EXPERIMENTAL STUDY OF BORON GEOCHEMISTRY: IMPLICATIONS FOR FLUID PROCESSES IN SUBDUCTION ZONES
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dc.contributor.author | You C.F. | |
dc.contributor.author | Spivack A.J. | |
dc.contributor.author | Gieskes J.M. | |
dc.contributor.author | Rosenbauer R. | |
dc.contributor.author | Bischoff J.L. | |
dc.date.accessioned | 2020-11-27T03:54:35Z | |
dc.date.available | 2020-11-27T03:54:35Z | |
dc.date.issued | 1995 | |
dc.identifier | https://elibrary.ru/item.asp?id=818336 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 1995, , 12, 2435-2442 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/19709 | |
dc.description.abstract | A comprehensive experimental study, utilizing an autoclave hydrothermal apparatus with a 10B isotopic tracer, has been conducted to monitor the geochemical behavior of sediment B during early subduction zone processes. The partition coefficient of exchangeable B (KD) was determined over a temperature range of 25-350°C, at 800 bars and a water/rock ratio of 3-1.5 w/w. These KD are shown to be a complex function of temperature, pH, and possibly mineralogy. At low temperatures, KD is significantly high at ~4 in contrast to the value of essentially zero at temperatures higher than ~100°C. A KD of zero represents no B adsorption, implying efficient mobilization of exchangeable B at shallow depths during sediment subduction.Our experimental results demonstrate high mobilization of bulk B in sediments (both exchangeable and lattice bound) at elevated temperatures (200-350°C), in good agreement with previous observations of B in metasediments indicating progressive depletion during metamorphism. In addition, this study emphasizes the importance of a possible water/rock ratio dependence of B mobilization. In other words, the degree of sedimentary B mobilization in subduction zones strongly depends on the local thermal structure and porosity distribution. In low geothermal gradient areas, large amounts of porewater are expelled before significant B mobilization has occurred, so that some sedimentary B will survive and get into the deeper parts of the subduction zone.Our results imply that efficient mobilization of B from the subducted slab must occur and that arc magmatism recycles most of the remaining subducted B back to surface reservoirs. A reconsideration of the B budget in subduction zones provides critical information with respect to B sources and sinks in the ocean. | |
dc.title | EXPERIMENTAL STUDY OF BORON GEOCHEMISTRY: IMPLICATIONS FOR FLUID PROCESSES IN SUBDUCTION ZONES | |
dc.type | Статья |
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