实习五岩浆岩

1、实习五实习五 岩浆岩（一）岩浆岩（一） 中酸性岩中酸性岩 目的：目的：1、学会岩石的鉴定和描述方法、学会岩石的鉴定和描述方法 2、掌握岩浆岩的结构、构造类型、掌握岩浆岩的结构、构造类型 3、认识几种主要的岩浆岩类岩石、认识几种主要的岩浆岩类岩石 内容：内容：1、观察并描述：花岗岩、似斑状观察并描述：花岗岩、似斑状 花岗岩、花岗斑岩、流纹岩、花岗岩、花岗斑岩、流纹岩、 伟晶岩、浮岩等伟晶岩、浮岩等 2、观察：细晶岩、黑曜岩、珍珠岩、观察：细晶岩、黑曜岩、珍珠岩、 花岗闪长岩等花岗闪长岩等岩石 Rocks 岩石：矿物的天然混合物或集合体。岩石：矿物的天然混合物或集合体。 Rocks are nat

2、ural mixtures or Rocks are natural mixtures or aggregates of mineralsaggregates of mineralsHow to Identify Rocks Rocks can be classified as igneous, metamorphic, or sedimentary according to the manner in which they were formed. Their specific characteristics depend on the minerals that constitute th

3、em. Based on this information, it is possible to know how rocks gained their color, texture, and crystalline structure. With a little experience and knowledge, people can learn to recognize and identify some of the rocks that they often see.Color The color of a rock is determined by the color of the

4、 minerals that compose it. Some colors are generated by the purity of the rock, whereas others are produced by the impurities present in it. Marble, for instance, can have different shades if it contains impurities.Texture Texture refers to the size and arrangement of grains that form a rock. The gr

5、ains can be thick, fine, or even imperceptible. There are also rocks, such as conglomerates, whose grains are formed by the fragments of other rocks. The texture is a small-scale property of a rock, but determined many of its large-scale properties.Mineral Composition Rocks are natural combinations

6、of two or more minerals. The properties of rocks will change in accordance with their mineralogical composition. For instance, granite contains quartz, feldspar, and mica; the absence of any of these elements would result in a different rock.The Three Great Rock Families 三大岩类：三大岩类： Sedimentary：沉积岩：沉

7、积岩 Has obvious stratification 层理 Very soft (easily scratched by a knife) 软 Obviously made of particles cemented together 碎屑被胶结在一起 Contains fossils 化石Igneous-Volcanic火山岩火山岩 Contains numerous bubble-like cavities that may or may not be lined with minerals 气孔 Has obvious bubbly or frothy texture 气孔 Is

8、fine-grained, uniform in texture, and hard 细粒、均匀、坚硬 Glassy or highly vesicular rocks are almost always igneous Igneous-Plutonic侵入岩侵入岩 Made of discrete mineral grains locked together (may be loosened by weathering) Contains large crystals in a finer-grained mass Rock mass obviously cuts across other

9、rock structures. Metamorphic变质岩变质岩 Has a fine texture with an obvious directional grain (foliation) 定向 Has obvious bands, streaks or clumps of different minerals 不同矿物的条带 Is made mostly of quartz or calcite but is coarse-grained and lacks sedimentary features 石英方解石 Contains distinctive metamorphic mi

10、nerals like garnet or kyanite 特殊的变质矿物 May often have features of original rock but is recrystallized or chemically changed. Igneous Rocks and Magma 火成岩和岩浆火成岩和岩浆火成岩的产状分类喷出岩喷出岩火山火山岩岩侵入岩侵入岩深成岩深成岩侵入岩浅成岩侵入岩浅成岩5kmIgneous Rocks are formed by crystallization from a liquid, or magma. They include two types：

11、Volcanic or extrusive igneous rocks form when the magma cools and crystallizes on the surface of the Earth Intrusive or plutonic igneous rocks wherein the magma crystallizes at depth in the Earth. 岩浆岩的结构岩浆岩的结构岩浆岩的结构岩浆岩的结构 按按照照结结晶晶程程度度划划分分显晶质结构显晶质结构隐晶质结构隐晶质结构流纹岩玻璃质结构黑曜岩斑状结构斑状结构斑状和似斑状结构：区别斑状和似斑状结构：区别主

12、要在基质的粒度主要在基质的粒度斑状结构斑状结构斑晶斑晶基质基质斑晶斑晶似斑状结构似斑状结构斑晶斑晶基质基质文象结构文象结构(Graphic Texture) 石英呈一定的外形(如象形文字）有规律地镶嵌在钾长石中。Some Igneous Rocks Are Named on Textural Criteria结构构造的命名结构构造的命名 Scoria: Porous 火山渣 Pumice 浮岩 Obsidian - Glass黑曜岩 Tuff - Cemented Ash 火山灰 Breccia - Cemented Fragments 角砾岩 Pegmatite - Extremely La

13、rge Crystals 伟晶岩 Aplite - Sugary Texture, Quartz & Feldspar 细晶岩 Porphyry - Fine Matrix, Large Crystals 斑岩岩石的构造岩石的构造 均一块状构造均一块状构造 斑杂构造斑杂构造 条带状构造条带状构造 流动构造流动构造 气孔构造气孔构造 杏仁构造杏仁构造 枕状构造枕状构造块状构造块状构造 条带状条带状 构造构造流纹构造气气 孔孔 状状 构构 造造杏仁构造化学组成及分类化学组成及分类 以氧化物形式表示：如以氧化物形式表示：如SiO2、Al2O3、CaO、Na2O、K2O等等等等 SiO2是最重

14、要的组分，是岩石分类的最是最重要的组分，是岩石分类的最主要指标，可以划分为：主要指标，可以划分为： 酸性岩，酸性岩， SiO2 65 中性岩，中性岩，65% SiO2 52 基性岩，基性岩，52% SiO2 45 超基性岩，超基性岩， SiO2 45岩石中的矿物组成岩石中的矿物组成 主要为硅酸盐矿物，分为浅色和暗色两主要为硅酸盐矿物，分为浅色和暗色两类：类： 浅色矿物：斜长石、正长石、石英浅色矿物：斜长石、正长石、石英 暗色矿物：橄榄石、辉石、角闪石、暗色矿物：橄榄石、辉石、角闪石、 黑云母黑云母 不同酸性程度的岩石具有特征的矿物组不同酸性程度的岩石具有特征的矿物组成成The geologis

15、t N.L. Bowen found that minerals tend to form in specific sequences in igneous rocks,橄 榄 石辉 石角 闪 石黑 云 母石 英白 云 母钾 长 石钠 长 石中 长 石钙 长 石岩石的观察描述岩石的观察描述 细粒细粒 颜色颜色 玻璃质或隐晶质结构玻璃质或隐晶质结构 构造构造 粗粒：粗粒： 颜色颜色 结构、构造结构、构造 主要矿物成分及其鉴定特征和含量主要矿物成分及其鉴定特征和含量 其它其它斑状结构斑状结构 颜色颜色 斑状或似斑状结构斑状或似斑状结构 斑晶：成分及其鉴定斑晶：成分及其鉴定 特征、大小、含量特征、大小、含量 基质：特征及含量基质：特征及含量 构造构造 其它其它实习五实习