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

这项建议为实地研究活动寻求经费，目的是建立一个坚实的岩石学、地球化学和地质年代学基础，以便深入了解伊朗锡斯坦缝合带（SSZ）的msamuange岩石。研究区为详细研究海洋高压/低温岩石及其逆行衍生物的发掘历史提供了极好的机会。计划的研究活动将集中在需要更详细关注的SSZ演变的关键方面：热状态和挖掘历史。建议的活动将结合野外活动、岩石学、大块岩石地球化学、同位素地球化学和地质年代学。计划应用Rb-Sr年代学对角闪岩和/或绿片岩相事件进行定年，并使用U-Pb锆石和独石定年来确定麻粒岩和绿泥石片岩中记录的年龄。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套件。综合这些数据是深入了解各种岩系所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样式和挖掘机制。重点将放在以下问题上：锡斯坦海的闭合是否与热俯冲环境有关？挖掘的时间尺度和速度是什么？挖掘是在一个短暂的事件中发生的，还是在一个漫长的时间跨度中不连续的事件？哪些程序控制挖掘？这些问题的答案将提供构造概念的测试，预测这种设置的快速和不连续的挖掘。新获得的知识将使SSZ的冷却路径和运动学发展与其他新特提斯缝合带联系起来，并评估缝合带动力学机制。该项目将促进对锡斯坦缝合带记录的俯冲-挖掘事件的理解，并有可能进一步了解增生复合体的演化。

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.