Talk:Grenville orogeny

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Name[edit]

Whence does the name Grenville refer? LeadSongDog 18:03, 24 September 2007 (UTC)

Grenville geologic province? Grenville County, Ontario? Wiki quote: "The historic county was created in 1792, and named in honour of William Wyndham Grenville, 1st Baron Grenville,..." --Chris.urs-o (talk) 11:57, 5 September 2010 (UTC)

Some questions[edit]

I am assumming that there is a large block of crust that was added to North America and exists as a continuous belt along the eastern US. This would be a Grenville block or Grenville terrane. The article mentions exposures of these rocks but the rocks are probably present at the subsurface of a greater area and may be covered with sedimentary rocks. So the Grenville terrane would extend to a much larger area than where these rocks are visible at the surface.

Does Grenville province refer to the entire block of crust that was accreted to North America by the orogeny, Gondwanan island arc collision event, the island arc which is the Grenville crustal block added to North America. Also, it is also true I am sure that the affects of the orogeny may be seen in rocks that belong to other blocks of crust that the Grenville terrane/block collided with, as well as being present in the terrane/block itself. So the term orogeny or mountain building event would not be exactly the same as the area of crust that is the Grenville terrane/block. Affects of the deformation may be seen in the Grenville block itself and the rocks of other older parts of North America it collided with.

It would also be interesting to have more links to articles with more information about the older crustal blocks further inland from the Grenville block, which the Grenville collided with. There are dozens of other island arc accretions in a sequence into North America and deep into the precambrian craton, which have been given names as well. The continental crust tends to get older towards the west. As well, the east it seems that the Grenville is bounded by the taconic terrane which is 500 my old, and exotic terranes such as the Carolina and Avalonian (added during to Acadian orogeny), which seem to be 700 my old crustal exotic Gondwanan blocks added 350 my years ago to North America, and to the South by Suwanee/Florida, seemingly a 1.4 by a exotic Gondwanan terrane, added during the Alleghanian orogeny.

Millueradfa (talk) 17:34, 3 June 2010 (UTC)

If I'm right. It is a closing of an ocean and a collision of cratons. As the closing of the Iapetus Ocean and the Caledonian/Acadian orogenies; Wilson Cycle. --Chris.urs-o (talk) 05:29, 17 August 2010 (UTC)
I do not believe that is correct. The Grenville terrane sounds what I have heard as a island arc collision with north america which is the main mechanisms by which continents expands. Basically a continent consists of a quilt of such island arcs to a large extent. The fact the article mentions there is no overprint over the original orogenic event implies that the Grenville is an island arc added to North America and has not seen much metamorphesis since. Different types of radiometric dating can show the age of separation of from the mantle and other later metamorphic dates. Grenville may be an island arc consisting of what was originally oceanic crust, then transformed by a subduction arc volcanism to continental crust, say, 100 million years later. Grenville, might have an associated orogenic event, as well as having an associated crustal block. The taconic is a later such event which added yet more crust. It is important to make a distintinction between orogeny and the crustal block that was added. Millueradfa (talk) 23:39, 22 August 2010 (UTC)
Well, wiki text quote: "From about ca. 1190-980 Ma (the actual timing varies by locality) two separate continental blocks collided with Laurentia" (North American craton). User:Zyzzy2, alias R. Stern (University of Texas, Dallas TX) did a good work. New England and the Taconic orogeny might were island arcs. The Labradorian events (1710-1600 Ma) accreated an arc. Maybe the main reference helps, follow the hyperlink to google books. The orogeny is huge (Labrador to Mexico), two cratons colliding is more probable.
  • Tollo, Richard P.; Louise Corriveau, James McLelland, and Mervin J. Bartholomew (2004). "Proterozoic tectonic evolution of the Grenville orogen in North America: An introduction". In Tollo, Richard P.; Corriveau, Louise; McLelland, James et al. Proterozoic tectonic evolution of the Grenville orogen in North America. Geological Society of America Memoir 197. :Boulder, CO. pp. 1–18. ISBN 9780813711973. 
    • Quotes, page 4: "1. A major series of tectonic events occurred throughout the Grenville Province of Canada at the Adirondacks at ca. 1080 to 980 Ma reflecting a period of strong continent-continent collision." - "2. An earlier period of largely accretionary tectonic activity ended at ca. 1180 Ma."
    • Quote: "The Grenville Province exposes the deep crustal root of a Himalayan-type collisional orogen. However, most of its components predate collisional orogeny, and the main episodes of crustal build-up are Andean in type." (Louise Corriveau, Serge Perreault and Anthony Davidson, Prospective Metallogenic Settings of the Grenville Province, Geological Survey of Canada)

To open this question again. The grenville is a huge orogen, however, island arcs tend to be very long, and could be as long as this orogen. It is also possible for there to be collisions of cratons involved, with an island arc sandwiched between, or to have some parts of the orogen a continent to continent collision and other parts an island arc collision. I seem to read a lot about The Grenville Province which sounds like to be referring to a large area of rock that was part of the grenville island arc that slammed into eastern North america. It exists in Alabama and Georgia and seems to underlie atlanta, ga, among other places.

