Definition of tectono-sedimentary elements for rifted continental margins of the Norwegian and Greenland seas

2021 ◽  
pp. M57-2021-31
Author(s):  
Harald Brekke ◽  
Halvor S. S. Bunkholt ◽  
Jan I. Faleide ◽  
Michael B. W. Fyhn
Keyword(s):  
Lower Jurassic ◽  
Passive Margin ◽  
Continental Margins ◽  
Axial Line ◽  
Continental Breakup ◽  
The North ◽  
Tectonic Development ◽  
Definition Of ◽  
Conjugate Margins ◽  
Greenland Margin

AbstractThe geology of the conjugate continental margins of the Norwegian and Greenland Seas reflects 400 Ma of post-Caledonian continental rifting, continental breakup between early Eocene and Miocene times, and subsequent passive margin conditions accompanying seafloor spreading. During Devonian-Carboniferous time, rifting and continental deposition prevailed, but from the mid-Carboniferous, rifting decreased and marine deposition commenced in the north culminating in a Late Permian open seaway as rifting resumed. The seaway became partly filled by Triassic and Lower Jurassic sediments causing mixed marine/non-marine deposition. A permanent, open seaway established by the end of the Early Jurassic and was followed by the development of an axial line of deep marine Cretaceous basins. The final, strong rift pulse of continental breakup occurred along a line oblique to the axis of these basins. The Jan Mayen Micro-Continent formed by resumed rifting in a part of the East Greenland margin in Eocene to Miocene times. This complex tectonic development is reflected in the sedimentary record in the two conjugate margins, which clearly shows their common pre-breakup geological development. The strong correlation between the two present margins is the basis for defining seven tectono-sedimentary elements (TSE) and establishing eight composite tectono-sedimentary elements (CTSE) in the region.

Middle Ordovician (Darriwilian) conodonts from southern Tibet, the Indian passive margin: implications for the age and correlation of the roof of the world

2020 ◽  
pp. 1-25
Author(s):  
Svend Stouge ◽  
David A. T. Harper ◽  
Renbin Zhan ◽  
Jianbo Liu ◽  
Lars Stemmerik
Keyword(s):  
Middle Part ◽  
Passive Margin ◽  
Continental Margins ◽  
Oceanic Circulation ◽  
Mount Everest ◽  
Southern Tibet ◽  
Middle Ordovician ◽  
The North ◽  
Carbon Isotope Excursion ◽  
Central Tibet

Abstract New occurrences of middle–late Darriwilian (Middle Ordovician) conodonts are reported from the Nyalam region, southern Tibet. The conodont-yielding strata, referred to the Chiatsun Group, accumulated on the north Indian continental margin of northern Gondwana. These Middle Ordovician conodonts include the informal species Histiodella sp. A in the middle part of the Lower Formation of the Chiatsun Group succeeded by a fauna of the Pygodus serra Zone in the upper part of that formation. Pygodus anserinus is recorded from the base of the Upper Formation of the Chiatsun Group. The Nyalam succession and its conodont taxa allow for precise correlation of the strata preserved on top of Mount Qomolangma (Mount Everest), eastern Tibet and the Peri-Gondwana Lhasa (north central Tibet), South China, North China, Tarim Basin and Thailand-Malaysia (Sibumasu Terrane) terranes and/or microcontinents. The middle Darriwilian positive increase in δ13Ccarb values (carbon isotope excursion, or MDICE) is recorded from most terranes, and can be related to a late middle Darriwilian global short-term cooling and sea-level drop. The cooling event prompted temperate- to warm-water taxa to migrate towards the palaeoequator and constrained the Australasian Province to locations near and at the palaeoequator. The intensified oceanic circulation and upwelling on continental margins probably caused some characteristic taxa to become extinct. The incoming fauna was mainly of cool-water taxa. The conodont specimens from southern Tibet are black to pale grey, corresponding to conodont colour index (CAI) values of 5 to 6, which demonstrates that the host sedimentary rocks were once heated to more than 360°C.

