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This paper presents an advanced theory for applied thermodynamic analysis of Earth’s crust and upper mantle. The approach offers qualitative and quantitative methods for analyzing such thermodynamic parameters as pressure, temperature, and volume. Main geologic and tectonic processes in the Earth’s crust and upper mantle were analyzed using the pro...
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... a graph representing thermodynamic equilibrium for water has been constructed ( Figure 1). The line of volume equilibrium for water ( Fig. 1) actually displays pairs of temperature and pressure (p o ,T o ) for which initial volume (V o ) of the matter on a depth will be unchanged relatively to its value on the earth's surface or any other initial point. ...
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... a graph representing thermodynamic equilibrium for water has been constructed ( Figure 1). The line of volume equilibrium for water ( Fig. 1) actually displays pairs of temperature and pressure (p o ,T o ) for which initial volume (V o ) of the matter on a depth will be unchanged relatively to its value on the earth's surface or any other initial point. It is a very important fact, which allows calculating change of a pressure p and temperature T not from (Pilchin, ...
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... values are constant for different depths in a region and it seems logical to accept these pressure values as a normal ones p o . Using the normal pressure value p o for a region and graph like one in Figures 1 and 3, we may calculate the respective values of the normal temperature T o for desired depths. In this case T ∆ value will be a difference between the real temperature (measured or calculated using geothermic methods) T and its normal value T o for some given depth. ...
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... on eq. (19) the values of temperature and pressure may be estimated using equations: ...
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... a graph representing thermodynamic equilibrium for water has been constructed ( Figure 1). The line of volume equilibrium for water ( Fig. 1) actually displays pairs of temperature and pressure (p o ,T o ) for which initial volume (V o ) of the matter on a depth will be unchanged relatively to its value on the earth's surface or any other initial point. ...
Context 6
... a graph representing thermodynamic equilibrium for water has been constructed ( Figure 1). The line of volume equilibrium for water ( Fig. 1) actually displays pairs of temperature and pressure (p o ,T o ) for which initial volume (V o ) of the matter on a depth will be unchanged relatively to its value on the earth's surface or any other initial point. It is a very important fact, which allows calculating change of a pressure p and temperature T not from (Pilchin, ...
Context 7
... values are constant for different depths in a region and it seems logical to accept these pressure values as a normal ones p o . Using the normal pressure value p o for a region and graph like one in Figures 1 and 3, we may calculate the respective values of the normal temperature T o for desired depths. In this case T ∆ value will be a difference between the real temperature (measured or calculated using geothermic methods) T and its normal value T o for some given depth. ...
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This paper presents an advanced theory for applied thermodynamic analysis of Earth’s crust and upper mantle. The approach offers qualitative and quantitative methods for analyzing such thermodynamic parameters as pressure, temperature, and volume. Main geologic and tectonic processes in the Earth’s crust and upper mantle were analyzed using the pro...
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... The presence of tectonic processes is a clear indication of the formation of overpressure and ultra-high pressure (UHP) within the lithosphere and asthenosphere . For instance, processes which are usually called anti-isostatic movements (e.g., Pilchin and Eppelbaum 2002) such as orogenic movements (uplift of huge amounts of rock), the formation of uplift and/or diapir structures, obduction, etc. defy the law of gravity. This means that at a certain depth, forces greater than that of gravity must be generated. ...
... It was shown (Pilchin and Eppelbaum 2002 ) that to analyze changes thermodynamic parameters with depth Eq. (2.7.19) can be written as: dV Vo ¼ a oT oz À b oP oz dz ð4:4:5Þ which for the purposes of practical calculation can be transformed into: DV=Vo Dz ¼ a DT Dz À b DP Dz : ð4:4:6Þ Equation (4.4.6) indicates the relationship between relative change in volume with depth DV=V 0 Dz , the vertical geothermal gradient ðDT=DzÞ, and the gradient of pressure with depth ðDP=DzÞ. This equation can be used to determine the type of tension in a region (Pilchin 1985a). ...
... (a) DV ¼ 0. This corresponds to equilibrium and an absence of tension Since the most advanced seismic methods have been developed in geophysics, including the determination of such physical properties of rocks and minerals as seismic velocity (v), change of seismic velocity with change in temperature (dv/dT) and pressure (dv/dP), in some cases it is preferable to use seismic data to analyze thermodynamic conditions at great depths (Pilchin and Eppelbaum 2002). The seismic wave velocity (v) depends to a great extent on the values of temperature (T) and pressure (P). ...
The presence of tectonic processes clearly indicates the formation of overpressure and ultra-high pressure (UHP) within the lithosphere and asthenosphere. For instance, processes usually called anti-isostatic movements (e.g., Pilchin and Eppelbaum 2002), such as orogenic movements (uplift of vast amounts of rock), the formation of uplift and/or diapir structures, obduction, etc. This means that forces more significant than gravity must be generated at a certain depth. Concerning pressure, this means that there are sources of overpressure or UHP that can overcome the lithostatic pressure (Pilchin and Eppelbaum, 2009). Cases of formation of volcanoes, mud volcanoes, hot springs, and rock exhumation, among others, defy gravity, even though these processes could be generated by buoyancy or some other isostatic forces because these forces work against the force of gravity. Any violation of the law of gravity must have a physical explanation behind it. It is also clear that for an uplifting process to begin, overpressure (P) is necessary and must be greater than the lithostatic pressure.
The presence of such contrasting tectonic processes as orogeny, obduction, subduction, uplift, immersion, and related ones means that in these cases, the lithostatic pressure cannot be taken as the real pressure since there is no isostatic equilibrium (Pilchin and Eppelbaum, 2009). In other words, the lithostatic pressure generated by gravity cannot represent the actual pressure in tectonically active regions, which are common worldwide. Let us discuss some processes of overpressure and UHP formation. The causes of the formation of overpressure, including overpressure greater than the lithostatic pressure, in porous fluid (see Sect. 2.7), volcanic magma (see Sect. 4.2), and mud volcanoes (see Sect. 4.3) were discussed in other sections. Wangen (2001) showed that mechanical compaction and cementation of porous space generate high overpressure and the strongest expulsions. Several models of the generation of overpressure and UHP have been developed to explain the enigmatic exhumation of high-pressure — low temperature (HP-LT) and UHP-LT rocks (Burov et al., 2001). One of the models is based on deep subduction of the continental crust to depths of about 200–250 km (Chemenda et al., 1995), followed by decoupling and positive buoyancy-driven exhumation of the crustal material from about 100 km. However, this model does not consider thermal evolution, which is crucial for reproducing P–T relationships, not to mention that rheology and buoyancy forces are highly dependent on temperature (Burov et al., 2001). There are also models of overpressure formation using subduction and large-scale compressive instabilities (Cloetingh et al., 1999; Burg and Podladchikov, 1999).
... where b s is the coefficient of compressibility of the solid part of the volume V 0 , and P 0 is the lithostatic pressure. At the same time, any volume of rock is surrounded by other rocks that tend to expand as well and could prevent the target volume from expanding (Pilchin 1983; Pilchin and Eppelbaum 2002). In other words, any change in the volume of the solid part of a rock can only take place at the expense of the volume of the fluidfilled porous space of the volume V 0 . ...
Thermal conductivity or the thermal conductivity coefficient of a material defines its ability to transfer heat. Consider an infinite plane wall of a certain material with a thickness of one unit in length. The sides of the wall are maintained at constant temperatures and the temperature difference is equal to 1 ^oC. Let us also assume that a sensor can measure the amount of heat per unit of the wall area per unit of time. In this case the amount of heat measured will be numerically equal to the thermal conductivity coefficient (k) of the given material. The dimension of this quantity in SI is J m^{-1} s^{-1} K^{-1} or W m^{-1} K^{-1}. It was found experimentally that the amount of heat transferred through the wall (qA) is proportional to the area (A) and to ratio of the temperature difference (DT) to the wall thickness (Dx). This statement is known as Fourier’s thermal diffusion law (or equation).
... However, even though, the effect of solid crust density inhomogeneities can also be estimated from data on the average velocities of seismic waves, the information is less reliable than that of other datasets that include constraints on the Moho boundary position [269]. On the other hand, in a number of cases the pressure generated by different processes [465] [468] has been shown to have the potential to overcome the lithostatic pressure. It was shown earlier [465], that pressure generated by high temperature during granulite facies metamorphism could have been greater than the lithostatic pressure. ...
... Even the overpressure generated in sedimentary strata by trapped heated water could in some cases have been greater than that of the lithostatic pressure [290] [371]. At the same time, numerous cases point to the formation of horizontal pressure and overpressure in slabs of the crust and upper mantle [456] [464] [465] [467] [468] [511]. Neither of these pressures is related to the lithostatic pressure generated by any block of the crust or lithosphere, however, they would still break the isostatic equilibrium, forcing the block to uplift in many cases without any change in the distribution of mass or values of density. ...
