Isotopes and a smoking gun
Article Abstract:
The earth's geochemical processes have been described as cyclical in nature. Salt changes itself from crystalline form to sedimentary rock when it goes through its cycle while carbon dioxide moves through the biosphere, atmosphere, hydrosphere and soil and rock reservoirs. However, some geochemists believe that a more complex geochemical cycle occurs between the earth's crust and mantle with oceanic crust and sediment settling into the mantle until it rises hundreds of millions of years later. This idea has been supported by isotope data obtained from volcanic rock near Pitcairn Island.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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Evidence from ultra-high-pressure marbles for recycling of sediments into the mantle
Article Abstract:
Analysis of ultra-high-pressure metasediments in the form of calcsilicate marble from the Bohemian massif in Lower Austria indicates that the metasediments equilibrated at a temperature greater than 1,100 degrees C and had an exhumation route different from most other sediments. These findings show that carbonate sediments were drawn from the crust to the mantle by subduction and that a geophysical process may exist whereby sediment is recycled into the mantle.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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Surviving subduction
Article Abstract:
The Earth's crust can lose mass to the mantle as well as gain it. Harry Becker and Rainer Altherr analysed the minerals in metamorphosed limestones from the Dunkelsteiner Wald in northeastern Austria and found evidence that subduction related to plate tectonics had transferred crustal material to the deeper mantle during the Paleozoic era. This discovery bolsters the already strong case for the recycling of crustal sediment.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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