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Cobb-Eickelberg Seamount Chain

Overview

The Cobb-Eickleberg seamount chain is a range of undersea mountains formed by volcanic activity of the Cobb hotspot located in the Pacific Ocean. The seamount chain extends to the southeast on the Pacific Plate, beginning at the Aleutian Trench and terminating at Axial Seamount, located on the Juan de Fuca Ridge.The seamount chain is spread over a vast length of approximately 1200 km. the location of the Cobb hotspot that gives rise to these seamounts is 46° N -130° W. The Pacific plate is moving to the northwest over the hotspot, causing the seamounts in the chain to decrease in age to the southeast. Axial is the youngest seamount and is located approximately 480 km west of Cannon Beach, Oregon. The most studied seamounts that make up this chain are Axial, Brown Bear, Cobb, and Patton seamounts. There are many other seamounts in this chain which have not been explored.

Cobb-Eickelberg seamount chain extending all the way to Aleutian Trench

Formation

Seamounts are created at hot spots. These are isolated areas within tectonic plates where plumes of magma rise through the crust and erupt at the surface. This creates a chain of submarine volcanoes and seamounts.

The Cobb hot spot is located at the Juan de Fuca Ridge in the Pacific ocean. The Pacific Plate is moving north-westward direction at a speed of ~5.5 cm per year. Periodic volcanic events have led to magma eruption onto the seafloor, forming seamounts. The last known volcanic activity was at Axial Seamount, which is currently directly overlying the hot spot. The total magamtic flux from the Cobb Hot Spot is about 0.3 cubic m/yr.

Although the Cobb hotspot is currently located beneath the Juan de Fuca ridge, this has not always been the case. It went under the Juan de Fuca Ridge when the Pacific plate started moving northwest and eventually the boundary came right on top of the hot spot.

Currently the Axial seamount is the only active seamount. The most recent eruption took place in April-May 2015.

Seamounts

1. Axial Seamount (46°03′ 36″ N, 130° 00′ 0″ W)

The most recent seamount

Axial Seamount is the youngest seamount in the Cobb Eickelberg Seamount chain. Since this is the most active of all the Cobb-Eickelberg Seamounts, it is studied the most to help understand the dynamics of seamounts, volcanic activity, earthquakes, biodiversity, geology and chemistry. The Axial Volcano is about 700 m higher than the Juan de Fuca Ridge and about about 1000 meters higher than the front of the flanking basins on either side. The Axial Volcano plateaus on top and has a relatively smoother relief with rectangular shape of size 3 km x 8 km. 42% of the lava surrounding the volcano ranges from ropy, whorly, or lineated poehoehoe to jumbled chaotic form. The remaining area is mostly pillow basalt. Colonial protozoans, bacterial mats, pogonophorans, meatzoans, polychaetes, bivalves, tubeworms, copepods and many other organisms were found in the region where there were hydro thermal vents present in the caldera. This helped study the varying biodiversity at great depths.

Axial seamount is the only active seamount because it's on top of the Cobb Hot spot. All the other seamounts are inactive since their source of magma, the Cobb hot spot, has moved from the underneath of them.

2. Brown Bear Volcano (6°02′ 40″ N, 130° 27′ 60″ W)

With an age of 0.5-1.5 Million years, Brown Bear Seamount is the second youngest seamount in the Cobb-Eickelberg chain. It is northwest of Axial Seamount and connected by a small ridge. Due to its separation from Juan de Fuca ridge, spreading has very little effect on Brown Bear, so it is not as geologically complex and is not studied in detail. It has a volcanic cone of width 5 km and rises approximately 1000 meters from the ocean floor. The Brown Bear Seamount summit is at a depth of 1400 meters. Geographically, the Brown bear Seamount is separated into two areas, Northwestern and Southeastern, with distinct morphological features. This is thought to be caused by the influence of the mid ocean ridge extensional stress regime. The morphology of the western portion also suggests that it was formed before the hot spot interacted with the Juan de Fuca ridge. The northwestern section of Brown Bear is dominated by large (5km diameter) rounded volcanic cone structure. . The southern portion extends sount of 46.1 deg North and consists of relatively smaller (1-2 km diameter) vlcanic cones.

3. Cobb Seamount (46° 44′ 0″ N, 130° 47′ 0″ W)

The Cobb Seamount rises from a 2750 m basin to within 37 meters of the ocean surface. It is located just 100 km to the northwest of the hot spot. This seamount is at least 3.3 million years old. The Cobb seamount has been extensively studied for its geological features. Cobb seamount was once an island that was 914 meters above sea level which due to erosion became a seamount. Samples collected from this location helped conduct studies that determined the age and geological composition of the rocks. The Cobb Seamount is all basalt and contains phenocrysts of plagioclase, clinopyroxene and the inter granular/interstitial matrix was found to have iron and titanium oxides in them. Video and photographs collected in 2012 from Cobb Seamount have shown a wide variety of biodiversity at the location. 17 benthic taxa were observed through pictures collected from the ROV dives. Most common species included sea cucumbers, squat lobsters, thornyheads, and corals.

