Yang Shun, Liang Xiaofeng, Jiang Mingming, Chen Lin, He Yumei, Thet Mon Chit, Hou Guangbing, Thant Myo, Sein Kyaing, Wan Bo
Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences (CAS), Beijing 100029, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Adv. 2022 Aug 26;8(34):eabo1027. doi: 10.1126/sciadv.abo1027.
Closure of the Neo-Tethyan Ocean is one of the most significant tectonic events of the Cenozoic, forming the longest continental collision belt on Earth and influencing global climate and biodiversity. However, whether late Mesozoic subduction of the Neo-Tethyan Ocean occurred along one single or a double subduction system remains controversial. Here, upper mantle imaging from seismic tomography and waveform modeling in the Myanmar region reveals two prominent, parallel, slab-like structures with high seismic velocities that trend to the north-south and dip to the east. The western high-velocity zone has been observed previously and represents the modern subducting slab. The eastern zone has not been previously reported and exhibits high-velocity anomalies of 1.0 to 2.5% to a depth of ~300 km. This zone likely represents a remnant of another Neo-Tethyan oceanic slab that subducted ~40 million years ago. Double subduction of the Neo-Tethyan Ocean during the late Mesozoic to early Cenozoic requires reevaluation of previous tectonic models.
新特提斯洋的闭合是新生代最重要的构造事件之一，形成了地球上最长的大陆碰撞带，并影响全球气候和生物多样性。然而，新特提斯洋在中生代晚期是沿单一俯冲系统还是双俯冲系统发生俯冲，仍存在争议。在此，通过缅甸地区地震层析成像和波形建模得到的上地幔成像显示出两个显著的、平行的、具有高地震速度的板状结构，它们呈南北走向且向东倾斜。西部高速区先前已被观测到，代表现代俯冲板块。东部区域此前未被报道，在约300千米深度范围内表现出1.0%至2.5%的高速异常。该区域可能代表了另一个约4000万年前俯冲的新特提斯洋板块的残余部分。新特提斯洋在中生代晚期至新生代早期的双俯冲需要对先前的构造模型进行重新评估。
