台湾中央山脉东部变质作用及热演化：玉里缝合带的俯冲折返作用

中国台湾中央山脉东部出露的玉里变质带作为板块构造的缝合带，拼接了欧亚大陆板块、俯冲的南海板块、未俯冲的弧前基底和菲律宾海板块（吕宋岛弧），是认识台湾造山运动地球动力学重建的关键。玉里变质带出露含蓝片岩相的铁镁质—超铁镁质变质火成岩块体，这些块体在构造上被以绿片岩相为主的多期变形的云母石英片岩所包围。而玉里带东南侧发育了以云母石英片岩、千枚岩为主的初来组地层，初来组地层是否属于玉里带近年来仍然存在争议。为了解决这一问题，本文对台湾玉里带及其周缘地区的构造演化重新研究，针对中央山脉东部玉里带和初来组地层分别采样，利用碳质物质拉曼光谱温度计（RSCM）计算出变质片岩峰值变质温度的均值。结果表明：玉里带的峰值变质温度范围在400 ℃~550 ℃之间，比台湾地区的其它次级构造单元温度高；玉里带内，峰值变质温度高于500 ℃的地区毗邻玉里带的3个最大的高压变质火成岩块体，说明高压变质块体可能存在与围岩之间的交代变质作用；初来组地层的峰值变质温度约为360 ℃，与玉里带的温差达100 ℃以上，说明初来组地层与玉里带是两个不同的次级单元，在中央山脉东南缘二者之间很可能是断层接触，在台湾造山带向东的反冲褶皱逆冲带变形之后，这两个单元可能经历了相同的形变历史。本次更新的峰值变质温度集合了台湾地区的所有已发表的RSCM数据，显示出横跨台湾东部中央山脉热演化的系统性空间展布，重新修正了台湾中央山脉东部地质图。

Thermal evolution of the metamorphism in the eastern Taiwan Central Range : Implications for Yuli Belt exhumation

The Yuli Belt exposed in the eastern part of Taiwan Central Range hosts slivers of blueschist-facies meta-igneous rocks that were tectonically emplaced into a mostly greenschist-facies, polyphase deformed metasedimentary succession. Suturing the Eurasian continental plate, the subducted South China Sea plate, the proposed subducted forarc basement, and the Luzon Island arc of the Philippine Sea Plate, the Yuli Belt is a key site for understanding the geodynamic reconstruction of the Taiwan orogeny. In this paper, we reinvestigated the tectonic evolution of the Yuli Belt. The Yuli Belt of the eastern Taiwan Central Range encloses high pressure (HP)mafic-ultramafic blocks and hosts intensely deformed greenschist-facies metasediments. It is still debated if the Chulai Formation to the east is part of the Yuli Belt. To solve this problem, we provide new maximum metamorphic temperature in both units using Raman spectroscopic geo-thermometry in relation to structural deformation. The new peak metamorphic temperatures compiled with published data support systematic spatial variations across the eastern Taiwan Central Range. The Yuli Belt shows peak temperatures of 400 ℃~550 ℃ higher than those of adjacent units. Temperatures > 500 ℃ in the Yuli Belt are close to three HP blocks. The temperature difference between the Yuli Belt and Chulai Formation reaches over 100 ℃. It is likely that the contact between both units is a fault and that they underwent the same deformation history after its E-vergent backfolding phase. The new peak metamorphic temperatures compiled with published data support systematic spatial variations across the eastern Taiwan Central Range. A revised geological map was generated by the incorporation of new structural data of the metasediments from several river-transects in the eastern Central Range.