Vertical tectonic movements of the crust in transform fracture zones of the Central Atlantic |
| |
Authors: | A A Peive |
| |
Institution: | (1) Geological Institute, Russian Academy of Sciences, Pyzhevskii per. 7, Moscow, 119017, Russia |
| |
Abstract: | The most significant vertical movements of the oceanic crust in the Central Atlantic are characteristic of transverse ridges
confined to transform fracture zones. These movements are also recorded in some local depressions of the Mid-Atlantic Ridge
(MAR) and in older structures of deep-sea basins. The amplitude of such movements substantially exceeds that related to the
cooling of lithospheric plates. Vertical movements can be driven by various factors: the thermal effect of a heated young
MAR segment upon a cold plate, thermal stress, thermal energy released by friction in the course of displacement of fault
walls relative to each other, serpentinization of the upper mantle rocks in the transform fault zone, and lateral compression
and extension. The alternation of compression and extension that arises because of the nonparallel boundaries of the transform
fracture zone and the unstable configuration of the rift/fracture zone junction was the main factor responsible for the formation
of the transverse ridge in the Romanche Fracture Zone. The most probable cause of the vertical rise of the southern transverse
ridge in the Vema Fracture Zone is the change in the spreading direction. In general, the fracture zones with active segments
more than 100 km long are characterized by extension and compression oriented perpendicularly to the main displacement and
related to slight changes in the spreading configuration. It is impossible to single out ambiguously the causes of vertical
movements in particular structural features. In most cases, the vertical movements are controlled by several factors, while
the main role belongs to the lateral compressive and tensile stresses that appear owing to changes in the movement of lithospheric
blocks in the course of MAR spreading. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|