Search results
Results From The WOW.Com Content Network
Original - The rock cycle is a fundamental concept in geology that describes the dynamic transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. Due to the driving forces of the rock cycle, plate tectonics and the water cycle , rocks do not remain in equilibrium and are forced to change as they ...
Grain size in igneous rocks results from cooling time so porphyritic rocks are created when the magma has two distinct phases of cooling. [18] Igneous rocks are classified on the basis of texture and composition. Texture refers to the size, shape, and arrangement of the mineral grains or crystals of which the rock is composed. [citation needed]
Monzonite is a coarse-grained igneous rock. Such rocks are classified by their relative percentages of quartz , plagioclase , alkali feldspar , and feldspathoid (the QAPF classification ). Monzonite is defined as rock having less than 5% quartz in its QAPF fraction and in which alkali feldspar makes up between 35% and 65% of the total feldspar ...
Mineralogical composition of igneous rocks with decreasing silica (SiO 2) content. The rock names for volcanic/extrusive and plutonic/intrusive rocks are written above. Notice that this is a rough way to determine a rock name: the exact difference between the given igneous rocks does not only depend on silica content. Date: March 2009: Source ...
For example, an igneous rock such as basalt may break down and dissolve when exposed to the atmosphere, or melt as it is subducted under a continent. Due to the driving forces of the rock cycle, plate tectonics and the water cycle , rocks do not remain in equilibrium and change as they encounter new environments.
Example of the application of identifying geological structures and rock contacts using aerial photographs. The black dash lines refer to some local faults which are determined according to the photo-lineaments. The yellow area is the deposits. The pale blue area is volcanic rock. The blue area (bottom right) is rhyolite. The pink area is granite.
Igneous rocks include rocks that have solidified from a melt either below the surface of a planet or natural satellite as intrusives or on the surface as extrusives or volcanic eruptions. The main article for this category is Igneous rock .
QAPF diagram for classification of plutonic rocks. A QAPF diagram is a doubled-triangle plot diagram used to classify intrusive igneous rocks based on their mineralogy. The acronym QAPF stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)", which are the four mineral groups used for classification in a QAPF diagram. The ...