New geophysical evidence for sea-floor spreading in central Baffin Bay

1979 ◽  
Vol 16 (11) ◽  
pp. 2122-2135 ◽  
Author(s):  
H. R. Jackson ◽  
C. E. Keen ◽  
R. K. H. Falconer ◽  
K. P. Appleton
Keyword(s):  
Magnetic Anomaly ◽  
Crustal Structure ◽  
Magnetic Anomalies ◽  
Geophysical Data ◽  
Plate Motion ◽  
Labrador Sea ◽  
Sea Floor ◽  
Baffin Bay ◽  
Spreading Rates ◽  
Sea Floor Spreading

Geophysical data collected during a detailed survey in Baffin Bay have shown that lineated magnetic anomalies trending north-northwest occupy the deep central region. These anomalies exhibit maximum amplitudes of about 300 nT and can be modelled by a 1-km thick magnetic source layer divided into blocks of normal and reversed polarity. The magnetizations required are comparable with those of oceanic basalts. A striking feature of the gravity field is a 20 mGal gravity low, about 20 km wide, which runs through the centre of the bay with approximately the same trend as the magnetic lineations. The gravity low is associated with a change in crustal structure measured from seismic refraction data and sometimes with a deepening of the sediment-basement interface, reminiscent of a median valley. These results suggest that the magnetic anomalies were produced by sea-floor spreading and that the gravity low marks an extinct spreading centre in Baffin Bay. Comparisons of the magnetic anomaly profiles with a model profile computed for magnetic anomalies 13–24 (38 to 60 Ma), show good correlation between the observed and computed anomalies in the time period represented by anomalies 13–21, with slow spreading rates of about 0.3–0.4 cm yr−1 perpendicular to the spreading axis. These results are in reasonable agreement with magnetic anomaly identifications and spreading rates deduced from geophysical data in the Labrador Sea. The direction of plate motion in Baffin Bay is not well defined from the data, but the Labrador Sea data require plate motions at a highly oblique angle to the spreading centre in the bay. Peculiarities of the postulated spreading centre, including the change in crustal structure beneath the gravity low along its strike from south to north, and the decrease in coherence and amplitude of the magnetic anomalies immediately north of the survey area, may be the result of these very low spreading rates, oblique spreading and changes in spreading direction, or the proximity of this area to the junction with a possible major transform fault through the Nares Strait.

New estimates of rapid sea-floor spreading rates and the identification of young magnetic anomalies on the East Pacific rise, 6° and 11° S

1973 ◽  
Vol 19 (2) ◽  
pp. 225-229 ◽  
Author(s):  
David K. Rea ◽  
Jack Dymond ◽  
G. Ross Heath ◽  
Donald F. Heinrichs ◽  
Stephen H. Johnson ◽  
...  
Keyword(s):  
East Pacific Rise ◽  
Magnetic Anomalies ◽  
Sea Floor ◽  
East Pacific ◽  
Spreading Rates ◽  
Sea Floor Spreading

Comoros – New Evidence and Arguments for Continental Crust

2016 ◽  
Author(s):  
John Milsom ◽  
Phil Roach ◽  
Chris Toland ◽  
Don Riaroh ◽  
Chris Budden ◽  
...  
Keyword(s):  
Continental Crust ◽  
Fracture Zone ◽  
Seismic Data ◽  
Gravity Anomalies ◽  
Magnetic Anomalies ◽  
Magnetic Data ◽  
The West ◽  
Sea Floor ◽  
Inappropriate Use ◽  
Sea Floor Spreading

