Geologic Constraints on Landscape Evolution of the Sierra Nevada, California: Paleochannels, Magmatism and Structure

加利福尼亚州内华达山脉景观演化的地质约束：古河道、岩浆作用和结构

• 批准号: 0711181
• 负责人: Cathy Busby
• 金额: $ 22.5万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-15 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711181&HistoricalAwards=false
• 关键词: Geologic; Constraints; Landscape; Evolution; Sierra

The age and uplift history of the Sierra Nevada are currently the subjects of geologic debate The goal of this research project is to characterize the landscape evolution of the central Sierra Nevada over a time period of tens of millions of years by using Cenozoic volcanic and sedimentary rocks in order to determine linkages of volcanism and faulting to tectonic events through a three-fold research effort. First, detailed mapping, sedimentary facies analysis, and dating of Tertiary strata preserved in paleochannels are being used to understand the evolution of the central Sierran landscape and how it compares with that of the rest of the range. These paleochannels had their headwaters in central Sierra Nevada, and material within them was transported westward to the present-day Sacramento Valley. Strata preserved in these paleochannels provide a record of uplift and re-incision events that can be linked to tectonic processes. The research project will test the idea that three episodes of Cenozoic uplift may have occurred in the central Sierra and the timing of these may correspond to the: (1) onset of arc magmatism about15 million years ago, (2) onset of Basin and Range faulting about10 million years ago, and (3) arrival of the triple junction about 6 million years ago. Second, structural mapping and dating of volcanic-volcaniclastic and intrusive rocks are being used to determine the inception age of range-front faulting in the central Sierra Nevada, its nature, and whether it proceeded continuously or episodically. Much of the present-day to Quaternary displacement between the Sierra Nevada block and the rest of the Great Basin is being taken up along the western edge of the Walker Lane belt (an approximately 150 km wide complex system of dominantly right-lateral strike slip faults that currently accommodates about 20-25% of the Pacific-North America plate motion) in the range-front faults of the Sierra Nevada. Third, Neogene volcanic and intrusive rocks centers in the central Sierra Nevada are bieing investigated to understand the paleogeographic and tectonic evolution of the Tertiary Ancestral Cascades arc. In particular, the project will explore the idea that three phrases of volcanism may have occurred in the ancestral Cascades arc of the Sierra Nevada: at about 14-15 million years ago, 9-10 million years ago, and 6-7 million years ago.The Sierra Nevada is the longest and tallest mountain chain in the coterminous U.S. It has also long been considered to be among the youngest, with uplift through Late Cenozoic tilting of a rigid block about faults along its eastern margin. More recent research, however, has proposed a more complex uplift history for the Sierra Nevada, and some have argued that the range is very old. Additionally, the Sierra Nevada is considered the prototype of a fundamental process in mountain building, accomplished by foundering of lithosphere into the Earth's mantle (root delamination). This research project will provide new data that will contribute to the understanding of this important mountain range and help resolve some of these controversies. Furthermore, results will inform the history of faulting in a heavily populated area of active seismicity, the Reno-Bridgeport area. Finally, the project will engage students in scientific research and will foster participation of underrepresented groups in the earth sciences.

内华达山脉的年龄和隆升历史目前是地质争论的主题，该研究项目的目标是在内华达州中部内华达州中部内华达州的景观演变中，在数百万年内，通过使用新生代的火山和沉积物岩石来确定通过火山和有缺陷的事件进行三分之二的事件，通过使用库诺卡的火山和沉积物来表征数千万年的时间。首先，正在使用详细的映射，沉积相分析和保存在古呼通道中的三级地层的约会，以了解中央塞兰景观的演变以及与其他范围的相比。这些古渠道在内华达州塞拉山脉中部设有源头，其中的材料向西运送到当今的萨克拉曼多山谷。这些古渠道保存的地层提供了可以与构造过程相关的隆升和重新切口事件的记录。该研究项目将测试以下想法：塞拉中部可能发生了三集新生代隆起，这些时间可能对应于：（1）大约1500万年前的弧岩岩岩发作，（2）盆地和范围的出现，大约1000万年前的断层，以及大约600万年前的三个三个月的到期。其次，使用火山岩塑形和侵入性岩石的结构映射和日期来确定内华达山脉中部的范围内断层的成立年龄，其性质，以及它是连续还是情节地进行。如今，内华达山脉街区和其余大盆地之间的大部分位移都沿着沃克巷带的西部边缘（大约150 km的右侧式撞击断层宽150 km，目前约有150公里的右侧式罢工断层系统，目前可容纳Pacific-North America Plate Plate Motion的20-25％），该系统可容纳大约20-25％的范围Fangront Fartront Fards seerra nevada seerra nevada。第三，内华达山脉中部的新金元火山和侵入性岩石中心正在研究中，以了解第三级祖先级联弧的古地理和构造进化。特别是，该项目将探讨以下想法：内华达山脉的祖先级联弧线可能发生了三个短语，大约在14-15亿年前，9-1000万年前，而6-700万年前，内华达山脉是内华达州塞拉山脉的最长和最高的山连锁店，这也是美国的最新山脉。沿其东部边缘的断层的僵硬块。然而，最近的研究提出了内华达山脉的更复杂的隆升历史，有些人认为该范围很古老。此外，内华达山脉被认为是山区建筑基本过程的原型，该原型是通过将岩石圈固定到地球的地幔中（根部分层）而实现的。该研究项目将提供新的数据，这些数据将有助于理解这一重要的山脉，并有助于解决其中一些争议。此外，结果将为人口稠密的地震活动区域（Reno-Bridgeport地区）的故障提供信息。最后，该项目将吸引学生参与科学研究，并将促进代表性不足的团体在地球科学中的参与。