| Project/Area Number |
06640636
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
地球化学
|
|---|
| Research Institution | KYUSHU UNIVERSITY |
|---|
Principal Investigator |
CHIDA Hitoshi Kyushu Univ.Dept.of Earth and Planet.Sci.Associate Prof., 理学部, 助教授 (30144736)
|
|---|
| Project Period (FY) |
1994 – 1995
|
| Project Status |
Completed (Fiscal Year 1995)
|
| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1994: ¥1,300,000 (Direct Cost: ¥1,300,000)
|
|---|
| Keywords | seawater / basalt / hydrothermal fluid / mid-ocean ridge / boron / lithium / fractionation / 水 / 岩石相互作用 / 同位体 / 熱水変質 |
|---|
| Research Abstract |
Seawaer and basalt are reacted using the Dickson-type and the cold-seal type equipments as 150 and 300ﾟC.The final target of this study is to measure boron and lithium isotopic fractionation during seawater-basalt interaction. Isotopic ratios of these two elements are the potential indicator whether seawater has reacted with fresh basalt or with altered basalt. The change in seawater chemistry during the reaction was continuously monitored using the Dickson-type equipment. The cold-seal type equipment was used to make samples, which are free from contamination, especially boron contamination from ambient air. Both equipments were constructed during this study from commercial pressure vessels and electric furnaces. The results obtained by the Dickson-type equipments are summarized as follows : After the temperature of the system was elevated, Mg and SO_4 concentrations in seawater decrease. On the other hand, K concentration increases and Ca also increases after initial depletion. The pH of the seawater decreases initially, but increases later. The change in seawater chemistry were caused by the reaction of Mg in seawater and basalt. Mg in seawater is used to produce hydrous alteration mineral, which makes the seawater pH low. Ca and K are released from the altered basalt instead of Mg. Ca and SO_4 ions form anhydrite (CaSO_4) and SO_4 ion concentration decreases. The rate of the Mg decreace is linear to the logarithm of the reaction time. From the quenched solid sample, smectite was detected by XRD.Boron isotopic compositions of samples will be measured in the coming academic year.
|
