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S.?Yu.?SokolovEmail author A.?O.?Mazarovich N.?N.?Turko K.?O.?Dobrolyubova A.?S.?Abramova Yu.?A.?Zaraiskaya E.?A.?Moroz 《Geotectonics》2018,52(4):401-420
Manifestations of fluids and deformations in the sedimentary cover, which are both factors of brightening (blanking anomalies) in seismoacoustic records, in the equatorial segment of the Atlantic coincide with the sublatitudinal zones of the activated passive parts of transform faults and with zones of lower gravity anomalies and higher values of remnant magnetization, which form as a result of serpentinization. The cause-and-effect sequence of intraplate phenomena includes: the contrasting geodynamic state → horizontal movements that form macrofractures → water supply to the upper mantle → serpentinization of rocks in the upper mantle → deformations associated with vertical uplift of basement and sedimentary cover blocks, coupled with fluid generation → and fluid accumulation in the sedimentary cover, accompanied by the formation of anomalies in seismoacoustic records. Based on the seismic data, we have identified imbricate-thrust deformations, diapir structures, stamp folds, and positive and negative flower structures, indicating the presence of strike-slip faults in the passive parts of transform faults. The general spatial distribution of deformation structures shows their concentration in cold mantle zones. Correlative comparison of the structural characteristics of deformations shows the direct relationship between the heights of structures and the development of serpentinization processes. As per the age of the basement, deformations range from 27–38 to 43–53 Ma; a quite thick sedimentary cover makes it possible to reveal them based on the characteristic types of seismoacoustic records. The formation of the Antilles arc ca. 10 Ma ago affected the equatorial segment of the Atlantic; it formed kink bands where lithospheric blocks underwent displacements with counterclockwise rotations, deformations related to compression and vertical uplift of crustal fragments, and local extension that favored degassing of endogenous fluids. Sublatitudinally oriented imbricate-thrust deformations with different vergences indicate irregularity and alternating strike-slip directions as blocks between fractures were laterally influenced. 相似文献
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Zayonchek A. V. Brekke H. Sokolov S. Yu. Ermakov A. V. Efimov V. N. Zaraiskaya Yu. A. Akhmedzyanov V. R. Kalinin N. D. Kokhan A. V. Moroz E. A. Ol’shanetskii D. M. Razumovskii A. A. Yampol’skii K. P. 《Doklady Earth Sciences》2010,430(2):265-270
Doklady Earth Sciences - 相似文献
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A. V. Zayonchek A. O. Mazarovich V. Yu. Lavrushin S. Yu. Sokolov M. D. Khutorskoi A. S. Abramova R. Kh. Aliulov V. R. Akhmedzyanov Yu. A. Zaraiskaya A. V. Ermakov V. N. Efimov E. A. Moroz A. A. Peive D. A. Prokhorov E. P. Radionova Yu. N. Raznitsyn A. A. Razumovskii A. A. Chernykh K. P. Yampol’skii 《Doklady Earth Sciences》2009,427(1):740-745
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S. Yu. Sokolov Yu. A. Zaraiskaya A. O. Mazarovich V. N. Efimov N. S. Sokolov 《Geotectonics》2016,50(3):223-237
The structure of the acoustic basement of the eastern part of the St. Paul multifault transform fracture system hosts rift paleovalleys and a paleonodal depression that mismatch the position of the currently active zones. This displacement zone, which is composed of five fault troughs, is unstable in terms of the position of the rift segments, which jumped according to redistribution of stresses. The St. Paul system is characterized by straightening of the transform transition between two remote segments of the Mid-Atlantic Ridge (MAR). The eastern part of the system contains anomalous bright-spot-like reflectors on the flattened basement, which is a result of atypical magmatism, that forms the standard ridge relief of the acoustic basement. Deformations of the acoustic basement have a presedimentation character. The present-day deformations with lower amplitude in comparison to the basement are accompanied by acoustic brightening of the sedimentary sequence. The axial Bouguer anomalies in the east of the system continue to the north for 120 km from the active segments of the St. Paul system. Currently seismically active segments of the spreading system are characterized by increasing amplitudes of the E–W displacement along the fault troughs. Cross-correlation of the lengths of the active structural elements of the MAR zone (segments of the ridge and transform fracture zones of displacement) indicates that, statistically, the multifault transform fracture system is a specific type of oceanic strike-slip faults. 相似文献
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S. Yu. Sokolov A. S. Abramova Yu. A. Zaraiskaya A. O. Mazarovich K. O. Dobrolyubova 《Geotectonics》2014,48(3):175-187
The walls of the Knipovich Ridge are complicated by normal and reverse faults revealed by a high-frequency profilograph. The map of their spatial distribution shows that the faults are grouped into domains a few tens of kilometers in size and are a result of superposition of several inequivalent geodynamic factors: the shear zone oriented parallel to the Hornsunn Fault and superposed on the typical dynamics of the midocean ridge with offsets along transform fracture zones and rifting along short segments of the Mid-Atlantic Ridge (MAR). According to the anomalous magnetic field, the Knipovich Ridge as a segment of the MAR has formed since the Oligocene including several segments with normal direction of spreading separated by a multitransform system of fracture zones. In the Quaternary, the boundary of plate interaction along the tension crack has been straightened to form the contemporary Knipovich Ridge, which crosses the previously existing magmatic spreading substrate and sedimentary cover at an angle of about 45° relative to the direction of accretion. The sedimentary cover along the walls of the Knipovich is Paleogene in age and has subsided into the rift valley to a depth of 500–1000 m along the normal faults. 相似文献
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