Collaborative Research: Magnitude and timing of shortening in the Greater Caucasus: Locus of Late Cenozoic Arabia-Eurasia convergence?

合作研究：大高加索地区缩短的幅度和时间：晚新生代阿拉伯-欧亚大陆交汇的地点？

• 批准号: 0810067
• 负责人: Nathan Niemi
• 金额: $ 26.78万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0810067&HistoricalAwards=false
• 关键词: Collaborative; Research; Magnitude; timing; shortening

The Greater Caucasus Mountains extend for nearly 1000 km between the Black and Caspian seas and form the northernmost margin of the Arabia-Eurasia collision zone. This range has long been speculated to play a central role in accommodating oblique convergence within the collision. Recent GPS studies indicate shortening rates of 10 to 13 mm/yr across the easternmost Greater Caucasus, which represents 50 to 85% of the total 15 to 20 mm/yr of far-field Arabia-Eurasia convergence. Although GPS and earthquake data clearly imply that the eastern Greater Caucasus now plays a central role in accommodating Arabia-Eurasia convergence, current available data are insufficient to confidently determine if strain has been similarly focused in the range throughout the late Cenozoic. In this three-year project, an international team of scientists from the United States, Azerbaijan, Georgia, and the Russian Federation is testing the hypotheses that: 1) the Greater Caucasus range is a first-order structural system that formed by strain localization within the Arabia-Eurasia collision; 2) surface uplift began approximately 10 million years ago due to focusing of 50 to 80% of total Arabia-Eurasia convergence in the range; 3) the timing and magnitude of both exhumation and shortening systematically decrease from west to east along-strike due to eastward propagation of the range; and 4) strain localization within the Greater Caucasus may be the result of the consumption of a relict ocean basin, of which the Black and South Caspian seas are remnants, that was trapped during formation of the orogen in the late Cenozoic. These hypotheses are tested through a field-based, integrated structural, neotectonic, and thermochronologic study of the Greater Caucasus Mountains and the Kura fold-thrust belt, which flanks the southeastern margin of the range in Georgia and Azerbaijan.Almost 40 years after the advent of the theory of plate tectonics, earth scientists are still debating how continents deform when they collide along the boundary between two converging plates. Addressing this question is important for understanding where, how often, and why deformation is suddenly released during earthquakes along faults, how those faults form and behave over time, why they form in some places and not others. The ongoing collision between the Eurasian and Arabian continents produced the highest mountain range in Europe, and the second largest region of active continental collision on Earth. The center of this collision is defined by the Greater Caucasus Mountains, which extend for approximately 1000 km between the Black Sea to the west and Caspian Sea to the east. This mountain belt appears to have formed in only the last 5 to 10 million years, thus providing an unusual opportunity to study the initial stages of continental deformation and mountain building. Results from this research will advance the understanding of continental deformation, the geological conditions in this region that led to the formation of rich oil reserves in the South Caspian basin and eastern Azerbaijan, and the earthquake hazards in this heavily populated and economically important region. This region has been struck by devastating earthquakes in the past, such as an earthquake in 1988 in Armenia that killed at least 25,000 people. The project will support the Ph.D. research of students at the University of California at Davis and the University of Michigan, while also providing important educational and research opportunities for undergraduate students at both universities.

大高加索山脉在黑海和里海之间延伸近1000公里，形成阿拉伯-欧亚大陆碰撞带的最北边缘。长期以来，人们一直推测这个范围在容纳碰撞内的倾斜会聚方面发挥着核心作用。最近的 GPS 研究表明，大高加索地区最东部的缩短率为每年 10 至 13 毫米，占远场阿拉伯-欧亚大陆辐合每年 15 至 20 毫米总缩短率的 50 至 85%。尽管 GPS 和地震数据清楚地表明，大高加索东部现在在适应阿拉伯-欧亚大陆辐合方面发挥着核心作用，但目前的可用数据不足以自信地确定应变是否在整个新生代晚期也同样集中在该范围内。在这个为期三年的项目中，来自美国、阿塞拜疆、格鲁吉亚和俄罗斯联邦的国际科学家团队正在测试以下假设：1）大高加索山脉是一个一级结构系统，由内部应变局部化形成。阿拉伯-欧亚大陆碰撞； 2) 由于阿拉伯-欧亚大陆总辐合的 50% 至 80% 集中在该范围内，地表隆起大约在 1000 万年前开始； 3）由于范围向东扩展，折返和缩短的时间和幅度从西向东沿走向系统地减少； 4）大高加索地区的应变局部化可能是新生代晚期造山带形成期间被困住的残余洋盆的消耗结果，黑海和南里海是其中的残余物。这些假说通过对大高加索山脉和库拉褶皱冲断带（位于格鲁吉亚和阿塞拜疆山脉东南边缘两侧）进行的实地综合结构、新构造和热年代学研究进行了检验。 距今已近 40 年根据板块构造理论，地球科学家仍在争论大陆沿两个聚合板块之间的边界碰撞时如何变形。解决这个问题对于理解地震期间沿断层突然释放变形的位置、频率和原因、这些断层如何形成和随时间变化、为什么它们在某些地方形成而不是其他地方很重要。 欧亚大陆和阿拉伯大陆之间正在进行的碰撞产生了欧洲最高的山脉，以及地球上第二大活跃的大陆碰撞区域。此次碰撞的中心是大高加索山脉，该山脉西起黑海，东至里海，绵延约 1000 公里。这条山脉似乎是在最近 5 至 1000 万年中形成的，因此为研究大陆变形和造山的初始阶段提供了一个不寻常的机会。这项研究的结果将增进对大陆变形、该地区导致南里海盆地和阿塞拜疆东部形成丰富石油储量的地质条件以及该人口稠密和经济重要地区的地震危害的了解。该地区过去曾遭受过毁灭性地震的袭击，例如 1988 年亚美尼亚发生的地震造成至少 25,000 人死亡。该项目将支持博士学位。加州大学戴维斯分校和密歇根大学的学生研究，同时也为两所大学的本科生提供重要的教育和研究机会。