Description of mudstone, sandstone and limestone (general)
Volcanic clastic rocks are mainly volcanic eruption debris from the air falling in situ deposition or by a certain distance of water erosion and sediment transport. It is related to the volcanic activity from the material source, but from the diagenetic process, it belongs to the forming law of sedimentary rock. Some components of clastic rocks in various volcano volcano clastics; some volcano clastic rocks with many lava and volcano clastic lava for the cementation; others are from the volcano debris and normal clastic (gravel, sand, silt and mud) mixed accumulation, containing sand and shale. And often contain fossils. Thus, between the rocks and lava volcano clastic, between volcano clastic rocks and normal sedimentary rocks, including many transition rock, according to the volcano clastic granularity can be divided into: 1 volcano agglomerate is mainly composed of coarse clastic volcano (more than 64mm) such as lava fragments (more than 50%), consolidation and rock. Lava fragments with edges and corners or by carrying round, filling and matrix for lava, volcanic ash, mud, calcium, silica, etc.. Generally poor sorting, bedding is not clear, often forming thick and massive layers. According to the rock fragments in lava composition, can be named andesitic agglomerate and rhyolitic agglomerate. This kind of rock is hard, and the thickness of the deposit is hundreds of meters up to several kilometers. In the eastern part of China, a large amount of pyroclastic rocks are formed in the middle and late mesozoic. 2 volcano breccia is mainly composed of a particle size of 2 64mm fragments or lava breccia (content above 50%) consolidation and rock, also contain other rock breccia, mostly with clear edges, poor sorting, ranging in size. Filler and matrix for lava, volcanic ash or mud, etc., can also be calcium, silica, etc.. According to the composition of breccia is named rhyolitic breccia, breccia, basaltic andesitic breccia.
Clastic rocks can be divided into two sub types: sedimentary clastic rock and pyroclastic rock. The sedimentary clastic rock is a kind of rock which is formed by clastic material of weathering and denudation. In addition to a small part of the in situ deposition, most of them have been transported, deposition process. According to the size of clastic rock composed of clastic rock, this kind of rock can be divided into conglomerate type clastic diameter above 2mm. Sandstone - the diameter of clastic rock is between 2 and 0.05mm. Siltstone - clastic diameter between 0.05 - 0.005mm. Clay rock - clastic diameter less than 0.005mm. The corresponding size of the clastic rocks, clastic debris content must be accounted for more than 50% of the total, such as gravel debris content in conglomerate is greater than 2mm should be accounted for more than half; if it contains 25 - 50% sand, can be called sandy conglomerate which contains 5 - 25%; if the sand is said to contain glutenite. Nomenclature of other rocks, and so on. 1 rocks, such as conglomerates of which the diameter is more than 2mm (more than 50%), belong to this category. Conglomerate gravel is usually a relatively hard rock fragment. It can be divided into two types: breccia and conglomerate according to the degree of roundness.
