User:Hilarynwilson/sandbox

Article Evaluation
Pluton - Stub class

This article is not very extensive, while everything pertains to the topic of plutons, there is a lack of citations and a lack of clear direction with the page. It does not even have a clear definition on what a pluton is. The information is not very recent, 2004 is the most recent date for the citations. There is more current information that could be used, like how they think plutons crystallize, maybe a link to the bowen's reaction series. Some more information into the formation of plutons or links to other mantle processes might be useful in this article, there is a link in the 'see also' section that links to the formation of plutons, and more of that information would be better on the main pluton page or at least linked directly in the article.

The article is neutral, there are no biases.

The citations links do not work, but when you read the articles the information is consistent with what is in the article, however there are interesting and important things in one of the papers that is not mentioned in the article that could have been. These sources are unbiased as they are all from peer-reviewed journals and as such they are reliable.

The conversations on the talk page are based on the confusion on the the definition on what a pluton is. The article is rated stub class and is of mid-importance, and it is part of the Geology WikiProject.

Editing an Article
Method of Pluton Emplacement - Structural relations around stoped blocks subsection

Magmatic fabrics will not record information of the stoping process as they are only formed near the end of the pluton emplacement. Furthermore, any magmatic fabrics that are recorded are likely to be affected by strain. Therefore, the causes of the magmatic fabrics may not be discernable, and at best can only give inferences to the mechanisms for emplacement of the pluton, or magma chamber internal mechanisms.

Critiquing articles
While critiquing Wikipedia articles I learned that it is more important to have up-to-date, accessible, and quality information summarized accurately and succinctly than to have more information. My approach for critiquing the article for Pluton was based on the confusing definition of pluton the article originally had, this was my main inspiration into what needed to be changed and added to the pluton article.

Summarizing contributions
I added a clear definition of what a pluton is, a system to classify plutons and how they differ from dikes and sills. I also added some information on two on the main theories of pluton formation. My article is not only longer but is also has twice as many sources and the sources are all linked so people can at least read the abstracts. The only thing that might be more difficult to find is the igneous and metamorphic textbook, but the information was best for the aim I had for the article.

Peer review
The peer review was helpful but I feel like it would have been more helpful if it were closer to the end of the article writing time, right after we started was a little rushed a I didn't have a clear aim of where I was going to take the article. I was helpful, I just think it could have been done a little later in the semester.

General
I learned to appreciate the articles I look at everyday for fact checking ect. To think that random people created every single article out of the kindness of their heart brings me joy. This assignment was definitely structured differently than I am used to but I did like the check points throughout the process. I hope that this assignment can be used to inspire earth science students to edit and create articles related to what they are studying while it is still fresh. This is important because it can help to inform anybody that wants to learn more about an earth science topic, and sometimes when I tell people I study geology, they still go 'What's that?' and it's not even a rare subject so its weird so many people don't know about it. On another side, geology and other earth sciences is being used to study other planets in our solar system and I personally think that science is at it's most efficient when all the disciplines come together with their personal perspectives to solve a problem. Who knows, one of these articles might inspire someone to enter the field of earth sciences or collaborate with someone else and get a breakthrough in science.

Editing Pluton Article
Notes

A pluton is a general term to describe an intrusive igneous body. Intrusive igneous bodies can be classified into two major groups; tabular or non-tabular. A tabular body is magma that has filled in a fracture. Igneous bodies can be further classified if the body crosses over another fabric or not. A concordant body is one that does not cut across another fabric of the country rock, be that bedding, or other intrusive bodies. A sill is a concordant tabular body, and is generally intruded parallel to the country rock. A discordant body cuts across pre-existing fabrics in the country rock. A dike is a discordant tabular intrusive body. A non-tabular body is classified on the fact it is not a tabular body, and therefore the shape can be irregular and dependent on the methods of emplacement. Non-tabular bodies are typically what are referred to when using the term pluton. Types of non-tabular bodies are stocks and batholiths, which are primarily classified by size. A stock is a pluton that has an exposed area of less than 100 km2, and a batholith is a pluton with an exposed area of anything larger than 100 km2. This is a field classification that does not take into account the true size of the pluton below that surface.

Around the world, the definition for pluton and batholith can be used interchangeably which leads to the confusion in the true definition. Pluton has been used to describe any non-tabular body, and batholith has been used to describe large composites of several plutons. Whereas central Europe describes smaller bodies as batholiths, and uses the term pluton to describe larger bodies.

