What kinds of textures are indicative of the exsolution process?
Exsolution texture, a general term for the texture of mineral intergrowth formed by solid exsolution, is a common texture in minerals from both magmatic and metamorphic rocks. This texture is important for understanding variations of metamorphic conditions.
What is exsolution lamellae?
Exsolution is a process by which a solid solution phase unmixes into two separate phases in the solid state. These lamellae result from the exsolution of a separate pyroxene phase from a host grain due to subsolidus re-equilibration (that occurs while the mineral is in the solid state) during slow cooling.
What is a exsolution lamellae in geology?
[¦ek·sə′lü·shən lə′mel·ē] (geology) Layers of sedimentary rock that solidify from solution by either precipitation or secretion.
What is graphic texture in geology?
Graphic texture refers to the regular intergrowth of two minerals, one of them generally serving as a host and the other appearing on surfaces of the host as striplike or cuneiform units with grossly consistent orientation; the graphic intergrowth of quartz in alkali feldspar is…
What is Orthopyroxene made of?
In Earth’s crust, pyroxenes are found in a wide range of igneous and metamorphic rocks. They are most abundant in the dark-colored igneous rocks, such as basalt and gabbro, that comprise most of the oceanic crust….
| Physical Properties of Pyroxenes | |
|---|---|
| Chemical Classification | Silicate |
| Specific Gravity | 3 to 4 |
What causes exsolution?
exsolution, in mineralogy, process through which an initially homogeneous solid solution separates into at least two different crystalline minerals without the addition or removal of any materials. In most cases, it occurs upon cooling below the temperature of mutual solubility or stability of the solution.
Which mineral has the exsolution lamellae structure?
pyroxene structure The lamellae are exsolved along specific crystallographic directions, producing oriented intergrowths with parallel and herringbone texture.
What is Corona texture?
Corona texture: several concentric layers of one or more minerals completely encircling an older phase. The layers (which range from one to five in number) represent a sequence of reactions that have taken place (none to completion) to replace the mineral in the core or center of the corona.
What is Myrmekitic texture?
Myrmekitic texture defined by wormy (rounded) intergrowths o quartz and K-feldspar in plagioclase which is adjacent to K-feldspar. Probably forms as a result of subsolidus exchange.
What is exsolution texture?
Exsolution texture, a general term for the texture of mineral intergrowth formed by solid exsolution, is a common texture in minerals from both magmatic and metamorphic rocks. This texture is important for understanding variations of metamorphic conditions.
What are the two views in subsubsolidus reaction textures?
Subsolidus reaction textures Many of the images have two views, most showing paired plane- and cross-polarized light images. Move the cursor over the visible image to see the other view. Degree of crystallinity
What are exsolution lamellae and how do they occur?
The exsolution lamellae are crystallographically controlled by the host minerals. They occur as one or more groups of oriented rods/needles strictly aligned along the structural defects of the host minerals. Exsolution texture induced by cooling: Clinopyroxene (Cpx) exsolution in orthopyroxene (Opx) or vice versa.
What is a subsolvus granite?
Granites containing two distinct populations of potassic and sodic feldspars are referred to as subsolvus granites. Modified from Tuttle and Bowen (1958). At PH 2 O = 200 MPa any feldspar precipitated from a melt is a homogeneous alkali feldspar solid solution.