The density of magmatic, ultrametamorphic rocks of the Ukrainian shield in model deep conditions of the Earth’s crust (experimental data)
Keywords:rock density, thermodynamic decompaction, pressure, temperature, «velocity—density», petrophysical thermobaric modeling
Analysis of the materials of geophysical studies using the data on the physical properties of rocks at various depths contributes to more substantiated understanding the structure of the Earth's crust horizons which are not accessible for drilling. In this regard, our method of petrophysical thermobaric modeling (PTBM) is a successful tool for this purpose. Its basic principle is a comparison (taking into account surface geology) of experimental data on changes in the physical parameters of rocks (in particular, the velocity of elastic longitudinal waves (Vp=f (Н)) and density (ρ=f (Н)) under РT-conditions of thermobaric deep regimes of the Earth’s crust of the study regions and DSS and gravimetric information. Continuing the study of the elastic-density characteristics of rocks and minerals under high pressures and temperatures, we present the results of experiments to examine changes in the density of igneous and ultrametamorphic rocks. They are widespread in the Ukrainian shield, mostly often found in the form of large blocks and massifs with the thickness of up to several tens of kilometers. Our long-term studies convincingly show that temperature significantly influences the relationships of Vp and ρ under conditions of great depths. As experiments demonstrate, they vary according to nonlinear laws with a depth indicating maxima and minima. The simultaneous effect of pressure and temperature on the mineral substance corresponding to the interval of depths of the Earth's crust of 5—20 km results in inversion zones of the elastic waves velocity and density. The zones are similar to the low velocity zones (LVZs) found in the Earth’s crust by DSS methods and are characterized by rocks decompaction. Like the LVZs of reduced density (according to experimental data), the inversion zones are sensitive to the temperature conditions of the Earth’s crust. With increasing deep heat flux, the rock density decreases, the ability of rocks decompaction increases, their permeability and hygroscopicity increase that can activate the process of fluid movement and their localization. Such crustal anomalies must be taken into account in refining the relationship of Vp=f (ρ) at various depths (the most important relation in seismic-gravity modeling and PTBM). In most cases, this relationship for all specimens of rocks at certain depths is far from linear one contrary to popular opinion. First of all, this observation is explained by the complex dependences of the elastic and density characteristics of rocks with depth. The materials of an experimental study of the elastic-density characteristics of igneous and ultrametamorphic rocks of the Ukrainian shield under model deep conditions of the Earth’s crust are widely used for petrophysical thermobaric modeling of specific sections of the deep horizons of the Earth’s crust of various regions of the planet.
Burtnyy, P.A., Korchin, V.A., & Karnaukhova, E.E. (2013). Modeling of the material composition of deep horizons of the earth’s crust (new concept of interpretation of geophysical data). Saarbrücken: LAPLambert Akademic Publishing, 188 p. (in Russian).
Starostenko, V.I., & Gintov, O.B. (Eds.). (2013). The Kirovograd ore area. Deep structure. Tectonophysical analysis. Ore deposits. Kiev: Galaktika, 500 p. (in Russian).
Korchin, V.A. (2015). Low velocity zones of thermobaric origin in the crystalline crust. Geofizicheskiy zhurnal, 37(5), 46—65. https://doi.org/10.24028/gzh.0203-3100.v37i5.2015.111145 (in Russian).
Korchin, V.A. (2013a). Crustal zones of low velocities are promising horizons for localization of deep hydrocarbons. Glubinnaya neft, 1(8), 1099—1116 (in Russian).
Korchin, V.A. (2011). Petrophysical features of low seismic velocity zones in the earth's crust and their thermobaric instability: Proc. of the XVII All-Russian conference with international participation: «Problems of seismotectonics», Moscow, September 20—22, 2011 (pp. 273—277) (in Russian).
Korchin, V.A. (2007). Structural features of the mineral environment in the PT-conditions of various depths of the earth's crust. Geofizicheskiy zhurnal, 29(3), 49—77 (in Russian).
