| Seafloor basalt alteration and chemical change in the ultra thinly sedimented South Pacific | |
| Zhang, Guo-Liang1; Smith-Duque, Christopher2; Zhang, GL (reprint author), Chinese Acad Sci, Key Lab Marine Geol & Environm, Inst Oceanol, Qingdao, Peoples R China. | |
| 2014-07-01 | |
| 发表期刊 | GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
 |
| 卷号 | 15期号:7页码:3066-3080 |
| 文章类型 | Article |
| 摘要 | Determining the relationship between ocean floor basalt alteration and sedimentation is fundamental to understanding how oceanic crust evolves with time. Ocean floor basalts recovered at IODP Sites U1365 (similar to 100 Ma) and U1368 (similar to 13.5 Ma) in the South Pacific have been subjected to remarkably low sedimentation rates (0.71 and 1.1 m/Myr(-1), respectively). We report detailed petrographic and geochemical analysis of basalt cores from these sites in order to investigate what impact sediment insulation has on seafloor alteration beyond 10-15 Myr of ocean crust formation. Both sites exhibit low-temperature (< 150 degrees C) alteration (e. g., iron-hydroxides, carbonate, and quartz) within a predominantly oxidative regime, albeit with markedly different alteration styles and intensity. Alteration at Site U1365, which is predominantly composed of sheet flows, occurs mainly near sheet flow boundaries and fractures. In contrast, Site U1368 comprises interlayered pillows and thin sheet flows that have been subjected to relatively even levels of alteration. Variation of alteration style and intensity between Sites U1365 and U1368 appear closely tied to lithology and crustal structure. Although alteration-induced elemental changes at both sites are similar in, e. g., increasing K, Rb, U, Ba, and Fe3+ and decreasing Fe2+, Ca, and Ni, they show distinct differences in Th, which is significantly decreased at Site U1365 but relatively constant at Site U1368. At both sites enrichment of LREEs relative to HREEs is ascribed to alteration. The greater vein abundance and notably higher Fe3+/TiO2, K2O/TiO2, LOI/TiO2, and Rb/TiO2 ratios of representative samples at Site U1365 compared to Site U1368 are attributed to increased alteration intensity. This is mirrored by greater overall chemical change (Fe2O3, FeO, CaO, K2O, Li, Rb, Pb, and U) observed at Site U1365 than those of Site U1368 and other DSDP/ODP sites between 6 and 46 Ma. Since both Sites U1365 and U1368 endured only minimal sedimentation, we attribute the differences in overall chemical change across the two sites to duration of exposure to seawater. |
| 学科领域 | Geochemistry & Geophysics |
| DOI | 10.1002/2013GC005141 |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS记录号 | WOS:000340557300021 |
| 引用统计 | |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://ir.qdio.ac.cn/handle/337002/23843 |
| 专题 | 海洋地质与环境重点实验室 |
| 通讯作者 | Zhang, GL (reprint author), Chinese Acad Sci, Key Lab Marine Geol & Environm, Inst Oceanol, Qingdao, Peoples R China. |
| 作者单位 | 1.Chinese Acad Sci, Key Lab Marine Geol & Environm, Inst Oceanol, Qingdao, Peoples R China 2.Univ Southampton, Natl Oceanog Ctr, Southampton, Hants, England |
| 第一作者单位 | 中国科学院海洋研究所 |
| 推荐引用方式 GB/T 7714 | Zhang, Guo-Liang,Smith-Duque, Christopher,Zhang, GL . Seafloor basalt alteration and chemical change in the ultra thinly sedimented South Pacific[J]. GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,2014,15(7):3066-3080. |
| APA | Zhang, Guo-Liang,Smith-Duque, Christopher,&Zhang, GL .(2014).Seafloor basalt alteration and chemical change in the ultra thinly sedimented South Pacific.GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,15(7),3066-3080. |
| MLA | Zhang, Guo-Liang,et al."Seafloor basalt alteration and chemical change in the ultra thinly sedimented South Pacific".GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS 15.7(2014):3066-3080. |
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