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Result search of : D
Title Description
 Dynamic Metamorphism   
The total of the processes and effects of orogenic movements and differential stresses in producing new rocks from old, with marked structural and mineralogical changes due to crushing and shearing at low temperatures and extensive recrystallization at higher temperatures. It may involve large areas of the Earth’s crust, i.e., be regional in character. CF: dynamothermal metamorphism; regional metamorphism. Syn: dynamometamorphism 
 Dynamic Geology   
A general term for the branch of geology that deals with the causes and processes of geologic phenomena; physical geology. 
 Deposit   
A. Anything laid down. Formerly applied only to matter left by the agency of water, but now includes mineral matter in any form that is precipitated by chemical or other agent, as the ores in veins.
B. Mineral deposit or ore deposit is used to designate a natural occurrence of a useful mineral, or an ore, in sufficient extent and degree of concentration to invite exploitation.
C. Earth material of any type, either consolidated or unconsolidated, that has accumulated by some natural process or agent. The term originally applied to material left by water, but it has been broadened to include matter accumulated by wind, ice, volcanoes, and other agents 
 Damping   
A. In seismology, a resistance, contrary to friction, independent of the nature of the contacting surface. Being proportional to the speed of motion, it diminishes with the latter to nothing. Schieferdecker
B. A force opposing vibration, damping acts to decrease the amplitudes of successive free vibrations. Damping may result from internal friction within the system, from air resistance, or from mechanical or magnetic absorbers. CF: attenuation
C. The loss of amplitude of an oscillation, owing to absorption. See also: critical damping; damping factor. 
 Dunkard Series   
Continental strata, including thin coal seams, similar to the Pennsylvanian, but of Permian age, occurring in North America. Strata of the same age are marine in Kansas, but include marginal red beds with gypsum, and thick salt deposits were formed later in the Kansas Basin.  
 Dunite   
Peridotite in which the mafic mineral is almost entirely olivine, with accessory chromite almost always present. Named by Hochstetter in 1864 from Dun Mountain, New Zealand.  
 Dam Stone   
The wall of firebrick or stone enclosing the front of the hearth in a blast furnace. 
 Dynamic Damping   
Usually found in seismographs or seismometers where damping of motion is desired that is in proportion to the velocity of the moving mass. 
 Dense    Said of a fine-grained, aphanitic igneous rock whose particles average less than 0.05 to 0.1 mm in diameter, or whose texture is so fine that the individual particles cannot be recognized by the unaided eye 
 Dacite   A fine-grained extrusive rock with the same general composition as andesite, but having a less calcic plagioclase and more quartz; according to many, it is the extrusive equivalent of granodiorite. Syn: quartz andesite ancient Roman province of Dacia (now part of Romania). 
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