.实习八碳酸盐岩.ppt

实习八沉积岩(二)碳酸盐岩
目的:1、熟悉碳酸盐岩的结构构造
2、认识几种最常见的碳酸盐岩
内容:1、观察并描述:石灰岩、鲕状灰
岩、竹叶状灰岩、生物碎屑灰岩、
泥灰岩、白云质灰岩等
2、观察:豹皮状灰岩、燧石条带灰
岩、板状泥灰岩等
生物和化学沉积岩
——碳酸盐岩
Types of sediments and sedimentary rocks
There are three principle types of sedimentary rocks:
1. Detrital or clastic sedimentary rocks, as described above, consist of aggregates of grains (orclasts) which have been lithified during diagenesis
2. Biogenic sedimentary rocks result from the accumulation of skeletal remains of plants oranimals. The most important types are (1) made up of calcium carbonate (calcareous) . limestone, and shelly sandstone; (2) made up of silica (siliceous) . chert; and (3) made up of coalified plant remains (carbonaceous) . coal.
3. Chemical sedimentary rocks form from precipitation within the environment of deposition, so position depends on the position of the acqueous solution from which they are deposited (. lake, ocean, groundwater) and chemical conditions (. carbon dioxide, oxygen, pH). Common chemical precipitates include siliceous (chert), phosphatic, iron-rich, calcareous and manganiferous varieties. In addition, evaporation of saline water, especially in large marine basins, can produce large volumes of various salts, termed evaporites.
Chemical Sediments
Evaporites -Water soluble
Halite岩盐
Gypsum石膏
Calcite 方解石
Precipitates
Example: Ca2+ + SO42- = CaSO4
Gypsum
Limestone 石灰岩
Iron Formations含铁建造
Biogenic Sediments
Limestone - Shells, Reefs, Etc.
Organic Remains
Coal
Petroleum
Alteration After deposition
Dolomite
Fossil Fuels
Coal Seams, Utah
Coal
Delta, continental environments
Carbonized Woody Material
Often fossilized trees, leaves present
Plant Fragments Are Often Visible in Coal