Episodic evolution of a protracted convergent margin revealed by detrital zircon geochronology in the Greater Caucasus

Convergent margins play a fundamental role in the construction and modification of Earth’s lithosphere and are characterized by poorly understood episodic processes that occur during the progression from subduction to terminal collision. On the northern margin of the active Arabia-Eurasia collision zone, the Greater Caucasus Mountains provide an opportunity to study a protracted convergent margin that spanned most of the Phanerozoic and culminated in Cenozoic continental collision. However, the main episodes of lithosphere formation and deformation along this margin remain enigmatic. Here, we use detrital zircon U-Pb geochronology from Paleozoic and Mesozoic (meta)sedimentary rocks in the Greater Caucasus, along with select zircon U-Pb and Hf isotopic data from coeval igneous rocks, to link key magmatic and depositional episodes along the Caucasus convergent margin. Devonian to Early Carboniferous rocks were deposited prior to Late Carboniferous accretion of the Greater Caucasus crystal...

汇聚边缘（convergent margin）在地球岩石圈（lithosphere）的形成与改造过程中发挥着根本性作用，其特征为伴随从俯冲作用到最终碰撞演化全过程的、迄今认知仍较为匮乏的幕式过程。在活跃的阿拉伯-欧亚碰撞带北缘，大高加索山脉（Greater Caucasus Mountains）为研究一个横跨显生宙（Phanerozoic）大部分时段、并以新生代（Cenozoic）大陆碰撞达到演化顶峰的长期汇聚边缘提供了绝佳研究契机。然而，该边缘带岩石圈形成与变形的主要幕式事件仍存在诸多未解谜团。本文依托大高加索地区古生界与中生界（变）沉积岩中的碎屑锆石U-Pb年代学（detrital zircon U-Pb geochronology）数据，并结合同期火成岩的精选锆石U-Pb与Hf同位素数据，以厘清高加索汇聚边缘带关键岩浆与沉积幕式事件的关联。泥盆纪至早石炭世的岩层沉积于晚石炭世大高加索晶体增生事件之前……