Deep structure in the vicinity of the ocean-continent transition zone under the southern Iberia Abyssal Plain

Minshull, T. A.; Dean, S. M.; Whitmarsh, R. B.; Russell, S. M.; Louden, K. E.; Chian, D.

doi:10.1130/0091-7613(1998)026<0743:dsitvo>2.3.co;2

Cited by 61 publications

(2 citation statements)

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“…Although transition zones like this have been widely studied over the past decade (e.g. Whitmarsh and Wallace, 2001;Manatschal et al, 2001;Pérez-Gussinyé and Reston, 2001;Péron-Pinvidic and Manatschal, 2009;Mohn et al, 2012), the identification so-called break-up features, which cannot be confidently attributed to either crustal type, renders kinematic reconstructions based on them difficult and susceptible to large uncertainties. In the literature, this transition is often referred to as continentocean transition zone (COTZ) (Minshull et al, 1998;Dean et al, 2000;Davy et al, 2016).…”

Section: Study Area -Tectonic Evolution and Controversiesmentioning

confidence: 99%

Uncertainties in break-up markers along the Iberia–Newfoundland margins illustrated by new seismic data

Causer

Pérez-Díaz²,

Adam

et al. 2020

Solid Earth

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Abstract. Plate tectonic modellers often rely on the identification of “break-up” markers to reconstruct the early stages of continental separation. Along the Iberian-Newfoundland margin, so-called break-up markers include interpretations of old magnetic anomalies from the M series, as well as the “J anomaly”. These have been used as the basis for plate tectonic reconstructions are based on the concept that these anomalies pinpoint the location of first oceanic lithosphere. However, uncertainties in the location and interpretation of break-up markers, as well as the difficulty in dating them precisely, has led to plate models that differ in both the timing and relative palaeo-positions of Iberia and Newfoundland during separation. We use newly available seismic data from the Southern Newfoundland Basin (SNB) to assess the suitability of commonly used break-up markers along the Newfoundland margin for plate kinematic reconstructions. Our data show that basement associated with the younger M-series magnetic anomalies is comprised of exhumed mantle and magmatic additions and most likely represents transitional domains and not true oceanic lithosphere. Because rifting propagated northward, we argue that M-series anomaly identifications further north, although in a region not imaged by our seismic, are also unlikely to be diagnostic of true oceanic crust beneath the SNB. Similarly, our data also allow us to show that the high amplitude of the J Anomaly is associated with a zone of exhumed mantle punctuated by significant volcanic additions and at times characterized by interbedded volcanics and sediments. Magmatic activity in the SNB at a time coinciding with M4 (128 Ma) and the presence of SDR packages onlapping onto a basement fault suggest that, at this time, plate divergence was still being accommodated by tectonic faulting. We illustrate the differences in the relative positions of Iberia and Newfoundland across published plate reconstructions and discuss how these are a direct consequence of the uncertainties introduced into the modelling procedure by the use of extended continental margin data (dubious magnetic anomaly identifications, break-up unconformity interpretations). We conclude that a different approach is needed for constraining plate kinematics of the Iberian plate pre-M0 times.

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Section: Study Area -Tectonic Evolution and Controversiesmentioning

confidence: 99%

Uncertainties in break-up markers along the Iberia–Newfoundland margins illustrated by new seismic data

Causer

Pérez-Díaz²,

Adam

et al. 2020

Solid Earth

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“…Various forms of the latter have been proposed to explain, for example, the distribution of lithologies and geophysical characteristics of the Iberian-Newfoundland conjugate margin pair [154][155][156][157][158], the Rockall Plateau-Hatton Bank conjugate margin to Greenland [159] and the Amazon conjugate margin to Liberia [160]. In terms of UK efforts, the Iberian margin is arguably the best-characterized continental margin, with seismic, magnetic, gravity and scientific drilling data [161][162][163][164][165][166][167][168][169][170].…”

Section: (D) Passive Continental Margin Structurementioning

confidence: 99%

Aspects of marine geoscience: a review and thoughts on potential for observing active processes and progress through collaboration between the ocean sciences

Mitchell

2012

Phil. Trans. R. Soc. A.

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Much progress has been made in the UK in characterizing the internal structures of major physiographic features in the oceans and in developing understanding of the geological processes that have created or shaped them. UK researchers have authored articles of high impact in all areas described here. In contrast to terrestrial geoscience, however, there have been few instrumented observations made of active processes by UK scientists. This is an area that could be developed over the next decades in the UK. Research on active processes has the potential ability to engage the wider public: Some active processes present significant geo-hazards to populations and offshore infrastructure that require monitoring and there could be commercial applications of technological developments needed for science. Some of the suggestions could involve studies in shallow coastal waters where ship costs are much reduced, addressing tighter funding constraints over the near term. The possibilities of measuring aspects of volcanic eruptions, flowing lava, turbidity currents and mass movements (landslides) are discussed. A further area of potential development is in greater collaboration between the ocean sciences. For example, it is well known in terrestrial geomorphology that biological agents are important in modulating erosion and the transport of sediments, ultimately affecting the shape of the Earth's surface in various ways. The analogous effect of biology on large-scale geomorphology in the oceans is also known but remains poorly quantified. Physical oceanographic models are becoming increasingly accurate and could be used to study further the patterns of erosion, particle transport and deposition in the oceans. Marine geological and geophysical data could in turn be useful for further verification of such models. Adapting them to conditions of past oceans could address the shorter-period movements, such as due to internal waves and tides, which have been barely addressed in palaeoceanography.

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Quantification and restoration of extensional deformation along the Western Iberia and Newfoundland rifted margins

Sutra

Manatschal

Mohn

et al. 2013

Geochem Geophys Geosyst

198

285

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[1] Many recent papers describe the structure of the Iberia and Newfoundland rifted margins; however, none of them propose kinematic restorations of the complete rift system to quantify the amount of extension necessary to exhume mantle and initiate seafloor spreading. In our study, we use two pairs of cross sections considered as conjugate lines: one across the Galicia Bank-Flemish Cap and the other across the Southern Iberia Abyssal Plain-Flemish Pass. Both transects have been imaged by reflection-and refraction-seismic methods and have been drilled during Ocean Drilling Program Legs 103, 149, 173, and 210. Drilling penetrated parts of the rift stratigraphy and the underlying basement. The cross sections can therefore be considered as the best-documented conjugate transects across present-day hyperextended, magma-poor rifted margins. The aim of this paper is threefold: (1) provide a detailed description of the crustal architecture of the two conjugate sections, (2) define the extensional structures and their ages, and (3) quantify the amount of strain and strain rate accommodated along these lines. This paper proposes a quantitative description of extension along the Iberia-Newfoundland rift system and discusses the limitations and problems in quantifying extensional deformation along hyperextended rifted margins.

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Deep structure in the vicinity of the ocean-continent transition zone under the southern Iberia Abyssal Plain

Cited by 61 publications

References 0 publications

Uncertainties in break-up markers along the Iberia–Newfoundland margins illustrated by new seismic data

Uncertainties in break-up markers along the Iberia–Newfoundland margins illustrated by new seismic data

Aspects of marine geoscience: a review and thoughts on potential for observing active processes and progress through collaboration between the ocean sciences

Quantification and restoration of extensional deformation along the Western Iberia and Newfoundland rifted margins

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