(in Polish) Kryształy w procesach geologicznych. Cz. 2. Agregaty i akumulacje kryształów 1300-WKPG2W
General characteristics of crystals and crystallization processes. Morphology and internal structure of crystals as a record of the history of their development. Crystallization from an aqueous solution, magma (liquid alloy), and in a solid state. Free crystallization and growth of crystals attached to the substrate. Single crystals, crystal aggregates and crystal accumulations. Nucleation and transport of crystals in aqueous solutions, brines and magma. Agglomeration and aggregation of crystals. Druses, brush-like crystal aggrergates, geodes and other forms of crystal clusters growing on the substrate. Competitive growth (geometric selection). Growth stages: isolated, competitive and parallel growth. Growth rate dispersion and morphology of compromise surfaces (induction striation). Competitive growth mechanisms: geometric selection, selection caused by the shape of the substrate, by earlier nucleation, and random selection (examples from evaporite and vein rocks). Competitive growth of dendrite branches. Syntaxial and non-syntaxial development of minerals. Crystals developing on the faces of other crystals; simultaneous and non-simultaneous growth. Graphic granite. Competitive growth of spherulites. Spherulites growing on the faces of other crystals. Development of botrioidal crystal clusters. Mineral veins and their origin. Filling in, displacement and replacement veins: criteria for their recognition. Veins with symmetrical and asymmetrical infilling. Mineral succession (simultaneity, overlap and subsequent crystallization). Syntectonic (syn-deformation) crystallization. Veins and aggregates of fibrous minerals. Growth fronts. Syntaxial and antitaxial growth, symmetrical and asymmetrical growth, complex (mixed) and unsystematic growth. Ataxial, syntaxial and antitaxial veins. Bi- and unitaxial veins. The crack-seal mechanism. Bands and trails of inclusions. Reconstruction of the course of deformation based on analysis of veins of fibrous minerals. Oulopholites (cave flowers) and their origin (salt hairs). Crystallization in a cave environment (speleotems). Stalactites, stalagmites, helictites. Calcite rafts in cave pools. Crust of barite, calcite and aragonite in hot springs (travertine) and growing directly on the seafloor. Environment of crystallization of salt minerals in evaporation basins. Saturation diagrams. The concept of crystallization path, eutonic and reaction point. Order of crystallization from solutions and of seawater (Usiglio sequence, crystallization path for seawater). Precipitation and growth of crystals on the surface of brine, in the brine column, and at the bottom of the basin. Halite rafts, evaporite cumulates (halite, gypsum, aragonite). Halite mushrooms and halite umbrellas. Selenite deposits. Synsedimentary dissolution surfaces and syntaxial growth. Criteria for primary (synsedimentary) crystal growth. Accretionary grains. Chemically coated grains. Ooids and their structure (concentric, radial, mixed). Contemporary and ancient carbonate (aragonite and calcite) ooids. Pizoids, cave pearls. Micrite, surface, asymmetrical, eccentric, broken and regenerated, cerebroid and complex ooids. Origin of ooids - snowball mechanism, sleep and motion stage (accretion and abrasion). Abrasion as a source of crystal seeds. The concept of a ooid factory (modern examples). Deformed, half-moon, and pitted ooids. Silica lepispheres and their origin. Pyrite framboids, their structure, occurrence and origin. Secretions and concretions. Syngenetic, cementation and replacement (metasomatic) concretions; criteria for their recognition. Mechanisms of concretion growth. Septarian concretions and their origin (loess puppets). Examples of carbonate and silica (flint) concretions. Desert roses and calcite from Fontainebleau. Crystals in the processes of diagenesis. Crystallization in pore spaces. Cementation and cements. Development of carbonate and silica cements. Pressure-solution. Cryosphere and ice crystals in nature. Ground ice of the periglacial zone. Needle ice, pore ice (cement, interstitial ice), segregated ice (Taber ice). Injection, vein, intrusive ice (ice wedges, hydrolacolites). Extrusion ice (icing, aufeisen). Fossil ice. Deformations caused by ground ice crystallization (frost wedging, cryoturbations, and others). Fossil ground ice traces. Transformation (metamorphosis) of snow into firn and glacial ice. Crystals in igneous processes. Crystallization environment in igneous and volcanic chambers. Shape and size of of igneous minerals grains. Order of crystallization and distribution of minerals in igneous rocks. Equilibrium and fractional crystallization. Cumulocrystals and magmatic cumulates. Cumulate textures. Magmatic corrosion (resorption). Spherical textures of igneous rocks. Orbicules, their origin and development. Crystal aggregates and accumulations in volcanic and sub-volcanic rocks. Microlites, phenocrystals, xenocrystals. Komatites and spinifex textures. Crystal growth in post-magmatic processes (pegmatites, miaroles, graphic intergrowths). Crystals in metamorphic processes. Processes determining the shape and size of grains in metamorphic rocks. Distribution of minerals in metamorphic rocks. Processes forming grain boundaries and interphase boundaries. Crystallization and recrystallization. Neomorphism. Metallurgical terminology in petrology. Recrystallizaton annealing, recovery, primary recrystallization and grain growth. Polygonization – creation of subgrains and transforation of dislocation tangles into high-angle boundaries during recovery. Dynamic (during deformation) and static (after deformation) recovery. Primary recrystallization (after recovery). Normal (continuous) and abnormal (discontinuous) grain growth. Forces driving grain growth. The role of free surface energy. Evolution of grain boundary shape during grain growth, contact lines of grain boundaries (triple-junctions). Grain boundary migration under hydrostatic and non-hydrostatic stress conditions. Crystals in tectonic deformations. Experimental evidences. Mechanisms of deformation. Brittle and ductile deformations. Plastic deformation of crystals. Formation and reproduction of dislocations during plastic deformation (Frank-Read source of disclocations). Deformation by gliding and twinning. Elements of petrotectonics. Pre-, syn- and post-kinematic crystallization. Mechanical twins as a record of ancient stress fields of rock massifs. Analysis of twinned calcite lamellae. Halite crystals in the processes of halokinesis and salt diapirism. Mechanisms of halite deformation: deformation creep, creep by dissolution-precipitation, creep by development of microcracks. Glacier ice flow and movement of salt "glaciers". Syntectonic (syn-deformation) development of porphyroblasts in shear zones. Cumuloblasts and glomeroblasts. Pre-, syn- and posttectonic porphyroblasts. Pressure shadows and pressure fringes. Syntaxial and antitaxial fringes. S-type and Z-type pressure fringes and pressure shadows. Symmetrical and asymmetrical pressure shadows. Rotated porphyroblasts with elongated pressure shadows of the type σ (sigma) and δ (delta). Textures and structures of minerals characteristic of metasomatosis. Aggregates and accumulation of crystals in mineral deposits (ore textures) and their use to recognize the origin of deposits (examples from native sulfur, zinc and lead, and other ore deposits).
Type of course
Prerequisites (description)
Learning outcomes
The lecture teaches you to understand the processes of growth and transformation of natural crystals (minerals), and to recognize (interpret) the record of these processes in macroscopically visible morphological features and the internal structure of crystals, their aggregates and accumulations. The lecture teaches understanding of Polish and English-language scientific terminology.
Assessment criteria
The final test or oral colloquium checking the level of knowledge acquired during the lecture.
Practical placement
none
Additional information
Additional information (registration calendar, class conductors, localization and schedules of classes), might be available in the USOSweb system: