Data of the International Bank of Digital Information on the time distribution of the virtual dipole moment (VDM), supplemented by data of more recent studies (a total of 5645 values), were used as ...the basis for analyzing the distribution of VDM values for Earth’s history using the concept of the Earth’s magnetic dipole field. The VDM behavior is characterized by a positive linear trend from 4.2 × 10
22
Am
2
(4.2 GA ago) to 5.15 × 10
22
Am
2
today. Against a linear increase in the field, VDM undulations nonuniformly distributed over time have been recorded, varying in magnitude from 1.7 to 3.7 × 10
22
Am
2
wavelength from 220 to 920 Ma. The average wavelength of such undulations is estimated at 570 Ma, which in order of magnitude approaches the period of the Wilson cycle. It has been revealed for the first time that the magnitudes of magnetic field undulations over time are oscillatory in nature and increase toward present day.
The paper analyzes the bottom stereoscopic imaging based on the interferometric side-scan sonar data, which provides for the more efficient identification of the bottom structures owing to the ...perception’s extensionality relative to the three-dimensional models. The stereopair construction enabling the three-dimensional perception of the formed images is discussed.
A new map of the axes of linear magnetic anomalies for eastern regions of the Eurasian Basin has been compiled. Based on the results of Russian geomagnetic surveys, paleoanomaly C25 was distinguished ...here for the first time, and the transition from rifting to spreading has been dated to the chron interval of С25r–С26n (57.656–59.237 Ma ago). The axis of the zone of splitting of marginal continental fragments of the Lomonosov Ridge from the Siberian shelf has been reconstructed. The Euler poles and angles of rotation that describe the splitting kinematics have been determined for the first time, as well as noncoincidence of conjugate isobaths related to sliding of peripheral continental crust areas along the lithospheric thrust plane.
The tectonic evolution of the transition zone from the Pacific Ocean to the Atlantic Ocean is closely linked with the destruction of the American–Antarctic continental bridge in the Scotia Sea. The ...western segment of the bridge combines the Terror, Pirie, and Bruce banks, as well as the Protector and Dove basins between them. Modeling—primarily based on original geological and geophysical materials—of linear magnetic anomalies and calculation of the floor kinematics in these basins have made it possible for the first time to reveal that the collapse of the western segment of the American–Antarctic continental bridge occurred 18–25 Ma ago via a two-stage separation of the Pirie Rise from the Bruce Rise with the formation of the Dove Basin and a two stage separation of the Terror Rise from the Pirie Rise with the formation of the Protector Basin.
The Lincoln Sea floor evolved during stretching of a segment of the continental Greenland –Barents Sea shelf. Prior to the onset of extension, the continental shallow-water Morris Jesup Rise and the ...Yermak Plateau were a single unit. During rifting, this single continental plateau broke apart, initiating propagation of the Gakkel mid-ocean ridge toward the Atlantic. The breakup continued for ~1.5 Ma, 35.3–33.7 Ma ago. The emplacement of numerous mafic dikes during rifting could have caused the high-amplitude magnetic anomalies on the single plateau. For the first time, the fracture geometry involved in the breakup of the continental crust has been reconstructed, the Euler poles and angle of rotation describing its kinematics have been determined, and the paleobathymetry on the flanks of the fracture have been reconstructed.
Age of the Scan Basin (Scotia Sea) Schreider, Al. A.; Schreider, A. A.; Galindo-Zaldivar, J. ...
Oceanology (Washington. 1965),
03/2017, Volume:
57, Issue:
2
Journal Article
Peer reviewed
Integrated geological and geophysical analysis of the anomalous magnetic field along with the previously unpublished profiles of Spanish expeditions onboard the R/V
Hesperides
and international ...databases of geomagnetic data processed in the context of the global tectonics concepts made it possible to identify paleomagnetic anomalies C11–C15 and compile the first map of the bottom geochronology of the Scan Basin. Unlike in earlier known publications, the paleoaxis of spreading does extend northeast, but approximately at an angle of 345°. According to calculations, spreading began 35.294‒35.706 Ma ago during chron C15r, and the spreading paleoaxis was abandoned 29.527‒29.970 Ma ago during chron C11n.2n. Thus, the destruction of the American–Antarctic bridge in the region joining the Bruce and Discovery banks with formation of oceanic crust in the Scan Basin started about 36 Ma ago. Regular spreading of the bottom has been continuing for about 6 Ma at a average rate close to 1.8 cm/year.
Data on the virtual dipole moment (VDP) is distributed nonuniformly with time, which significantly complicates qualitative and quantitative analysis of its evolution. In addition to the moving ...average method and median values, for the first time, a technique is presented for a quasi-uniform presentation of data (interpolation method), as well as results of calculating the evolution of the VDM by this method for the Phanerozoic.
The structure of sediments in the Scotia Sea is used as a basis for reconstructing the geological history of its bottom in the Late Quaternary. The Scan Basin is one of the main elements of the ...topography of the southern Scotia Sea. Its formation played a considerable role in the fragmentation of the continent, which included the Bruce and Discovery banks. The main parameters of the sediment layer in the Scan Basin have been reconstructed by the present time, but its top part has not been studied. In this work, we analyze the first data obtained on the R/V
Gesperidas
with the use of a TOPAS PS 18/40 high-resolution seismic profilograph in 2012. Three layers in the subsurface sediments on the bottom of the Scan Basin were specified for the first time. The mean periods of their deposition in the Late Quaternary were determined as 115000 years for the first, 76000 years for the second, and 59 000 years for the third layer from the surface of the bottom. The duration of the total accumulation period of the three layers is about 250000 years.
The structure of the sediment sequence of the Scotia Sea is the basis for reconstructing the geological history of the development of its floor in the late Quaternary. One of the most important ...elements of the floor of the southern Scotia Sea is the Scan Basin, the formation of which played a substantial role in the breakup of the American–Antarctic continental bridge that connected the Bruce and Discovery banks. By now, the main parameters of the sediment sequence in the Scan Basin have been reconstructed, but the literature reflects the lack of data on the upper part of the section. On an observation profile, the Spanish R/V
Hesperides
, using a TOPAS PS 18/40 high-resolution seismic profiler, distinguished three beds in the central part of the basin. The total mean thickness of the first reflector is 3.7 ms; the second, 2.3 ms; and the third, 1.8 ms. The beds have a relatively consistent thickness and are distinctly traced along the profile. The literature data on the sedimentation parameters make it possible to estimate the total mean deposition time for the first bed of 133 ka; the second, 84 ka; and the third, 64 ka; the total mean sediment accumulation time for all three beds is 281 ka.
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