How cracking explains underwater volcanoes and the Hawaiian bend -- ScienceDaily
The discovery helps explain the spectacular bend in the famous underwater range, the Hawaiian-Emperor seamount chain, where the bottom half kinks at a sixty degree angle to the east of its top half.
"There has been speculation among geoscientists for decades that some underwater volcanoes form because of fracturing," said Professor Dietmar Muller, from the University of Sydney's School of Geosciences in Australia and an author on the research findings published in Nature Geoscience.
"But this is the first comprehensive analysis of the rocks that form in this setting that confirms their origins."
It has long been accepted that as Earth's plates move over fixed hot spots in its underlying mantle, resulting eruptions create chains of now extinct underwater volcanoes or 'seamounts'.
One of the most famous is the Hawaiian-Emperor chain in the northern Pacific Ocean. The seamounts of that chain are composed mainly of ocean island basalts -- the type of lava that erupts above hot spots.
But north of the Hawaiian chain, in a formation called the Musicians Ridge, researchers found samples from seamounts that were not made up of the ocean island basalts you would expect from plates moving over a hot spot.
"The oldest part of the Musicians Ridge formed approximately 90 million years ago from hot spots but these new samples are only about 50 million years old and have a different geochemistry," said Professor Muller.
"They did not form because of a hot spot but because of plates cracking open at their weakest point, allowing new magma to rise to the seabed and restart the formation of underwater volcanoes. They are near extinct hot spot volcanoes because that hot spot action millions of years earlier helped weaken the crust (the layer directly above the mantle) where new volcanoes now form."
Vulnerable spots in Earth's plates crack when they are stressed, in this case due to movement of the Pacific Plate which started to dive or submerge back into Earth's crust at its northern and western edges around 50 million years ago.
The formation of these younger seamounts caused by the deformation of the Pacific Plate at its margins suggests a link to the unique bend in the Hawaiian-Emperor chain.
"We believe tectonic changes along the margins of the Pacific Plate around 50 million years ago put the weakest points of the Pacific Ocean crust under tension and created the youngest Musicians Ridge seamounts," said Professor Muller.
"It also caused the flow in the slowly convecting mantle under the Pacific to change dramatically, to the point that the Hawaiian hot spot in Earth's mantle changed its position.
"The resulting seamounts along the Hawaii-Emperor chain changed their position accordingly and the bend was born."
This work provides a solid foundation for understanding other 'non-hot spot' volcanism seen elsewhere, for example the Puka Puka Ridge in the South Pacific.
Welcome to SUV System Ltd!
SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.
We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.
SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com
Electronic Components distributor:http://www.suvsystem.com
Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html
IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html
LED Distributor:http://www.suvsystem.com/l/LED-1.html
Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html
Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html
Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html
Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html
SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc
we are focus on the following fields,and hope we can help you.
Low Ohmic Resistors Civil IC Capacitor ST Diodes MURATA IC Dialight LED IDT IC Thick Film Resistors AD IC Bipolar Transistors Renesas parts IC PANASONIC Fairchild Semiconductor Transistors FAIRCHILD diodes NEC Diodes ALTERA IC Resistor Arrays Current Sensors Resistors NXP Diodes Ligitek LED TOSHIBA Diodes ROHM Resistors Electronic News ST Transistors Diodes Inc Multi-units Transistors Infineon Technologies Transistors components Switching Diodes Chip Inductors TI IC LINEAR IC Military IC LED IR Diodes LITTELFUSE Diodes INTERSIL IC Cypress IC Freescale Semiconductor Texas Instruments(TI) IC
http://www.suvsystem.com/a/44609.aspx
