Navigation Links
Oldest Earth mantle reservoir discovered
Date:8/11/2010

Researchers have found a primitive Earth mantle reservoir on Baffin Island in the Canadian Arctic. Geologist Matthew Jackson and his colleagues from a multi-institution collaboration report the finding--the first discovery of what may be a primitive Earth mantle--this week in the journal Nature.

The Earth's mantle is a rocky, solid shell that is between the Earth's crust and the outer core, and makes up about 84 percent of the Earth's volume. The mantle is made up of many distinct portions or reservoirs that have different chemical compositions.

Scientists had previously concluded that the Earth was slightly older than 4.5 billion years old, but had not found a piece of the Earth's primitive mantle.

Until recently, researchers generally thought that the Earth and the other planets of the solar system were chondritic, meaning that the mantle's chemistry was thought to be similar to that of chondrites--some of the oldest, most primitive objects in the solar system. Assuming a chondritic model of the Earth, a piece of the primitive mantle would have certain isotope ratios of the chemical elements of helium, lead and neodymium.

The model that the Earth was chondritic was called into question with a discovery five years ago by a team at the Carnegie Institution of Washington, which suggested the ratio of neodymium on Earth was higher than what would be expected if the Earth were indeed chondritic.

That finding changed the neodymium ratio expected in the primitive mantle and in turn, changed where researchers should be looking to find evidence of a primitive mantle. According to the lead author, Matthew Jackson, "We had been looking under the wrong rock."

Since many of the ancient rocks have melted over time, finding a piece of the primitive mantle means studying lavas. Lavas retain the same isotopic composition of the rocks that have melted into the lava. Therefore, testing the lava's composition is identical to testing the original rock's composition.

When the assumption about the neodymium ratio was altered, Jackson and his colleagues knew they should take a look at lava samples from Baffin Island, since those samples contained the correct ratios of helium and neodymium. They discovered that the lavas also had the correct ratio for lead. The lead isotopes suggest that the samples from Baffin Island date the lava's mantle source reservoir to between 4.55 and 4.45 billion years old, only a little younger than the age of the Earth. The lava sample comes from an ancient rock that melted 62 million years ago.

When the researchers studied the composition of the lava found at Baffin Island, they discovered that the sample had the correct ratios of all three chemical elements--helium, lead, and the new non-chronditic neodymium ratio. This discovery suggests that the sample from Baffin Island is the first evidence for the oldest mantle reservoir.

This study challenges the idea that the Earth has a chondritic primitive mantle and according to Matthew Jackson is, "suggesting an alternative." One possibility, according to Jackson, is that "the early Earth went through a differentiation event and the Earth's crust was extracted from the early mantle and is now hidden in the deep earth; the hidden crust and the mantle found on Baffin Island would sum to chondritic."


'/>"/>

Contact: Kimberly J. Montgomery
kmontgom@nsf.gov
703-292-8463
National Science Foundation
Source:Eurekalert  

Related biology news :

1. Dinosaur-chewing mammals leave behind oldest known tooth marks
2. Ardi displaces Lucy as oldest hominid skeleton
3. Kent State University Professor C. Owen Lovejoy helps unveil oldest hominid skeleton
4. 4,000-year-old coral beds among worlds oldest living things, prof says
5. Researchers uncover worlds oldest fossil impression of a flying insect
6. Breath of the Earth: Cycling carbon through terrestrial ecosystems
7. New book provides summary of research into the origins of life on Earth
8. LSU professor uses volcanic emissions to study Earths atmospheric past
9. Earth microbes may contaminate the search for life on Mars
10. Expert commentary on Earth Days 40th anniversary
11. Touch the Earth to display at Earth Day on National Mall
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Oldest Earth mantle reservoir discovered
(Date:2/2/2017)... 2017   TapImmune, Inc. (NASDAQ: ... in the development of innovative peptide and gene-based ... and metastatic disease, announced today it has successfully ... a second clinical lot of TPIV 200, the ... The manufactured vaccine product will be used to ...
(Date:2/2/2017)... 2017  Central to its deep commitment to ... The Japan Prize Foundation today announced the laureates ... the envelope in their respective fields of Life ... are being recognized with the 2017 Japan Prize ... contribute to the advancement of science and technology, ...
(Date:1/31/2017)... 31, 2017  Spero Therapeutics, LLC, a biopharmaceutical ... treatment of bacterial infections, today announced it has ... from Pro Bono Bio Ltd (PBB) to bolster ... resistant forms of Gram-negative bacteria.   The assets acquired ... a PBB group company. "The acquisition ...
Breaking Biology News(10 mins):
(Date:2/23/2017)... SAN JOSE, Calif. , Feb. 23, 2017 ... an exclusive license for two key immunotherapy technologies ... The first technology provides a method to monitor ... therapy such as PD-L1 and CTLA-4.  The second ... detect if a patient is likely to have ...
(Date:2/23/2017)... ... February 23, 2017 , ... Baltimore ... multiple immunoassay-based threat detection technologies by researchers from the Pacific National Northwest ... detection technology was found to have the best level of detection (LOD) ...
(Date:2/23/2017)... , Feb. 23, 2017 Aviva ... tools, announced the acquisition of GenWay Biotech Incorporated, ... comprehensive service and product offering for both the ... will facilitate growth and enhance capabilities for both ... and ELISA assays will nicely complement ASB,s objective ...
(Date:2/22/2017)... (PRWEB) , ... February 22, 2017 , ... Park ... free AFM Luncheon for all SPIE attendees and Park customers ... just one block from the San Jose Convention Center. The luncheon will feature ...
Breaking Biology Technology: