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| Geochemical investigations of mineral weathering: Quantifying weathering intensity, silicate versus carbonate contributions, and soil -plant interactions | |
| Reynolds, Amanda Christine | |
| 出版年 | 2009 |
| 学位类型 | 博士 |
| 导师 | Quade, Jay |
| 学位授予单位 | The University of Arizona |
| 英文摘要 | This study is the geochemical examination of mineral weathering and its path from hinterland, through sediment deposition and pedogenesis, to its dissolution and eventual uptake into plants or precipitation as carbonate minerals. The three papers examine the rate and character of carbonate and silicate mineral weathering over a wide range of climatic and tectonic regimes, time periods, and lithologies, and focus on very different questions. Examination of the 87Sr/86Sr ratios of architectural ponderosa pine in Chaco Canyon, New Mexico confirms a societally complex style of timber procurement from the 10th to the 12th centuries. In El Malpais National Monument, New Mexico, we measured the 87Sr/ 86Sr ratios in local bedrock and soils and compared them to the leaf/wood cellulose of four conifers (Pinus ponderosa, Pinus edulis, Juniperus monosperma, Juniperus scopulorum), a deciduous tree (Populus tremuloides), three shrubs (Chrysothamus nauseosus, Fallugia paradoxa, Rhus trilobata), and an annual grass (Bouteloua gracilis) and a lichen (Xanthoparmelia lineola). We found that plant 87Sr/86Sr ratios covaried with variations in plant physiognomy, life history, and rooting depth. In addition, the proportion of atmospheric dust and bedrock mineral contributions to soil water 87Sr/86Sr ratios varied predictably with landscape age and bedrock lithology. On the Himalayan floodplain, soils and paleosol silicate weathering intensities were measured along a climatic transect and through time. Overall, carbonate weathering dominates floodplain weathering. But, periods of more intense silicate weathering between 9 - 2 Ma, identified in soil profile and in the 87Sr/86Sr ratios of pedogenic carbonates, appear to be driven by changes in tectonic, rather than climatic, regime. All three papers are good examples of how 87Sr/86Sr isotopic tracer studies can shed light on pedogenic formation rates and internal processes. The complexity of each system warns against generalizations based on just one locale, one species or lithology, or a few isotopic ratios. |
| 英文关键词 | Chaco Canyon El Malpais Mineral weathering Nutrients Silicate weathering Siwalik Soil-plant interactions Strontium isotopes |
| 语种 | 英语 |
| 国家 | United States |
| 来源学科分类 | Geology; Geochemistry |
| URL | https://pqdtopen.proquest.com/doc/304845714.html?FMT=AI |
| 来源机构 | University of Arizona |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/244331 |
| 推荐引用方式 GB/T 7714 | Reynolds, Amanda Christine. Geochemical investigations of mineral weathering: Quantifying weathering intensity, silicate versus carbonate contributions, and soil -plant interactions[D]. The University of Arizona,2009. |
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