Gradov OV*
FRC CP RAS, Senior Researcher, Russia
*Corresponding author:Gradov OV, FRC CP RAS, Senior Researcher, Russia
Submission: May 01, 2024;Published: May 10, 2024
ISSN 2637-8035Volume6 Issue3
This article is a brief summary of my lecture entitled “Physicochemical mechanics approach for natural soft mater (including inorganic polymer and liquid crystal structures) in analysis of weathering’s and formations of chemogenic, mechanogenic and biogenic sediments”, which was prepared in 2018 for the 19th International Conference “Physical-Chemical and Petrophysical Research in Earth Sciences” (Moscow, Institute of Geochemistry and Analytical Chemistry named after. V.I. Vernadsky RAS (GEOKHI RAS) - Borok, Schmidt Institute of Physics of the Earth). This material has never been told in English and has not been published in English-language literature, which has made the corresponding discourse less widespread, although it is based on quite fundamental problems that can help applied geologists, geochemists, soil scientists and petrographers solve their applied problems. Therefore, the author considers it necessary, despite the lack of time, to provide an abbreviated machine translation of the notes from that lecture in order to support the dissemination of the ideas indicated in this lecture in the international community. The author obviously apologizes for possible inaccuracies in context and synonymy associated with machine translation (AI-Assisted Translation).
Keywords:Sedimentology; Colloids in the earth’s crust; Van der Waals forces; Volterra process; Kano geometry; Colloidal and metacolloidal mineral systems; Bernal holes; Deryagin-Landau-Verwey-Overbeck theory; Helfrich theory; Physico-chemical mechanics; Inorganic soft matter; Pourbaix diagrams
The formation of sedimentary rocks, starting from the early stages (before diagenesis and accordingly, an increase in the compactness and hardness of the substance of sedimentary rocks) is determined by the physics of disperse systems and the chemical physics of sedimentation processes. Consequently, according to Rebinder ideas, such a process can be described on the basis of the concepts of physicochemical mechanics/physicochemical geomechanics. This is qualitatively different from simplified mechanistic ideas, since for dispersed systems ideas about the mechanical nature of the interaction forces leading to the adhesion of particles are ineffective and do not provide an adequate approximation of empirical data. It is necessary to take into account surface physical and chemical phenomena, especially absorption, adhesion, wetting, electrochemical processes on active developed surfaces, etc., and therefore the forces that determine this class of processes. The interaction of particles of dispersed phases, without taking into account specific chemistry, can be studied within the framework of the soft matter physics. This implies the introduction
of a number of approaches exotic for classical sedimentology, such
as:
A. The problem of mesoscopic distances between particles
interacting with each other, and in particular, the concept of
“coherence lengths”, which determine the lengths of mesoscopic
distances at which certain types of order can be transmitted
with weakening force from one boundary to another. Mean field
approximation for a number of inorganic mineral polymers in
sedimentary systems.
B. The emphasis of the study is on taking into account
non-covalent interactions-dispersion forces/van der Waals
forces (Keesom, London and Debye interactions/effects),
which are extremely necessary for an adequate description
of phenomena in a disperse system. Accordingly, taking into
account the geometric limitation of fluctuations that cause
interaction between particles, within the framework of
Casimir interactions, and different dielectric and orientation
characteristics of particles, since the van der Waals interaction
depends not only on the scalar distances between particles, but
also on the mutual orientation of anisotropic dielectric media.
The need for sedimentology to analyze processes taking into
account van der Waals forces can also be proven by the fact that
only by taking into account the Casimir-Polder effect and as a
consequence, assuming the absence of lag up to a scale of about
30μm, is a plausible analysis of real sedimentological samples
possible, so as, in fact, the retardation effect is significant in the
range from 5 to 20nm.
C. A topological approach different from the Volterra process
for a solid “geological medium”, which assumes relaxation and
complete viscous relaxation, in a partially ordered medium. The
intersections of dislocations and disclinations can be the subject
of topological analysis within the framework of the “emergent”
(that is, based on the formation conditions when describing
and explaining the set of resulting properties) system of ideas
about the formation of sedimentary rocks.
D. The difference in the considered nomenclature of
phase transitions is that Landau’s theory, taking into account
short-range order, does not entirely take into account the
phenomenology of short-range order, which is essential for
first-order transitions.
