野外岩石学研究方法简介(张立飞PPT).pdf

野外岩石学研究方法简介 张立飞 北京大学地球与空间科学学院 1、野外研究 岩石产状、构造分析、测制剖面、填图 2、室内研究 显微镜薄片观察、矿物成分和结构分析、 岩石化学成分分析、数据处理和计算 3、岩石成因解释 岩石学研究方法 一、岩浆岩野外特征  岩浆岩的野外产状 火山岩的野外产状 岩浆岩的野外岩石学观察 1、颜色一般浅色为酸性岩（花岗岩类）或 中性岩（正长岩类）；深色为基性岩或 超基性岩。 2、结构构造晶质、半晶质、隐晶质，分为喷出 、浅成和深成岩。 3、矿物成分岩石定名的基础。 4、定名 酸性岩花岗岩 流纹岩 中性岩闪长岩 安山岩 基性岩辉长岩 玄武岩 Plate Tectonic - Igneous Genesis 1. Mid-ocean Ridges 2. Intracontinental Rifts 3. Island Arcs 4. Active Continental Margins 5. Back-arc Basins 6. Ocean Island Basalts 7. Miscellaneous Intra- Continental Activity kimberlites, carbonatites, anorthosites... 二、沉积岩的野外特征 沉积岩的野外观察 1、碎屑的粒度 2、结构构造 3、定名 沉积大地构造 三、变质岩石学野外特征 1、结构构造 2、矿物组成 3、特殊颜色 4、岩石命名 等化学系列原岩类型化学成分特征特征变质矿物 富铝系列泥岩、页岩等富Al2O3、 SiO2铁铝榴石、硬绿泥石、 蓝晶石、红柱石、夕线石 K2O，贫CaO十字石 基性系列基性岩浆岩和富CaO、FeO*、绿帘石/黝帘石、角闪石、 铁质白云质MgO，Na2OK2O单斜辉石、斜方辉石、石榴石 泥灰岩绿泥石 长英质系列各种砂岩、富SiO2、Na2O、K2O石英、斜长石、钾长石 粉砂岩，云母等 中酸性岩浆岩贫FeO,MgO,CaO 碳酸盐系列石灰岩和白云岩 富CaO或富MgO滑石、铁铝榴石、透闪石 透辉石、镁橄榄石和硅灰石等 超基性系列超基性岩浆岩富MgO FeO滑石、蛇纹石、透闪石、 五个等化学系列特征对比表 shale slate phyllite schist gneiss melt. Shale is a sedimentary term. Slate refers to a fine-grained, low-grade metasedimentary rock in which bedding is typically still visible lineation a linear fabric; typically defined by either linear minerals, such as hornblende, or stretched grains, such as quartz. Rocks with purely linear fabrics are called L tectonites and by a constrictional deation prolate strain ellipsoid. Here is a mylonitic granite from Norway, with clearly stretched K-feldspar grains in a fine-grained matrix of quartz, plagioclase, and biotite Schist refers to a medium- to high-grade, medium- to coarse-grained metamorphic rock of any composition that has a fabric. For example, Complex and blobby plutonic compls can become extremely layered as a result of deation foliation a planar fabric; typically defined by platy minerals such as mica or flattened grains such as quartz. This is a more general term that encompasses cleavage and schistosity. Rocks with purely planar fabrics are called S tectonites and by a flattening deation oblate strain ellipsoid. Most metamorphic rocks are L-S tectonites that from a more general strain history. Eclogites consist mostly of two minerals garnet and Na-rich clinopyroxene known as omphacite 16OC/公里 25OC/公里 变质相－变质相系 －PTt轨迹 变质地质学 Metamorphic Geology 岩石的野外特征 岩浆岩的侵入接触关系 形成世代 沉积岩的层序 不整合接触关系 变质程度及其相互关系 构造变形 新疆西南天山超高压变质带新疆西南天山超高压变质带 的岩石学研究的岩石学研究 H74-11 阿 克 牙 孜 105-3 科普尔特萨依 Geological OccurrencesGeological Occurrences 1、Pillow eclogites 2、Lenticular eclogites 3、Banded eclogites The country rocks of eclogites Gt-Ms schist, Gt blueschist and Chtd-gt blueschist. UHP1 Coesite pseudomorph . Zhang et al., 2002a Am.Min. Lv and Zhang 2008, Am Min in press GrtOmpGl Lws Phase modeling for basaltic eclogite Zhang et al., 2007, Lithos. 西南天山超高压变质带的构造演化西南天山超高压变质带的构造演化 260 Ma 236236- -238 Ma238 Ma 2005年夏西天山 UHPM in western Tianshan, China 1、区域地质概况、区域地质概况 HP-UHP eclogite-blueschist belt Low-P belt