... This means that for the analysis of isostatic equilibrium, the distribution of pressure and stress both within and below the lithosphere is more essential than the distribution of the masses and densities within its blocks. At the same time, lithostatic pressure should be viewed as the normal pressure for the corresponding depth, and in most cases (excluding processes of immersion) it is the minimal pressure at that depth [464] [465] [467] [468]. ...
Some physical problems related to modeling the conditions of the formation and evolution of the lithosphere are discussed. It is shown that if we consider both the effects of thermal expansion and compressibility, we could receive results with no change or even an increase of density under the P-T conditions within the lithosphere. During planetary accretion and differentiation of Earth, the planet could have been entirely molten and, at some point in its evolution, was entirely covered by a magma ocean. The formation and composition of the early lithosphere were mainly related to processes of matter differentiation and the magma ocean's cooling rate. The process of the differentiation of the magma ocean would begin during its formation and continue until its solidification. This stratification of the composition of Earth caused an initial state of separation of rocks and minerals into slabs within the upper mantle and crust, which was strictly regulated by their density, whether solid or melted. The difference in density between felsic, intermediate, mafic, and ultramafic magmatic slabs within the magma ocean was enough to prevent the exchange of matter between them. Therefore, mantle-wide convection could not have taken place. The solidification of the magma ocean, upon which the process of the formation of the lithosphere is dependent, most likely began with the formation of forsterite (or forsterite-rich peridotite) slab at a depth of about 100 km followed by the solidification of Earth's surface, cooled by heat radiation from the surface and the cooling effect of the early atmosphere. It is shown that under the thermal conditions of the magma ocean, carbonate rocks were unstable and decomposed, releasing carbon dioxide into the atmosphere. Water could also not exist in its liquid state at the time of the magma ocean, and together with the carbon dioxide, it would form a thick and dense early atmosphere. The formation of the water ocean was under the constraints of the boiling point of water at the pressure of the early atmosphere and the critical point of water. Cooling rates of the magma ocean and the early lithosphere are compared to the cooling rates of the mantle and numerous magmatic and/or metamorphic complexes. The main periods of the appearance of komatiites and the formation of the first large igneous provinces (LIPs) indicate temperature maximums in the mantle at about 2.8-2.7 Ga and a maximum volume of mafic magmatism related to the formation of LIPs at about 2.5 Ga. Analysis of the periods of the formation of granulites suggests an increase in temperature at a depth of about 30 km from ~3.0 Ga to ~2.7 Ga, with its continuing increase to ~2.5 Ga. It is shown that at the end of the Archean, the thickness of the lithosphere was ≤100 km, including a solid forsterite slab at ~100 km depth with possible pockets of magma above it.
... However, even though, the effect of solid crust density inhomogeneities can also be estimated from data on the average velocities of seismic waves, the information is less reliable than that of other datasets that include constraints on the Moho boundary position [200]. On the other hand, in a number of cases the pressure generated by different processes [355] [357] has been shown to have the potential to overcome the lithostatic pressure. It was shown earlier [355], that pressure generated by high temperature during granulite facies metamorphism could have been greater than the lithostatic pressure. ...
... This means that for the analysis of isostatic equilibrium, the distribution of pressure and stress both within and below the lithosphere is more essential than the distribution of the masses and densities within its blocks. At the same time, lithostatic pressure should be viewed as the normal pressure for the corresponding depth, and in most cases (excluding processes of immersion) it is the minimal pressure at that depth [354] [355] [356] [357]. ...
... In the most general form, the relationships between such thermodynamic parameters as volume (V), pressure (P), and temperature (T) could be presented in the following form [357] ...
Some physical problems related to modeling the conditions of the formation and evolution of the lithosphere are discussed. It is shown that if we consider both the effects of thermal expansion and compressibility, we could receive results with no change or even an increase of density under the P-T conditions within the lithosphere. During planetary accretion and differentiation of Earth, the planet could have been entirely molten, and at some point in its evolution, it was entirely covered by a magma ocean. The formation and composition of the early lithosphere were mainly related to processes of matter differentiation and the magma ocean's cooling rate. The process of the differentiation of the magma ocean would begin during its formation and continue until its solidification. This stratification of the composition of Earth caused an initial state of separating rocks and minerals into slabs within the upper mantle and crust, which was strictly regulated by their density, whether solid or melted. The difference in density between felsic, intermediate, mafic, and ultramafic magmatic slabs within the magma ocean was enough to prevent the exchange of matter between them. Therefore, mantle-wide convection could not have taken place. The solidification of the magma ocean, upon which the process of the formation of the lithosphere is dependent, most likely began with the formation of a forsterite (or forsterite-rich peridotite) slab at a depth of about 100 km. It is followed by solidifying the Earth's surface, cooled by heat radiation from the surface, and the cooling effect of the early atmosphere. It is shown that under the thermal conditions of the magma ocean, carbonate rocks were unstable and decomposed, releasing carbon dioxide into the atmosphere. Water could also not exist in its liquid state at the time of the magma ocean, and together with the carbon dioxide, it would form a thick and dense early atmosphere. The formation of the water ocean was under the constraints of the boiling point of water at the pressure of the early atmosphere and the critical point of water. Cooling rates of the magma ocean and the early lithosphere are compared to the cooling rates of the mantle and numerous magmatic and/or metamorphic complexes. The main periods of the appearance of komatiites and the formation of the first large igneous provinces (LIPs) indicate temperature maximums in the mantle at about 2.8-2.7 Ga and a maximum volume of mafic magmatism related to the formation of LIPs at about 2.5 Ga. Analysis of the periods of the formation of granulites suggests an increase in temperature at a depth of about 30 km from ~3.0 Ga to ~2.7 Ga, with its continuing increase to ~2.5 Ga. It is shown that at the end of the Archean, the thickness of the lithosphere was ≤100 km, including a solid forsterite slab at ~100 km depth with possible pockets of magma above it.
There are a number of events and processes that can take place at some very specific thermodynamic conditions which can serve as markers of these specific conditions. Some examples of such events and processes are the formation of BIFs, red beds and/or paleosols, the state of decomposition of carbonates, iron sulfides and other rocks and minerals, the process of serpentinization, the formation of oxic or anoxic environments, and many others. At the same time there are situations where the expected process or event did not take place and this could be used as a marker of specific conditions which prevented some events and processes from occurring, and some rocks and minerals from forming. For example, the absence of significant amounts of sediments in the Early Archean (before ~3.26 Ga), as well as the absence of carbonate rocks and evaporites in the Early Archean point to the absence of water-oceans. There are numerous cases
with P–T conditions when both eclogites and blueschists were formed, but there are a number of cases when even though P–T conditions (overlapping conditions) were favorable for the formation both eclogites and blueschists only one of them was formed and not the other.
Like any other groundwaters, the behavior of thermal waters is described by hydrogeology and hydrology. For this reason, we will first look at some definitions and primary characteristics used in hydrogeology in Section 4.1.1. Thermal waters is an extensive term for all kinds of waters with high and elevated temperatures, which are usually divided into more specific kinds of waters such as hot springs, geysers, and fumaroles into the land areas, and different kinds of vents (including black and white smokers) in marine areas. The main difference between them is the temperature and state of the water and its behavior upon discharge. Geysers differ from hot springs by the presence of a significant amount of steam and water and how the water discharges. Fumaroles differ from hot springs and geysers because they have a vent that emits a mixture of steam and other volcanic gases. The difference between various vents is both in temperature and the fact that in some cases (primarily for black smokers), water may be in critical (have either temperature or pressure above their critical conditions (Hall, 1995; Pilchin and Eppelbaum, 2009; Pilchin, 2011)), supercritical (both temperature and pressure above their critical conditions) or subcritical (the water temperature is above its boiling point but below the critical temperature) conditions.
