Magmatic ocean-continent transitions

Guan, Huixin; Geoffroy, Laurent; Gernigon, Laurent; Chauvet, François; Grigné, Cécile; Werner, Philippe

doi:10.1016/j.marpetgeo.2019.04.003

Cited by 32 publications

(26 citation statements)

References 117 publications

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“…However, several authors propose that the outer SDRs do not simply reflect the deposition in successively deeper water but may represent tholeiitic basalt, underlain by a midcrustal imbricate layer comprising gabbro, and a lower crustal mobile layer comprising mafic and ultramafic rocks within a magmatic crust (Elliott & Parson, 2008;Paton et al, 2017;Quirk et al, 2014). Alternatively, magmatically overprinted remnants of continental crust have been suggested (Geoffroy et al, 2015;Guan et al, 2019).…”

Section: Breakup-related Magmatism and Sdrsmentioning

confidence: 99%

Polyphase Magmatism During the Formation of the Northern East Greenland Continental Margin

et al. 2019

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New marine geophysical data acquired across the partly ice‐covered northern East Greenland continental margin highlight a complex interaction between tectonic and magmatic events. Breakup‐related lava flows are imaged in reflection seismic data as seaward dipping reflectors, which are found to decrease in size both northward and southward from a central point at 75°N. We provide evidence that the magnetic anomaly pattern in the shelf area is related to volcanic phases and not to the presence of oceanic crust. The remnant magnetization of the individual lava flows is used to deduce a relative timing of the emplacement of the volcanic wedges. We find that the seaward dipping reflectors have been emplaced over a period of 2–4 Ma progressively from north to south and from landward to seaward. The new data indicate a major post‐middle Eocene magmatic phase around the landward termination of the West Jan Mayen Fracture Zone. This post‐40‐Ma volcanism likely was associated with the progressive separation of the Jan Mayen microcontinent from East Greenland. The breakup of the Greenland Sea started at several isolated seafloor spreading cells whose location was controlled by rift structures and led to the present‐day segmentation of the margin. The original rift basins were subsequently connected by steady‐state seafloor spreading that propagated southward, from the Greenland Fracture Zone to the Jan Mayen Fracture Zone.

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Section: Breakup-related Magmatism and Sdrsmentioning

confidence: 99%

Polyphase Magmatism During the Formation of the Northern East Greenland Continental Margin

et al. 2019

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“…This process leaves a complex, and highly variable, transition from relatively undeformed continental crust, sometimes called the proximal zone/domain, through necking and possibly exhumed domains, to oceanic crust (Lundin et al, 2018;Nirrengarten et al, 2018;Peron-Pinvidic and Manatschal, 2019). Passive margins are structurally diverse, but are typically classified as either magma-rich or magma-poor, in Manuscript under review for Interpretation reference to the volume of widespread rifting and breakup-related magmatism (Geoffroy, 2005;Franke, 2013;Guan et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Conjugate margins — An oversimplification of the complex southern North Atlantic rift and spreading system?

Peace

Welford

2020

Interpretation

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The prevalence of conjugate margin terminology and studies in the scientific literature is testimony to the contribution that this concept and approach has made to the study of passive margins, and more broadly extensional tectonics. However, when applied to the complex rift, transform, and spreading system of the southern North Atlantic (i.e., the passive margins of Newfoundland, Labrador, Ireland, Iberia, and southern Greenland), it becomes obvious that at these passive continental margin settings, additional geologic phenomena complicate this convenient description. These aspects include (1) the preservation of relatively undeformed continental fragments, (2) formation of transform systems and oblique rifts, (3) triple junctions (with rift and spreading axes), (4) multiple failed rift axes, (5) postbreakup processes such as magmatism, (6) localized subduction, and (7) ambiguity in identification of oceanic isochrons. Comparison of two different published reconstructions of the region indicates the ambiguity in conducting conjugate margin studies. This demonstrates the need for a more pragmatic approach to the study of continental passive margin settings where a greater emphasis is placed on the inclusion of these possibly complicating features in palinspastic reconstructions, plate tectonics, and evolutionary models.

