Knowledge Resource Center for Ecological Environment in Arid Area
| 项目编号 | 0230383 |
| An Apatite/Zircon (U-th)/He Thermochronometric Study of the Rapid Tectonic Denudation of an Oblique Crustal Section-Southern Sierra Nevada, California | |
| Jason Saleeby | |
| 主持机构 | California Institute of Technology |
| 开始日期 | 2002-12-01 |
| 结束日期 | 2005-11-30 |
| 资助经费 | 268873(USD) |
| 项目类别 | Continuing Grant |
| 资助机构 | US-NSF（美国国家科学基金会） |
| 项目所属计划 | Tectonics |
| 语种 | 英语 |
| 国家 | 美国 |
| 英文简介 | PROJECT SUMMARY The PI's propose to produce a series of (U-The)/He apatite and zircon thermochronologic profiles in the southernmost Sierra Nevada region as a test of the very rapid tectonic denudation of the Sierran batholithic rocks by low-angle detachment faulting in latest Cretaceous-early Paleogene time. This phase of denudation exposed an oblique crustal section through the southernmost Sierra Nevada batholith to a paleodepth of ~35 km. Apatite He studies in the greater Sierra Nevada region to the north have revealed the persistence of a high standing orogenic plateau with long wavelength-high relief fluvial dominated topography during the same time interval. In marked contrast the deepest level exposures of the batholith to the south had subsided to marine conditions by early Eocene time in conjunction with tectonic denudation. These profound along strike variations in the paleogeomorphology of the Sierran magmatic arc can be linked to the tectonic removal of the sub-batholithic mantle lithosphere beneath the southernmost Sierra-northern Mojave Desert region by a shallow flat-slab segment of the subducting oceanic plate, and the related tectonic underplating of Franciscan trench-affinity metamorphic assemblages. The PI's have identified an array of known and apparent high- level batholithic detachment sheets along the southernmost Sierra and northern Mojave Desert region that appear to represent part of the upper crustal rocks that were displaced by the detachment system. They have also identified modern topographic anomalies and anomalous structural-textural overprints in the basement rocks of the southern Sierra region which correspond to the onset of steep gradients in batholith emplacement barometry and its implicit depth of denudation. They interpret these areas to represent the remnants of footwall complexes proximal to the breakaway zones where the northernmost detachment sheets calved off the edge of the orogenic plateau. Vertical apatite and zircon thermochronologic profiles are proposed across these zones as a test of very rapid cooling and tectonic denudation. These profiles will be extended southward along constant elevation profiles to the deepest exposed levels of the batholith in order to further test for regional rapid cooling, and to test for a possible southward migration in progressively deeper levels of denudation with time. The broader goals are to relate the paleogeomorphic evolution of the southern Sierra region to lithosphere-scale tectonics and dynamics, and to relate these findings to the globally important problem of the upward migration and surface exposure of deep crystalline basement rock as related to uplift, erosion, tectonic denudation, and the evolution of lower crust and upper mantle. The proposed research program runs for a period of three years and includes a vigorous program of sample collecting, mineral separation, geochemical analysis, and the synthesis of the new data with existing geological and geochemical data sets. The project will entail partial efforts of the joint PI's and their technical staff, and constitute a major component of a Caltech Ph.D. Dissertation. |
| 来源学科分类 | Geosciences |
| URL | https://www.nsf.gov/awardsearch/showAward?AWD_ID=0230383 |
| 资源类型 | 项目 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/342291 |
| 推荐引用方式 GB/T 7714 | Jason Saleeby.An Apatite/Zircon (U-th)/He Thermochronometric Study of the Rapid Tectonic Denudation of an Oblique Crustal Section-Southern Sierra Nevada, California.2002. |
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