U-Pb zircon age constraint for late Neoproterozoic rifting and initiation of the lower Paleozoic passive margin of western Laurentia

2002 ◽  
Vol 39 (2) ◽  
pp. 133-143 ◽  
Author(s):  
Maurice Colpron ◽  
James M Logan ◽  
James K Mortensen
Keyword(s):  
Volcanic Rocks ◽  
Passive Margin ◽  
Canadian Cordillera ◽  
Lower Paleozoic ◽  
Zircon Age ◽  
Continental Breakup ◽  
North American Cordillera ◽  
The North ◽  
Windermere Supergroup ◽  
Late Neoproterozoic

A concordant U–Pb zircon age of 569.6 ± 5.3 Ma from synrift volcanic rocks of the Hamill Group, southeastern Canadian Cordillera, provides the first direct U–Pb geochronologic constraint on timing of latest Neoproterozoic rifting along western Laurentia. This age confirms a previous estimate of 575 ± 25 Ma for timing of continental breakup, as derived from the analysis of tectonic subsidence in lower Paleozoic miogeoclinal strata of the North American Cordillera. It also corresponds to the timing of passive margin deposition in the "underlying" Windermere Supergroup of the northern Cordillera, as determined by chemostratigraphic correlations. These timing relationships imply a different breakup history for the northern, as compared to the southern, Cordillera. We propose a model that attempts to explain this paradox of Cordilleran geology. The earlier Neoproterozoic (Windermere-age) rifting event probably records breakup of a continental mass from northern Laurentia followed by development of a passive margin. Accordingly, the Windermere Supergroup of the southern Canadian Cordillera was deposited in an intracontinental rift. The second Neoproterozoic rifting (Hamill–Gog) is interpreted to indicate continental breakup and establishment of a passive margin along western Laurentia.

SEQUENCE STRATIGRAPHIC INTERPRETATION OF CARBONATE WIRELINE LOG MOTIFS: AN EXAMPLE FROM THE NORTH WEST SHELF OF AUSTRALIA

1998 ◽  
Vol 38 (1) ◽  
pp. 188 ◽  
Author(s):  
J.N.F. Hull ◽  
S.A. Smith ◽  
H.C. Young
Keyword(s):  
Sharp Increase ◽  
Passive Margin ◽  
Log Analysis ◽  
North West ◽  
Sequence Stratigraphic ◽  
Carbonate Sedimentation ◽  
The North ◽  
Wireline Logs ◽  
Definition Of ◽  
Sequence Boundaries

An integrated biostratigraphic, wireline and seismic sequence stratigraphic study has been conducted to constrain the timing and evolution of Late Cretaceous to Tertiary depocentres along the North West Shelf of Australia. During this study a model for the sequence stratigraphic interpretation of wireline logs in this carbonate-dominated regime has been developed.A series of readily identifiable, lowstand clastic deposits interspersed within the predominantly carbonate passive margin section of the North West Shelf provide well-defined correctable events with which to divide the section. Biostratigraphic data have indicated the presence of missing section at the base of these clastic deposits and their shelfal equivalents. These events have been correlated to define sequence boundaries that are represented on wireline log data by a sharp increase in the gamma signature. Lowstand systems tracts exhibit an irregular sonic and upwardly increasing gamma signature. Transgressive systems tracts show characteristically upward-decreasing gamma and sonic profiles. Maximum flooding surfaces have been identified as the point of cleanest carbonate sedimentation represented by gamma minima on wireline logs. Log motifs exhibiting little character have been interpreted as highstand systems tracts. On seismic these sequence stratigraphic events are represented by stratal geometries that would be expected for these systems tracts.The model has enabled the definition of a higher resolution chronostratigraphic framework for the Mid Cretaceous to Recent section of the North West Shelf than has previously been possible. Forty basin-wide events have been identified from the biostratigraphic and wireline log analysis, thirty of which can be tied throughout the Barrow, Dampier and Roebuck basins.

Segmentation and structural style evolution during continental breakup: observations from the Northern Bay of Biscay passive margin (offshore France)

2020 ◽  
Author(s):  
Julie Tugend ◽  
Emmanuel Masini ◽  
Sylvie Leroy ◽  
Laurent Jolivet
Keyword(s):  
North Atlantic Ocean ◽  
Passive Margin ◽  
Distal Margin ◽  
Bay Of Biscay ◽  
Progressive Change ◽  
Continental Breakup ◽  
Passive Margins ◽  
The North ◽  
Structural Style ◽  
The Impact

<p>The extension and thinning of the continental lithosphere during rifting may eventually lead to continental breakup. Related mechanisms are recorded within the Continent-Ocean Transitions (COT) of distal passive margins, showing different, often complex, tectono-magmatic interactions as revealed by the variability of basement architectures imaged by seismic data. Different extensional structures are interpreted in the COT, including high-angle or low-angle extensional faults dipping either oceanward or continentward. This variability appears mainly controlled by the initial rheological stratification of the lithosphere and its evolution during rifting. As a result, the relative influence between lower crustal ductility, crustal embrittlement, and serpentinization of the underlying mantle are the main parameters considered to explain the structural variability observed in the COT.</p><p>In this contribution, we document the tectonic evolution of the northern Bay of Biscay passive margin and show the impact of passive margin segmentation in controlling along strike changes in structural style during rifting and continental breakup. The Bay of Biscay is a V-shaped oceanic basin, which opened during the northward propagation of the North Atlantic Ocean. Its bordering magma-poor passive margins formed subsequently to a Late Jurassic to Early Cretaceous oblique rifting and Aptian-Albian oceanic spreading onset. A large number of studies already focused on this margin revealing a first-order along strike segmentation, but the structures accommodating the passage from one to the other segment remained poorly constrained.</p><p>We used a series of reflection seismic sections and complementary marine data sets such as dredges and drilling results from the Deep Sea Drilling Project to map the structural pattern and stratigraphic evolution related to this segment transition. Our seismic interpretations and mapping of the main rift structures define a relatively loose segment transition marked by a progressive change in structural style expressed differently between the COT and the rest of the passive margin. The differences observed between the proximal and distal parts of the margin can be explained by an evolution of the nature and depth of the main fault décollement level; crustal embrittlement and serpentinization becoming important controlling parameters oceanward. However, the progressive change in structural style observed in the distal margin from west to east from oceanward dipping to mainly continentward dipping faults is more likely to be related a different accommodation of extensional deformation across the transfer zone. This segmentation occurs near major pre-existing structures identified further continentward, suggesting a key role of inheritance.</p><p>Results of this work reveal the impact of margin segmentation in controlling changes in structural style at the end of rifting. If this soft transfer zones do not seem to be observed as far as the first oceanic crust, further work is required to determine how far it can control different interplay between tectonic and magmatic processes further oceanward in the COT.</p>

scholarly journals Geological perspectives of the -East Greenland continental margin

1980 ◽  
Vol 29 ◽  
pp. 77-101
Author(s):  
Hans Christian Larsen
Keyword(s):  
Continental Margin ◽  
Fracture Zone ◽  
Middle Part ◽  
Passive Margin ◽  
Active Part ◽  
East Greenland ◽  
The North ◽  
Plate Separation ◽  
Sea Floor Spreading ◽  
Greenland Margin

The East Greenland continental margin can be divided into a northern area showing evidence for plate separation and suturing of Hudsonian, Grenvillian and Caledonian ages followed by post-Late Caledonian molasse sedimentation and Mesozoic rifting, and a southern area which apparently formed a cratonic block from the Early Proterozoic to the Middle Cretaceous. The whole margin was finally separated from the NW European margin by sea floor spreading in the latest Paleocene to earliest Eocene and now forms a rifted passive margin. The Tertiary consists of thin pre-drift sediments overlain by 1-7 km of Late Paleocene basaltic lavas extruded immediately prior to active spreading. Subsequent subsidence of the shelf led to accumulation of 2--8 km of post-basaltic sediments offshore whereas the land area was uplifted 1-2 km. Initiation of spreading along the Kolbeinsey Ridge during the late Oligocene was accompanied by renewed tectonism within the middle part of the margin. Finally the shelf was characterized by strong progradation during the Miocene. Backwards rotation of the inferred ocean-to-continent transition, through the total pole of opening, favours a slightly modified Talwani and Eldholm pole which provides a pre-drift fit of the two margins with no major overlap or gaps between the southern tip of Greenland and the Greenland-Senja Fracture Zone. Comparison of the Greenland margin and the V0ring Plateau implies a genesis for the latter, different from that proposed by Talwani and Eldholm. Minor revisions of the spreading history are presented including repeated westward displacement of the southernmost part of Mohns Ridge between anomaly 24 and 21, commencement of spreading around Kolbeinsey Ridge not later than anomaly 6 and associated activation of the recent active part of Jan Mayen Fracture Zone (JMFZ), to the north of the previous active part. The area between the fossil part of JMFZ and the recent active part including the northern part of Jan Mayen Ridge is suggested to have formed around a southern extension of Mohns Ridge active until about anomaly 6 and the predicted position of the extinct axis correlates well with bathymetry.

The Ammassalik Rifted Margin TSE, southern East and South-East Greenland margin

2021 ◽  
pp. M57-2016-8
Author(s):  
Michael B. W. Fyhn ◽  
John R. Hopper ◽  
Joanna Gerlings
Keyword(s):  
Petroleum System ◽  
Continental Margins ◽  
East Greenland ◽  
Marine Strata ◽  
The North ◽  
Main Challenge ◽  
Fault Structures ◽  
Uplift And Erosion ◽  
Greenland Margin ◽  
Rifted Margin

AbstractThe Ammassalik Rifted Margin TSE comprises the Ammassalik and the Kangerlussuaq rift basins located on the southern East and South-East Greenland margin. The offshore Ammassalik Basin is one of the last virtually undescribed segments of the North Atlantic continental margins with a very sparse seismic coverage. The basin is compartmentalized into smaller sub-basins up to at least 4 km deep blanketed by Paleocene-Eocene basalt towards the east. Albian sediments cored in the basin suggest an at least partly Cretaceous age, making the Ammassalik Basin a likely analogue to basins on the conjugate outer British continental margin. However, the deeper, undated succession could include pre-Cretaceous strata. Located onshore southern East Greenland, the Kangerlussuaq Basin contains a Barremian/Aptian-Danian succession of estuarine-marine strata overlain by Paleocene fluvial sediments, basalts and thinner marine interludes. The sedimentary succession is less than 1 km thick. Cenozoic uplift and erosion affected both basins. Unlike the Kangerlussuaq Basin, the Ammassalik Basin may contain a working petroleum system. Together with the very large fault structures identified in the basin, this makes the Ammassalik Basin an interesting future exploration target, with the main challenge being to demonstrate a mature source rock, together with qualifying the effects of the Paleocene-Eocene magmatism and Cenozoic exhumation on the potential petroleum system.

scholarly journals Lateral propagation–induced subduction initiation at passive continental margins controlled by preexisting lithospheric weakness

2020 ◽  
Vol 6 (10) ◽  
pp. eaaz1048 ◽  
Author(s):  
Xin Zhou ◽  
Zhong-Hai Li ◽  
Taras V. Gerya ◽  
Robert J. Stern
Keyword(s):  
Subduction Zones ◽  
Plate Tectonics ◽  
Numerical Models ◽  
Three Dimensional ◽  
Passive Margin ◽  
Continental Margins ◽  
Subduction Initiation ◽  
Passive Margins ◽  
The North ◽  
Lateral Propagation

Understanding the conditions for forming new subduction zones at passive continental margins is important for understanding plate tectonics and the Wilson cycle. Previous models of subduction initiation (SI) at passive margins generally ignore effects due to the lateral transition from oceanic to continental lithosphere. Here, we use three-dimensional numerical models to study the possibility of propagating convergent plate margins from preexisting intraoceanic subduction zones along passive margins [subduction propagation (SP)]. Three possible regimes are achieved: (i) subducting slab tearing along a STEP fault, (ii) lateral propagation–induced SI at passive margin, and (iii) aborted SI with slab break-off. Passive margin SP requires a significant preexisting lithospheric weakness and a strong slab pull from neighboring subduction zones. The Atlantic passive margin to the north of Lesser Antilles could experience SP if it has a notable lithospheric weakness. In contrast, the Scotia subduction zone in the Southern Atlantic will most likely not propagate laterally.

scholarly journals The Jan Mayen microplate complex and the Wilson cycle

2018 ◽  
Vol 470 (1) ◽  
pp. 393-414 ◽  
Author(s):  
Christian Schiffer ◽  
Alexander Peace ◽  
Jordan Phethean ◽  
Laurent Gernigon ◽  
Ken McCaffrey ◽  
...  
Keyword(s):  
North Atlantic ◽  
Passive Margin ◽  
Passive Margins ◽  
The North ◽  
Deformation And Fracture ◽  
Wilson Cycle ◽  
The North Atlantic ◽  
Conjugate Margins ◽  
East West

