The Sistan Suture Zone, eastern Iran: the exhumation history of oceanic HP/LT rocks and the geological significance of presumed granulite-facies mélange rocks.

该提案寻求为实地研究活动提供资金，这些研究活动旨在为深入了解伊朗南缝合带的混杂岩建立坚实的岩石学、地球化学和地质年代学基础。该研究区提供了一个极好的机会，详细研究大洋高压/低温岩石及其退变质衍生物的折返历史。计划中的研究活动将侧重于SSZ演变的关键方面，需要更详细的关注：热状况和剥露历史。该提案建议开展综合实地活动、岩石学、大块岩石地球化学、同位素地球化学和地质年代学的活动。计划应用Rb-Sr地质年代学测定角闪岩和/或绿片岩相事件的年代，并使用U-Pb锆石和独居石年代测定法确定假定麻粒岩和绿片岩中记录的年龄。裂变径迹（锆石、磷灰石）和（U-Th-Sm）/He（磷灰石）分析将为后续冷却阶段提供信息。大块岩石地球化学和Sr-Nd同位素数据将用于充分表征所研究的样品组。这些数据是深入了解各种混杂岩记录的地质历史的先决条件，这将有助于深入了解特定的俯冲带风格和折返机制。重点将放在以下问题上：南大洋的闭合是否与热俯冲背景有关？挖掘的时间表和速度如何？掘尸是在一个短暂的事件中发生的，还是在一段长时间内不连续地发生的？哪些程序控制挖掘？这些问题的回答将提供对构造概念的测试，预测此类环境下的快速且不连续的折返。新获得的知识将允许链接的冷却路径和运动学发展的SSZ到其他Neotethyan缝合带，并评估缝合带动力学的机制。该项目将促进对Sunday缝合线中记录的俯冲-折返事件的理解，并有可能进一步深入了解增生复合体的演变。

This proposal seeks funding for field-based research activities that aim at establishing a solid petrological, geochemical and geochronologic foundation for in-depth understanding of mélange rocks from the Sistan Suture Zone (SSZ), Iran. The study area provides the excellent opportunity to examine in detail the exhumation history of oceanic HP/LT rocks and their retrograde derivatives. The planned research activities will focus on key aspects of the SSZ evolution that demand more detailed attention: the thermal regime and the exhumation history. The proposal suggests activities which will integrate field activities, petrology, bulk-rock geochemistry, isotope geochemistry and geochronology. It is planned to apply Rb-Sr geochronology for dating the amphibolite and/or greenschist-facies event, and to use U-Pb zircon and monazite dating to determine ages recorded in presumed granulites and in chlorite schists. Fission-track (zircon, apatite) and (U-Th-Sm)/He (apatite) analyses will provide information for subsequent cooling stages. Bulk-rock geochemical and Sr-Nd isotope data will be used to fully characterize the studied sample suite. Taken together such data is a prerequisite for in-depth understanding of the geologic histories recorded by various mélange rocks that will help gaining insights into the specific subduction zone style and exhumation mechanisms. Emphasis will be placed on the following questions: Is the closure of the Sistan ocean associated with a hot subduction setting? What are the timescales and rates of exhumation? Did exhumation occur in a single short-lived event or in discontinuous episodes over a protracted time span? Which processes control exhumation? Answering of these questions will provide a test of tectonic concepts predicting fast and discontinuous exhumation for such settings. The newly gained knowledge will allow to link the cooling path and kinematic development of the SSZ to other Neotethyan suture zones, and to assess the mechanisms of suture zone dynamics. This project will advance the understanding of the subduction-exhumation events recorded in the Sistan suture and has the potential to provide further insight into the evolution of accretionary complexes.