What is the rock formed in shock metamorphism?
Rocks produced as mixtures of highly shocked materials ( impactites ) include suevite , a glass-rich breccia first described from the Ries crater, Germany, and large bodies of impact melt rocks (Grieve et al., 1977).
How are metamorphic rocks made by shock metamorphism formed?
A foliated or banded metamorphic rock, which forms when igneous or sedimentary rocks are buried to deep levels in the Earth’s crust (up to several kilometers deep!) where they are changed by extreme heat and pressure.
What are the characteristic features of shock metamorphism?
Shock metamorphism is also characterized by a pro- gressive destruction of original textures with increasing shock pressure, a process that eventually leads to complete melting or vaporization of the target rock (Figs. 4.3, 4.4, and 4.5).
What is the process of formation of metamorphic rocks?
Metamorphic rocks are formed through the transformation of pre-existing rocks in a process known as metamorphism (meaning “change in form”). The original rock, or protolith, is subjected to heat and pressure which cause physical, chemical and mineralogical changes to the rock.
How is shocked quartz formed?
Shocked quartz is usually associated in nature with two high-pressure polymorphs of silicon dioxide: coesite and stishovite. These polymorphs have a crystal structure different from standard quartz. This structure can be formed only by intense pressure (more than 2 gigapascals), but at moderate temperatures.
Does shock metamorphism cause foliation?
Contact metamorphism occurs to solid rock next to an igneous intrusion and is caused by the heat from the nearby body of magma. Because contact metamorphism is not caused by changes in pressure or by differential stress, contact metamorphic rocks do not become foliated.
What is impact or shock metamorphism?
The term ‘shock metamorphism’, synonymous with ‘shock wave metamorphism’ or ‘impact metamorphism’, refers to the range of effects produced by the collision of two bodies, e.g., by the collision of an asteroid with the Earth.
What are the 3 ways metamorphic rocks form?
There are three ways that metamorphic rocks can form. The three types of metamorphism are Contact, Regional, and Dynamic metamorphism. Contact Metamorphism occurs when magma comes in contact with an already existing body of rock.
How are metamorphic rocks formed explain with example?
Answer: They may be formed simply by being deep beneath the Earth’s surface, subjected to high temperatures and the great pressure of the rock layers above it. Some examples of metamorphic rocks are gneiss, slate, marble, schist, and quartzite.
What does shock quartz look like?
Shocked quartz is characterized by the presence of planar deformation features (PDFs)1. They consist of thin, straight, planar lamellae of amorphous or high-dislocation-density material, forming sets of features spaced 2–10 µm apart, oriented along rational crystallographic orientations, e.g., Refs.1,10.
What does shocked quartz indicate?
Quartz grains with shock metamorphic features, commonly referred to as “shocked quartz,” are a typical diagnostic criterion used for the identification of hypervelocity impact structures on Earth (e.g., Stöffler and Langenhorst 1994; Grieve et al.
What causes shock metamorphism?
Shock metamorphism exclusively occurs locally around impact craters and possibly around some diatremes. It is characterized by extremely high P/T conditions (tens of hundred of kilobars) over very short time spans. These conditions result from the passing of a shock wave through the rocks.
Where does shock metamorphism occur?
impact craters
Except for certain laboratory experiments and outdoor detonations of high explosives (including nuclear weapons), evidence of shock metamorphic conditions of extreme pressure and heat on Earth exist only within and around impact craters.
Why is shock metamorphism important?
The recognition, however, of diagnostic mineralogical indicators of, so-called, shock metamorphism established reliable criteria for the occurrence of extreme transient and dynamic pressures in the geologic environment and, hence, the occurrence of an impact event.
What are the two ways metamorphic rocks form?
Metamorphic rocks form when heat and pressure transform an existing rock into a new rock. Contact metamorphism occurs when hot magma transforms rock that it contacts. Regional metamorphism transforms large areas of existing rocks under the tremendous heat and pressure created by tectonic forces.
How is a metamorphic rock formed and what is an example?
Metamorphic rocks formed from direct magma heating and intrusions are termed as thermal or contact metamorphic rocks. Those formed as a result of widely distributed pressure and temperature changes induced by tectonic movements are known as regional metamorphic rocks.
How are metamorphic rocks formed and classified?
Metamorphic rocks are broadly classified as foliated or non-foliated. Non-foliated metamorphic rocks do not have aligned mineral crystals. Non-foliated rocks form when pressure is uniform, or near the surface where pressure is very low.
Is shocked quartz a rock?
Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. Under intense pressure (but limited temperature), the crystalline structure of quartz is deformed along planes inside the crystal.
What event causes shocked quartz?
High pressure associated with volcanic activity can fracture quartz crystals, and proponents of the volcano theory of dinosaur extinction say this is the source of the shock crystals found in sediments from the period.
What is the another name of shock metamorphism?
Introduction. The term ‘shock metamorphism’, synonymous with ‘shock wave metamorphism’ or ‘impact metamorphism’, refers to the range of effects produced by the collision of two bodies, e.g., by the collision of an asteroid with the Earth.
How are metamorphic rocks formed give examples?
Where are metamorphic rocks usually formed?
We often find metamorphic rocks in mountain ranges where high pressures squeezed the rocks together and they piled up to form ranges such as the Himalayas, Alps, and the Rocky Mountains. Metamorphic rocks are forming deep in the core of these mountain ranges.
Why are metamorphic rocks formed by contact metamorphism?
Contact metamorphic rocks form when rocks are heated to high temperatures, usually through contact with an igneous intrusion at a relatively low pressure. The effects of contact metamorphism usually only extend for a short distance from the cooling igneous rock that is providing the heat.
How are metamorphic rocks formed give two examples?
Answer. Metamorphic rocks are formed by complete change of texture and composition of pre-existing rocks through volcanism and diastrophism. For example, slate is formed from clay and graphite from coal.
How are contact metamorphic rocks formed?
Contact Metamorphism occurs when magma comes in contact with an already existing body of rock. When this happens the existing rocks temperature rises and also becomes infiltrated with fluid from the magma. The area affected by the contact of magma is usually small, from 1 to 10 kilometers.