Plutons can be further classified based on their shape as opposed to their size. This shape classification is based on the shape of the bottom of the pluton. If the pluton pushes the overlying layers of host rock up, and has a flat, concordant with the host rock bottom, then it is classified as a laccolith. If the pluton is emplaced in a basin, it is classified as a lopolith. A lopolith is characterized by a curved bottom and a flat top. The types of magma affect what shape the pluton will have. A laccolith is typically a more siliceous (higher in silica content) and viscous, which means the horizontal flow of the magma is limited enough to push up the overlying rocks. Lopoliths are typically mafic, and therefore less viscous and tend to be much larger than laccoliths. Lopoliths can get their shape from either the weight of the magma that makes up the lopoliths compressing the underlying rock, or the evacuation of a magma chamber deeper in the Earth. Many different shapes of plutons are possible after metamorphic events.

As a pluton is formed when hot magma goes into cool country rock, there can be several chemical or physical interactions in the contact zone. A physical interaction that can be observed would be the presence of xenoliths. Xenoliths are little pieces of country rock that are broken of into the intruding magma and are brought up with the magma and generally represent what is thought to be the deeper parts of the mantle, or crust. Chemical interactions can be alterations in the country rock based on the differences in chemistry. The heat from the injected magma can also cause the country wall rock to undergo contact metamorphism.

= Pluton =

In geology, a pluton is a body of intrusive igneous rock (called a plutonic rock) that is crystallized from magma slowly cooling below the surface of the Earth. ''While pluton is a general term to describe an intrusive igneous body, there has been some confusion around the world as to what is the definition of a pluton. Pluton has been used to describe any non-tabular intrusive body, and batholith has been used to describe systems of plutons. In other literature, batholith and pluton have been used interchangeably. In Central Europe, smaller bodies are described as batholiths and larger bodies as plutons. In practive ther term pluton most often means a non-tabular igneous intrusive body.'' The most common rock types in plutons are granite, granodiorite, tonalite, monzonite, and quartz diorite. Generally light colored, coarse-grained plutons of these compositions are referred to as granitoids. Examples of plutons include Denali (formerly Mount McKinley) in Alaska; Cuillin in Skye, Scotland; Cardinal Peak in Washington State; Mount Kinabalu in Malaysia; and Stone Mountain in the US state of Georgia.

Classification
''Intrusive bodies of igneous rock can be classified from one distinctions. If the body is tabular or not. The bodies can be further classified based on their shape and their concordancy with the surrounding country rocks. A tabular body is magma that has filled in a fracture or another plane of weakness. A non-tabular body however, can vary in shape much more than tabular bodies and tend to be much larger. A concordant body is one that does not cross a pre-existing fabric in the country rock, a sill is an example of a concordant tabular intrusive body. A discordant body is one that does cross pre-existing fabrics in the country rock, a dike is an example of a discordant tabular body. A non-tabular intrusive body is further classified by shape and size. Stock is a term that is used for a non-tabular body that is exposed for less than 100 Km2, and batholith is used to describe anything exposed for larger than 100 Km2. This size classification does not take into account the true size of the body, which is why some ambiguity in the use of pluton came about. A non-tabular body can also be classified based on shape, if the bottom of the body is parallel with the underlying country rock then it is termed a laccolith. If the bottom of the body is in a basin and the top of the body is flat then it is a lopolith. A laccolith is thought to be formed when more siliceous and thus more viscous magma is intruded. The horizontal movement of the magma is limited by the viscosity, which leads to the magma pushing the rock above it up creating a dome shape. Lopoliths are believed to have a more mafic, and therefore less viscous, source. Lopoliths tend to be larger than laccoliths, and are believed to get their lenticular shape from the weight of the intruding magma compressing the underlying country rock, or the shapes comes from the evacuation of a magma chamber below the intruding magma, causing the country rock to collapse and creating a basin. Some of these terms might be outdated to accurately describe the shape of a pluton but they are still commonly used.''

Formation
Plutons are believed to be formed from either one single magmatic event, or several incremental events. Recent evidence suggests the incremental formation model is more likely. While there is little visual evidence of multiple injections in the field, there is geochemical evidence. Zircon zoning is a key part to determining if a single magmatic event or a series of injections were the methods of emplacement. Another side of this incremental theory is that plutons formed from the amalgamation of small intrusions, which would mean the pluton would be less heterogeneous because the small intrusions would occur around the same time as each other and from similar sources. The incremental model suggests that there is more time inbetween injections to account for the fractional crystallization that allows the newest injection to go in to the least crystallized part of the body.

See also[edit]

 * Methods of pluton emplacement
 * Subvolcanic rock
 * Volcanic rock

References[edit]

 * Glazner, A. F., Bartley, J. M., Coleman, D. S., Gray, W. and Taylor, R. Z. (2004). "Are plutons assembled over millions of years by amalgamation from small magma chambers?" GSA Today, 14 (4: April), pp. 4–11.
 * Young, Davis A. (2003). Mind Over Magma: the Story of Igneous Petrology. Princeton University Press. ISBN 0-691-10279-1.