On the territory of Armenia neither oceans nor seas, however on a north-east part of lake Sevan availability relicts of  oceanic crust is stipulated fact. However, from what part of oceanic crust the territory of Armenia  was formulated is debatable.

1.   How was formed the serpentinezed  3-rd layer  of  oceanic crust, according to known specialists? 

                   2 .   What  relationship  exist between geostructures of  oceanic crust?           

3.   What relation exist between  tsunamis and   underwater sliding phenomenas?

 The partial answers to these problems are introduced in the animated file in the blog 2,

the materials which one are organically connected to materials introduced in blog 1.

ABOUT RELATION OF OCEANIC CRUST GEOSTRUCTURS ,SUBMARIN LANDSLIDES AND TSUNAMIS

Harutyunyan A. V.

State Engineering University of Armenia. Yerevan, Armenia.

 E-mail: avhk@seua.am

Numerous geological and geophysical data prove the presence of oceanic crust relicts of Tethys in the territory of Lesser Caucasus. However, from which part of oceanic crust were forming the territory of Armenia is debatable. To discover the deep structure, composition and evolution of the modern Earth crust, the seismic and density properties of basites, ultrabasites and serpentinites of lesser Caucasus at high pressures and temperatures were investigated. On the basis of obtained results, and numerous geological-geophysical factual data concerning mid ridges, transform faults, subdaction zones, island arcs and marginal seas, are presented same new elements in their relationships, also the relation between submarine landslides and tsunamis [1-4]. 

To view the animation click here

The numerous volcanic and seismic centers, serpentinized protrusions and also hydrothermal sources are dated in the rang of mid ridges and transform faults. The formation of serpentinized ultrabasites 3-rd layer affects an infiltration of oceanic waters on ultrabasites of the upper mantle. At the same time, on an axial part of the ridge, the horizontally cramping forces, on the 5-6км depth, are established, which step-by-step pass on expanding in the top of the ridge. It can explain forming of rift structures on the top of the ridge.

More than a dozen of models for formation the mid oceanic ridge are introduced, which provide essential progress in the solution of the problem, but in a number of cases remain internally contradictory.

Analyzing the data about composition and properties of oceanic crust, we suspect that during the formation of geostructures of oceanic crust, including mid ridges, the main role belongs to serpentinized rocks of the 3-rd oceanic layer. Owing to high plasticity and low density, the serpentinized masses, by tectonic faults, in the central zone of mid ridges, from both parties, protrusions implanted to the upper part of ridge. Then the serpentinized masses are grasp by basalts lavas and under influence of gravitation forces make slides to the foot of ridge. Low-powered sedimentary layers between these masses are saved.

In the proposed model we attempted to interpret the above mentioned phenomena in the following sense:

1. Because of serpentinization of ultrabasits, the horizontal stress in the 3-rd layer  growth is more than 40- 50% [1]. Spreading of oceanic floor can be partially conditioned by these forces. At impossibility to distensible in the lateral direction, the serpentinized masses increase vertically in the axial part of the ridge also in transform faults. Serpentinized blocks of the 3-rd layer from the axial part of the ridge involved by basalt lava and under gravitation forces slides downwards. The data of drilling has shown the availability of serpentinized blocks in the 2-end  volcanogenic layer.

2 .On formation transform faults a definite role played the processes of basalt masse slides in the mid redges, which naturally takes place permanently, owing to which  between blocks the faults are forming.  In the transform faults the serpentinized protrusions and hydrotherms are also dated, which can be results of dehydration of serpentinized mass in the definite depts of crust.

3. The chemical composition of basalts of island arcs (andezit-alkalian basalts) and mid ridges (toleit basalts) basically coincide, which give us the basis to suppose that they are source commune. We suppose that in definite depth of subdaction zone there exist connection with astenosphere. During subdaction  in the upper mantle molten substrate is enriched by rare elements (toleit basalts) and erupted in the rift zones of mid ridges.

4. Marginal seas extension speed, by the data of specialists, is 5-7cm/year. Esteeming the proposed model, it is possible to mark that spreading of marginal seas takes place owing to eruption of magmatic masses as directly from in the region of island arcs, as well as from astenosphere in the Mid oceanic ridges.

      5. The studies of catastrophic tsunamis in different part of Glob has resulted in judgment, that the formation of high  surges took place because the sliding process in the mid ridges also in the other parts of ocean.  The volume of sliding structures, between transform faults can reach several million  km³. The sliding masses at the bottom of the ocean should invoke a movement of oceanic water and provoke the surges on the surface of the ocean.

      6. On the proposed model of relationships of geostructurs of oceanic crust and astenosphere, we tender to the specialists to discuss the problem of communication of large eruption and catastrophic earthquakes sometimes tracking with  tsunamis (for example tsunami on the Japanese island 12.03. 2011, and eruption of 24.05.2011 on the territory of Iceland). On our submissions earthquake and eruption should takes place in turn. The submergence of definite quantity of masses of rocks of under- layers of  oceanic crust in astenosphere through subdaction  zone, results in surplus of  same quantity of masses and augmentation of pressure in the astenosphere, which one results in eruption of the same quantity masses in the volcanic areas.

We tender to esteem statistics of queue of large earthquakes and eruption of volcanoes, even for the last several hundred  years.

            Proposed model we offer to broad discussion of the specialists, the solution of many suspected problems, naturally, demands cooperation of specialists from different countries of the World.

References:

1. Aslanian A.T., Harutyunyan A.V., 1988.  The formation of Mid Oceanic Ridges in the light of experimental investigations at high thermodynamically parameters. Reports of the AS of Arm. SSR, vol.61, N2, p.12-17.

2. Harutyunyan A.V., Grigoryan S.A., Abazyan E. V., Karapetyan S.N.2005. Landslides processes on the Mid oceanic ridges as possible reasons of originating  of tsunamis. Abstracts, 14^th Meeting of the Association of European Geological Societies. Torino- Italy.

3. Harutyunyan A.V., Grigoryan S. A., Abazyan E. V. 2006. Formation of oceanic crust geostructures and relation between submarine landslides and tsunamis. Abstracts, Asian Seismological Commission (ASC 2006), Bankok, Thailand.

4. Harutyunyan A.V., Grigoryan S. A., Abazyan E. V. 2008. Formation of oceanic crust geostructurs and relation between submarine landslides and tsunamis. Abstracts, 33rd International Geological Congress, Oslo, Norway.