顯微構(gòu)造地質(zhì)學(xué)-microstructure-中英雙語(yǔ)復(fù)習(xí)資料.docx

顯微構(gòu)造復(fù)習(xí)資料1.u Elastic displacement creates a differential stress increase at the tip of the fracture that depends on fracture length, applied bulk stress, elastic properties of the material and resistance to breaking atomic bonds at the crack tip, known as fracture toughness. Displacement on a microfracture can lead to fracture propagation if a certain critical differential stress is reached, in extension, sliding or tearing mode.2.u Intragranular晶內(nèi): occur within a single grain, most commonly along a mineral cleavage plane, and form where the fracture strength of the grain is less than that of grain boundaries. u Intergranular晶間: exploit grain boundaries, propagating around rather than through grains; they indicate that the grain boundaries were easier to “crack” than the adjacent grains.u Transgranular穿晶: cut across adjacent grains and their mutual grain boundaries. Several conditions favor transgranular microcracking, including strong grain boundaries and similar orientations of cleavage in neighboring grains 3. 碎裂 Cataclasis: is the pervasive brittle fracturing and granulation of rocks, generally along faults and fault zones. It produces an aggregate of highly fractured grains and rock fragments in a matrix of even smaller, crushed grains . Once formed, such crushed aggregates are able to flow by repeated fracturing, frictional sliding, and rigid-body rotation of grains and fragments, a process termed cataclastic flow. Cataclastic rocks are characterized by pervasive cracks and generally sharp, angular grains and fragments. Often similar at all scale of observation. Cataclasite fabric: angular fragments of all sizes, some transecting grain boundaries, are embedded in a fine-grained matrix. Many larger fragments are crossed by healed fractures, aligned with fluid- and solid inclusions. Recrystallised fabric of small new grains that grew at the expense of old grains. The new grains show little variety in grain size. 4. Dissolution-Precipitation溶解-沉淀In rocks that contain an integranular fluid 晶間液體 pressure-solution can occur as deformation mechanism.u Pressure-solution: dissolution at grain boundaries in a grain boundary fluid phase at high differential stress. Pressure solution is localised where stress in the grain is high, mostly where grains are in contact along surfaces at a high angle to the instantaneous shortening direction u the grain lattice near contact points is more strongly compressed than elsewhere; as a result, material will dissolve near these contact points and be redeposited at sites of low differential stress. A locally higher density of crystal defects near contact points may also enhance solubility u 5. Processes of dissolution creep 溶解蠕變（壓溶作用）低溫 低應(yīng)力 低應(yīng)變速率 實(shí)質(zhì)是coble蠕變u 3 processes: dissolution at the source, diffusion or migration of the dissolved material along some pathway reprecipitationu Dissolution: In response to an applied differential stress, grains become preferentially corroded along segments of grain boundaries that are being subjected to high compressive stress. Such segments include