Korchin, V.A. (2014). Thermobaric modeling of anomalies of increased porosity in rocks of the earth's crust — horizons of possible migration and localization of deep hydrocarbons. Electronic magazine «Deep Oil», 2(9), 1434—1448 (in Russian).
Korchin, V.A. (2013b). Thermodynamics of crustal zones of low seismic velocities (new scientific hypothesis). Saarbrücken: LAP Lambert Academic Publishing, 280 p. (in Russian).
Korchin, V.A. (2012). Elastic-density thermobaric stratification of the lithosphere, crustal zones of low seismic velocities: Proc. of the III tectonophysical conference at the IPE RAS «Tectonophysics and topical issues of Earth sciences», Moscow, October 8—12, 2012 (Vol. 2, pp. 390—393) (in Russian).
Korchin, V.A., & Burtnyy, P.A. (2011). Thermobaric petrophysical modeling of the lithosphere of the parts of the earth’s crustal of the Ukrainian Shield with zones of low seismic velocities. Geofizicheskiy zhurnal, 33(6), 82—95. https://doi.org/10.24028/gzh.0203-3100.v33i6.2011.116795 (in Russian).
Korchin, V.A., Burtnyy, P.A., & Karnaukhova, E.E. (2007). Rocks of the Granulite Complex: Their Elastic Parameters and Prediction of Distribution in the Earth's Crust of the Ukrainian Shield. Geofizicheskiy zhurnal, 29(3), 99—109 (in Russian).
Korchin, V.A., Burtnyy, P.A., & Karnaukhova, E.E. (2011). Petrophysical modeling of areas of the earth's crust with zones of low seismic velocities: Proc. of the X international conference "Geoinformatics: theoretical and applied aspects”, Kiev (P056, CD ROM) (in Russian).
Korchin, V.A., Burtnyy, P.A., & Karnaukhova, E.E. (2018). Decompaction of metamorphic rocks under thermodynamic conditions of the earth’s crust (experimental data). Geofizicheskiy zhurnal, 40(4), 107—132. https://doi.org/10.24028/gzh.0203-3100.v40i4.2018.140612 (in Russian).
Korchin, V.A., Burtnyy, P.A., & Kobolev, V.P. (2013). Thermobaric petrophysical modeling in geophysics. Kiev: Naukova Dumka, 312 p. (in Russian).
Kutas, R.I. (1978). Heat flow field and theoretical model of the earth’s crust. Kiev: Naukova Dumka, 140 p. (in Russian).
Lebedev, T.S., Korchin, V.A., & Burtnyy, P.A. (1989). Geophysical applications of the results of RT-study of the elastic characteristics of rocks. In Properties and state of mineral matter in the bowels of the Earth (pp. 56—72). Moscow: Nauka, (in Russian).
Lebedev, T.S., Korchin, V.A., Savenko, B.Ya., Shapoval, V.I., & Shepel, S.I. (1986). Physical properties of mineral matter under thermobaric conditions of the lithosphere. Kiev: Naukova Dumka, 198 p. (in Russian).
Raider, E. (1987). Fluid inclusions in minerals. Moscow: Mir, 632 p. (in Russian).
Shcherbakov, I.B. (2005). Petrology of the Ukrainian Shield. Lvov: Publishing house ZUKTs, 364 p. (in Russian).
Korchin, V. (2017). Anomalies of low density in the crystalline crust of thermobaric origin: a new insight into migration and localization of hydrocarbons. In Oil and Gas Exploration: Methods and Application (pp. 237—257). American Geophysical Union, Wiley.
Korchin, V.А., & Karnaukhova, E.E. (2007). Effect of mineral content of granitoids of the Ukrainian shield on the change of their elastic parameters in different thermobaric conditions of the lithosphere (by experimental data). XXIV IUGG General Assembly «Earth: our changing planet», July 2nd—13th, 2007. Perugia, Italy, JSS001.
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