal state of the mantle below oceanic ridges, islands, and plateaus, on the basis of the petrology and geochemistry of erupted lavas. One leads to the conclusion that mantle potential temperature (i.e., TP) of ambient mantle below oceanic ridges is 1430°C, the same as Hawaii. Another has ridges with a large range in ambient mantle potential temperature (i.e., TP = 1300–1570°C), comparable in some cases to hot spots (Klein and Langmuir, 1987; Langmuir et al., 1992). A third has uniformly low temperatures for ambient mantle below ridges, ∼1300°C, with localized 250°C anomalies associated with mantle plumes. All methods involve assumptions and uncertainties that we critically evaluate. A new evaluation is made of parental magma compositions that would crystallize olivines with the maximum forsterite contents observed in lava flows. These are generally in good agreement with primary magma compositions calculated using the mass balance method of Herzberg and O'Hara (2002), and differences reflect the well-known effects of fractional crystallization. Results of primary magma compositions we obtain for mid-ocean ridge basalts and various oceanic islands and plateaus generally favor the third type of model but with ambient mantle potential temperatures in the range 1280–1400°C and thermal anomalies that can be 200–300°C above this background. Our results are consistent with the plume model

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“…[45] It is important to note that the time of exhumation of the plutonic igneous rocks at the seafloor gives only a minimum age for their intrusion because they could have been emplaced at a significant depth beneath the spreading axis [e.g., Schwartz et al, 2005;Grimes et al, 2008]. Conversely, the age of the lithosphere on which volcanics appear provides a maximum age for those rocks, which could have been extruded at any time after that lithosphere was exhumed.…”

Section: Geochemistry Geophysicsmentioning

confidence: 99%

Advanced geophysical studies of accretion of oceanic lithosphere in Mid-Ocean Ridges characterized by contrasting tectono-magmatic settings

Xu¹

2012

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The structure of the oceanic lithosphere results from magmatic and extensional processes taking place at mid-ocean ridges (MORs). The temporal and spatial scales of the variability of these two processes control the degree of heterogeneity of the oceanic lithosphere, represented by two end-member models: the classical Penrose Model exemplified by layered magmatic crust formed along fast-spreading MORs, e.g., East Pacific Rise (EPR); and the recently defined Chapman Model describing heterogeneous mafic and ultramafic lithosphere formed in settings of oceanic detachment faulting common along slow-spreading MORs, e.g., Mid-Atlantic Ridge (MAR). This thesis is using advanced marine geophysical methods (including finite-difference wave propagation modeling, 3D multi-channel seismic reflection imaging, waveform inversion, streamer tomography, and near-bottom magnetics) to study lithospheric accretion processes in MORs characterized by contrasting tectono-magmatic settings: the magmatically dominated EPR axis between 9°30'-10°00'N, and the Kane Oceanic Core Complex (KOCC), a section of MAR lithosphere (23°20'-23°38'N) formed by detachment faulting. At the EPR study area, I found that the axial magma chamber (AMC) melt sill is segmented into four prominent 2-4-km-long sections spaced every ~5-10 km along the ridge axis characterized by high melt content (>95%). In contrast, within the intervening sections, the AMC sill has a lower melt content (41-46%). The total magma volume extracted from the AMC sill was estimated of ~46 × 10 6 m 3 , with ~24 × 10 6 m 3 left unerupted in the upper crust as dikes after 2005-06 eruption. At the KOCC, I used streamer tomography to constrain the shallow seismic velocity structure. Lithological interpretation of the seismic tomographic models provides insights into the temporal and spatial evolution of the melt supply at the spreading axis as the KOCC formed and evolved. Investigation of a magnetic polarity reversal boundary in crosssection at the northern boundary of KOCC suggests that the boundary (representing both a frozen isotherm and an isochron) dips away from the ridge axis along the Kane transform fault scarp, with a west-dipping angle of ~45° in the shallow (<1 km) crust and <20° in the deeper crust. Many thanks to my project advisors and cooperators, Brian Tucholke, RalphStephen, and Maurice Tivey, who have worked with me during the past five and a half years. These research experiences have greatly broadened my horizons on marine geology and geophysics, synthetic seismology, and geomagnetism. Brian introduced me into the geological world of detachment fault system, and his patience and insightful comments on our scientific paper on Kane oceanic core complex are greatly appreciated.I am very thankful for Ralph who introduced me to the world of time-domain finite difference (TDFD) synthetic seismology and Tom Bolmer for setting up the workstation for my TDFD calculations. Ralph's encouragement, enthusiasm, and interactions with me have inspired me to dig out more intere...

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Dating the Growth of Oceanic Crust at a Slow-Spreading Ridge

Cited by 94 publications

References 22 publications

Oceanic Core Complex Development in Modern and Ancient Oceanic Lithosphere: Gabbro‐Localized versus Peridotite‐Localized Detachment Models

Oceanic Core Complex Development in Modern and Ancient Oceanic Lithosphere: Gabbro‐Localized versus Peridotite‐Localized Detachment Models

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Advanced geophysical studies of accretion of oceanic lithosphere in Mid-Ocean Ridges characterized by contrasting tectono-magmatic settings

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