those oriented at high angles to the greatest principal compressive stress (1) and those in which rigid grains or objects impinge on one another to concentrate stress. highly soluble minerals will dissolve preferentially to those with lower solubilities. In impure carbonate rocks, for example, calcite typically dissolves more readily than quartz, clays, and iron-manganese oxides. Grains with impurities and those with crystalline lattices that have been somehow damaged, perhaps by the work of other deformation mechanisms, are likewise more susceptible to dissolution than pristine原始的 grains. 溶解：響應(yīng)于施加的差異應(yīng)力，晶粒優(yōu)先被沿著受高壓應(yīng)力的晶界區(qū)段腐蝕。 這些部分包括與最大主壓應(yīng)力（1）成高角度取向的部分，以及剛性顆粒或物體相互碰撞以集中應(yīng)力的部分。 高度可溶的礦物質(zhì)將優(yōu)先溶解于溶解度較低的礦物質(zhì)。 例如在不純的碳酸鹽巖中，方解石一般比石英，粘土和鐵錳氧化物更容易溶解。 含有雜質(zhì)的晶粒和晶格已經(jīng)受到某種程度損壞的晶粒，也許是由于其他變形機(jī)制的作用，同樣比原始晶粒更容易溶解。 Migration and reprecipitation: As solid grains dissolve, they enrich the fluid in their constituents, especially near sites of more rapid dissolution. In contrast, little or no dissolution may occur near grain boundaries normal to the least principal compressive stress (3). The differences in dissolution rates result in chemical concentration gradients within the fluid, causing dissolved constituents to diffuse away from the dissolution sites and toward sites of lower compressive stress.遷移和再沉淀：由于固體顆粒溶解，它們富集成分中的流體，特別是在溶解速度更快的附近。 相反，在與最小主壓應(yīng)力（3）垂直的晶界附近幾乎不發(fā)生溶解。溶解速率的差異導(dǎo)致流體內(nèi)的化學(xué)濃度梯度（實(shí)質(zhì)），導(dǎo)致溶解成分從溶解位點(diǎn)擴(kuò)散到較低壓縮應(yīng)力的位置。比較常見(jiàn)的是難熔物質(zhì)的兩側(cè)，周圍的易溶物被溶解遷移到難熔礦物的低應(yīng)力區(qū)沉淀，形成以難溶物為核晶，以易溶物為陰影的壓力影構(gòu)造。Condition of dissolution creep: Intergranular fluid Low differential stress Low to moderate temperature Small grain size favor dissolution: Strain rate is inversely proportional to the cube of the grain size; hence, grain-size reduction by dissolution leads to a quickening of the pace of dissolution, a type of strain softening. 6. Intracrystalline Deformation晶內(nèi)缺陷u Crystals can deform internally without brittle fracturing by movement of so-called lattice defects, a process known as intracrystalline deformation u Lattice defects: Point defect, line defects and planar defectDislocation glide 位錯(cuò)滑動(dòng)u Linear defect in the Crystalu Burgers Vector: A dislocation is characterized by a Burgers vector which indicates the direction and minimum amount of lattice displacement caused by the dislocation. 通常將柏氏矢量稱為位錯(cuò)強(qiáng)度，位錯(cuò)的許多性質(zhì)如位錯(cuò)的能量，所受的力，應(yīng)力場(chǎng)，位錯(cuò)反應(yīng)等均與其有關(guān)。它也表示出晶體滑移時(shí)原子移動(dòng)的大小和方向。位錯(cuò)可定義為柏氏矢量不為零的晶體缺陷，它具有連續(xù)性，不能中斷于晶體內(nèi)部。其存在形態(tài)可形成一個(gè)閉合的位錯(cuò)環(huán)，或連接于其他位錯(cuò)，或終止在晶界，或露頭于晶體表面。邊緣位錯(cuò)和螺旋位錯(cuò)可以互相連接成位錯(cuò)環(huán)u Dislocation glide easier on specific slip-systems depending on P, T, fH2O, etcDislocation Climb位錯(cuò)攀移u Migration of vacancies to the dislocation plane can cause the climb of the dislocation 雜質(zhì)Dislocation Creep位錯(cuò)蠕變 moderate T and stress蠕變creep：在地質(zhì)條件下，應(yīng)變極其緩慢。礦物中的位錯(cuò)有足夠的時(shí)間順序移動(dòng)。所以能在不增加應(yīng)力的情況下使應(yīng)變繼續(xù)增加，這就是蠕變。就像挪動(dòng)很重的地毯。應(yīng)力保持一定，應(yīng)變隨時(shí)間不斷增加的現(xiàn)象。