Oceanic corrugated surfaces and the strength of the axial lithosphere at slow spreading ridges

Cannat, Mathilde; Sauter, Daniel; Escartı́n, J.; Lavier, L. L.; Picazo, Suzanne

doi:10.1016/j.epsl.2009.09.020

Cited by 59 publications

(62 citation statements)

References 52 publications

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“…In addition to breccias, the talc-and chlorite-rich matrix of Type 3 shows close similarities with products of original hydrous mineral rich-levels associated with present-day submarine oceanic core complexes, which are exhumed along low-angle detachment faults during periods of pronounced tectonic extension and associated circulation of hydrothermal fluids (e.g. Escartín et al 2003;Boschi et al 2006aBoschi et al , 2006bCannat et al 2009). Talc-amphibole-chlorite metasomatism characterizes rocks associated with those detachment faults, suggesting multiple phases of fluid infiltration and a high strain deformation regime in limited domains (Boschi et al 2006a).…”

Section: Significance Of Blocks and Bims In The Geological Frame Of Tmentioning

confidence: 96%

Tectonic significance of different block-in-matrix structures in exhumed convergent plate margins: examples from oceanic and continental HP rocks in Inner Western Alps (northwest Italy)

Balestro

Festa

Tartarotti

2014

International Geology Review

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In the Inner Western Alps, three different types of block-in-matrix structures (BIMs) formed sequentially through time at a convergent plate margin. These show the superposition of progressive deformation from (i) subduction to eclogite-facies depths, (ii) collision, accretion, and exhumation of oceanic crust, represented by the Monviso Meta-ophiolite Complex, to (iii) collision, accretion, and exhumation of the continental Dora Maira units. The Type 1 occurs in the metasedimentary cover of the Dora Maira Unit and consists of a map-scale broken formation with boudinaged 'native' blocks of marble (Early Jurassic) in a calcschist matrix. It results from the tectonic overprinting of exhumation-related folding (D2-stage) on an earlier subduction-related dismembered succession (D1-stage). Type 1 also includes 'non-mappable' BIMs with 'exotic' blocks, resulting from the gravitational collapse of the Triassic carbonate platform of European Continental Margin, triggered by the Early Jurassic rifting. In the Monviso Meta-ophiolite Complex, Types 2 and 3 represent tectonically induced broken and dismembered formations, respectively. They differ from each other in the degree of stratal disruption of primary interbedded horizons of mafic metabreccia (Type 3) and mafic metasandstone (Types 2 and 3) sourced by the Late Jurassic-Early Cretaceous denudation of an oceanic core complex. Dismembered interbeds (Type 2) and isolated blocks were mixed together (Type 3) by the overlap of D2 tectonics and late-to post-exhumation extensional shearing (D3-stage). Development of these types of BIMs may be common in many exhumed convergent plate margins, where severe tectonics and metamorphic recrystallization under high-pressure conditions normally prevent the reconstruction of BIMs or mélange-forming processes. Our findings show that documenting the mode and time of the processes forming BIMs is highly relevant in order to reconstruct the oceanic seafloor morphology and composition of associated stratigraphic successions, and their control in the evolution of those convergent plate margins.

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Section: Significance Of Blocks and Bims In The Geological Frame Of Tmentioning

confidence: 96%

Tectonic significance of different block-in-matrix structures in exhumed convergent plate margins: examples from oceanic and continental HP rocks in Inner Western Alps (northwest Italy)

Balestro

Festa

Tartarotti

2014

International Geology Review

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“…Again, similar to slow ridges, outcrops of serpentinized peridotites are common (Dick 1989;Dick et al 2003;Michael et al 2003;Seyler et al 2003;Hayman et al 2011;Sauter et al 2013). These ultramafic complexes are exhumed by detachment faults that locally bear spreading-parallel 100 m-scaled corrugations (Searle et al 2003;Cannat et al 2009;Hayman et al 2011;Zhao et al 2013) and are similar to corrugated detachment faults at slow ridges (Fig. 9b).…”

