|
ИСТИНА |
Войти в систему Регистрация |
Интеллектуальная Система Тематического Исследования НАукометрических данных |
||
Major and trace element fluxes at carbonated metabasite-peridotite interface: insight from experimental modelingтезисы доклада Тезисы
- Авторы: Perchuk A.L., Yupaskurt V.O., Griffin W.L., Shur M.Yu, Gain S.E.M
- Сборник: 12th International Eclogite Conference High- and ultrahigh-pressure rocks - keys to lithosphere dynamics through geologic time cre, Abstract book and mid-conference excursion field guide
- Тезисы
- Год издания: 2017
- Место издания: Sweden
- Первая страница: 103
- Последняя страница: 103
- Аннотация: Although there is a consensus that dehydration of downgoing oceanic lithosphere can release tremendous volumes of fluid, there are no decisive arguments to favor its porous or focused flow and related element transfer through the mantle wedge. We present the results of pistoncylinder experiments with natural rocks and mineral separates, carried out at 750-900o C and 2.9 GPa - conditions relevant to hot subduction zones. The experiments illustrate the mechanisms of metasomatic alteration of the mantle-wedge rocks such as dunite and lherzolite and transfer of trace elements by infiltration of СОH fluids and/or rhyolitic melts (at T=850o C) released from the carbonate-bearing amphibolite during its eclogitization. Element transfer from the slab to the mantle lithologies in the capsules was implemented by porous, focused and diffusion flow regimes that totally obliterate melt and carbon, and partially water, from the metabasite layer. The porous flow is recorded by growth of OpxrGrtrMgsrChl along the grain boundaries and the dissolution of clinopyroxene in the peridotite layers. The porous flow of the same fluids/melts produces harzburgite mineralogy in the both dunite and lherzolite layers. The focused flow is developed along the side walls of the capsules and is manifested by the development of melt segregations, separated from the host peridotite layers by newly formed OmprGrtrPhl+Opx+Mgs. The diffusion flow leads to the formation of OpxrMgsrGrt reaction zones at the metabasite-peridotite interface. Trace-element compositions of the glasses agree well with high-silica adakites and TTGs, though enriched in K2O compared to TTGs. Trace-element profiling reveals the development of a Eu anomaly in the peridotite layers and diffusion of many trace elements out of the respective layers toward the contact zone. Since the contact zone itself actually is low in these elements, we assume their transfer by fluid/melt migration to the sides. The documented processes might applicable to both Phanerozoic and Precambrian subduction zones. This study was supported by RFBR grant 16-05-00495.
- Добавил в систему: Перчук Алексей Леонидович