Dislocation creep = Dislocation Glide + Dislocation Climb （當(dāng)位錯(cuò)的增值引起的內(nèi)應(yīng)力增加（硬化）與由攀移等引起的內(nèi)應(yīng)力減?。ɑ謴?fù)）之間達(dá)到動(dòng)態(tài)平衡時(shí)，變形進(jìn)入穩(wěn)態(tài)蠕變階段）u 三個(gè)階段：微應(yīng)變階段：彈性應(yīng)變 塑性應(yīng)變階段穩(wěn)態(tài)流動(dòng)階段：應(yīng)力不再增加。結(jié)果是在礦物晶粒中產(chǎn)生了以位錯(cuò)陣列為邊界的亞晶粒subgrain（而不是形成新晶粒）Undulose extinction波狀消光：low T high stressSubgrain boundaries 亞晶界 /Kink扭折: high T low stressu Slip-System: A specific slip plane coupled with a slip direction (the Burgers vector) is known as a slip system. u Slip-system: crystallographic direction and plane in which the dislocation glide.u Denomination using Miller indices: Directions: hkl (or = all hkl equivalent direction by symmetry)Plane: (hkl) (or hkl = all hkl equivalent plane by symmetry)Crystal Preferred Orientations（CPO）u In most common rock forming minerals such as quartz, feldspars, calcite and olivine, several slip systems of different orientation can be active. The type of slip system that will be active in a crystal depends on the orientation and magnitude of the stress field in the grain and on the critical resolved shear stress (CRSS) c for that slip-system; c must be exceeded on the slip system to make the dislocation move. u The magnitude of cdepends strongly on temperature, strain rate, differential stress and the chemical activity of certain components such as water that may influence the strength of specific bonds in a crystal. 在石英，長(zhǎng)石，方解石和橄欖石等大多數(shù)常見(jiàn)的成巖礦物中，不同取向的幾種滑動(dòng)體系可以起作用。 在晶體中活動(dòng)的滑移系統(tǒng)的類型取決于晶粒中的應(yīng)力場(chǎng)的方向和大小以及該滑移系統(tǒng)的臨界分解剪切應(yīng)力（CRSS） 必須在滑移系統(tǒng)上超過(guò)，以使位錯(cuò)移動(dòng)。的大小主要取決于溫度，應(yīng)變速率，微分應(yīng)力和某些組分（如水）的化學(xué)活性，這些組分可能會(huì)影響晶體中特定鍵的強(qiáng)度。u In aggregate: rotation of the crystallographic network to accommodate deformation between neighbors dominant slip-systems CPODiffusion Creep 擴(kuò)散蠕變u Diffusion : Migration of singular defectsu Diffusion : 2 mechanisms u 體積擴(kuò)散蠕變Nabarro-Herring (n = 2) NabarroHerring creep is a mode of deformation of crystalline materials that occurs at low stresses and held at elevated temperatures in fine-grained materials. In NabarroHerring creep, atoms diffuse through the crystals, and the creep rate varies inversely with the square of the grain size so fine-grained materials creep faster than coarser-grained ones. This type of creep results from the diffusion of vacancies from regions of high chemical potential at grain boundaries subjected to normal tensile stresses to regions of lower chemical potential where the average tensile stresses across the grain boundaries are zero. 晶體中的空位趨向于集中于晶體的界面或晶體內(nèi)其他有利于空位聚集的部分?？瘴粡母呙芏鹊牟糠?jǐn)U散，而原子或離子則向相反方向擴(kuò)散。發(fā)生在高溫 低應(yīng)變速率 晶粒很細(xì)的多晶體中u 晶粒邊界擴(kuò)散蠕變Coble (n = 3) T時(shí)占優(yōu)勢(shì) T時(shí)兩者一起作用u The change of shape of the crystals is accom by migration of the vacancies (= diffusion)晶粒邊界的缺陷要發(fā)生擴(kuò)散所需的激活能只等于晶格擴(kuò)散激活能的一半與NH的區(qū)別：晶粒更大更完整，空位沿著GB移動(dòng)。Grain Boundary Sliding（GBS）Dislocation accommodated grain boundary sliding (GBS)Diffusion accommodated grain boundary sliding (GBS) = diffusion creepGrain Boundary Sliding is a deformation mechanism of materials which includes displacement of grains against each other at high homologous temperature and low strain rate. This mechanism is the main reason of ceramics failure at high temperatures due to formation of glassy phase in their grain boundary. 