Any process involving water is a part of the water cycle, also known as the hydrologic cycle or H_2O cycle (Berner and Berner, 1987), and plays an important role in the process of cooling of the Earth’s lithosphere and Earth itself. From this point of view, processes involving ground waters (water infiltration and its
underground flow; see Fig. 4.1) are related to the collection of heat energy by ground water and the delivery of this energy to the surface and surface water reservoirs. Infiltrating water (meteoric water; usually low-temperature rainwater or water from melting snow; etc.) in a recharge zone enters an aquifer and flows
through it to the discharge zone (an artesian aquifer), where it exits the aquifer to the surface or surface water reservoir. However, while it is moving through the aquifer it is heated to higher temperatures than it initially had, and at the same time
it reduces the temperature of the sedimentary layer by absorbing some of the heat from the layers confining the aquifer. In some cases infiltrating water moves through aquifers in regions of ongoing magmatic activity or past young magmatic activity. Under such circumstances, these ground waters may be heated to very
high temperatures and can deliver significant amounts of heat to the surface or water reservoirs (i.e. ocean by vents) which assists in cooling the rock layers in contact with magma more quickly. In the case of magmatic activity in a region, significant amounts of magmatic waters (or juvenile waters), existing within and in
equilibrium with the magma or water-rich volatile fluids related to the magma are released into the atmosphere during either a volcanic eruption or hydrothermal fluid release during the late stages of magmatic crystallization within the Earth’s crust. It is clear that in all these cases some amount of heat energy is absorbed from rocks of different layers of the crust and delivered to the surface. Depending on the conditions governing each individual case, the location of the discharge of groundwater or thermal water is characterized by thermal anomalies of different magnitudes, because heat transfer by circulating water is much more intensive than heat transferred by conduction. This thus leads to the cooling of crustal layers and the lithosphere. It should be taken into account that ground waters mostly cool upper layers of the crust, which generate an increased gradient between the upper crustal layers and the lower crustal/lithosphere layers, hence increasing heat flow by heat conduction, which leads to quicker cooling of the lithosphere. In this section, we only discuss processes related to groundwater and thermal water activity. Any manifestation of thermal waters (springs, geysers, fumaroles, etc.) on land or the sea bottom (vents, black and white smokers, etc.) is a hydrogeological process that follows the laws of hydrogeology and hydrology. Hydrogeology is the area of geology that deals with the distribution and movement of groundwater within the Earth’s crust (mostly its sedimentary layer). Groundwater is water that fills pores and fractures in the ground. Let us first take a look at some key definitions in hydrogeology (e.g., Harter, 2008).
During the formation of the Earth as a planet, the heat energy released by accretion and specific other processes was sufficient to heat the entire Earth beyond the melting point of composing its rocks. This led to hundreds of kilometers of magma-ocean formation or the melting of the whole planet. That molten stage could have existed for quite some time. Such processes as a possible collision of Earth with a Mars-size body (Moon-forming event) and bombardment of the surface by substantial cosmic objects [e.g., “late heavy bombardment” at about 3.85–3.9 Ga] could have significantly slowed down the process of solidification of magma-ocean and/or create local magma-oceans. The solidification of magma-ocean led to the formation of the lithosphere through complex processes of formation and recycling of rocks and minerals, the interaction of surface rocks with the atmosphere, the formation of crust, the formation of water-ocean, and many others. All these processes took place during the general process of Earth cooling. In this Chapter, such processes as the formation and evolution of magma-ocean, the evolution of early Earth’s atmosphere, the formation of the water-ocean, the thermal regime during early lithosphere formation, dynamic interactions of the asthenosphere and the lithosphere, and many other problems are discussed.
This Chapter describes the most critical thermal parameters, such as conductivity, capacity, and diffusivity, and the interrelation of these parameters between themselves. In some cases, the effect of thermal anisotropy may significantly change the studied geothermal pattern. Investigating melting points of rocks and minerals, temperature and pressure influence the thermal properties of rocks and minerals, and fluid density plays an essential role in developing deep geothermal models. It is shown that analysis of the early Earth's atmosphere is significant for detecting some peculiarities of the modern geothermal regime of the Earth. Problems related to the evolution of the early Earth's atmosphere during the Earth's cooling and the water ocean's formation are discussed in Section 6.2.
Thermal waters (hot springs, geysers) and volcanoes were among the first manifestations of the Earth’s internal heat that people encountered in ancient times. This helps explain the long history of scientific analysis of such events as volcano and geyser eruptions, hot spring regions, etc. The first tales of the Great Geysir (Iceland) date back to 1294 (Iceland on the Web 2013). One of the oldest publications on geyser problems is by Bunsen and Descloizeaux (1846) on the geysers of Iceland. Depending on the amount of heat and energy released by an event, it may be a heat source (spa, a bathtub full of warm to hot water) or a natural hazard (volcanic eruption, volcanic gases, geyser eruption). Hot springs and geysers are typical features in volcanic regions or areas of other magmatic activity (continuing cooling of young intrusives), which are also seismically active. Some of the most thermally active regions in the world are Yellowstone National Park in the USA, one of the most remarkable volcanic zones on Earth, and areas with extreme volcanic and seismic activity in the Kamchatka Peninsula in Russia, Iceland, which is located on the Mid-Atlantic Ridge, Japan, and New Zealand.
