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地质概况 本区位于龙门山北东向构造带的北段,区域地质概况的特点是大量的古生代沉积岩出露;构造线为北东至北东东向,较紧密的褶皱和压性、压扭性断裂均十分发育。 坝址区出露的地层,主要是中奥陶系条带状砂岩(O_2~2),属浅海相碎屑岩建造,依据岩性的差异可分成如下四大层: O_2~(2-4):钙硅质粉砂岩夹极薄层钙泥质粉砂岩。厚39米。 O_2~(2-3):厚层块状钙质粉砂岩,偶夹极薄层钙泥质粉砂岩。厚20米。 O_2~(2-2-2):厚层钙质粉砂岩,夹少量钙泥质粉砂岩。厚53米。 O_2~(2-2-1):钙硅质粉细砂岩夹极薄层钙泥质粉砂岩。厚3米,与O_2~(2-2-2)归并为同一大层。 O_2~(2-1):由钙泥质、泥质、泥钙质粉砂岩三种岩性组成。厚46米。 各层层间夹的极薄层钙泥质粉砂岩和粉砂质页岩,是相对较软弱的岩石,与上下层构成软硬相间的岩性组合。这些软弱夹层经过顺层的构造错动和地下水长期作用而泥化,发育成具有夹泥的层间错动带(剪切破碎夹泥层),即称泥化夹层。与原岩相比,泥化夹
Geological overview The area is located in the northern segment of Longmen Mountain north-east tectonic belt, the regional geological overview is characterized by a large number of Paleozoic sedimentary rocks exposed; tectonic line from the north to the northeast to the east, more compact folds and pressure, Fractures are well developed. The formation exposed in the dam site area is mainly composed of middle-Ordovician banded sandstone (O_2 ~ 2), which belongs to the shallow marine clastic rock. According to the difference of lithology, it can be divided into four layers: O_2 ~ (2-4) ): Siliceous siliceous sandstone Very thin layer calcareous siltstone. 39 meters thick. O_2 ~ (2-3): thick calcareous siltstone and even extremely thin calcareous siltstone. Thick 20 meters. O_2 ~ (2-2-2): thick calcareous siltstone with a small amount of calcareous siltstone. Thick 53 meters. O_2 ~ (2-2-1): Calcareous siliceous fine sandstone Occant thin calcareous siltstone. Thick 3 meters, and O_2 ~ (2-2-2) merged into the same large layer. O_2 ~ (2-1): Calcareous muddy, muddy, mud calcareous siltstone three kinds of lithology. Thick 46 meters. The extremely thin layers of calcareous siltstone and silty shale sandwiched between the layers are relatively weaker rocks and constitute a combination of soft and hard phases with the upper and lower layers. These weak intercalations are muddy through long-term action of bedding faults and long-term groundwater and developed into interlaminar staggered zones (shear crushed mud silt) with clayey mud, called muddy intercalations. Compared with the original rock, clay folder