User:Pwise8/sandbox

EAS 4220 Draft your Contributions

Trapped in a time capsule the same size as the diameter of a human hair, the ore-forming liquid in this inclusion was so hot and contained so much dissolved solids that when it cooled, crystals of halite, sylvite, gypsum, and hematite formed. As the samples cooled, the fluid shrank more than the surrounding mineral, and created a vapor bubble. Source: USGS

Fluid inclusion

A fluid inclusion is a microscopic bubble of liquid and gas that is trapped within a crystal. As minerals often form from a liquid or aqueous medium, tiny bubbles of that liquid can become trapped within the crystal, or along healed crystal fractures. These small inclusions range in size from 0.01 to 1mm and are usually only visible in detail by microscopic study.

These inclusions occur in a wide variety of environments. For example, they are found within cementing minerals of sedimentary rocks, in gangue minerals such as quartz or calcite in hydrothermal circulation deposits, in fossil amber, and in deep ice cores from the Greenland and Antarctic ice caps. The inclusions can provide information about the conditions existing during the formation of the enclosing mineral. Fourier transform infrared spectroscopy and Raman spectroscopy can be used to determine the composition of fluid inclusions.

Formation

Hydrothermal ore minerals, which typically form from high temperature aqueous solutions, trap tiny bubbles of fluids or gases when cooling and forming solid rock. The trapped fluid in an inclusion preserves a record of the composition, temperature and pressure of the mineralizing environment. An inclusion often contains two or more phases. If a vapor bubble is present in the inclusion along with a liquid phase, simple heating of the inclusion to the point of resorption of the vapor bubble gives a likely temperature of the original fluid. If minute crystals are present in the inclusion, such as halite, sylvite, hematite, or sulfides are present, they provide direct clues as to the composition of the original fluid.

Fluid Inclusions and Mineral Exploration

Photomicrographs from Pea Ridge, MO, USA of secondary fluid inclusions in apatite (image A) and quartz (images B–H).

Fluid inclusions can provide useful data in mineral exploration due to fluid inclusions characteristics being defined by the mineralization process. The methods used for using fluid inclusions to identify mineral deposits include assessing the abundance of a specific inclusions type, looking into variations in the inclusions' temperatures of phase changes during heating and cooling, and variations in other properties such as decrepitation behavior, and inclusions chemistry. To identify the occurrence of specific inclusion types, observation and point-counting of thin-sections of samples is utilized. If an abundance of similar fluid inclusions are found in a close geographic proximity, one can conclude that the surround rock types are similar if not the same. Using microthermometric properties (changes in temperature during phases changes) is used to characterize and categorize areas that witnessed thermal activity during mineral formation

Fluid inclusions have been used to identify deposits of oil and gas. Drilling cuts, cores, and/or outcrop materials are preserved for their pore-fluids, and the chemistry of the fluid is analyzed with Fluid Inclusion Stratigraphy (FIS). FIS analysis takes the spectrometric reading of a fluid inclusions volatile species and the volatile species are indicative of a natural gas or oil deposit nearby. The abundance of similar fluid inclusions could, however, be attributed to hydrocarbon migration and accumulation, so other techniques such as microphones are used to confirm the presence of the oil deposit after initial detection from fluid inclusions.

Metamorphic signatures

In the recent years, fluid inclusion research has been extensively applied to understand the role of fluids in the deep crust and crust-mantle interface. Fluid inclusions trapped within granulite facies rocks have provided important clues on the petrogenesis of dry granulite facies rocks through the influx of CO₂-rich fluids from sub-lithospheric sources. CO₂-rich fluid inclusions were also recorded from a number of ultrahigh-temperature granulite facies terranes suggesting the involvement of CO₂ in extreme crustal metamorphism. Some recent studies speculate that CO₂ derived by sub-solidus decarbonation reactions during extreme metamorphism has contributed to the deglaciation of the snowball Earth.

This 84-million-year-old air bubble lies trapped in amber (fossilized tree sap). Using a quadrupole mass spectrometer, scientists can learn what the atmosphere was like when the dinosaurs roamed the earth. Source: USGS

Paleoclimate applications

Trapped bubbles of air and water within fossil amber can be analyzed to provide direct evidence of the climate conditions existing when the resin or tree sap formed. The analysis of these trapped bubbles of air provides a record of atmosphere composition going back 140 million years. The data indicate that the oxygen content of the atmosphere reached a high of nearly 35% during the Cretaceous Period and then plummeted to near present levels during the early Tertiary. The abrupt decline corresponds to or closely follows the Cretaceous–Paleogene extinction event and may be the result of a major meteorite impact that created the Chicxulub Crater.