晶界滑移是一種材料的變形機(jī)制，包括晶粒在高同質(zhì)溫度和低應(yīng)變速率下的相互位移。 這種機(jī)制是陶瓷在高溫下由于晶界中形成玻璃相而失效的主要原因。Recovery恢復(fù)作用u Crystals have a Internal strain energy:Minimum when lattice free of dislocationsIncrease with the amount of dislocationsu Recovery: mechanisms reducing dislocation densityRecrystallization重結(jié)晶分為動(dòng)態(tài)重結(jié)晶（退火）和靜態(tài)重結(jié)晶u Dynamic recrystallization: deformationu Annealing or static recrystallization: no-deformationGrain boundary mobility2 grain with different dislocation densities:- Atoms along GB of the high dislocation density crystal can be displaced to fit the lattice of the low dislocation density crystals Displacement of the GB- The less deformed crystal growth at the expense of the more deformed one晶粒邊界流動(dòng)性：2個(gè)不同位錯(cuò)密度的晶粒：邊界高位錯(cuò)密度晶體的原子可以移動(dòng)，以適應(yīng)低位錯(cuò)密度晶體的晶格邊界的位移變形較少的晶粒的生長(zhǎng)是以變形大的晶粒為代價(jià)的u Minimizing energyu Surface energyu Internal energy (strain energy)u Small crystal growth to reduce surface energy減少的能量：表面能（小晶粒的生長(zhǎng)為了減少表面能），內(nèi)部能量（應(yīng)變能）Dynamic Recrystallization 動(dòng)態(tài)重結(jié)晶Bulging recrystallization 顆粒遷移重結(jié)晶（T strain rate）New grain bulge from the grain boundary into grain with highest dislocation density become independent grain 白色是位錯(cuò)低的，向高的灰色里擠，灰色被擠得只能在旁邊突出來(lái)。顆粒在某一側(cè)邊界失去一部分，而在另一側(cè)邊界得到一部分，相當(dāng)于顆粒整體在遷移或解體，最后形成新顆粒 如下圖subgrain rotation（SGR）亞晶粒旋轉(zhuǎn)重結(jié)晶（T- strain rate-）由動(dòng)態(tài)恢復(fù)作用所形成的的亞晶粒逐漸旋轉(zhuǎn)，使相鄰亞顆粒形成大角度邊界，產(chǎn)生新晶粒。亞晶?？赡鼙华?dú)立出來(lái)，根據(jù)形狀成為面理。grain boundary migration（GBM）顆粒邊界遷移重結(jié)晶 （T strain rate）Boundary migrates from low density to high density of dislocations.Dislocation migrates then into grain boundaries在晶粒的高應(yīng)變區(qū)，當(dāng)位錯(cuò)密度高于一個(gè)臨界值時(shí)，以晶內(nèi)應(yīng)變能為驅(qū)動(dòng)力，顆粒以突出成核的方式遷移，形成拉長(zhǎng)狀、鋸齒狀等不規(guī)則界面的新晶粒。Microtructures showing GBMAnnealing (Static Recrystallization)u Grain boundary can be consedered as planar defects straight GB and large area are therefore favored.u 靜態(tài)恢復(fù)過(guò)程是在宏觀變形停止后，動(dòng)態(tài)重結(jié)晶顆粒形狀再調(diào)整的過(guò)程。因?yàn)閯?dòng)態(tài)重結(jié)晶顆粒都具有不規(guī)則形狀，彈性應(yīng)變能雖然已經(jīng)消失，但礦物的表面能卻依然很高。在單位體積里，顆粒越細(xì)，總表面積越大，表面能越大。在粒度相同的情況下，顆粒形狀越不規(guī)則，彎曲程度越高，總表面積越大，表面能也越大。表面能是一種勢(shì)能，有自動(dòng)降低的趨勢(shì)，結(jié)果是表面積盡量減小，這就導(dǎo)致了靜態(tài)恢復(fù)作用。 下圖中的不規(guī)則邊界的港灣逐漸變成了多角形，三個(gè)礦物邊界交匯處形成三個(gè)角盡量是120Sense Of Shear 剪切方向u Direction of movement on a shear zone is usually shown by the lineationDisplacement and deflection of Markers:u Displacement of marker such as dykes, veins, bedding along a shear zone.巖脈 層理 剪切帶u Markers are also commonly deflected near the shear zone. 剪切帶旁往往有標(biāo)志物u Keep in mind the difference between the apparent offset and the true offsetu Non-coaxial progressive deformation 非共軸漸進(jìn)變形u Rotation of elements (foliations, lineation, finite strain axes) towards the shear plane.u Sense of rotation = SOSu Observation in the deformation XZ plane 在xz面觀察（1）Shear Band Cleavageu C-type Shear Band (C/S fabric) S-C面理u S-plane transected by horizontal Shear bands (C-plane)u Shear bands or C-plane are parallel to the shear zoneu Angle between C and S 45S面理是礦物長(zhǎng)軸的定向排列，C面理就是剪切面理或條帶，總體上與剪切帶邊界大致平行。