Later on exotic blocks, in the USA were added to the eastern edge of this, Such as Avalonia-Carolina and Suwanee.


Look at this, it certaintly sounds like they talk of Grenville as being a block of crust: [1]

Edit:

more stuff http://geosphere.gsapubs.org/content/3/4/220.full [2]

Millueradfa (talk) 04:30, 24 September 2012 (UTC)

I do see that it is a continent to continent collision. Confusing the issue, is various maps that show a grenville province, as if this is a distinctive area of crust that has a particular lithospheric age and is made to look like it is an island arc added on. So this creates confusion, is it an island arc of new crust, or is it a zone of deformation of existing crust. As wel the maps even show rock that is of the same age as the grenville orogen in those areas. More confusion. Is th rock intrusive into long pre-existing rock, or is it intrusive into a new island arc? Granite in a new island arc may only be just 300 million years seperated from the lithosphere age, which would be the initial formation of the oceanic crust, due to the probable 300 million year turnover of oceanic crust, later intruded by granites and other island arc rocks. In geology, we all know that the earths crust is initially solidified and cooled into igneous rock. It may then be later intruded into by plutons and other intrusive rocks, as well as crossed by failed rift centers. We know rock can be subject to metamorphosis that may alter some radiometric dates. I of course know that it is a mistake to take the date of a intrusive rock as the date of the lithosphere of a location, since intrusive rocks can be injected much later. Some people also tend to think of mountains having an age, as if the mountains rock was formed at the same time as the mountains. Things like the "appallachians are the oldest mountains on earth" is wrong at so many levels. It leaves one to believe that the appallachians rocks are very old, or that the mountains we see today are the same ones as 400 million years ago. This is clearly nonsense. The fact the mountains occur due to uplift at the same location does not make them the same mountains, since the old mountains previously eroded away, even the rock is different. As well, they are caused by different tectonic events. As well, the rock they are made of us much older than the mountain. — Preceding unsigned comment added by 24.73.53.145 (talk) 03:04, 25 September 2012 (UTC)

Timeline of Laurentia[edit]

Seriously in need of revision[edit]

This article on this very important event is just a very sad effort. It is filled with geology jargon rendered in the most boring manner conceivable - it literally is sleep inducing to read through all this, factual though it may be. I know traditionally geologists are boring writers, but this is just a poor effort. There must be someone who knows the geology yet can write about it with some sense of historical sweep and within the entire context of Earth's history. Antimatter33 (talk) 05:27, 22 December 2011 (UTC)


lightning strikes twice ???[edit]

The proposed Grenville orogeny precisely, exactly, and completely overlies known, later, mountain building events, e.g. Taconic orogeny, Acadian orogeny, from the Phanerozoic eon. Perhaps those later orogenies merely uplifted and exposed older, highly metamorphosed, rock? But perhaps those older rocks did not themselves form, in a "pre-Appalachian" orogeny? What is the probability, that Laurentia would converge on other plates, from exactly the same angle, uplifting mountains in exactly the same place, along exactly the same line, over a half billion years apart ?? Would somebody please acknowledge, or logically prove why otherwise, that as lightning never strikes the same place twice, so a hypothetical Grenville orogeny occurring in exactly the same regions of Laurentia, a billion and a quarter years ago, as the Appalachian-related orogenies, a quarter billion years ago, seems prima facie implausible?

Repetitiously, in broad brush strokes, all of the alleged "Grenville" rocks are amphiboles, metamorphosed at depths up to 50km (eclogite). That is about the depth of continental crust underlying the Himalayas; and the Phanerozoic Appalachian-related orogenies, which uplifted the central Pangean mountains, are thought to have generated "Alps or higher" mountains. Appealing to parsimony, perhaps those known, more recent, orogenies, (re-)metamorphosed, & uplifted, deep crustal (amphibole) rocks? Is there no other, alternative, explanation for observations, other than speculating, that over a billion years ago, a "Grenville mountain range" was uplifted, along exactly the same track, across exactly the same span, as the Pangea-related Appalachians, over three-quarters of a billion years later?66.235.38.214 (talk) 00:35, 29 October 2012 (UTC)

Get some good references and add some solid content ... or is it all speculation? This page is for discussing improvements to the article -- so what improvements are you suggesting? Vsmith (talk) 12:47, 29 October 2012 (UTC)

Amazonia[edit]

I am no specialist of geology. But I looked after the reference stating that Amazonia was NOT the continent at the origin of the Grenville orogeny. Actually, the reference is a secondary source and only mentions that this question has been investigated earlier. I then went at the primary source: http://globalchange.umich.edu/ben/Publications/EPSL02a.pdf and that primary source provides evidence that is actually rather supporting to the Amazonia-Laurentia collision. Unless I'm wrong, I think the text should be amended. — Preceding unsigned comment added by 184.160.212.197 (talk) 05:58, 19 August 2013 (UTC)