The timing and cause of mountain building in central Asia

中亚造山的时间和原因

• 批准号: NE/J014141/1
• 负责人: Richard Walker
• 金额: $ 3.7万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ014141%2F1
• 关键词: timing; cause; mountain; building; central

Plate tectonics (the idea that the Earth's surface consists of a few rigid fragments that deform only in narrow bands round their edges) has been accepted for almost 40 years as an accurate description of the behaviour of the oceanic parts of the Earth's surface. At the same time, it has been equally clear that the continents do not behave like the oceanic plates. Deformation in continents is not restricted to narrow bands at their edges, but is spread many hundreds of kilometres through their interiors. A major example is the the collision of India with Asia, which has led to the formation of mountains stretching from the Himalaya to Siberia, over a distance of 3000 km. A fundamental challenge in the study of continental tectonics is to understand the forces that give rise to the observed deformation - the study of the 'dynamics' of continental deformation. Before we can investigate the dynamics of mountain-building we must first develop an understanding of how the deformation has evolved to the state in which we see it today. Providing precise constraints on the times of initiation of mountain-building, and on its spatial evolution, are thus central to understanding the mechanics of continental deformation. The collision between India and Asia began more than 45 Million years ago, and deformation within the Himalaya and Tibetan Plateau is recorded very soon after that time. The initiation of the major mountain ranges in the northern part of the collision zone is known to be much younger than in the south, but the existing constraints on initiation and subsequent growth in these northerly ranges are too few in number for the full geographic extent, and hence the likely cause, of each stage in the development of the evolving India-Eurasia collision to be examined. I propose a reconnaissance study of the Tien Shan, Dzungar Alatau and Altay mountains of Kazakhstan and western Mongolia. These ranges constitute some of the northernmost parts of the collision between the continents of India with Asia, and very little is known of their development at present. Constraints on the tectonic evolution will come from fission-track and U-Th/He thermochronometry. These techniques, which record the cooling of rocks through the top 1-3 km of the Earth undertaking, will be performed in collaboration with Dr. A. Carter. Of particular interest is the question as to why deformation in the mountain ranges of central Asia started much later than in the Himalaya and Tibet. One potential explanation is that the deformation zone is gradually increasing in width, with the initiation ages of mountain ranges younging to the north. Other leading suggestions are that a rapid rise of the Tibetan plateau 10-15 Million years ago introduced forces in the Asian continent that caused mountain-building to step northwards, or that changes in the forces at the Pacific margin of the Asia caused reorganization of deformation within the interior of the continent. By unravelling the history of mountain building in Kazakhstan and western Mongolia, and by placing firm age constraints on the timing of each stage in their history, I will be able to distinguish between these differing scenarios for the forces responsible for producing the distribution of mountains we see at the present day.We have chosen to focus on the history of mountain building in Kazakhstan and western Mongolia because: (1) The tectonic history of the mountain ranges in this area is poorly understood but is potentially very important for understanding the mechanics of continental deformation in Asia; (2) The mountains are easily accessible, and we have experience of travel in Kazakhstan through a reconnaissance visit in July 2011, such that we are confident that all sampling can be completed successfully in one field-season; (3) Our initial measurements from samples collected from the Altay of western Mongolia indicate that tectonically useful cooling signals are present.

近40年来，板块构造学(地球表面由几个刚性碎片组成，它们只在边缘周围的窄带中变形)一直被认为是对地球表面海洋部分行为的准确描述。与此同时，同样明显的是，大陆的行为与海洋板块不同。大陆的变形并不局限于其边缘的狭窄地带，而是在其内部蔓延数百公里。一个主要的例子是印度与亚洲的碰撞，导致了从喜马拉雅到西伯利亚的山脉的形成，距离超过3000公里。研究大陆构造的一个根本挑战是理解引起观测到的形变的力--研究大陆形变的“动力学”。在我们可以研究造山的动力学之前，我们必须首先了解变形是如何演变到我们今天所看到的状态的。因此，对造山开始的时间及其空间演变提供准确的限制，对于理解大陆变形的机制至关重要。印度和亚洲之间的碰撞始于4500万多年前，喜马拉雅和青藏高原内部的变形在那之后不久就被记录下来。已知碰撞带北部主要山脉的启动时间比南部年轻得多，但对于印度-欧亚大陆碰撞演变过程中每个阶段的发展，对这些北部山脉启动和随后增长的现有限制因素太少，因此无法研究其可能的原因。我建议对哈萨克斯坦和蒙古西部的天山、准噶尔·阿拉托和阿勒泰山脉进行勘察研究。这些山脉构成了印度大陆与亚洲碰撞的最北端，目前人们对它们的发展知之甚少。对构造演化的制约将来自裂变径迹和U-Th/He热年代学。这些技术记录了穿过地球任务顶部1-3公里的岩石冷却过程，将与A·卡特博士合作进行。尤其令人感兴趣的问题是，为什么中亚山脉的变形比喜马拉雅和西藏的变形开始得晚得多。一种可能的解释是，变形带的宽度逐渐增加，山脉的起始年龄向北延伸。其他主要的推测是，1000-1500万年前青藏高原的快速崛起在亚洲大陆引入了力量，导致造山活动向北移动，或者是亚洲太平洋边缘力量的变化导致了大陆内部变形的重组。通过解开哈萨克斯坦和蒙古西部造山的历史，并对他们历史上每个阶段的时间设定严格的年龄限制，我将能够区分导致我们今天看到的山脉分布的不同力量的不同情况。我们选择关注哈萨克斯坦和蒙古西部的造山历史，因为：(1)该地区山脉的构造史知之甚少，但对于理解亚洲大陆变形的机制可能非常重要；(2)山区交通便利，我们有2011年7月在哈萨克斯坦进行考察访问的经验，因此我们有信心在一个野外季节内成功完成所有采样；(3)我们对从蒙古西部阿尔泰采集的样品的初步测量表明，存在构造上有用的冷却信号。

项目成果

Links between climate, erosion, uplift, and topography during intracontinental mountain building of the Hangay Dome, Mongolia

• DOI: 10.1002/2013gc004859
• 发表时间: 2013-12
• 期刊: Geochemistry
• 影响因子: 3.7
• 作者: A. West;M. Fox;R. Walker;A. Carter;T. Harris;A. Watts;B. Gantulga

Variability in surface rupture between successive earthquakes on the Suusamyr Fault, Kyrgyz Tien Shan: implications for palaeoseismology

• DOI: 10.1093/gji/ggy457
• 发表时间: 2018-10
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: E. Ainscoe;K. Abdrakhmatov;S. Baikulov;A. Carr;A. Elliott;C. Grützner;R. Walker

Active Tectonics Around Almaty and along the Zailisky Alatau Rangefront

• DOI: 10.1002/2017tc004657
• 发表时间: 2017-10
• 期刊: Tectonics
• 影响因子: 4.2
• 作者: C. Grützner;R. Walker;K. Abdrakhmatov;A. Mukambaev;A. Elliott;J. Elliott

The Dzhungarian fault: Late Quaternary tectonics and slip rate of a major right-lateral strike-slip fault in the northern Tien Shan region

准噶尔断层：北天山地区一条主要右旋走滑断层的晚第四纪构造和滑动速率

• DOI: 10.1002/jgrb.50367
• 发表时间: 2013
• 期刊: Solid Earth
• 影响因子: 3.4
• 作者: Campbell G