在綠片巖相的花崗質(zhì)糜棱巖中很發(fā)育，一般S面理先形成。最初S面理與C面理角度45，隨著變形增強(qiáng)，夾角逐漸減小，直至趨于平行?？梢灾甘炯羟羞\(yùn)動(dòng)方向u C-type Shear BandC planes (shear bands cleavage) are oblique to the shear zone boundaries and the foliation C平面（剪切帶解理）傾斜于剪切帶邊界和面理u Angle between C and shear zone boundary is 15-35.C和剪切帶邊界之間的角度為15-35u （2）Naked clasts: equidimensional and sharp boundary with the matrix基質(zhì)u （3）Mineral fish云母魚: elongate shape with monoclinic 單斜的symmetry Strong SPO No evidence for Rotation They commonly occur in micaceous quartzitic mylonites. They characteristically lie with their longest dimension at a small angle to the mylonitic foliation. 云母魚的頭部和尾部一般平行于剪切方向（C面理）u 可以指示剪切運(yùn)動(dòng)方向u （4）Mantled Porphyroclast旋轉(zhuǎn)碎斑系: u surrounded by a rim with tapering shape on opposite side of the porphyroclast and same composition.A porphyroclast is a clast or mineral fragment in a metamorphic rock, surrounded by a groundmass of finer grained crystals. Porphyroclasts are fragments of the original rock before dynamic recrystallisation or cataclasis produced the groundmass. This means they are older than the groundmass. They were stronger pieces of the original rock, that could not as easily deform and were therefore not or hardly affected by recrystallisation. They may have been phenocrysts or porphyroblasts in the original rock.斑狀碎屑巖是變質(zhì)巖中的碎屑或礦物碎片，被細(xì)粒晶體的基質(zhì)所包圍。 在動(dòng)態(tài)再結(jié)晶或碎裂作用產(chǎn)生基質(zhì)之前，斑狀碎屑巖是原始巖石的碎片。 這意味著它們比基質(zhì)更老。 它們是原始巖石的較強(qiáng)部分，不容易變形，因此不會(huì)或幾乎不受再結(jié)晶的影響。 它們可能是原始巖石中的斑晶或斑晶。u 4 types:- type- type- type- typeWings: the fine-grained soft mantle can be deformed into wings (or trails) that extend on both sides of the porphyroclast parallel to the shape preferred orientation in the mylonite u （5）Strain Shadows: rim has a different compositionu （6）Sigmoid: aggregates of grains of a mineral A in a matrix of another mineral, lacking a clear porphyroclast core. They can have a similar shape to -type mantled clasts or mineral fish. u Sigmoids lack a rigid central clast, and usually show signs of internal deformation and recrystallisation in the entire object. They may have formed by boudinage and separation of -type asymmetric boudins of layers or veins, by ductile deformation of rectangular grains which recrystallised completely by complete recrystallisation of the core of a -type mantled clast, or inhomogeneous flow in the edge of a lens shaped aggregate. u 缺少一個(gè)剛性的中心碎屑，并且通常在整個(gè)物體上顯示出內(nèi)部變形和再結(jié)晶的跡象。 它們可能是通過(guò)層狀或脈狀的型不對(duì)稱布丁的布丁和分離，通過(guò)完全再結(jié)晶的型包裹的碎屑的核心再結(jié)晶的矩形顆粒的延性變形，或者在邊緣的不均勻流動(dòng)的透鏡狀的集合體。（7）Spiral Porphyroblast 雪球構(gòu)造之類的Progressive rotation of inclusions trails in the porphyroblast during the shearing 剪切過(guò)程中變斑晶一直在轉(zhuǎn)A porphyroblast變斑晶 is a large mineral crystal in a metamorphic rock which has grown within the finer grained groundmass. Porphyroblasts are commonly euhedral crystals, but can also be partly to completely irregular in shape. 