November GEOLOGY and GSA TODAY Media ...(rust growth that are essential issues fo...)
rust growth that are essential issues for understanding the evolution of Earth. They are: (1) Crust of continental composition is generated beneath basaltic volcanic centers in an intra-oceanic arc; (2) the bulk composition of the crust does not change during evolution from juvenile arc crust to mature arc crust; and (3) a process is required to return mafic to ultramafic components of the crust to the mantle to accomplish the evolution from arc crust to continental crust. These new findings resolve a longstanding paradox in the current understanding of the growth of continental crust in intra-oceanic arcs.
Mantle detachment faults and the break up of cold continental lithosphere
Roberto F. Weinberg et al., Monash University, School of Geosciences, Clayton, Melbourne, Victoria 3800, Australia. Pages 1035-1038.
Africa is currently in the process of splitting apart along its famous rift. The matching coasts of Africa and South America mark where these two continents, that now lie thousands of kilometers apart separated over 100 million years ago. There is considerable scientific interest in understanding why and how a stable continent like Africa splits into two, but there are also economic reasons for this interest: sediments deposited in the deep basins formed during continental rifting are currently our major source of oil and gas.
Weinberg et al. used a novel computational approach to investigate how stable continents split and become separated by newly formed oceans in the absence of active volcanism. The numerical models were designed to simulate the splitting of Europe from North America, so that the results could be checked against rock formations preserved offshore Spain and Portugal. Weinberg et al. found that flat-lying fault planes, known as detachment faults, develop naturally in the deeper part of rift systems. These detachments allow doming and exhumation of the deeply buried mantle rocks from underneath the cont
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| Contact: Ann Cairns acairns@geosociety.org 303-357-1056 Geological Society of America Source:Eurekalert |
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