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“…Increasing obliquity to the extension direction and curvature of the zone of thickened crust produce more asymmetric and segmented rift zones (Van Wijk 2005;Corti et al 2007). In contrast, a thinned crust with a shallow Moho prior to extension and/or longer periods of thermal relaxation (>30-50 Ma) can produce a cold and strong lithosphere, impeding rift localisation (Harry and Bowling 1999;van Wijk and Cloetingh 2002;Guan et al, 2019). If the mantle is weaker than the crust, it flows laterally whilst the crust is locally thinned, forming narrow necking zones and impeding pre-breakup melt generation (Petersen and Schiffer 2016) ( Figure 6).…”

Section: Bulk Lithosphere Structure Composition and Thermal Historymentioning

confidence: 99%

“…The lithosphere beneath stagnated rifts may cool and harden, leading to rift jumps away from the stronger lithosphere of the old rift, producing asymmetric continental margins (van Wijk and Cloetingh 2002;Naliboff and Buiter 2015). Such a process has been proposed to explain the formation of the volcanic margins in the NE Atlantic off-axis from previously thinned crust and failed rifts hosting Palaeozoic and Jurassic sedimentary basins (Gernigon et al this volume;Guan et al 2019). The zone of rheological contrast of such cooled/re-equilibrated rift zones and associated sedimentary infill may be reactivated during later episodes of extension, or may partition deformation (Odinsen et al 2000;Frederiksen et al 2001;Brune et al 2017).…”

Section: Bulk Lithosphere Structure Composition and Thermal Historymentioning

confidence: 99%

“…2). This line forms the shortest path from the Aegir Ridge to the Labrador Sea, and may have been created or exploited by dextral strike-slip associated with Labrador Sea opening or high geopotential energy associated with th forming ridge triple junction located south of Greenland at that time (Kristoffersen and Talwani 1977;Roest and Srivastava 1989;Guan et al 2019). An alternative hypothesis is that after Early Cretaceous rifting, the lithosphere in the Rockall-Hatton shelf re-equilibrated, cooled and strengthened (Guan et al 2019), thereby leaving the SE Greenland shelf as the weakest pathway for breakup due to its thick, warm crust (45-55 km) and weak lithosphere.…”

Section: Segment 2 -Se Greenland-rockall-hatton Marginsmentioning

confidence: 99%

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Structural inheritance in the North Atlantic

Schiffer

Doré²,

Foulger

et al. 2020

Earth-Science Reviews

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The North Atlantic, extending from the Charlie Gibbs Fracture Zone to the north Norway-Greenland-Svalbard margins, is regarded as both a classic case of structural inheritance and an exemplar for the Wilson-cycle concept. This paper examines different aspects of structural inheritance in the Circum-North Atlantic region: 1) as a function of rejuvenation from lithospheric to crustal scales, and 2) in terms of sequential rifting and opening of the ocean and its margins, including a series of failed rift systems. We summarise and evaluate the role of fundamental lithospheric structures such as mantle fabric and composition, lower crustal inhomogeneities, orogenic belts, and major strike-slip faults during breakup. We relate these to the development and shaping of the NE Atlantic rifted margins, localisation of magmatism, and microcontinent release. We show that, although inheritance is common on multiple scales, the Wilson Cycle is at best an imperfect model for the Circum-North Atlantic region. Observations from the NE Atlantic suggest depth dependency in inheritance (surface, crust, mantle) with selective rejuvenation depending on timescales , stress field orientations and thermal regime. Specifically, post-Caledonian reactivation to form the North Atlantic rift systems essentially followed pre-existing orogenic crustal structures, while eventual breakup reflected a change in stress field and exploitation of a deeper-seated, lithospheric-scale shear fabrics. We infer that, although collapse of an orogenic belt and eventual transition to a new ocean does occur, it is by no means inevitable.

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Magmatic ocean-continent transitions

Cited by 32 publications

References 117 publications

Polyphase Magmatism During the Formation of the Northern East Greenland Continental Margin

Polyphase Magmatism During the Formation of the Northern East Greenland Continental Margin

Conjugate margins — An oversimplification of the complex southern North Atlantic rift and spreading system?

Structural inheritance in the North Atlantic

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