Федеральное государственное бюджетное учреждение науки
Геологический институт им. Н.Л. Добрецова
Сибирского Отделения Российской академии наук
(ГИН СО РАН)
Мир Бурятия "Гравитация науки: Геологический институт БНЦ СО РАН"
Дайджест мировых новостей:
Seismic evidence for overpressured subducted oceanic crust and megathrust fault sealing [2008-12-31] Water and hydrous minerals play a key part in geodynamic processes at subduction zones by weakening the plate boundary, aiding slip and permitting subduction—and indeed plate tectonics—to occur. The seismological signature of water within the forearc mantle wedge is evident in anomalies with low seismic shear velocity marking serpentinization. However, seismological observations bearing on the presence of water within the subducting plate itself are less well documented. Here we use converted teleseismic waves to obtain observations of anomalously high Poisson’s ratios within the subducted oceanic crust from the Cascadia continental margin to its intersection with forearc mantle. On the basis of pressure, temperature and compositional considerations, the elevated Poisson’s ratios indicate that water is pervasively present in fluid form at pore pressures near lithostatic values. Combined with observations of a strong negative velocity contrast at the top of the oceanic crust, our results imply that the megathrust is a low-permeability boundary. The transition from a low- to high-permeability plate interface downdip into the mantle wedge is explained by hydrofracturing of the seal by volume changes across the interface caused by the onset of crustal eclogitization and mantle serpentinization. These results may have important implications for our understanding of seismogenesis, subduction zone structure and the mechanism of episodic tremor and slip. www.nature.com
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Основные научные направления
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Эволюция тектонических структур, магматизма и рудообразования в различных геодинамических обстановках складчатых поясов;
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Геоэкология Байкальского региона
Диссертационный совет Д 003.002.01.
К защите принимаются диссертации на соискание ученой степени кандидата и доктора наук по специальностям: 25.00.04 - петрология, вулканология; 25.00.11 - геология, поиски и разведка твердых полезных ископаемых, минерагения
Действует аспирантура по направлению наук 05.06.01 Науки о Земле по следующим специальностям:
