Structural Geology Flashcards
A rule that states that microstructures are keys to mimic the styles and orientation of macrostructures of the same generation within a particular area.
Pumpelly’s rule
An isostasy hypothesis which accounts for regional isostasy created due to flexural folding of the lithosphere. When load on the crust causes downward flexural folding of the crust, with buoyancy forces acting opposite of it, and can possibly create bulging around the load.
Vening Meinesz’ Hypothesis
also called “Uniform pressure”
Hydrostatic pressure
It measures the stiffness or stretcheability of a material, defined as the ratio of stress over strain.
Young’s Modulus
It expresses the relationship between volume change and stress. The ratio of lateral change due to compression or tension.
Poisson’s Ratio
The study of the ability of stressed solid materials, as well as fluids, to flow or deform due to strain rate, elasticity, and viscosity.
a. Speleology
b. Pedology
c. Rheology
d. Palynology
a. Speleology - caves
b. Pedology - soils
c. Rheology - solids/fluids ability to flow due to strain
d. Palynology - nanometer-sized organic-walled fossils
occurs where two subparallel thrusts of approximately equal displacement are separated by a deformed interval that is thin relative to its total area extent.
Duplex
A fault surface parallel to a mechanically weak horizon or layer, or parallel to bedding, that detaches or separates deformed rocks above from undeformed or differently deformed rocks below.
Decollements
Differentiate buckling and bending
Bending - force is applied not parallel to the layer, results in folding
Buckling - force applied is parallel to the layer, resulting in folds
Joints that exhibit feathered structure
a. nonsystematic
b. pinnate
c. plumose
d. Griffith
Answer: Plumose
a. nonsystematic (no common orientation)
b. pinnate (merges with the fault at 30-45-degrees angle)
d. Griffith (pre-existing microcracks/flaws in a rock)
Which among the following are classified as metamorphic rock with inequant grains and foliation?
a. Hornfels
b. Skarn
c. Anthracite
d. Migmatite
Migmatite
Deformation of a rock by extreme microbrecciation, due to mechanical forces applied in a definite direction, without noteworthy chemical reconstitution of granulated minerals.
Mylonitization
is a low temperature, brittle grain fracturing process that involves grain size reduction through the mechanical grinding, rotation and crushing of rock. This process produces small, angular grains that infill between larger grains as in cement mortar
Cataclasis
involves the dissolution of solid grains under high compressive stress conditions so that one grain impinges upon another grain, initiating a soluble phase in the indented grain.
Pressure Solution (e.g. Stylolites)
refers to the nucleation and growth of new minerals as pre - existing minerals become unstable due to temperature/ pressure changes.
Neocrystallization
is an extremely fine-grained to glassy, dark, cohesive rock occurring as veins that form through frictional melting and subsequent quenching during earthquakes,large-scale landslides, and impacts events
Pseudotachylites
is a general term for fine - grained, contact metamorphic rock rich in silicate minerals
Hornfels
wollastonite, tremolite, grossular garnet, spessartine garnet and andradite garnet are common calc - silicate minerals produced by
contact metamorphism of carbonate
is a common alteration product of periclase in marble and is created during serpentinization of Forsterites
Brucite - Mg(OH)2 … (Talc is also a product of serpentinization of pyroxene)
occurs as a result of the exchange of sodium from seawater for calcium in plagioclase, which converts the plagioclase into albite.
Spilitization
is the name for sodium - rich basalts that form along ocean ridges and volcanic arcs
Spilities
refers to the uniform compressive force directed radially inward by the surrounding mass of water.
Hydrostatic stress
refers to a uniform compressive force exerted radially inward due to the mass of surrounding rock.
Lithostatic stress
What is the lithostatic pressure gradient value?
3 kbar for every 10 km