Featured Research

from universities, journals, and other organizations

Arctic Impact Crater Lake Reveals Interglacial Cycles In Sediments

Date:
December 21, 2007
Source:
University of Arkansas, Fayetteville
Summary:
Scientists have taken cores from the sediments of a Canadian Arctic lake and found an interglacial record indicating two ice-free periods that could pre-date the Holocene Epoch. By examining relationships between modern diatom communities and their environment,they can reconstruct various historic environmental changes quantitatively.

The researchers had to pull the equipment into the crater-fed lake using sleds.
Credit: Courtesy of Sonja Hausmann.

A University of Arkansas researcher and a team of international scientists have taken cores from the sediments of a Canadian Arctic lake and found an interglacial record indicating two ice-free periods that could pre-date the Holocene Epoch.

Related Articles


Sonja Hausmann, assistant professor of geosciences in the J. William Fulbright College of Arts and Sciences at the University of Arkansas, and her colleagues recently reported their preliminary findings at the American Geophysical Union meeting.

The researchers traveled by increasingly smaller planes, Ski-doos and finally sleds dragged on foot to arrive at the Pingualuit Crater, located in the Parc National des Pingualuit in northern Quebec. The crater formed about 1.4 million years ago as the result of a meteorite impact, and today it hosts a lake about 267 meters deep. Its unique setting – the lake has no surface connection to other surrounding water bodies – makes it a prime candidate for the study of lake sediments.

Scientists study lake sediments to determine environmental information beyond historical records. Hausmann studies diatoms, unicellular algae with shells of silica, which remain in the sediments. Diatoms make excellent bioindicators, Hausmann said, because the diatom community composition changes with environmental changes in acidity, climate, nutrient availability and lake circulation.

By examining relationships between modern diatom communities and their environment, Hausmann and her colleagues can reconstruct various historic environmental changes quantitatively.

However, most sediments of lakes in previously glaciated areas have limitations – they only date back to the last ice age.

“Glaciers are powerful. They polish everything,” Hausmann said. Glaciers typically carve out any sediments in a lake bed, meaning any record before the ice age is swept away.

However, the unique composition of the Pingualuit Crater Lake led Michel A. Bouchard to speculate in 1989 that the sediments beneath its icy exterior might have escaped glacial sculpting. So in May of this year, Hausmann and her colleagues donned parkas, hauled equipment on ski-doos and slogged through sub-zero temperatures for three weeks so they could core sediments and collect data from the lake.

They carefully carved squares of ice out to make a small hole for equipment, then began a series of investigations that included pulling up a core of the topmost 8.5 meters of sediment. An echosounder indicated that the lake bottom may have more than 100 meters of relatively fine-grained sediments altogether. During the time since the expedition, researchers have examined the physical, magnetic and sedimentological properties of the sediment core.

The sediment core contains mostly faintly laminated silts or sandy mud with frequent pebble-size rock fragments, which is typical of deposits found in water bodies covered by an ice sheet. Sandwiched in the middle of the faintly laminated silts and sandy mud, the researchers found two distinct and separate layers containing organically rich material that most likely date back well before the Holocene, representing earlier ice-free periods. The samples they found contain the remains of diatoms and other organic material, suggesting that they represent ice-free conditions and possibly interglacial periods.

“There are no paleolimnological studies of lakes that cover several warm periods in this area,” Hausmann said. The terrestrial record will be complementary to marine records or to long ice-core records from Greenland.

The international team of researchers in the field included Guillaume St-Onge; Reinhard Pienitz, principal investigator; Veli-Pekka Salonen of the University of Helsinki, Finland; and Richard Niederreiter, coring expert.


Story Source:

The above story is based on materials provided by University of Arkansas, Fayetteville. Note: Materials may be edited for content and length.


Cite This Page:

University of Arkansas, Fayetteville. "Arctic Impact Crater Lake Reveals Interglacial Cycles In Sediments." ScienceDaily. ScienceDaily, 21 December 2007. <www.sciencedaily.com/releases/2007/12/071215212916.htm>.
University of Arkansas, Fayetteville. (2007, December 21). Arctic Impact Crater Lake Reveals Interglacial Cycles In Sediments. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2007/12/071215212916.htm
University of Arkansas, Fayetteville. "Arctic Impact Crater Lake Reveals Interglacial Cycles In Sediments." ScienceDaily. www.sciencedaily.com/releases/2007/12/071215212916.htm (accessed October 25, 2014).

Share This



More Fossils & Ruins News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Fossil Treasures at Risk in Morocco Desert Town

Fossil Treasures at Risk in Morocco Desert Town

AFP (Oct. 23, 2014) Hundreds of archeological jewels in and around the town of 30,000 people prompt geologists and archeologists to call the Erfoud area "the largest open air fossil museum in the world". Duration: 02:17 Video provided by AFP
Powered by NewsLook.com
Oldest Bone Ever Sequenced Shows Human/Neanderthal Mating

Oldest Bone Ever Sequenced Shows Human/Neanderthal Mating

Newsy (Oct. 23, 2014) A 45,000-year-old thighbone is showing when humans and neanderthals may have first interbred and revealing details about our origins. Video provided by Newsy
Powered by NewsLook.com
Weird-Looking Dinosaur Solves 50-Year-Old Mystery

Weird-Looking Dinosaur Solves 50-Year-Old Mystery

Newsy (Oct. 23, 2014) You've probably seen some weird-looking dinosaurs, but have you ever seen one this weird? It's worth a look. Video provided by Newsy
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