Collaborative Research: Cenozoic Tectonics and Surface Uplift in North-Central Tibet

合作研究：西藏中北部新生代构造与地表隆起

• 批准号: 0633891
• 负责人: Xixi Zhao
• 金额: $ 38.31万
• 依托单位: University of California-Santa Cruz
• 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: 2007-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0633891&HistoricalAwards=false
• 关键词: Collaborative; Research; Cenozoic; Tectonics; Surface

The collision between India and Asia has forcefully raised the Tibetan plateau, the most extensive region of elevated topography and thick crust on the Earth's surface. The uplift of the plateau may also have played a major role in controlling global climate during Cenozic time. Understanding the uplift history of the Tibetan plateau is one of the main challenges in earth sciences today. Despite more than three decades of active research, there is little consensus regarding the timing of plateau uplift and the tectonic processes by which the plateau was raised. In this collaborative study, researchers from the University of California at Santa Cruz and Indiana University are carrying out an integrated research program combining paleomagnetism (magnetostratigraphy and tectonics), sedimentology (facies descriptions, and paleocurrent and provenance studies), isotopoic dating, and paleoaltimetry (basalt vesicularity and oxygen isotopes) in a series of three latitudinally spaced basins in North-Central Tibet. The primary goals are to reconstruct the Paleogene tectonic history of north central Tibet, assess the relative contribution of upper crustal processes to plateau growth and maintenance, and assess the relative roles of tectonic models that predict early (e.g., approximately 40 million years ago) gradual uplift and those that predict more recent (less than 15 million years ago) abrupt uplift. To achieve these goals, lithostratigraphy and depositional environments in each basin are being compared using standard basin-analysis techniques to characterize the tectonic setting of sedimentation. The detailed new magnetostratigraphic results and radiometric dates will clarify the age of and correlation between these basins. The new paleomagnetic results will also provide pole positions and paleolatitudes to constrain the calculation for the Indo-Asian convergence rate and the amount and timing of tectonic rotation between tectonic blocks in the region. Times series of oxygen isotopes from these basins will provide quantitative information on their topographic development and climatic history. Comparison with vesicularity paleoaltimetry of the lavas may provide an independent check on elevation and remove ambiguity as to whether low oxygen-isotope values signal high paleoelevation of the basins themselves or of regions downwind along the vapor transport path. This research will improve understanding of the tectonic processes of intracontinental deformation related to the India-Asia collision. A definitive uplift history of northern Tibet is important for understanding climate change during Cenozoic time and will place fundamental constraints on the mechanism(s) of plateau formation, which interests a broad scientific community. This project forms the basis for two graduate students' PhD studies, and parts of the project are suitable for undergraduate research theses.

印度和亚洲之间的碰撞强行升高了藏高原，这是地形升高和地壳上最广泛的区域。高原的升高也可能在控制全球气候的时间里发挥了重要作用。了解藏族高原的隆升历史是当今地球科学的主要挑战之一。尽管进行了三十多年的积极研究，但关于高原隆起的时机和高原的构造过程几乎没有共识。 In this collaborative study, researchers from the University of California at Santa Cruz and Indiana University are carrying out an integrated research program combining paleomagnetism (magnetostratigraphy and tectonics), sedimentology (facies descriptions, and paleocurrent and provenance studies), isotopoic dating, and paleoaltimetry (basalt vesicularity and oxygen isotopes) in a series of three西藏中北部的纬度间隔盆地。主要目标是重建西藏北部中部的古近纪构造历史，评估上层地壳过程对高原增长和维持的相对贡献，并评估构造模型的相对作用，这些构造模型的相对作用（例如，早期（例如，大约4000万年前）逐渐提升，以及那些预测最新（不到100万年前）的逐渐增长。为了实现这些目标，正在使用标准盆地 - 分析技术比较每个盆地中的岩性地层学和沉积环境，以表征沉积的构造设置。详细的新磁层学结果和辐射日期将阐明这些盆地之间的年龄和相关性。新的古磁结果还将提供极点位置和古介质，以限制印度亚洲收敛速度的计算以及该地区构造块之间构造旋转的数量和时机。来自这些盆地的Times系列氧同位素将提供有关其地形发展和气候历史的定量信息。与熔岩的囊泡古征比例比较可以为高程提供独立检查，并消除低氧 - 同位素值是否信号信号信号的盆地本身或沿蒸气传输路径下风的区域的古平均化。这项研究将提高人们对与印度 - 亚洲碰撞有关的室内变形的构造过程的理解。西藏北部的明确提升历史对于理解在新生代期间的气候变化很重要，并且将对高原形成机制的基本限制（S）对广泛的科学界感兴趣。该项目构成了两位研究生的博士学位研究的基础，该项目的一部分适用于本科研究。