變質(zhì)巖中，在基質(zhì)中的單個(gè)自形大晶體The most common porphyroblasts in metapelites (metamorphosed mudstones and siltstones) are garnets and staurolites, which stand out in well foliated metapelites (such as schists) against the platy mica matrix. 常是石榴石和十字石出現(xiàn)在板狀云母基質(zhì)中（呈面理）雪球構(gòu)造（snowball structure）是指在剪應(yīng)力下，雪球構(gòu)造巖石組分發(fā)生差異性塑性流動(dòng)，同構(gòu)造生長(zhǎng)的石榴子石等變斑晶發(fā)生滾轉(zhuǎn)而成的形似雪球的構(gòu)造。其中包裹體呈S形螺旋狀排列。它的形成機(jī)制類似滾雪球，故名。（8）Fringe structures 邊緣構(gòu)造Rigid objects in a ductilely deforming rock cause local perturbations of the stress field and flow pattern. In the case of low temperature deformation and high fluid pressure, increased pressure solution may occur adjacent to the rigid object on the side of the max shortening, while extensional gashes may open on the contact of the object and the matrix on the side of the max stretching. New crystalline material may grow in these gashes and form strain shadows on both sides of the rigid core object. If the crystals in such strain shadows are elongate or fibrous, these are known as strain fringes. The combination of core object and fringes is called a fringe structure.剛性物體在韌性變形巖石中引起應(yīng)力場(chǎng)和流動(dòng)模式的局部擾動(dòng)。 在低溫變形和高流體壓力的情況下，在最大壓縮一側(cè)剛性物體附近可能出現(xiàn)增壓溶解，而在物體與最大側(cè)拉伸。 新的晶體材料可能會(huì)在這些凹坑中生長(zhǎng)，并在剛性核心物體的兩側(cè)形成應(yīng)變陰影。 如果這種應(yīng)變陰影中的晶體是細(xì)長(zhǎng)的或纖維狀的，則這些被稱為應(yīng)變條紋。 核心物體和條紋的組合被稱為邊緣結(jié)構(gòu)。Strain fringes也叫不對(duì)稱壓力影Mantled porphyroclasts superficially resemble strain shadows but they have the same mineral composition as the core object (porphyroclast), form bydifferent mechanisms and have a different kinematic significance as strain shadows. We therefore do not include mantled porphyroclasts in the category of strain shadows. It is preferable to reserve the terms strain shadow and strain fringe for domains of material that have a different composition from the core object. However, mantled porphyroclasts and strain shadows are end members of a range of possible combinations; some strain shadows may be difficult to distinguish from mantled porphyroclasts with wings that have undergone chemical or mineralogical changes.碎斑系看上去像壓力影，但碎斑系與其核心（碎斑）有相同的礦物組成，由不同的機(jī)制形成，并與壓力影具有不同的運(yùn)動(dòng)學(xué)意義。（9）Fragmented porphyroclasts Elongate rigid porphyroclasts can be separated into aggregates of fragments by seams of cataclasite Low grade deformation Sense or rotation indicated by the sense if displacement between the different fragments 看它左行還是右行剪切要看兩個(gè)部分之間的相對(duì)運(yùn)動(dòng)方向 常見(jiàn)于碎裂流中 下圖第一種情況，“書斜式構(gòu)造（多米諾骨牌構(gòu)造）”，書向右倒，那么之間是左行剪切；向左倒，就是右行剪切。內(nèi)部與外剪力是反著的?？梢灾甘炯羟羞\(yùn)動(dòng)方向Lineation 線理Lineation: any linear feature that occurs penetratively in a body of rock. Fibres and striations on fault planes are not lineations since they only occur on specific planar surfaces in the rock, not penetratively.Object Lineations are defined by constiuting elements that have a specific volume Trace Lineations are intersections of planes or microfolds on foliation planes that lack a distinct volumePlatelet lineations are defined by planar minerals such as micas that share a common axis. They have elements of object- and trace lineations. Foliation 面理Foliation: general term