Featured Research

from universities, journals, and other organizations

What lies beneath modern New England? Mountain-building and the end of an ancient ocean

Date:
April 26, 2014
Source:
Geological Society of America, The
Summary:
When and where did the ancient Iapetus Ocean suture (the most fundamental Appalachian structure) form? Is part of New England made up of ancient African-derived rocks? What is the Moretown terrane? A new study finds new evidence for an earlier closing of the Iapetus that is farther west than previous studies have reported.

When and where did the ancient Iapetus Ocean suture (the most fundamental Appalachian structure) form? Is part of New England made up of ancient African-derived rocks? What is the Moretown terrane? This new GEOLOGY study by researchers from Harvard, Middlebury College, Boise State University, and Williams College finds new evidence for an earlier closing of the Iapetus that is farther west than previous studies have reported.

Mountain-building events, called "orogenies," in the northern U.S. Appalachia record the closure of the Iapetus Ocean, an ancient precursor to the Atlantic. The Iapetus separated continental fragments of ancestral North America and Africa more than 450 million years ago.

The mountain-building period that affected most of modern-day New England, known as the "Taconic orogeny," is commonly depicted as a collision during the Ordovician period (435 to 500 million years ago) of a North American-derived arc (the Shelburne Falls arc) and the North American margin, followed by accretion of African-derived terranes (groups of rocks with geologic histories different from surrounding rocks) during the Silurian period (410 to 435 million years ago).

New uranium-lead (U-Pb) zircon dating presented here by Harvard researcher Francis A. Macdonald and colleagues demonstrates instead that the Shelburne Falls arc was constructed on an African-derived terrane, which they have named the Moretown terrane. Their geochronologic data reveal that the main Iapetan suture, which marks the location of the Iapetus as it was consumed through subduction, is more than 50 km west than previously suspected.

Macdonald and colleagues conclude that the Moretown terrane lies below North American-derived volcanic and sedimentary rocks of the Hawley Formation, which proves a link between North American- and African-derived terranes. The Moretown terrane and Hawley Formation were both intruded by 475-million-year-old plutonic rocks (rocks formed by magma rising from great depths beneath Earth's surface), suggesting that these terranes were together by this time and that the Iapetus Ocean closed approx. 20 million years earlier than documented elsewhere.


Story Source:

The above story is based on materials provided by Geological Society of America, The. Note: Materials may be edited for content and length.


Journal Reference:

  1. F. A. Macdonald, J. Ryan-Davis, R. A. Coish, J. L. Crowley, P. Karabinos. A newly identified Gondwanan terrane in the northern Appalachian Mountains: Implications for the Taconic orogeny and closure of the Iapetus Ocean. Geology, 2014; DOI: 10.1130/G35659.1

Cite This Page:

Geological Society of America, The. "What lies beneath modern New England? Mountain-building and the end of an ancient ocean." ScienceDaily. ScienceDaily, 26 April 2014. <www.sciencedaily.com/releases/2014/04/140426155348.htm>.
Geological Society of America, The. (2014, April 26). What lies beneath modern New England? Mountain-building and the end of an ancient ocean. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2014/04/140426155348.htm
Geological Society of America, The. "What lies beneath modern New England? Mountain-building and the end of an ancient ocean." ScienceDaily. www.sciencedaily.com/releases/2014/04/140426155348.htm (accessed October 21, 2014).

Share This



More Fossils & Ruins News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Fish Fossil Shows First-Ever Sex Was Done Side By Side

Fish Fossil Shows First-Ever Sex Was Done Side By Side

Newsy (Oct. 19, 2014) A 380-million-year-old fish may be the first creature to have copulative sex - and it was side by side with arms linked, like square dancers. Video provided by Newsy
Powered by NewsLook.com
As Sweden Hunts For Sub, "Cold War" Comparisons Flourish

As Sweden Hunts For Sub, "Cold War" Comparisons Flourish

Newsy (Oct. 19, 2014) With Sweden on the look-out for a suspected Russian sub, a lot of people are talking about the Cold War, but is it an apt comparison? Video provided by Newsy
Powered by NewsLook.com
So, Kangaroos Didn't Always Hop

So, Kangaroos Didn't Always Hop

Newsy (Oct. 16, 2014) Researchers believe an extinct kangaroo species weighed 500 pounds or more and couldn't hop. Video provided by Newsy
Powered by NewsLook.com
1000-Year-Old Viking Treasure Hoard Found in Scotland

1000-Year-Old Viking Treasure Hoard Found in Scotland

Reuters - Light News Video Online (Oct. 14, 2014) A hoard of Viking artifacts dating back over 1,000 years is discovered by a treasure hunter with a metal detector in Scotland. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins