Catherine Mottram on Dating Rock Deformation

Glossary

calc–silicate - a rock produced by chemical alteration of a rock by hydrothermal and other fluids in which calcium silicate minerals are produced.  Commonly formed by metamorphism of impure limestone or dolostone.

deformation twinning - a response to shear stress where atoms on one side of a boundary plane are located in mirror-image positions relative to the atoms on the other side of the boundary to form twinned crystals.

diagenesis - physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition.

golden spike - a geologic marker created to define the boundary of two geological time periods, such as an epoch, age, or era.

meteoric water - water derived from precipitation, i.e., snow and rain, which includes water from lakes, rivers, and ice melts..

ophiolite - a thrust sheet of oceanic crust and upper mantle rocks that have been obducted over continental rocks to become exposed above sea level.

orogeny - a large-scale process in which a section of the Earth's crust is folded and deformed and compressed to form a mountain range.

pedogenesis - the study of soil formation.

porphyry deposits - a type of mineral deposit that forms from large-scale hydrothermal systems associated with intrusive igneous rocks.

slickenfibres - secondary minerals that form along fault surfaces where the two sides creep past one another rather than sliding suddenly as a result of an earthquake.

slickenside - a polished and striated rock surface that results from friction along a fault or bedding plane.

solidus - in a temperature-pressure phase diagram of a mixture such as a magma, the boundary below which the mixture is entirely solid.

syntectonic - a geologic process or event occurring contemporaneously with tectonic activity such as folding or faulting.

thermochronology - the determination of thermal history of rocks from the recording of events such as mineral crystallization.  Becky Flowers talked about this in her Geology Bites episode.