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桐柏山太白顶、殷店和天河口一带,发育有大量的L构造岩,拉伸线理极其发育,面理较弱,线理产状向南东东倾伏,倾伏角为1°~20°。桐柏山L构造岩具有以下主要特征:在三维空间上,L构造岩强烈发育杆状构造,这种“杆”状构造是由大量沿X轴方向定向排列连在一起的椭球体矿物构成的;其变形机制主要为石英的颗粒边界迁移和长石的位错蠕变;形成的平均压力为0.59GPa,平均温度为550℃~600℃,形成于中一高温一中压环境,变质相为高绿片岩相到低角闪岩相,形成深度大致在15~20km,属于中地壳的产物。L构造岩在桐柏山的发现可能反映了桐柏山造山带中桐柏杂岩岩块相对两侧榴辉岩岩片具有近东西向挤出构造的特征。
Tongbai Mountain Taibai Ding, Yin shop and the Tianhekou area, the development of a large number of L tectonic rocks, stretching line extremely developed, the weaker face, line shape to the east and south tilt, pitch angle of 1 ° ~ 20 °. The tectonic rocks in Tongbai Mountain L have the following main features: In the three-dimensional space, the L tectonic rocks strongly develop rod-shaped structures which are composed of a large number of ellipsoidal minerals oriented together in the X-axis direction ; The deformation mechanism is mainly the grain boundary migration of quartz and the dislocation creep of feldspar; the average pressure is 0.59GPa, the average temperature is 550 ℃ ~ 600 ℃, formed in the medium-high temperature and medium pressure environment, metamorphic phase For the high greenschist facies to low amphibolite facies, the depth of about 15 ~ 20km, belonging to the product of the crust. The discovery of T-tectonic rocks in Tongbai Mountain may reflect that the eclogite slices on the opposite sides of the Tongbang complex in the Tongbai Mountain orogenic belt have a nearly EW-trending extrusion structure.