Clay mineral formation in DSDP Leg 34 basalt |
| |
| Authors: | WE Seyfried WC Shanks WE Dibble |
| |
| Institution: | Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN U.S.A.;Department of Geology and Geophysics, University of Wisconsin, Madison, WI U.S.A.;Department of Geology, Stanford University, Stanford, CA U.S.A. |
| |
| Abstract: | A blue-green smectite (iron-rich saponite) and green mica (celadonite) are the dominant sheet silicates in veins within the 10.5 m of basalt cored during DSDP Leg 34, Site 321, in the Nazca plate. Oxygen isotopic analyses of these clays, and associated calcite, indicate a formation temperature of≤25°C.Celadonite contains appreciable Fe2O3, K2O and SiO2, intermediate MgO, and very little Al2O3. Celadonite is commonly associated with goethite and hematite, which suggests that this phase formed by precipitation within a dominantlyoxygenated environment of components leached from basalt and provided by seawater. A mass balance estimate indicates that celadonite formation can remove no more than 15% of the K annually transported to the oceans by rivers. In contrast, iron-rich saponite containing significant Al2O3 appears to have precipitated from anon-oxidizing, distinctly alkaline fluid containing a high Na/K ratio relative to unmodified seawater.Seawater-basalt interaction at low temperatures, resulting in the formation of celadonite and smectite may explain chemical gradients observed in interstitial waters of sediments overlying basalts. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
