Navigation Links
Geological cycle causes biodiversity booms and busts every 60 million years, research suggests
Date:2/23/2012

A mysterious cycle of booms and busts in marine biodiversity over the past 500 million years could be tied to a periodic uplifting of the world's continents, scientists report in the March issue of The Journal of Geology.

The researchers discovered periodic increases in the amount of the isotope strontium-87 found in marine fossils. The timing of these increases corresponds to previously discovered low points in marine biodiversity that occur in the fossil record roughly every 60 million years. Adrian Melott, a Professor of Physics and Astronomy at the University of Kansas and the study's lead author, thinks these periodic extinctions and the increased amounts Sr-87 are linked.

"Strontium-87 is produced by radioactive decay of another element, rubidium, which is common in igneous rocks in continental crust," Melott said. "So, when a lot of this type of rock erodes, a lot more Sr-87 is dumped into the ocean, and its fraction rises compared with another strontium isotope, Sr-86."

An uplifting of the continents, Melott explains, is the most likely explanation for this type of massive erosion event.

"Continental uplift increases erosion in several ways," he said. "First, it pushes the continental basement rocks containing rubidium up to where they are exposed to erosive forces. Uplift also creates highlands and mountains where glaciers and freeze-thaw cycles erode rock. The steep slopes cause faster water flow in streams and sheet-wash from rains, which strips off the soil and exposes bedrock. Uplift also elevates the deeper-seated igneous rocks where the Sr-87 is sequestered, permitting it to be exposed, eroded, and put into the ocean."

The massive continental uplift suggested by the strontium data would also reduce sea depth along the continental shelf where most sea animals live. That loss of habitat due to shallow water, Melott and collaborators say, could be the reason for the periodic mass extinctions and periodic decline in diversity found in the marine fossil record.

"What we're seeing could be evidence of a 'pulse of the earth' phenomenon," Melott said. "There are some theoretical works which suggest that convection of mantle plumes, rather like a lava lamp, should be coordinated in periodic waves." The result of this convection deep inside the earth could be a rhythmic throbbingalmost like a cartoon thumb smacked with a hammerthat pushes the continents up and down.

Melott's data suggest that such pulses likely affected the North American continent. The same phenomenon may have affected other continents as well, but more research would be needed to show that, he says.


'/>"/>

Contact: Kevin Stacey
kstacey@press.uchicago.edu
401-284-3878
University of Chicago Press Journals
Source:Eurekalert

Related biology news :

1. Geological Society of America honors Judge Jones for upholding science in the classroom
2. Scientist uses geological observatories to monitor the health of soils
3. Darwins theory of gradual evolution not supported by geological history, NYU scientist concludes
4. Geological Society of America member scientists, students, and colleagues meet in Texas
5. Breast cancer cells recycle to escape death by hormonal therapy
6. Corralling the carbon cycle
7. Lifecycles of tropical cyclones predicted in global computer model
8. A win-win: U-pick pumpkin farms recycle urban leaves
9. Fish guts explain marine carbon cycle mystery
10. Study finds hemlock trees dying rapidly, affecting forest carbon cycle
11. MicroRNAs help control HIV life cycle
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/20/2016)... DALLAS , June 20, 2016 ... criminal justice technology solutions for public safety, investigation, ... by the prisons involved, it has secured the ... Corrections (DOC) facilities for Managed Access Systems (MAS) ... (4) additional facilities to be installed by October, ...
(Date:6/9/2016)... June 9, 2016  Perkotek an innovation leader in attendance control systems is proud ... work hours, for employers to make sure the right employees are actually signing in, ... ... ... ...
(Date:6/3/2016)... Das DOTM (Department ... hat ein 44 Millionen $-Projekt ... einschließlich Personalisierung, Registrierung und IT-Infrastruktur, an Decatur ... Implementierung von Identitätsmanagementlösungen. Zahlreiche renommierte internationale Anbieter ... aber Decatur wurde als konformste und innovativste ...
Breaking Biology News(10 mins):
(Date:12/2/2016)... 2, 2016 CytRx Corporation (NASDAQ: ... in oncology, today announced the appointment of Earl ... consultant, and private healthcare investor, to its Board of ... with clinical and strategic experience at the highest level," ... CEO. "As one of the world,s leading orthopedic surgeons, ...
(Date:12/2/2016)... ... December 01, 2016 , ... Aerocom Healthcare ( ... hospitals, will present its chain-of-custody solution for tracking and securing medications at booth ... Dec. 4-8, 2016. , Aerocom has a proven solution for tracking medications via ...
(Date:12/2/2016)... ... December 01, 2016 , ... ... Nanowear on their recent FDA Class II 510(k) clearance for their flagship medical ... in commercializing remote cardiac monitoring devices that rely on cloth-based nanosensors. While other ...
(Date:12/2/2016)... The immunohistochemistry (IHC) market is projected ... of 7.3% during the forecast period of 2016 to 2021 dominated ... accounted for the largest share of immunohistochemistry (IHC) market, by end ... , , ... market spread across 225 pages, profiling 10 companies and supported with ...
Breaking Biology Technology: