How does the continental crust thin in a hyperextended rifted margin? Insights from the Iberia margin

Sutra, Emilie; Manatschal, Giänreto

doi:10.1130/g32786.1

Cited by 150 publications

(123 citation statements)

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“…Consequently, much of the distal domain can potentially comprise a permanently weakened zone (Masson et al, 1994;Faccenna et al, 1999;Péron-Pinvidic et al, 2008Mohn et al, 2010;Lundin & Doré, 2011;Sutra & Manatschal, 2012;Redfield & Osmundsen, 2013; this paper).…”

Section: The Extended Marginmentioning

confidence: 90%

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Redfield¹,

Osmundsen²

2015

NJG

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To a first order, patterns of Fennoscandia's seismicity reflect the benchmark domain boundaries of its Mesozoic rifted margin. Three distinct belts of earthquakes strike sub-parallel to the generalized line of breakup. The outermost seismic belt (SB1) marks the Taper Break (TB), or the zone of flexural coupling/decoupling between the distal (seaward) and proximal/necking (landward) domains. A coastal belt (SB2) follows the Innermost Limit of Extension, defined as the onset of 39 km-thick crystalline continental crust. An interior belt (SB3) follows the Hinterland Break in Slope, or the landward limit of the Scandinavian rifted margin. Between each belt, large portions of the necking, proximal, and hinterland domains are seismically quiescent. Evaluation of the 'Cumulative Seismic Moment' (CSM w ) per unit area indicates that the release of seismic energy is asymmetric. Although some of Fennoscandia's largest seismic events occur in the dominantly Proterozoic to Archean lithosphere of the eastern craton, 80% of Fennoscandian CSM w maps to the domain boundaries of the western rifted margin. CSM w energy tends to be highest at the TB and decreases system atically towards the continental interior.As proposed by many previous studies, a first-order spatial correlation between Scandinavia's offshore earthquake belt and voluminous, geo logically rapid, sedimentary loading during the Neogene period is evident. However, the presence of thinned, faulted crystalline basement is also a very important factor behind Scandinavia's offshore seismicity. Where the Neogene deposits are at their thickest the underlying crust is dominantly oceanic; CSM w is lower per unit area there than where lesser Plio-Pleistocene loading impacts continental crust that was fully prepared by Mesozoic necking and hyperextension. CSM w data suggest that the 'strength' of the TB and the continental margin's distal domain is significantly less than that of relatively young (ca. 54 Ma) oceanic lithosphere. Our data imply that ridge push does not contribute significantly to Fennoscandia's seismicity. Rather, we find that thin-plate bending stresses stemming from offshore depositional loading conspire with unbuttressed Gravitational Potential Energy (GPE), onshore erosion, and post-glacial isostatic rebound to generate Fennoscandia's earthquakes.We present a conceptual seismological model for Fennoscadia that is consistent with modern hypotheses of extended margin evolution, including post-breakup reactivation by footwall uplift in regions adjacent to sharp crustal taper. Illustrated by simple concepts of elastic thin-plate theory, the model honors our conclusion that Fennoscandian seismicity is principally the product of locally derived stress fields and that far field stress from the oceanic domain is unlikely to penetrate deeply into a hyperextended continental margin. It predicts the locations of the observed seismic belts and seismic gaps with the mathematics of thin-plate bending. It describes how the outer seismic belt will remain localized in the...

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Section: The Extended Marginmentioning

confidence: 90%

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Redfield¹,

Osmundsen²

2015

NJG

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“…One scenario (Type I of Huismans and Beaumont, 2011) is the Iberia-Newfoundland-type margin described above. In this case, lithospheric thinning initially occurs in the (upper) crust, with extensional faults profoundly thinning the continental crust (hyperextension), eventually reaching the mantle and causing serpentinization (Whitmarsh et al, 2001;Pérez-Gussinyé and Reston, 2001;Pérez-Gussinyé et al, 2006;Reston, 2009;Sutra and Manatschal, 2012). Alternative modeling scenarios suggest that final plate rupture can occur without exhumation of the subcontinental mantle and associated serpentinization during breakup ( Figure F2).…”

Section: Global Questions Regarding Formation Of Rifted Marginsmentioning

confidence: 99%

Expedition 367 Preliminary Report: South China Sea Rifted Margin

Sun¹,

Stock²,

Klaus³

2018

International Ocean Discovery Program Preliminary Report

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International Ocean Discovery Program Expedition 367 is the first of two consecutive cruises that form the South China Sea Rifted Margin program. Expeditions 367 and 368 share the common key objectives of testing scientific hypotheses of breakup of the northern South China Sea (SCS) margin and comparing its rifting style and history to other nonvolcanic or magma-poor rifted margins. Four primary sites were selected for the overall program: one in the outer margin high (OMH) and three seaward of the OMH on distinct, margin-parallel basement ridges. These ridges are informally labeled A, B, and C within the continent-ocean transition (COT) zone going from the OMH to the steady-state oceanic crust of the SCS. The main scientific objectives include 1. Determining the nature of the basement within critical crustal units across the COT of the SCS that are critical to constrain style of rifting, 2. Constraining the time interval from initial crustal extension and plate rupture to the initial generation of igneous ocean crust, 3. Constraining vertical crustal movements during breakup, and 4. Examining the nature of igneous activity from rifting to seafloor spreading.In addition, sediment cores from the drill sites will provide information on the Cenozoic regional tectonic and environmental development of the Southeast Asia margin.Expedition 367 successfully completed operations at two of the four primary sites (Site U1499 on Ridge A and Site U1500 on Ridge B). At Site U1499, we cored to 1081.8 m in 22.1 days, with 52% recovery, and then logged downhole data from 655 to 1020 m. In 31 days at Site U1500, we penetrated to 1529 m, cored a total of 1012.8 m with 37% recovery, and collected log data from 842 to 1133 m. At each site we drilled to reach the depth of the main seismic reflector (acoustic basement), which prior to the expedition had been interpreted to be crystalline basement. Our objective was to determine which lithospheric layer constitutes the basement of the COT and whether there was middle or lower continental crust or subcontinental lithospheric mantle exhumed in the COT before the final lithospheric breakup. At Site U1499, coring ~200 m into the acoustic basement sampled sedimentary rocks, including early Miocene chalks underlain by pre-Miocene polymict breccias and poorly cemented gravels composed of sandstone pebbles and cobbles. Preliminary structural and lithologic analysis suggested that the gravels might be early synrift to prerift sediment. At Site U1500, the main seismic reflector corresponds to the top of a basalt sequence at ~1379.1 m. We cored 149.90 m into this volcanic package, recovering 114.92 m (77%) of sparsely to moderately plagioclase-phyric basalt comprising numerous lava flows including pillow lavas with glass, chilled margins, altered veins, hyaloclastites, and minor sediment. Preliminary geochemical analyses show that the basalt is tholeiitic. We speculate that the basalt might belong to the very early stage of magmatism prior to steady-state seafloor spreading (known as an "...

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“…Müntener and Manatschal 2006;Bernoulli et al 2003) or may change over time from magmapoor to magma-rich (e.g. Osmundsen and Ebbing 2008 Manatschal 2004;Manatschal et al 2007Manatschal et al , 2011Sutra and Manatschal 2012). This final asymmetric phase of extension may be superimposed on an earlier phase of more symmetric extension (Huismans and Beaumont 2002) during which mantle detachments can form below both extending margins (e.g.…”

Section: Characteristics Of Hyperextended Marginsmentioning

confidence: 99%

Evidence of Late Ediacaran Hyperextension of the Laurentian Iapetan Margin in the Birchy Complex, Baie Verte Peninsula, Northwest Newfoundland: Implications for the Opening of Iapetus, Formation of Peri-Laurentian Microcontinents and Taconic – Grampian Orogenesis

Staal

Chew

Zagorevski

et al. 2013

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The Birchy Complex of the Baie Verte Peninsula, northwestern Newfoundland, comprises an assemblage of mafic schist, ultramafic rocks, and metasedimentary rocks that are structurally sandwiched between overlying ca. 490 Ma ophiolite massifs of the Baie Verte oceanic tract and underlying metasedimentary rocks of the Fleur de Lys Supergroup of the Appalachian Humber margin. Birchy Complex gabbro yielded a Late Ediacaran U–Pb zircon ID–TIMS age of 558.3 ± 0.7 Ma, whereas gabbro and an intermediate tuffaceous schist yielded LA–ICPMS concordia zircon ages of 564 ± 7.5 Ma and 556 ± 4 Ma, respectively. These ages overlap the last phase of rift-related magmatism observed along the Humber margin of the northern Appalachians (565–550 Ma). The associated ultramafic rocks were exhumed by the Late Ediacaran and shed detritus into the interleaved sedimentary rocks. Psammite in the overlying Flat Point Formation yielded a detrital zircon population typical of the Laurentian Humber margin in the northern Appalachians. Age relationships and characteristics of the Birchy Complex and adjacent Rattling Brook Group suggest that the ultramafic rocks represent slices of continental lithospheric mantle exhumed onto the seafloor shortly before or coeval with magmatic accretion of mid-ocean ridge basalt-like mafic rocks. Hence, they represent the remnants of an ocean – continent transition zone formed during hyperextension of the Humber margin prior to establishment of a mid-ocean ridge farther outboard in the Iapetus Ocean. We propose that microcontinents such as Dashwoods and the Rattling Brook Group formed as a hanging wall block and an extensional crustal allochthon, respectively, analogous to the isolation of the Briançonnais block during the opening of the Alpine Ligurian–Piemonte and Valais oceanic seaways.SOMMAIRELe complexe de Birchy de la péninsule de Baie Verte, dans le nord-ouest de Terre-Neuve, est constitué d’un assemblage de schistes mafiques, de roches ultramafiques et de métasédiments qui sont coincés entre des massifs ophiolitiques d’ascendance océanique de la Baie Verte au-dessus, et des métasédiments du Supergroupe de Fleur de Lys de la marge de Humber des Appalaches en-dessous. Le complexe de gabbro de Birchy a donné une datation U-Pb sur zircon ID-TIMS correspondant à la fin de l’Édiacarien, soit 558,3 ± 0,7 Ma, alors qu’un gabbro et un schiste tufacé intermédiaire montrent une datation LA-ICP-MS Concordia sur zircon de 564 ± 7,5 Ma et 556 ± 4 Ma, respectivement. Ces datations chevauchent la dernière phase de magmatisme de rift observée le long de la marge Humber des Appalaches du Nord (565-550 Ma). Les roches ultramafiques associées ont été exhumées vers la fin de l’Édiacarien et leurs débris ont été imbriqués dans des roches sédimentaires. Les psammites de la Formation de Flat Point susjacente ont donné une population de zircons détritiques typique de la marge laurentienne de Humber des Appalaches du Nord. Les relations chronologiques et les caractéristiques du complexe de Birchy et du groupe de Rattling Brook adjacent, permettent de penser que ces roches ultramafiques pourraient être des écailles de manteau lithosphérique continental qui auraient été exhumées sur le plancher océanique peu avant ou en même temps que l’accrétion magmatique de roches mafiques basaltiques de type dorsale médio-océanique. Par conséquent, elles seraient des vestiges d’une zone de transition océan-continent formée au cours de l’hyper-extension de la marge de Humber avant l’apparition d’une dorsale médio-océanique plus loin au large dans l’océan Iapétus. Nous proposons que des microcontinents comme de Dashwoods et du groupe de Rattling Brook ont constitués respectivement un bloc de toit et un allochtone crustal d’extension, de la même manière que le bloc Briançonnais a été isolé lors de l’ouverture des bras océaniques alpins de Ligurie-Piémont et de Valais.

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How does the continental crust thin in a hyperextended rifted margin? Insights from the Iberia margin

Cited by 150 publications

References 19 publications

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Expedition 367 Preliminary Report: South China Sea Rifted Margin

Evidence of Late Ediacaran Hyperextension of the Laurentian Iapetan Margin in the Birchy Complex, Baie Verte Peninsula, Northwest Newfoundland: Implications for the Opening of Iapetus, Formation of Peri-Laurentian Microcontinents and Taconic – Grampian Orogenesis

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