贝加尔湖滨奥里洪地区新构造特征及其成因模式初探

Preliminary discussions on characters and genetic pattern of Neotectonsm in Pri-Olkhon,Lake Baikal, Russia

贝加尔裂谷带是全球典型的大陆裂谷带之一,新构造运动强烈。滨奥里洪地区是贝加尔裂谷带断裂发育最完好的地区。位于滨奥里洪中部的萨尔玛河谷和奥里洪门新构造运动非常强烈,萨尔玛河谷在地形上呈规则的折线状,而奥里洪门发育有两侧对称的湖湾。沿萨尔玛河谷发育有一组X型节理,而奥里洪门两侧发育有完好的断层三角面山,因此,萨尔玛河谷和奥里洪门可能是在早期追踪张裂的基础上发育起来的。滨奥里洪地区还发育有一系列NE和NW走向的次级断裂,它们的发育受滨海断裂铲式枢纽断层特征的控制。分析这些次级断裂的特征和性质,提出了与它们发育有关的三种作用力:①枢纽断层造成的NE-SW向局部拉张;②铲式断层的旋转效应产生反向滑动;③铲式断层的不均匀旋转产生剪切效应,并在此基础上对滨奥里洪地区的新构造运动过程作了概括和总结。

With intense neotectordc movement, Baikal rift zone is one of the typical continental rift zones in the world. Faults in Pri- Olkhon is developed perfectly in Baikal rift zone. Located in the central Pri-Olkhon, intensive neotectonic movement is developed in Sarma Valley with a regular topographical zigzag and Olkhon Gate with zygomorphic lake bays. A series of X-type joints are developed in Sarma Valley while some well-developed triangular fault surfaces occur on the both sides of Olkhon Gate. Therefore, Sarma Valey and Olkhon Gate can be developed on the basis of early tracing fracture. Also a series of NE or NW strike subsidiary fractures are de- veloped in Pri-Olkhon area, controlled by characters of littoral and listric hinge faults, and also an important border fault between north Baikal basin and central Baikal basin. The study of subsidiary fractures shows that three acting forces related to fault development are 1. partial tension caused by hinge fault; 2. reverse slip caused by the rotation of listric fault; 3. shear effect caused by inhomogenous rotation of listric fault. Then, the neotectonic movement process of the area is summarized on the basis of above-mentioned analyses.