Геодинамика и тектонофизика (Sep 2015)
SPECIFIC FEATURES OF DEFORMATION OF THE CONTINENTAL AND OCEANIC LITHOSPHERE AS A RESULT OF THE EARTH CORE NORTHERN DRIFT
Abstract
Drifting and submeridional compression of the continental and oceanic lithosphere, both with the northward vector (Figure 1) are revealed at the background of various directions of horizontal displacement combined with deformations of horizontal extension, compression and shear of the lithosphere (Figures 7–14). Among various structural forms and their paragenezises, indicators of such compression, the north vergence thrusts play the leading role (Figures 15–17, 19, and 22–24). This process was discontinuous, manifested discretely in time, and superimposed on processes of collisional orogenesis and platform deformations of the continental lithosphere and accretion of the oceanic lithosphere in spreading zones. Three main stages of submeridional compression of the oceanic lithosphere are distinguished as follows: Late Jurassic-Late Cretaceous, Late Miocene, and the contemporary stages.Based on the concept of balanced tectonic flow in the Earth’s body, a model of meridional convection (Figure 25) is proposed. In this case, meridional convection is considered as an integral element of the overglobal convective geodynamic system of the largest-scale rank, which also includes the western component of the lithosphere drift (Figure 6) and the Earth’s ‘wrenching’. At the background of this system, geodynamic systems of smaller scale ranks are functioning (Table 1; Figures 2, and 3). The latters are responsible for the periodic creation and break-up of supercontinents, plate tectonics and regional geodynamical processes; they also produce the ‘structural background’, in the presence of which it is challenging to reveal the above mentioned submeridional compression structures. Formation of such structures is caused by the upper horizontal flow of meridional convection.Meridional convection occurs due to drifting of the Earth core towards the North Pole (which is detected by a number of independent methods) and resistance of the mantle to drifting (Figures 26, and 27).By comparing the equations that describe the model of the northern drift of the lithosphere and the model of the core drift towards the North Pole, it is possible to establish a quantitative ‘bridge’ between the structures of meridional compression of the lithosphere and the core drifting structures.Conclusions based on the model of the northern drift of the lithosphere conform to many independent data and concepts, such as disturbance of the isostatic equilibrium of the Antarctica lithosphere and its high standing; the anomalously wide shelf of the Arctic ocean (Figure 28а) and the increased thickness of the sediment cover, that is rich in hydrocarbons, in combination with the ultralow velocity of spreading in Gakkel Ridge; the approximately equal areas of Antarctica and the Arctic ocean as antipodes (Figure 28б); elongation (according to GPS data) of the parallels in the Southern hemisphere, and their shortening in the Northern hemisphere (Figure 26); radial (relative to the South Pole) rifts and other lineaments in Antarctica (Figures 29, and 30); the sub-concentric (relative to the same pole) system of spreading around Antarctica, which develops northward into the submeridional system including three ‘trunks’ at a distance of about 90° (Figure 31).Due to the higher velocity of the northern drift of the lithosphere within the band with the middle meridian 100° E – 80° W, wherein the main mass of the continental lithosphere is concentrated and whose two ‘poles’ are marked by the axes of the African and Pacific superplumes (Figures 3, 4, 5, and 32), the following specific features have developed: maximum elongation of the Antarctic continent in the Southern (‘stretched’) hemisphere (Figure 28 б); maximum shortening of the Arctic ocean in the Northern (‘compressed’) hemisphere (Figure 28а); maximum spreading velocity in the SouthEastern Indian Ridge (Figure 33); maximum northern component of the horizontal displacements velocity (according to GPS data) (Figure 34); the mantle Sunda diapir of maximum width and depth (to 400 km); the Himalayas as an orogen of maximum height; Tibet as a plateau of maximum width and height; and Baikal as a rift of maximum length and depth. The Hindustan indenter is neighboring this meridional band (Figure 20). The Himalayas, Tibet and more remote Baikal are located at its front, and the zone of intra-plate deformations (also caused by the meridional compression) is revealed in the rear. Also associated with this band is the Taimyr Peninsula (Figure 28а), in the direction of which the Earth core drifts.
Keywords
