Sedimentary Rocks

沉积岩

Weathering processes break down rock into finer and finer material and such material is often transported and deposited as sediment. The processes of compaction and cementation of this sediment over a long period of time turn the sediment into rock. The formation of rock in this way is termed "lithification".

风化作用将岩石分解成更细的物质，这种物质常常被搬运并沉积。经过长时间的压实和胶结作用，这种沉积物会转变为岩石。这种形成岩石的过程称为‘岩化’。

Sedimentary rocks are divided into two broad classes, detrital sedimentary rocks and chemical sedimentary rocks as described below. Sedimentary rocks make up perhaps only five percent or so of the outer 16 kilometers (10 miles) of the Earth (Lutgens and Tarbuck), but the majority of surface rocks are sedimentary. About 75% of the rock outcroppings on continents are sedimentary rocks.

沉积岩可分为两大类，即碎屑沉积岩和化学沉积岩，如下所述。沉积岩可能只占地球外16公里（10英里）的表面约5%左右（Lutgens和Tarbuck），但地表大部分岩石都是沉积岩。大陆上的岩石露头约有75%是沉积岩。

Detrital sedimentary rocks are those for which the material has been transported as solid particles. The particles themselves may have derived from either physical weathering or chemical weathering. Sedimentation means settling from a fluid, either water or air. The texture of sedimentary rocks is described as "clastic", meaning that they are composed of discrete particles that are compacted and cemented together. An example of a non-clastic texture would be crystalline material.

碎屑沉积岩是指其成分已作为固体颗粒被搬运的岩石。这些颗粒本身可能来源于物理风化或化学风化。沉积作用指的是从流体（如水或空气）中沉降的过程。沉积岩的粒度特征称为“碎屑状”，意味着它们由相互紧密压实并胶结在一起的独立颗粒组成。非碎屑状的例子则是结晶性物质。

Detrital Sedimentary Rocks 碎屑沉积岩
Sediment name and particle size 沉积物名称和颗粒大小	Description 描述	Rock Name 岩石名称
Gravel (>2 mm) 碎石 (>2 mm)	Rounded rock fragments 圆润的岩石碎片	Conglomerate Conglomerate（矿物名）
Gravel (>2 mm) 碎石 (>2 mm)	Angular rock fragments 角状岩石碎片	Brecia 布雷西亚
Sand (1/16 to 2 mm) 砂（1/16至2毫米）	Quartz predominates 石英占主导地位	Quartz sandstone 石英砂岩
	Quartz with considerable feldspar 含大量长石的石英	Arkose 岩浆岩
	Dark color, quartz with considerable feldspar, clay and rocky fragments 暗色，含大量长石、粘土和岩石碎片的石英	Graywacke 灰绿色泥岩
Mud (<1/16 mm) 泥（< 1/16 mm）	Splits into thin layers 分成薄层	Shale 页岩
Mud (<1/16 mm) 泥（< 1/16 mm）	Breaks into clumps or blocks 形成块状或块体	Mudstone 泥岩

Chemical sedimentary rocks derive from material that is carried in solution to lakes and seas. If the solute precipitates out of the solution to form chemical sediments, rocks such as limestone can be formed.

化学沉积岩来源于被携带至湖泊和海洋的物质。如果溶液中的溶质沉淀出来形成化学沉积物，就能形成如石灰岩这样的岩石。

Chemical Sedimentary Rocks 化学沉积岩
Group 组	Texture 纹理	Composition 组成	Rock Name 岩石名称
Inorganic 无机	Clastic* or nonclastic 碎屑型或非碎屑型	calcite, CaCO₃ 方解石，CaCO₃	Limestone 石灰石
	Nonclastic 非碎屑的	Dolomite, CaMg(CO₃)₂ 方解石，CaMg(CO₃)₂	Dolostone 方解石
	Nonclastic 非碎屑的	Microcrystalline quartz, SiO₂ 微晶石英，SiO₂	Chert 切特
	Nonclastic 非碎屑的	Halite, NaCl 石盐，NaCl	Rock salt 岩盐
	Nonclastic 非碎屑的	gypsum, CaSO₄.2H₂O 石膏，CaSO₄·2H₂O	Rock gypsum 岩石石膏
Biochemical 生物化学	Clastic or nonclastic 碎屑状或非碎屑状	calcite, CaCO₃ 方解石，CaCO₃	Limestone 石灰石
	Nonclastic 非碎屑的	Microcrystalline quartz, SiO₂ 微晶石英，SiO₂	Chert 切特
	Nonclastic 非碎屑的	Altered plant remains 改变的植物遗存	Coal 煤

*Clastic means that they are composed of discrete particles that are compacted and cemented together.

The data in both tables above is taken from Lutgens and Tarbuck, Essentials of Geology, 7th Edition.

上述两个表格中的数据来源于Lutgens和Tarbuck的《地质学基础》第七版。

Examples of sedimentary rock

沉积岩的例子

Grand Canyon sedimentary rock

大峡谷沉积岩

脆性是指它们由离散的颗粒组成，这些颗粒被压实并胶结在一起。