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EUROPEAN GEOSCIENCES UNION GENERAL ASSEMBLY 2014. Vienna, Austria, 27 April – 02 May 2014. DENSITY VARIABILITY - FUNDAMENTAL BASIS OF STRUCTURE FORMATION AND TECTONIC-GEODYNAMIC EVOLUTION OF THE EARTH. Hatam Guliyev 1 , Ibrahim Guliyev 1 , Gurban Yetirmishli 2.

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slide1

EUROPEAN GEOSCIENCES UNION GENERAL ASSEMBLY 2014

Vienna, Austria, 27 April – 02 May 2014

DENSITY VARIABILITY - FUNDAMENTAL BASIS OF STRUCTURE

FORMATION AND TECTONIC-GEODYNAMIC EVOLUTION OF THE EARTH

HatamGuliyev1, Ibrahim Guliyev1, GurbanYetirmishli2

Geology Institute of Azerbaijan National Academy of Sciences1

Republican Seismic Survey Centerof Azerbaijan National Academy of Sciences2

E-mail: hatamguliyev@gmail.com

slide2

DENSITY VARIABILITY - FUNDAMENTAL BASIS OF STRUCTURE FORMATION

AND TECTONIC-GEODYNAMIC EVOLUTION OF THE EARTH

Abstract

It was shown that there are some common geomechanical basis of processes of consolidation, deconsolidation, phase transitions, formation of zones of small shear stiffness (waveguides), realization of material and energetic mass flow in the internal structures of the Earth based on fundamental properties of basic systems of equations of nonlinear mechanics of the deformed bodies, data and results of Green, Ringwood, Liu’s known experimental studies.

Its instability for different geological media was shown studying the distribution of medium density depending on deformation changes.

It was shown that distinguishing various forms of instability there is general deformation mechanism of consolidation process of compressible medium according to which transfer to deconsolidation occurs at certain stages due to specific change of equilibrium states.

Instability of deformation process contributes to emergence of geometric structures in composition of geological medium which are favorable to form deconsolidation zones and zones of small shear stiffness.

Destruction by delamination at various depth of the Earth's interior can lead to formation of voids of various scale. Various forms of instability can be realized in the process of further evolution in the vicinity of these free surfaces, and voids can be filled by the loosened mass, i.e. deconsolidation process occurs under compression conditions.

More hard bodies of local scale in the form of rod, strips, plates, cylindrical bodies, voids etc. can exist at different depth of mantle. These bodies can lose the stability within compression conditions. Therefore, part of their material and environment are loosened and deconsolidation process occurs again.

The above described cases significantly depends on the realized form of deformation. Unevenness of deformation has a great value.

Partial melting and magma formation can occur in these deconsolidated zones depending on mineral associations, petrochemical properties, thermobaric conditions and depth. This process becomes more feasible in case, when water appears as a result of dehydration in the considered zones.

Some of these zones of deconsolidation can turn to focus of liquefied mass and give the beginning to mass flow on various directions in further evolution.

slide3

Problem statement

a)

b)

Diagram of the matter density distribution of the Earth on depth:

a) the existing notionb) the proposed notion

Distribution of the medium density depending on its arbitrarydeformation (Hatam Guliyev,2007-2008).

– current density; – initial density;– the main components of Green deformation tensor

slide4

In case of homogeneous deformation:

then

Comprehensive deformation

For elastic body under compression

Р – pressure; – Poisson’s ratio; Е – elasticity modulus

slide5

Influence of deformation non-uniformity

28

28

28

28

24.55

24.55

24.55

21

21

21

21

17.14

17.14

17.14

14

14

14

14

8.44

8.44

8.44

7

7

7

7

Enstatit

Enstatite

Enstatit

Garnet

Ilmenit

Ilmenit

Ilmenite

Perovskit

Perovskite

Perovskit

0

0

0

0

2

2

2

2

2.64

2.64

2.64

2.64

4

4

4

4

5.34

5.34

5.34

5.34

6

6

6

6

7.69

7.69

7.69

7.69

8

8

8

8

a=b=g=1

a=b=1; g=0.01

a=b=1; g=0.1

a=b=1; g=0.5

12

a=b=1; g=1.5

a=b=1; g=2

10

8

6

on

Dependence

Lin-Gong Liu’s experimental results on phase transition of orthopyroxene (90% MgSiO3Al2O3).

4

2

0

0.1

0.2

0.3

0.4

-0.4

-0.3

-0.2

-0.1

0.05

0.15

0.25

0.35

-0.35

-0.25

-0.15

-0.05

Dependence

andsequenceof phase transitionsfor orthopyroxene

on

instability of deformation process

P

P

Instability of deformation process

Instability of deformation process is one of sources of inhomogeneity

Various possible variants

Diagram of half-space loading in the vicinity of the cylindrical void

Dependence of critical pressures on the thin-walled parameter.

(uniaxial compression along axis of the cylinder);

- Euler’s critical load

- Critical value under comprehensive compression, when an external impact

on the cylindrical surface is given in the form of conservative loads.

Subsurface instability

Instability in the structure

slide8

Some numerical results

Critical values

in case of comprehensive deformation of the medium

and

in the presence of the cylindrical void in it

.

slide9

Alternative magmatic foci

As a result of the instability, walls of the reformed voids and disturbances are "went-off" as in mines and the medium fills voids by shattering. At the same time, in case of dehydration, water may also appear here. It`s also necessary to take into account the fact that such zones are transformed into natural "pumps". They attract the temperature of the medium, accumulate along and partial melting starts at a relatively low pressure. Various variants of magma formation can be implemented at various depths.

slide10

CONCLUSION

1. The new approach that allows studying processes of non-uniform deformation under high pressures considering appropriate phase transitions for various rocks was developed basing on non-linear theory of deformation of the continuous medium.

2. It was shown that specific deformations that differ from processes of comprehensive deformed homogeneous media occur due to inhomogeneity of structural constructions of the Earth interior and a variety of impact systems.

3. Consolidation processes can turn into deconsolidation process - a density variation can occur with the growth of the Earth's depth. Voids, zones of small shear stiffness (waveguides) can form due to the deformation at various depths; foci of the diluted mass can form in these zones in certain cases which can become a source of mass flow in further evolution.

THANK YOU FOR YOUR ATTENTION!