Collaborative Research: Extensional Unroofing of the Central Menderes Metamorphic Complex, Southwestern Turkey

从晚白垩世到始新世，爱琴海地区经历了一系列大陆板块碰撞。该地区的碰撞后伸展，尽管在其时间和性质上存在争议，但导致了几条变质带的发掘。其中最大的Menderes地块发生了明显的地壳伸展，其原因可能是：(1)构造逃离和侧向挤压，安纳托利亚板块沿北安纳托利亚和东安纳托利亚断层向西移动；(2)沿希腊弧俯冲引起的弧后扩张/板块回滚；(3)热减弱岩石圈的造山崩塌经历了古近纪收缩。这些假设用地质年代学进行了检验，使门德雷斯地块成为识别促进大陆岩石圈扩展的基本板块构造过程的关键地点。研究的主要目的是表征门德勒斯地块中部岩石的岩石学演化特征，以确定爱琴海地区构造由挤压向伸展转变的原因。该项目包括实地考察和地球化学数据采集，包括最近开发的原位离子探针独居石地质年代学和氩-氩钾长石多扩散域建模技术。离子微探针技术保存了颗粒和岩石结构，当与电子微探针化学分析相结合时，可以清楚地解释年龄的含义。氩-氩多扩散域模型表明，单个钾长石样品可以揭示冷却历史的一个广泛部分，而不是单一的基准。该项目由Elizabeth Catlos博士、Ibrahim Cemen博士（俄克拉荷马州立大学地质学院）和Matt Kohn博士（南卡罗莱纳大学地质科学系）等美国团队和Cemal Goncuoglu博士（中东技术大学地质工程系，安卡拉）等土耳其团队合作完成。这两位研究生参与了这个项目，他们将接触到不同的文化、激烈的田野工作和各种各样的地球化学方法。

The Aegean region experienced a series of continental plate collisions from Late Cretaceous to Eocene time. Post-collisional extension in the region, although controversial in its timing and nature, caused the exhumation of several metamorphic belts. The largest of these, the Menderes Massif, accommodated significant crustal extension, which may have been caused by: (1) tectonic escape and lateral extrusion, in which the Anatolian plate moves westward along the North and East Anatolian Faults, (2) back-arc spreading/slab roll back due to the subduction along the Hellenic Arc, or (3) orogenic collapse of thermally weakened lithosphere that experienced Paleogene contraction. These hypotheses are tested using geochronology, making the Menderes Massif a key locale in identifying the fundamental plate tectonic processes that facilitate extension in the continental lithosphere. The main goal of the research is to characterize the petrologic evolution of rocks in the central Menderes Massif to identify the cause of tectonic transition from compression to extension in the Aegean Region. The project involves fieldwork and geochemical data acquisition, including recently developed techniques of in situ ion microprobe monazite geochronology and argon-argon K-feldspar multi-diffusion domain modeling. The ion microprobe technique preserves the grain and rock fabric, and, when combined with electron microprobe chemical analyses, allow for a clear interpretation of meaning of the age. The argon-argon multi-diffusion domain model shows that a single K-feldspar sample can reveal a broad segment of a cooling history, rather than a single datum. This project is collaborative between a U.S. team including Dr. Elizabeth Catlos, Dr. Ibrahim Cemen (School of Geology; Oklahoma State University) and Dr. Matt Kohn (Dept. Geological Sciences; University of South Carolina), and a Turkish team including Dr. Cemal Goncuoglu (Middle East Technical University, Department of Geological Engineering, Ankara). The two graduate students participating in this proposal are exposed to a different culture, intense fieldwork, and a variety of geochemical methods.