ABSTRACT As part of an ongoing exploration effort, approximately 4000 line-km of seismic data have recently been acquired and interpreted within the Comoros Exclusive Economic Zone (EEZ). Magnetic and gravity values were recorded along the seismic lines and have been integrated with pre-existing regional data. The combined data sets provide new constraints on the nature of the crust beneath the West Somali Basin (WSB), which was created when Africa broke away from Gondwanaland and began to move north. Despite the absence of clear sea-floor spreading magnetic anomalies or gravity anomalies defining a fracture zone pattern, the crust beneath the WSB has been generally assumed to be oceanic, based largely on regional reconstructions. However, inappropriate use of regional magnetic data has led to conclusions being drawn that are not supported by evidence. The identification of the exact location of the continent-ocean boundary (COB) is less simple than would at first sight appear and, in particular, recent studies have cast doubt on a direct correlation between the COB and the Davie Fracture Zone (DFZ). The new high-quality reflection seismic data have imaged fault patterns east of the DFZ more consistent with extended continental crust, and the accompanying gravity and magnetic surveys have shown that the crust in this area is considerably thicker than normal oceanic and that linear magnetic anomalies typical of sea-floor spreading are absent. Rifting in the basin was probably initiated in Karoo times but the generation of new oceanic crust may have been delayed until about 154 Ma, when there was a switch in extension direction from NW-SE to N-S. From then until about 120 Ma relative movement between Africa and Madagascar was accommodated by extension in the West Somali and Mozambique basins and transform motion along the DFZ that linked them. A new understanding of the WSB can be achieved by taking note of newly-emerging concepts and new data from adjacent areas. The better-studied Mozambique Basin, where comprehensive recent surveys have revealed an unexpectedly complex spreading history, may provide important analogues for some stages in WSB evolution. At the same time the importance of wide continent-ocean transition zones marked by the presence of hyper-extended continental crust has become widely recognised. We make use of these new insights in explaining the anomalous results from the southern WSB and in assessing the prospectivity of the Comoros EEZ.

Baffin Bay Composite Tectono-Sedimentary Element

2021 ◽  
pp. M57-2016-7
Author(s):  
Paul C. Knutz ◽  
Ulrik Gregersen ◽  
Christopher Harrison ◽  
Thomas A. Brent ◽  
John R. Hopper ◽  
...  
Keyword(s):  
Structural Complexity ◽  
Large Data ◽  
Source Rocks ◽  
Sea Floor ◽  
Baffin Bay ◽  
Early Oligocene ◽  
Oceanic Basin ◽  
Late Paleocene ◽  
Transitional Crust ◽  
Sea Floor Spreading

AbstractBaffin Bay formed as a result of continental extension during the Cretaceous, which was followed by sea floor spreading and associated plate drift during the early to middle Cenozoic. Formation of an oceanic basin in the central part of Baffin Bay may have begun from about 62 Ma in tandem with Labrador Sea opening but the early spreading phase is controversial. Plate-kinematic models suggests that from Late Paleocene the direction of sea floor spreading changed to N-S generating strike-slip movements along the transform lineaments, e.g. the Ungava Fault Zone and the Bower Fracture Zone, and structural complexity along the margins of Baffin Bay. The Baffin Bay Composite Tectono-Sedimentary Element (CTSE) represents a 3-7 km thick Cenozoic sedimentary and volcanic succession that has deposited over oceanic and rifted continental crust since active seafloor spreading began. The CTSE is subdivided into 5 seismic mega-units that have been identified and mapped using a regional seismic grid tied to wells and core sites. Thick clastic wedges of likely Late Paleocene to Early Oligocene age (mega-units E and D2) were deposited within basins floored by newly formed oceanic crust, transitional crust, volcanic extrusives and former continental rift basins undergoing subsidence. The middle-late Cenozoic is characterized by fluvial-deltaic sedimentary systems, hemipelagic strata and aggradational sediment bodies deposited under the influenced of ocean currents (mega-units D1, C and B). The late Pliocene to Pleistocene interval (mega-unit A) displays major shelf margin progradation associated with ice-sheet advance-retreat cycles resulting in accumulation of trough-mouth fans and mass-wasting deposits products in the oceanic basin. The Baffin Bay CTSE has not produced discoveries although a hydrocarbon potential may be associated with Paleocene source rocks. Recent data have improved the geological understanding of Baffin Bay although large data and knowledge gaps remain.

Sea-floor spreading in the Labrador Sea: A new reconstruction

Geology ◽  
1989 ◽  
Vol 17 (11) ◽  
pp. 1000 ◽  
Author(s):  
W. R. Roest ◽  
S. P. Srivastava
Keyword(s):  
Labrador Sea ◽  
Sea Floor ◽  
Sea Floor Spreading

Fission Track Age of Magnetic Anomaly 10: A New Point on the Sea-Floor Spreading Curve

Science ◽  
1969 ◽  
Vol 164 (3887) ◽  
pp. 1516-1517 ◽  
Author(s):  
B. P. Luyendyk ◽  
D. E. Fisher
Keyword(s):  
Magnetic Anomaly ◽  
Fission Track ◽  
Sea Floor ◽  
Sea Floor Spreading

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.

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