E. Classification of types of precipitation according to the
types of forces with which they are formed. This should have
a correlation (both in the empirical and in the model aspect)
with the mathematical morphology of the structures formed
in this way, the reactions that ensure their transformation in
the phenomena of diagenesis, and the physical and chemical
mechanics of the resulting structures.
F. Qualitatively different rheological concepts of formation
environments based on sedimentary structures formed in a
“partially ordered” or oriented state (for example, stratified or
layered microstructures in sedimentology and also, in particular,
in the products of diagenesis and subsequent metamorphism
and weathering, can be successfully interpreted within the
framework of Kano geometry, the principle of operation of
which was illustrated back in the last century using mica and
silicate plates).
G. Possibility of analyzing random dense packing of particles
(which is relevant for sedimentology and physical chemistry
of diagenesis processes) of sedimentary rocks of arbitrary
polyhedral (and in particular, deltahedral) geometries, taking
into account percolation phenomena (the so-called “Bernal
hole”) and accordingly, developed surface. Definability of
irregularity of sedimentary environments using certain classes
of geometric frustration.
H. Analysis of colloidal and meta colloidal mineral systems
within the framework of the concepts of colloidal mineralogy
with reduction to the principles of physics of partially ordered
media in model cases of physical stability of geocolloids. For
example, electrochemical criteria for structural stability are
applicable in practice for colloidal components of sedimentary
rocks and their precursors: in the presence of a weak electrolyte
in the medium, electrostatic forces propagate over significant
distances and weaken fluctuations and in the presence of
a strong electrolyte, charges are shielded, which promotes
the development of fluctuations and, as a result, repulsion
(Helfrich theory). The competition of electrostatic forces and
van der Waals forces, within the framework of the Deryagin-
Landau-Verwey-Overbeck theory, leads to a qualitatively
different (from simple electrostatic or mechanical) nature
of the interaction, which regulates the shape of sedimentary
structures according to physical-chemical/colloid-chemical
principles. The Gowey-Chapman length\thickness of the
solution in contact with the phase boundary, containing exactly
half of the counterions, regulates the behavior of geocolloids if
they are in an environment of weak electrolytes (which is most
often encountered in practice) and in the case of strong ones,
another criterion works-the screening length (Debye-Hückel).
I. Taking into account osmotic factors that classically applied
only to bio membrane and polymer structures. For example,
if we take into account the energy density of the electric
double layer, then the free energy (when differently charged
ions are in the system) is written as the sum of electrostatic
volumetric energy and excess configuration entropy-that is, the
total forces of electrostatic and osmotic origin that determine
the presence of repulsion (and its specific contribution to
the state of the system) of geocolloids. If we use the Maxwell
stress tensor, then a differentiated (longitudinal and transverse
pressure) analysis of the orientation of the components of
formation or physicochemical/geoelectrochemical degradation
of sediment under the influence of environmental conditions
and its own properties is necessary. This can become one of
the multidimensional anisometric techniques for analyzing not
only geomorphogenesis, but also weathering
J. Analysis of membrane phenomena in sediments (not only
biogenic), including those caused by the presence of “inorganic
soaps” (by Rebinder), which can take place in real mineral and,
in particular, chemogenic systems. Inorganic membranes and
surfactants are involved in sedimentation and diagenesis and
therefore cannot be excluded from the analysis, which (alas) is
often done in simplified models.
K. Analysis of mesomorphic liquid crystalline phases in
sedimentary structures, the presence of which directly follows
conceptually from Chukhrov’s ideas about colloids in the earth’s
crust; in particular, analysis of the phases of associated colloids.
L. Control of sol-gel transitions, in particular irreversible
ones, on the dehydration scale and with the projection of
data onto Pourbaix-type diagrams. It is a well-known fact that
colloidal-mineralogical structures as products of hydrothermal
processes are characteristic of areas of volcanic activity, but less
known is the fact of the deposition of their amorphous masses
(precursor nature) in the form of gels, which is characteristic
of a number of minerals - such as sulfides in particular arsenic,
copper, zinc, antimony, iron. Starting with the works of L.M.
Lebedev 1960s-1980s. this fact is known, but so far it has
not received exhaustive argumentation as a physicochemical
phenomenon.
M. Inorganic polymers, with the exception of threedimensional
networks of a rigid structure such as quartz, also
cannot be eliminated from analysis within the framework of the
physics of partially ordered geomedia, since their microphase
separation contributes to the morphogenesis of sedimentary
structures, and in the melt their chains of geopolymers can be
described within the framework of the theory of average fields
(Flory-Huggins).