scholarly journals Full-fit reconstruction of the Labrador Sea and Baffin Bay

2013 ◽  
Vol 5 (2) ◽  
pp. 917-962 ◽  
Author(s):  
M. Hosseinpour ◽  
R. D. Müller ◽  
S. E. Williams ◽  
J. M. Whittaker
Keyword(s):  
North America ◽  
Continental Crust ◽  
Seafloor Spreading ◽  
Labrador Sea ◽  
Gravity Inversion ◽  
Seismic Profiles ◽  
Baffin Bay ◽  
Davis Strait ◽  
Break Up ◽  
Magnetic Lineations

Abstract. Reconstructing the opening of the Labrador Sea and Baffin Bay between Greenland and North America remains controversial. Recent seismic data suggest that magnetic lineations along the margins of the Labrador Sea, originally interpreted as seafloor spreading anomalies, may lie within the crust of the continent–ocean transition. These data also suggest a more seaward extent of continental crust within the Greenland margin near the Davis Strait than assumed in previous full-fit reconstructions. Our study focuses on reconstructing the full-fit configuration of Greenland and North America using an approach that considers continental deformation in a quantitative manner. We use gravity inversion to map crustal thickness across the conjugate margins, and assimilate observations from available seismic profiles and potential field data to constrain the likely extent of different crustal types. We derive end-member continental margin restorations following alternative interpretations of published seismic profiles. The boundaries between continental and oceanic crust (COB) are restored to their pre-stretching locations along small circle motion paths across the region of Cretaceous extension. Restored COBs are fitted quantitatively to compute alternative total-fit reconstructions. A preferred full-fit model is chosen based on the strongest compatibility with geological and geophysical data. Our preferred model suggests that (i) the COB lies oceanward of magnetic lineations interpreted as magnetic anomaly 31 (70 Ma) in the Labrador Sea, (ii) all previously identified magnetic lineations landward of anomaly 27 reflect intrusions into continental crust, and (iii) the Ungava fault zone in Davis Strait acted as a leaky transform fault during rifting. This robust plate reconstruction reduces gaps and overlaps in the Davis Strait and suggests that there is no need for alternative models proposed for reconstructions of this area including additional plate boundaries in North America or Greenland. Our favored model implies that break up and formation of continent–ocean transition (COT) first started in the southern Labrador Sea and Davis Strait around 88 Ma and then propagated north and southwards up to onset of real seafloor spreading at 63 Ma in the Labrador Sea. In the Baffin Bay, continental stretching lasted longer and actual break up and seafloor spreading started around 61 Ma (Chron 26).

scholarly journals Full-fit reconstruction of the Labrador Sea and Baffin Bay

Solid Earth ◽  
2013 ◽  
Vol 4 (2) ◽  
pp. 461-479 ◽  
Author(s):  
M. Hosseinpour ◽  
R. D. Müller ◽  
S. E. Williams ◽  
J. M. Whittaker
Keyword(s):  
North America ◽  
Continental Crust ◽  
Seafloor Spreading ◽  
Labrador Sea ◽  
Gravity Inversion ◽  
Seismic Profiles ◽  
Baffin Bay ◽  
Davis Strait ◽  
Break Up ◽  
Magnetic Lineations

Abstract. Reconstructing the opening of the Labrador Sea and Baffin Bay between Greenland and North America remains controversial. Recent seismic data suggest that magnetic lineations along the margins of the Labrador Sea, originally interpreted as seafloor spreading anomalies, may lie within the crust of the continent–ocean transition. These data also suggest a more seaward extent of continental crust within the Greenland margin near Davis Strait than assumed in previous full-fit reconstructions. Our study focuses on reconstructing the full-fit configuration of Greenland and North America using an approach that considers continental deformation in a quantitative manner. We use gravity inversion to map crustal thickness across the conjugate margins, and assimilate observations from available seismic profiles and potential field data to constrain the likely extent of different crustal types. We derive end-member continental margin restorations following alternative interpretations of published seismic profiles. The boundaries between continental and oceanic crust (COB) are restored to their pre-stretching locations along small circle motion paths across the region of Cretaceous extension. Restored COBs are fitted quantitatively to compute alternative total-fit reconstructions. A preferred full-fit model is chosen based on the strongest compatibility with geological and geophysical data. Our preferred model suggests that (i) the COB lies oceanward of magnetic lineations interpreted as magnetic anomaly 31 (70 Ma) in the Labrador Sea, (ii) all previously identified magnetic lineations landward of anomaly 27 reflect intrusions into continental crust and (iii) the Ungava fault zone in Davis Strait acted as a leaky transform fault during rifting. This robust plate reconstruction reduces gaps and overlaps in Davis Strait and suggests that there is no need for alternative models proposed for reconstructions of this area including additional plate boundaries in North America or Greenland. Our favoured model implies that break-up and formation of continent–ocean transition (COT) first started in the southern Labrador Sea and Davis Strait around 88 Ma and then propagated north and southwards up to the onset of real seafloor spreading at 63 Ma in the Labrador Sea. In Baffin Bay, continental stretching lasted longer and actual break-up and seafloor spreading started around 61 Ma (chron 26).

scholarly journals Cenozoic Relative Movements of Greenland and North America by Closure of the North Atlantic-arctic Plate Circuit: the Labrador Sea, Davis Strait and Baffin Bay

2021 ◽  
Author(s):  
Annabel Causer ◽  
Graeme Eagles ◽  
Lucía Pérez-Díaz ◽  
Jürgen Adam
Keyword(s):  
North America ◽  
North Atlantic ◽  
Data Uncertainty ◽  
Plate Motion ◽  
Labrador Sea ◽  
Motion Model ◽  
Continental Breakup ◽  
Baffin Bay ◽  
The North ◽  
Davis Strait

Abstract The processes that accommodated plate divergence between Greenland and North America are most confidently interpretable from a short-lived (61-42 Ma) sequence of magnetic isochrons in the Labrador Sea. Understanding of the preceding and following periods is impeded by the lack of clear isochrons in the basin’s continent-ocean transition and axial zones. By closing the regional plate circuit, we build and interpret a detailed plate motion model for Greenland and North America that is applicable in, but unaffected by data uncertainty from, the Labrador Sea, Davis Strait, and Baffin Bay. Among our findings, we show the Labrador Sea initially opened during a ~8.3-16.5 Myr-long period of focused extension culminating in continental breakup no earlier than 74-72 Ma, and experienced a ~80° change in spreading direction around 56 Ma. We describe some possible implications for the accommodation of strain prior to continental breakup and during extreme spreading obliquity.

scholarly journals Faults and fractures in central West Greenland: onshore expression of continental break-up and sea-floor spreading in the Labrador – Baffin Bay Sea

2006 ◽  
Vol 11 ◽  
pp. 185-204 ◽  
Author(s):  
Robert W. Wilson ◽  
Knud Erik S. Klint ◽  
Jeroen A.M. Van Gool ◽  
Kenneth J.W. McCaffrey ◽  
Robert E. Holdsworth ◽  
...  
Keyword(s):  
Dominant Role ◽  
Field Studies ◽  
Labrador Sea ◽  
Tectonic Structures ◽  
Two Phase ◽  
Baffin Bay ◽  
Fault Systems ◽  
Davis Strait ◽  
Regional Tectonic ◽  
Sea Floor Spreading

The complex Ungava fault zone lies in the Davis Strait and separates failed spreading centres in the Labrador Sea and Baffin Bay. This study focuses on coastal exposures east of the fault-bound Sisimiut basin, where the onshore expressions of these fault systems and the influence of pre-existing basement are examined. Regional lineament studies identify five main systems: N–S, NNE–SSW, ENE–WSW, ESE–WNW and NNW–SSE. Field studies reveal that strike-slip movements predominate, and are consistent with a ~NNE–SSW-oriented sinistral wrench system. Extensional faults trending N–S and ENE–WSW (basement-parallel), and compressional faults trending E–W, were also identified. The relative ages of these fault systems have been interpreted using cross-cutting relationships and by correlation with previously identified structures. A two-phase model for fault development fits the development of both the onshore fault systems observed in this study and regional tectonic structures offshore. The conclusions from this study show that the fault patterns and sense of movement on faults onshore reflect the stress fields that govern the opening of the Labrador Sea – Davis Strait – Baffin Bay seaway, and that the wrench couple on the Ungava transform system played a dominant role in the development of the onshore fault patterns.

scholarly journals Cretaceous and Cenozoic dinoflagellate cysts and other palynomorphs from the western and eastern margins of the Labrador–Baffin Seaway

2016 ◽  
Vol 36 ◽  
pp. 1-143 ◽  
Author(s):  
Robert A. Fensome ◽  
Henrik Nøhr-Hansen ◽  
Graham L. Williams
Keyword(s):  
New Combination ◽  
Labrador Sea ◽  
New Genera ◽  
The West ◽  
Palynological Analysis ◽  
Baffin Bay ◽  
Davis Strait ◽  
History Of ◽  
Greenland Margin ◽  
Plant Microfossil

New palynological analysis of samples from 13 offshore wells on the Canadian Margin and six wells on the West Greenland Margin has led to a new event biostratigraphic framework for Cretaceous–Cenozoic strata of the Labrador Sea – Davis Strait – Baffin Bay (Labrador–Baffin Seaway) region. This framework is based on about 150 dinoflagellate cyst taxa and 30 acritarch, algal, fungal and plant microfossil (mostly miospore) taxa. In the systematics we include three new genera of dinocysts (Scalenodinium, Simplicidinium and Taurodinium), 16 new species of dinocysts (Chiropteridium gilbertii, Chytroeisphaeridia hadra, Cleistosphaeridium elegantulum, Cleistosphaeridium palmatum, Dapsilidinium pseudoinsertum, Deflandrea borealis, Evittosphaerula? foraminosa, Ginginodinium? flexidentatum, Hystrichosphaeridium quadratum, Hystrichostrogylon digitus, Impletosphaeridium apodastum, Scalenodinium scalenum, Surculosphaeridium convocatum, Talladinium pellis, Taurodinium granulatum and Trithyrodinium? conservatum), four emendations of dinocyst genera (Alterbidinium, Chatangiella, Chiropteridium and Surculosphaeridium), six new combinations for dinocyst species (Alterbidinium biaperturum, Deflandrea majae, Kleithriasphaeridium mantellii, Simplicidinium insolitum, Spongodinium grossum, Spongodinium obscurum), one new acritarch species (Fromea quadrangularis), one new miospore species (Baculatisporites crenulatus) and one new combination for miospores (Tiliaepollenites crassipites). Most of the taxa included provide age information, almost exclusively last occurrences (range ‘tops’), but some are useful mainly for environmental interpretations. Collectively, they provide a powerful tool for helping to establish the geological history of the Labrador–Baffin Seaway.  

Uncertainties in breakup markers along the Iberian Newfoundland margin: The need for a new North Atlantic plate model

2020 ◽  
Author(s):  
Annabel Causer ◽  
Lucía Pérez-Díaz ◽  
Graeme Eagles ◽  
Jürgen Adam
Keyword(s):  
North Atlantic ◽  
Magnetic Anomalies ◽  
Oceanic Lithosphere ◽  
Seafloor Spreading ◽  
Inversion Method ◽  
Seismic Profiles ◽  
Potential Field Data ◽  
Rifted Margins ◽  
Basement Faults ◽  
Break Up

<p>The Iberian-Newfoundland conjugate margins are one of the most extensively studied non-volcanic rifted margins in the world. In recent years, researchers have focused their efforts at better understanding the earliest stages of continental rifting, often relying heavily on the identification of so-called “break-up features” imaged in seismic profiles or interpreted from potential field data. Along the Iberian-Newfoundland margins, widely used break-up markers include interpretations of old magnetic anomalies from the M-Series, as well as the J-anomaly, believed to mark the occurrence and spatial extent of first oceanic lithosphere. However, uncertainties in the location and interpretation of these features have led to discrepancies between modelled depictions of the palaeopositions of Iberia and Newfoundland during the early Cretaceous as well as the timing of first seafloor spreading between the two. </p><p>Using new seismic data from the Southern Newfoundland Basin (SNB) we are able to illustrate the unsuitability of “break-up” features along the Iberian – Newfoundland Margin for plate kinematic reconstructions. Our data shows 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. Magmatic activity in the SNB as early as M4 times (128 Ma), and the presence of SDR packages onlapping onto basement faults suggest that, at this time, plate divergence was still being accommodated by tectonic faulting. Therefore, young M-series anomalies (including the J-anomaly) are not suitable basis on which to reconstruct plate positions during the early stages of continental separation.</p><p>We instead follow an alternative modelling approach, not reliant on the identification of extended continental margin features, to robustly constrain North Atlantic tectonics pre-M0 (~121 Ma) times. We do this by using seafloor spreading data and a statistically robust inversion method as the basis for a number of purpose built two-plate models for Africa, Iberia, Eurasia, Greenland and North America, with quantified uncertainties. Together, these models will provide an invaluable framework within to study the evolution of the extended continental margins immediately prior to and during continental separation.</p><p> </p><p> </p><p> </p><p> </p><p> </p>

Tectono-magmatic and thermal evolution of the SE China margin-NW Palawan breakup

2020 ◽  
Author(s):  
Geoffroy Mohn ◽  
Michael Nirrengarten ◽  
Andrea Schito ◽  
Nick Kusznir ◽  
Sveva Corrado ◽  
...  
Keyword(s):  
Continental Crust ◽  
Thermal Evolution ◽  
Oceanic Lithosphere ◽  
Seafloor Spreading ◽  
Spreading Ridge ◽  
Thermal Maturity ◽  
Seismic Profiles ◽  
Thinned Continental Crust ◽  
Conjugate Margins ◽  
Se China

<p>Continent Ocean Transitions (COTs) record the processes leading to continental breakup and localized oceanic accretion initiation. The recent IODP Expeditions 367-368 and 368X at the SE China margins combined with high quality multi-channel seismic profiles provide a unique dataset to explore the tectono-magmatic and thermal evolution from final rifting to early seafloor spreading. To investigate these issues, we developed a multi-disciplinary approach combining reflection seismic interpretations with geophysical quantitative analysis calibrated thanks to drilling results, from which we measured and modelled the thermal maturity in pre-/syn- to post-rift sediments.</p><p>Drilling results show that the transition from the most thinned continental crust to new, largely igneous crust is narrow (~20 km). During final rifting, decompression melting forming Mid-Ocean Ridge type magmatism emplaced within thinned continental crust as deep intrusions and shallow extrusive rocks concomitant with continued deformation by extensional faults. The initial igneous crust of the conjugate margins is asymmetric in width and morphology. The wider and faulted newly accreted domain on the SE China side indicates that magmatic accretion was associated with tectonic faulting during the formation of initial oceanic lithosphere, a feature not observed on the conjugate Palawan side. We suggest that deformation and magmatism were not symmetrically distributed between the conjugate margins during the initiation of seafloor spreading but evolved asymmetrically prior to the spreading ridge stabilising.</p><p>Organic matter from post-rift sediments has low thermal maturities due to limited burial and the absence of late post-rift magmatism. In contrast, pre to syn-rift sediments show significant variability in thermal maturities across the COT. Localised high thermal maturities for the pre- to syn-rift sediments requires that significant additional heat be imparted at shallow depths during breakup, likely related to magmatic intrusion or subsurface expressions of volcanism. The heterogeneous variation in thermal maturity observed across the COT reflects localised thermal perturbations caused by magmatic additions.</p>

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