桐柏造山带中剪切带的位移量及年代学研究

桐柏造山带在形成和演化过程中产生了多条韧性剪切带, 本文选取其中大河-固县剪切带和殷店-马垅剪切带作为研究对象, 分析其构造变形特征, 并利用数学法和图解法, 分别计算出两条韧性剪切带的位移量; 对殷店-马垅剪切带尝试用同构造变形石英脉的ESR测年来确定剪切带的活动年龄, 其结果与前人在该地区所获得的年龄十分吻合。大河-固县剪切带具右旋剪切的运动学特征, 运动学涡度W_k明显大于0.75, 指示以简单剪切为主, 位移量为857~867 m。殷店-马垅剪切带同样为右行剪切, 其位移量为1 081~1 113 m, 石英ESR测年结果140.6~131.5 Ma, 表明桐柏造山带碰撞后的构造变形以剪切活动为主, 活动年龄在早白垩世时期。

Study on the displacement and geochronology of shear band in Tongbai orogenic belt

There are many shear zones formed in the process of formation and evolution of the Tongbai orogenic belt. This article focuses on the Dahe-Guxian shear zone and Yindian-Malong shear zone and analyzes their structural deformation characteristics, and uses mathematical method and graphical method to calculate displacement of the two ductile shear zones. The activities age of the Yindian-Malong shear zone is obtained by ESR dating of syntectonic quartz veins. The results are in good consistent with previous research in this area. The Dahe-Guxian shear zone has dextral shear sense and with displacement of 857~867 m. Its kinematic vorticity W_k is significantly greater than 0.75, which indicates a simple shearing. The Yindian-Malong shear zone also has dextral shear sense with displacement of 1 081~1 113 m, the quartz ESR dating results of 140.6~131.5 Ma, show that after Tongbai orogenic belt collision, the main tectonic deformation is shear activity, occurred in the Early Cretaceous period.