Section: Ultraslow-spreading Ridgesmentioning

confidence: 99%

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

Carbotte

Smith

Cannat

et al. 2015

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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

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“…Numerous oceanic core complexes have been identified along the MidAtlantic Ridge (MAR) (e.g., Cann et al, 1997;Escartin et al, 2008; http://dx.doi.org/10.1016/j.epsl.2016.05.047 0012-821X/© 2016 Elsevier B.V. All rights reserved. MacLeod et al, 2002;Smith et al, 2006;Tucholke et al, 1998) and Southwest Indian Ridge (SWIR) (Cannat et al, 2006(Cannat et al, , 2009Dick et al, 1991;Searle et al, 2003), and detachment faulting may occur along ∼50% of the MAR from 12 • 40 N to 35 • 15 N (Escartin et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

The temporal and spatial distribution of magmatism during lower crustal accretion at an ultraslow-spreading ridge: High-precision U–Pb zircon dating of ODP Holes 735B and 1105A, Atlantis Bank, Southwest Indian Ridge

Rioux

Cheadle

John

et al. 2016

Earth and Planetary Science Letters

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Ocean Drilling Program Hole 735B at Atlantis Bank on the Southwest Indian Ridge sampled 1508 m of plutonic oceanic crust, hosted in the footwall of an oceanic detachment fault. We present new high-precision isotope dilution-thermal ionization mass spectrometry (ID-TIMS) U-Pb zircon dates from samples spanning the length of Hole 735B, and from the shallower adjacent Hole 1105A (158 m). The new dates provide the most complete and precise record of both the spatial and temporal distribution of magmatism during accretion of the lower oceanic crust to date. Whole rock and mineral geochemistry from Hole 735B define three main igneous series. Weighted mean 206 Pb/ 238 U dates suggest each igneous series intruded beneath the preceding series. Weighted mean 206 Pb/ 238 U dates range from 12.175 to 11.986 Ma in Series 1; 11.974 to 11.926 Ma in Series 2; and 11.936 to 11.902 Ma in Series 3 (±0.015 to 0.069 Ma). Weighted mean 206 Pb/ 238 U dates from Hole 1105A range from 11.9745 to 11.9573 Ma (±0.0082 to 0.0086 Ma). The Hole 1105A dates are coeval with Series 2 in Hole 735B, consistent with previous correlations of Fe-Ti oxide-rich layers between the two holes, suggesting individual magmatic series formed sheet-like bodies that were ≥250 m thick and extended ≥1.1 km parallel to the ridge axis (E-W) and ≥0.48 km in the spreading direction (N-S). The data suggest a total duration of magmatism in Hole 735B of ≥0.214 ± 0.032 Ma, corresponding to accretion over a horizontal distance of ≥2.6 ± 0.4 km.The crust at Atlantis Bank was formed during active detachment faulting, and the successive underplating of each magmatic unit may have been favored in this environment. The combined U-Pb dates, and reported Ti-in-zircon temperatures, are consistent with magmatic cooling rates of 10 3 -10 4 • C/Ma over the temperature interval of 900-700 • C.

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Oceanic corrugated surfaces and the strength of the axial lithosphere at slow spreading ridges

Cited by 59 publications

References 52 publications

Tectonic significance of different block-in-matrix structures in exhumed convergent plate margins: examples from oceanic and continental HP rocks in Inner Western Alps (northwest Italy)

Tectonic significance of different block-in-matrix structures in exhumed convergent plate margins: examples from oceanic and continental HP rocks in Inner Western Alps (northwest Italy)

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

The temporal and spatial distribution of magmatism during lower crustal accretion at an ultraslow-spreading ridge: High-precision U–Pb zircon dating of ODP Holes 735B and 1105A, Atlantis Bank, Southwest Indian Ridge

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