AbstractThe opening of the North Atlantic region was one of the most important geodynamic events that shaped the present day passive margins of Europe, Greenland and North America. Although well-studied, much remains to be understood about the evolution of the North Atlantic, including the role of the Jan Mayen microplate complex. Geophysical data provide an image of the crustal structure of this microplate and enable a detailed reconstruction of the rifting and spreading history. However, the mechanisms that cause the separation of microplates between conjugate margins are still poorly understood. We assemble recent models of rifting and passive margin formation in the North Atlantic and discuss possible scenarios that may have led to the formation of the Jan Mayen microplate complex. This event was probably triggered by regional plate tectonic reorganizations rejuvenating inherited structures. The axis of rifting and continental break-up and the width of the Jan Mayen microplate complex were controlled by old Caledonian fossil subduction/suture zones. Its length is related to east–west-oriented deformation and fracture zones, possibly linked to rheological heterogeneities inherited from the pre-existing Precambrian terrane boundaries.

scholarly journals A Risk-Based Approach to Assess the Operational Resilience of Transmission Grids

2020 ◽  
Vol 10 (14) ◽  
pp. 4761
Author(s):  
Milorad Papic ◽  
Svetlana Ekisheva ◽  
Eduardo Cotilla-Sanchez
Keyword(s):  
Power System ◽  
North American ◽  
Response Times ◽  
Transmission System ◽  
Energy Delivery ◽  
The North ◽  
System Components ◽  
Bulk Power ◽  
Definition Of ◽  
The Relationship

Modern risk analysis studies of the power system increasingly rely on big datasets, either synthesized, simulated, or real utility data. Particularly in the transmission system, outage events have a strong influence on the reliability, resilience, and security of the overall energy delivery infrastructure. In this paper we analyze historical outage data for transmission system components and discuss the implications of nearby overlapping outages with respect to resilience of the power system. We carry out a risk-based assessment using North American Electric Reliability Corporation (NERC) Transmission Availability Data System (TADS) for the North American bulk power system (BPS). We found that the quantification of nearby unscheduled outage clusters would improve the response times for operators to readjust the system and provide better resilience still under the standard definition of N-1 security. Finally, we propose future steps to investigate the relationship between clusters of outages and their electrical proximity, in order to improve operator actions in the operation horizon.

scholarly journals Multi-Proxy Provenance Analyses of the Kingriali and Datta Formations (Triassic—Jurassic Transition): Evidence for Westward Extension of the Neo-Tethys Passive Margin from the Salt Range (Pakistan)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 573
Author(s):  
Shahid Iqbal ◽  
Michael Wagreich ◽  
Mehwish Bibi ◽  
Irfan U. Jan ◽  
Susanne Gier
Keyword(s):  
Lower Jurassic ◽  
Sediment Supply ◽  
Heavy Mineral ◽  
Passive Margin ◽  
Indian Plate ◽  
Late Triassic ◽  
Indian Shield ◽  
Margin Setting ◽  
Salt Range ◽  
Mineral Data

The Salt Range, in Pakistan, preserves an insightful sedimentary record of passive margin dynamics along the NW margin of the Indian Plate during the Mesozoic. This study develops provenance analyses of the Upper Triassic (Kingriali Formation) to Lower Jurassic (Datta Formation) siliciclastics from the Salt and Trans Indus ranges based on outcrop analysis, petrography, bulk sediment elemental geochemistry, and heavy-mineral data. The sandstones are texturally and compositionally mature quartz arenites and the conglomerates are quartz rich oligomictic conglomerates. Geochemical proxies support sediment derivation from acidic sources and deposition under a passive margin setting. The transparent heavy mineral suite consists of zircon, tourmaline, and rutile (ZTR) with minor staurolite in the Triassic strata that diminishes in the Jurassic strata. Together, these data indicate that the sediments were supplied by erosion of the older siliciclastics of the eastern Salt Range and adjoining areas of the Indian Plate. The proportion of recycled component exceeds the previous literature estimates for direct sediment derivation from the Indian Shield. A possible increase in detritus supply from the Salt Range itself indicates notably different conditions of sediment generation, during the Triassic–Jurassic transition. The present results suggest that, during the Triassic–Jurassic transition in the Salt Range, direct sediment supply from the Indian Shield was probably reduced and the Triassic and older siliciclastics were exhumed on an elevated passive margin and reworked by a locally established fluvio-deltaic system. The sediment transport had a north-northwestward trend parallel to the northwestern Tethyan margin of the Indian Plate and normal to its opening axis. During the Late Triassic, hot and arid hot-house palaeoclimate prevailed in the area that gave way to a hot and humid greenhouse palaeoclimate across the Triassic–Jurassic Boundary. Sedimentological similarity between the Salt Range succession and the Neo-Tethyan succession exposed to the east on the northern Indian passive Neo-Tethyan margin suggests a possible westward extension of this margin.

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