Collaborative Research: Retreating-trench, extension, and accretion tectonics (RETREAT): a multidisciplinary study of the northern Apennines

合作研究：后退-海沟、伸展和增生构造（RETREAT）：亚平宁山脉北部的多学科研究

• 批准号: 0208299
• 负责人: Darrel Cowan
• 金额: $ 39.03万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-10-15 至 2010-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0208299&HistoricalAwards=false
• 关键词: Collaborative; Research; Retreating; trench; extension

0208299CowanThe paradox of how horizontal contraction and extension can occur simultaneously in convergent mountain belts remains a fundamental and largely unresolved problem in continental dynamics. The Apennines represent one of the most accessible "type locality" areas of syn-convergent extension. Rollback - which describes the tendency of a subducting plate to retreat from the orogenic front - is commonly invoked as an explanation for syn-convergent extension, but this idea does not address how the retrograde motion of the subducting plate, which is a mantle-based process, causes horizontal extension in the overlying zone of crustal convergence, especially in light of the large accretionary fluxes typically associated with continental subduction.The goal of the project (project RETREAT) is to develop a self-consistent dynamic model of syn-convergent extension, using the Northern Apennines as a natural laboratory. This part of the Apennine orogen has been the site of relatively steady orthogonal convergence and 2D (plane strain) orogenic deformation since ~30 Ma. GPS measurements indicate that convergence is presently active, and tomography indicates that the full length of subducted slab is still intact to depths of 250 km. Syn-convergent extension has been active since at least 15 Ma. The Northern Apennines are well studied, and all important features of the orogen are onland and thus directly accessible for detailed geological and geophysical research.The specific objectives of project RETREAT are 1) to determine in detail the velocity field across the orogen, including deformation in the orogenic wedge, the motion of lithospheric plates, and the flow fields in the surrounding asthenospheric mantle, and 2) to use this kinematic information to develop and test specific dynamic models for deformation in the orogenic wedge and underlying mantle. The research techniques to be used include; geodesy, tectonic geomorphology, low-temperature thermochronometry, structural geology and tectonic syntheses, seismic studies, and geodynamic modeling. The RETREAT project links together a broad multidisciplinary group with eleven PIs from six institutions, plus some 27 foreign collaborators in Italy, Switzerland, Canada, and France.***

0208299Cowan 汇聚山带中水平收缩和伸展如何同时发生的悖论仍然是大陆动力学中一个基本且很大程度上尚未解决的问题。亚平宁山脉代表了最容易到达的同步趋同延伸的“类型地点”区域之一。 回滚（Rollback）——描述了俯冲板块从造山带前撤退的趋势——通常被用来解释同辐合伸展，但这个想法并没有解决俯冲板块的逆行运动，而俯冲板块是基于地幔的过程，导致地壳汇聚上覆区域的水平延伸，特别是考虑到通常与大陆俯冲相关的巨大增生通量。该项目（项目 RETREAT）的目标是开发一种自洽的动态同步聚合延伸模型，使用北亚平宁山脉作为天然实验室。自约 30 Ma 以来，亚平宁造山带的这一部分一直是相对稳定的正交收敛和二维（平面应变）造山变形的场所。 GPS 测量表明聚合目前正在活跃，断层扫描表明俯冲板片的全长在 250 公里深处仍然完好无损。 同步趋同延伸至少从 15 Ma 起就一直活跃。 北亚平宁山脉得到了充分研究，造山带的所有重要特征都在陆地上，因此可以直接进行详细的地质和地球物理研究。 RETREAT 项目的具体目标是 1) 详细确定整个造山带的速度场，包括造山带的变形造山楔、岩石圈板块的运动以及周围软流圈地幔的流场，以及 2) 使用这些运动学信息来开发和测试造山带变形的特定动态模型楔形物和下伏地幔。 要使用的研究技术包括：大地测量学、构造地貌学、低温测时法、构造地质学和构造综合、地震研究和地球动力学建模。 RETREAT 项目将一个广泛的多学科小组联系在一起，其中包括来自 6 个机构的 11 名 PI，以及意大利、瑞士、加拿大和法国的约 27 名外国合作者。***