In paleoceanography studies, fluid inclusions can inform about the chemical composition of seawater. The trapped seawater in sediments evaporates and leaves behind the salt content. The depth at which these evaporites are found relative to the composition of the trapped salt allows oceanographers to reconstruct seawater evolution. Air bubbles trapped within the deep ice caps can also be analyzed for clues to ancient climate conditions.

See also

• Melt inclusions
• Inclusion (mineral)

External Links

• Fluid inclusions - USGS
• Amber inclusion - USGS*
• Fluid Inclusion Research at NUI, Galway.

Category:Petrology Category:Mineralogy Category:Geochemistry

EAS 4220 Evaluating Articles

Silica Cycle

Content

The content of the article is very well laid out. The opening paragraph summarizes what the silica cycle is and also the relevance of the cycle other scientific concepts like the carbon cycle. Cycles are better explained with schematics and the author provided diagrams for the reader to visualize the entire cycle with the various sources and sinks. It was a good idea to separate the different spheres of the cycle, that way the reader can read about the silica cycle on terrestrial biomes, marine systems and freshwater systems and then see how they all integrate into each other. Including a section of anthropogenic contributions or disruptions was a good idea because it infers that the understanding of the silica cycle is still not complete and that future research is needed to see how humans have impacted the cycle.

Tone

The tone is formal, neutral, and unbiased. In the "Anthropogenic Influences" section, the author kept the tone unbiased and only provided facts, not an opinion on climate change.

Sources

There are plenty of sources listed and most of the sources are from scientific journals so the information is credible.

Mercury Cycle

Content

The first two paragraph of the introduction section were great, the last paragraph seemed out of place a bit. It should have talked about the mercury cycle as a whole and not a blurb about atmospheric mercury. The author include a diagram of the cycle which was helpful but I would try to find another one with more detail. I would also have preferred that some of the more uncommon vocabulary was linked to another wiki article explaining the word or a brief definition in parentheses. I think adding a section on the relevance of the mercury cycle to day-to-day life or current research would allow the reader to think about how the mercury cycle affects them/others.

Tone

The tone is neutral, informative, and unbiased.

Sources

The sources are all from scientific journals, which attributes to the credibility of the content

Selenium Cycle

Content

The opening section was very informative and descriptive in a short amount of text. The author does a good job describing the special setting that the selenium cycle takes place in. Breaking down the cycle into the two phases is helpful in understanding how the reduction and oxidation of selenium allows for the cycle to be a closed system. Adding a section on current or anticipated research on the selenium cycle or how the selenium cycle is applicable to humans would allow the reader to see the relevance of studying selenium.

Tone

Tone was formal, neutral, and informative; no detection of bias.

Sources

This article only has 4 sources. Even though they all come credible journals, it would be more reassuring seeing more sources because it shows that in the science field, there is a general consensus on the understanding of the Se cycle.

Article Evaluation- Oolitic Aragonite Sand

Content

The article focuses on a basic definition, one common area where the oolitic sand is found (giving more examples would be beneficial), and highlights one commercial use. These are all relevant, however they could be investigated more and multiple examples and explanations would give a more holistic view on the concept. It would be beneficial to describe the process the oolitic aragonite sand undergoes and how it differs from other oolitic sand. All links and citations are working and the article presents accurate data.

Tone

The tone is formal and neutral. The article is unbiased but elaboration on concepts would give the article more depth; as of now, since few examples are listed, the reader gets a 2-dimensional view of the concept

Sources

There are only two references and neither are peer-reviewed. More scholarly sources would benefit the article and would provide the reader with reliable sources for further reading. That being said, the two references are represented well and the content is displayed accurately without bias.

Talk Page

This topic is apart of two WikiProjects: Oceanography and Geology. The talk page was empty and I have uploaded this contribution:

'Hi everyone! My name is Paige and I am an assigned student editor for this page. After reading over the article, I think it would benefit from more sources that are peer-reviewed in order to present content that is put forth by scientific journals. I plan on highlighting the biogeochemical process of oolitic aragonite sand formation and intend to include more commercial uses, engineering applications, and locations. I have listed some sources below, let me know what you think or if you have any sources (preferably recent) you would like to contribute!

Harris, Paul & Purkis, Sam & Ellis, James. (2011). Analyzing Spatial Patterns in Modern Carbonate Sand Bodies From Great Bahama Bank. Journal of Sedimentary Research - J SEDIMENT RES. 81. 10.2110/jsr.2011.21.

Lucia Simone. (1980) Ooids: A review, Earth-Science Reviews, Volume 16, Pages 319-355, ISSN 0012-8252, https://doi.org/10.1016/0012-8252(80)90053-7.

David Altman and Robert G. Dean. (2000), Evaluation of the Suitability and Efficacy of Oolitic Aragonite Sand for Beach Nourishment, Carbonate Beaches

Pwise8 (talk) 19:33, 4 March 2021 (UTC)'

link: Talk:Oolitic aragonite sand#Student Editor