郯庐断裂带肥东桃源韧性剪切带构造分析及时限探究

郯庐断裂带在肥东桃源地区为一混合杂岩带，温压数据显示区域内变形变质环境为中下地壳构造环境。本文对剪切带的应变大小、应变速率、涡度以及应力场等构造特征进行分析测量，结果显示该剪切带所受应力方向为170°左右，夹角为40°～50°，并以简单剪切为主，其变形矿物被拉长。此外，带内发育的长英质糜棱岩流体以及伟晶岩流体均发生同构造变形，本文结合前期年代学研究结果，整合出了3种不同流体之间的关系，并有效限定出带内韧性剪切活动发生在140～124 Ma之间。同时，通过对郯庐断裂带中南段年代学数据统计，发现郯庐断裂带肥东段主要记录了早白垩世的剪切活动，而大别造山带东缘、苏鲁西缘分别记录了同造山年代学数据，断裂带中南段在年代学分布上呈现出明显的空间差异性，反映出郯庐断裂带递进变形的特征。

Structural and geochronology characteristics of Taoyuan ductile shear zone in Tanlu fault belt and their significance

The outcrop in Feidong Taoyuan， Anhui Province， shows a migmatitic complex belt. The estimated P-T conditions shows the deformation and metamorphic environment is like that in the mid-lower crust. We calculated the strain strength， strain rate， vorticity， stress field of the ductile shear belt， and results indicate that the stress direction is about 170°， 40°～50° to the strike direction of the shear belt； simple shear takes advantage in the deformation of it and the deformation mineral is stretched. The felsic mylonite fluid, pegmatitie fluid all deformed during different periods of the shearing. Based on our former work results， we analysis three different fluids on their structural relationships and the timing they deformed， with which we calculated that Taoyuan ductile shear belt sheared during 140～124 Ma. Furthermore， synthesizing the relevant chronology data along the Tanlu fault belt， it’s easy to find that the Feidong segment just record shearing during Early Cretaceous， while synorogenic ages can just be found on the edges of Dabie and Sulu orogenic belts. These demonstrate the spacial difference of chronology distribution in Tanlu fault belt.