4. Patton Seamount (54° 34′ 48″ N, 150° 26′ 24″ W)

3-D bathymetric map of Patton Seamount, a Gulf of Alaska seamount, with two smaller seamounts in the foreground. Deep areas are blue, and shallow areas are red.

Patton Seamount is about 33 million old.Although there is not much information about its geology, the biology at the Patton Seamount is very well studied. The seamount is 183 meters below the ocean surface and the height from the seafloor is 3048 meters.

In July 1999, DSV Alvin was used to explore the biodiversity at the Patton Seamount. The Shallow water community mostly consisted of rockfish, flatfish, sea stars and attached suspension feeders. The community at mid-depths consist of attached suspension feeding organisms like corals, sponges, crinoids, sea anemones and sea cucumbers. The common fish species were the sablefish and the giant grenadier. The deep water community consists of fewer attached suspension feeders and more highly mobile species like Pacific grenadier, popeye grenadier, Pacific flatnose and large mobile crabs.

Volcanic Activity in the past and Eruptions

Currently, the only active seamount is Axial Seamount located directly overtop the hotspot at Juan de Fuca Ridge. The most recent eruption was in April-May 2015, with a prior eruption in 2011. In January 1998, there was also an eruption that was detected seismically. Lava erupted from a 9 km long fissure and the caldera subsided by 3 m during the eruption. In 1983, hydrothermal venting was discovered.

Foraminiferan fossil studies have suggested that Cobb Seamount was a pre-late Eocene volcano. Thus, it was likely volcanically active approximately 40 million years ago. And remained volcanically active until about 3.3 million years ago when the Cobb seamount was formed.

Ar40-Ar39 dating of deep basalt from the Patton seamount shows the age to be 33 million years old, which coincides with the time when the seamount was above the Cobb hot spot. However, there are samples collected from shallower depths of basalt which are younger, suggesting that even after the hotspot volcanism ceases, non-hotspot volcanism can sometimes take place.

Other seamounts of Cobb Eickelberg seamount chain:

• Thompson
• Son of Brown Bear
• Corn
• Pipe
• Warwick
• Eickelberg
• Forster
• Miller
• Murray

References

'It would be good to see some specific articles from the journals you mentioned. You can search directly within those journals' websites, or use databases like Web of Science and Georef through the library's website: http://guides.lib.uw.edu/az.php Erikphred (talk) 03:32, 24 April 2017 (UTC)

Peer Review by Chanelle Cadot

This is looking good so far; I really like the detail that you went into on the different seamounts within the chain. Here are some recommendations:

I think for the introduction that you start off too broad. You don't have to spend that much time talking about seamounts in general, so I would recommend getting rid of that information and go straight into talking about your specific Cobb-Eickelberg chain. I would do this by having your overview actually consist of most of the information that you have listed in the second paragraph of your "location" section. I would start off the overview directly with that first sentence "The Cobb-Eickelberg seamount chain is located in the Pacific ocean" but I would maybe change it to be something to the effect " The Cobb-Eickleberg seamount chain is a range of undersea mountains formed by volcanic activity located in the Pacific Ocean." But yeah, I think you should basically delete all the information prior to that. The second paragraph of your location section has good overview information of your seamount chain so I think you should just convert that paragraph into your overview section. Some additional details you could include would be the exact location of the chain like the range of latitude and longitudes it covers. A figure here showing a seamount or a map of the seamount chain would add a lot. You could also add more quantitative information like what rate the plate is moving at in cm/year, and the location of the Cobb hot spot. You could even give a timeline of how long ago the Cobb hot spot became active and etc. I would also say something at the end like "The primary seamounts that make up this chain are the Axial, brown bear, Cobb, and Patton seamount".

Since I suggested making your location section the overview section, I think you should just get rid of the location section and maybe replace it with a different one like maybe "timeline" or "history of the Cobb-Eickelberg SC". For this section I would give details on how long ago the chain was created, and the evolution of the chain with time.

I like your section on the four different seamounts. I think the content is good but there are some grammar issues so some editing there could be used. As for addition of content, I would like to see more quantitative data like age of all the seamounts. I liked that you had depth and height for them. You could also give a latitude, longitude location of the seamounts. This section would also benefit from a picture of one of the seamounts.

Suggestions for additional sections: If you were looking to add more sections you could do a section on the biology primarily found around this seamount chain. This would include some specific species and you could even talk about the unique chemical and physical properties that make up the living conditions of this area and the ways that the organisms living there have adapted.

References: I tried a couple of links for your references and they seem legit. I like the variety of sources you included. 2601:602:9D01:A02B:35E7:EC6F:5FF9:6F1B (talk) 05:48, 21 May 2017 (UTC)Cadotc (talk) 04:06, 22 May 2017 (UTC)

Peer Review - Kevin

I left this on this page's talk page, here. Pszczolak (talk) 23:10, 21 May 2017 (UTC)

Cobb-Eickelberg Seamount Chain

Currently the article has only basic information about the seamount chain. For eg., its geographical location, the last volcanic event, names of the mounts. I would add more about information about the origin of the seamount, how long it has been in existence, the elevation, any surrounding environments like coral reefs, or islands, biology around it. It is missing information about how it affects the surrounding environment. Knowing information about the chemical, geological, biological and physical changes/effects on the seamount chain's surroundings would be helpful in understanding the role of the seamounts in the oceanographic processes if any. Including magmatic activities happening around the seamount would be helpful. Since there is not much information adding any relevant information should be considered.For eg., Seismological activities,

The Cobb-Eickelberg Seamount Chain: Hotspot volcanism with mid-ocean ridge basalt affinity by Dana L. Desonie, Robert A. Duncan. Journal of Geophysical Research, Solid Earth Journal of geomagnetism and geoelectricity Geological Society of America 1988 centennial celebration.

Part of the week 4 assignment is to "Compile a list of relevant, reliable books, journal articles, or other sources". You only have one so are behind on this. You can use google and the GeoRef database from the UW libraries page. William Wilcock (talk) 05:46, 24 April 2017 (UTC)

Also note that Ashley Lobao (Ailobao) is doing the Cobb Hotspot which is related to your article. You have the seamount chain and Ashley has the hotspot that created it. You should chat with each other William Wilcock (talk) 05:59, 24 April 2017 (UTC)

For the week 3 assignment you added a really good citation for the importance of slab pull but messed up the reference list by adding one into the middle of the article. Somebody fixed that. Look at the article history to see what I mean. I moved your sentence into the end of the previous paragraph since it added to that rather than having it as a paragraph on its own William Wilcock (talk) 00:37, 17 April 2017 (UTC)

This is a thorough review of the two articles. Note that sometimes the introductory paragraphs do not include citations if the material is discussed in more depth below. William Wilcock (talk) 00:37, 17 April 2017 (UTC)

PLATE BOUNDARIES •Is each fact referenced with an appropriate, reliable reference? No. There are a lot of statements that are not being supported by any citations. Right in the first paragraph, the statatement, "The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s and early 1960s" has no citation to verify it. Over all the article lacks citations significantly. There are some citation with links in the references which are to the same article. So that doesn't count as citation.For example 67 is the link to the same page.But there are also some valid citation present. To simply put it, the article needs to be worked on for citations.

•Is everything in the article relevant to the article topic? Is there anything that distracted you? Sometimes the lack of citations would carry me to do my own fact checking which could turn out to be a distraction if I found out something interesting in the process. But other than that, the article has a good and continuous flow, especially in the section "Development of the theory" and "Driving Forces".

•Is the article neutral? Are there any claims, or frames, that appear heavily biased toward a particular position? The article is neutral and whatever references are being used are from reliable resources.

•Where does the information come from? Are these neutral sources? Although some references are simply "goofy", for eg, 67, some are from reliable journals like Nature (for eg., 19).

•Are there sub-topics that are over represented, underrepresented or missing? Personally, for an article that is simply titled "Plate tectonics", this article had enough information in the right amounts.

•Do the illustrations and images add to the article and are there illustrations/images that could be usefully added? Yes, the illustrations and images make it more interesting and help in understanding. A picture could definitely be added for the mid ocean ridge spreading subtopic.

•Check a few citations. Do the links work? Is there any close paraphrasing or plagiarism in the article? Most links do work but some are links to the same article (eg., 67).

•Is any information out of date? Is anything missing that could be added? The theories and information is old but it still holds up true .

•What is the article rated? The article is rated as B class. The rating could improve with adding citations and fixing the references links.

•How does the way these subjects are discussed on Wikipedia differ from how they have been discussed in your prior Earth Science classes? The last topic about celestial bodies has not been mentioned with the plate tectonics sections in the the Earth Science classes I have taken so far. It has always been a different topic withing itself. Yashmeghare (talk) 11:14, 11 April 2017 (UTC)Yashwant

CONVERGENT BOUNDARY

•Is each fact referenced with an appropriate, reliable reference? No, the article lacks citation completely. There is only one citation and it is reliable.

•Is everything in the article relevant to the article topic? Is there anything that distracted you? Yes the article has relevant material but is highly in satisfying due to lack of credibility.

•Is the article neutral? Are there any claims, or frames, that appear heavily biased toward a particular position? There are no biases in the article and it is completely neutral.But none of the information (except one) is scientifically supported.

•Where does the information come from? Are these neutral sources? There is nothing to verify the information except the one source from University of Leeds, mentioned in the Notes section.

•Are there sub-topics that are over represented, underrepresented or missing? There is not enough information presented in this article. It is underrepresented and missing a lot of information.

•Do the illustrations and images add to the article and are there illustrations/images that could be usefully added? The figures mention int he article are good but there could be addition figures like a world map that could point out where the convergent margins are present, as it talks about them.

•Check a few citations. Do the links work? Is there any close paraphrasing or plagiarism in the article? There is only one citation/reference and the link to that works. There is a lot of information which is simply copied and pasted. Plagiarism knows no bounds in this one.

•Is any information out of date? Is anything missing that could be added? The one reference in the article is fairly new.The rest of the article can't be verified due to lack of citations.

•What is the article rated? The article is rated at "start class".