User:Ewalde1/Homework1

This is my wikipedia sandbox. It is also where I will complete my first homework to satisfy the requirements of Alex Webb's Tectonics Course.

Identifying and Analyzing Other Tectonics Articles That Can Relate to a 'Slab Graveyard'

Subduction

• Basic Concept: Subduction is the mechanism by which lithospheric crust is recycled into the mantle.
• Suggestions: A more succinct style with links to other articles and smaller divisions between topics of interest might help compartmentalize pieces of the subduction cycle, making it easier for the average user to move through the subduction process with understanding.
• Written Communication: The article is lengthy and in-depth, appropriate for how important subduction is. This is, however, daunting to the average user.
• Visual Communication: Lots of diagrams provide multiple views of the subduction process, but simplistic cartoons like the subduction factory do not help the user understand what is actually going on.

Slab pull

• Basic Concept: Slab pull is a proposed force at work in "pulling down" pieces of lithospheric crust into the mantle during subduction processes.
• Suggestions: The slab pull page could be reorganized to be more clear about the origins of the 'slab pull' term, other proposed forces at work, locations this force is in play.
• Written Communication: The written style of this page is kind of jumbled up and has formatting problems (subscripts, etc). It is reasonably correct in most of its assertions, though.
• Visual Communication: The page has no figures, so this would be a place to improve, especially with a figure from the subduction page that has 'slab pull' written on it.

Seismic tomography

• Basic Concept: Seismic tomography uses the properties of seismic waves to make an 'image' of materials, their structure and their densities inside the earth.
• Suggestions: Tightening up the text could help a lot; it is written in a more informal style with no citations.
• Written Communication: Shorter, more precise sentence structure would help, as would the addition of citations. As is, it explains tomography to the layman well, and this is an approach that should be preserved.
• Visual Communication: There are no figures. It would benefit from some, seeing as how tomography is a visually-oriented technique.

Proposal for a Tectonics Article on Wikipedia

Outline

1. Brief explanation of subduction processes and the role a slab graveyard would play in them
2. Discussion of geochemical importance
   1. Where does sial come from, how is it reclaimed or reused in mantle processes, and why the slab graveyard can be critical to understanding the budgets of chemical elements in the entire Earth system.
3. Outline of slab graveyard theory
   1. Geochemical evidence
   2. Seismic tomography
   3. Heat flow measurements?
4. Criticism and opposing theories

Discussion of Value

The slab graveyard is one theory attempting to explain how crustal recycling at subduction zones affects the geochemical composition of the mantle, and why we have (or have not) seen certain expected geochemical markers. Explaining the sources of our evidence for and against the 'slab graveyard' can lead readers to new insights about large chemical systems and processes beneath the crust.

Structure of Article

The article will be structured to inform the casual reader of the importance of the slab graveyard in understanding the chemical processes at work: why we have enriched magmas that yield tourmalines or gold deposits or diamonds. It is expected that the average reader will arrive at the page through Wikipedia click-throughs, which can consume hours of a user's time. Rather than have the user navigate away from the page because of information density or language that is too arcane, this article will explain the framework within which a slab graveyard is understood, with directions for further reading.

Figures

A figure will be constructed to show seismic tomographic images of the core-mantle boundary, including the area suspected of being a slab graveyard.