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Environmental Science
Nick Eyles

EESA06 FINAL REVIEW Chapter 10: Metamorphism, Metamorphic Rocks, and Hydrothermal Rocks -Metamorphism: Changes to rocks that take place in the earth’s interior -Metamorphic Rocks: The new rocks after the transformation occur in the solid state (meaning the rock does not melt) -Two critical condition for rocks to ductile(延展): Temperature, and certain pressure -Confining pressure(围压, 封闭压⼒力力): Pressure applied equally on all surfaces of a substane as a result of burial or submergence. -Lithostatic pressure(岩⽯石静压⼒力力): The strong confining pressure that press the objects deep buried within Earth’s crusts. -Pressure gradient: The increase in lithostatic pressure with depth, in approximately 1 Kpa/3.3 km of burial in crust rock. -Quatizite(⽯石英岩): Produced when grains of quartz in sandstone are welded together while the rocks in subjected to high temperature. -Gneiss(⽚片麻岩): A rock consisting and dark mineral layers or lenses. -Contact metamorphism (Thermal metamorphism)(接触变质作⽤用): Metamorphism in which high temperature is the dominant factor. -Regional metamorphism(dynamo thermal metamorphism)(局部变质,区域变质): Metamorphism that takes place at considerable depth underground (generally > 5km). -Metamorphic grade(变质程度): The mineral present in a rock indicates its metamorphic grade. -Prograde metamorphism(进级变质): When a rock becomes buried to increasingly greater depths, it is subjected to increasingly greater temperature and pressures, and will undergo prograde metamorphism — that is, it recrystallize into a high-grade rock. - Slate(板岩): The lowest grade rock in progressive metamorphism. -Migmatite(混合岩):After the megma that has collected in layers within the foliation panes of solid rocks, it becomes migmatite. It is an mixed igneous and metamorphic rock -A migmatite is neither fully igneous nor entirely metamorphic. - Isotherm(等温线): Dashed red lines that indicate the temperature, they connect points of equal temperature. -Hydrothermal minerals(热液矿物):Form in void spaces or between the grains of a host rock. -Hydrothermal rock(热液岩): An aggregate of hydrothermal mineral, it crystallize within a pre- existing fracture in a rock to form a hydrothermal vein. - The role of water in Hydrothermal process - In metamorphism: Water transports ions between grains in a rock, some water may ne incorporated into crystal structures. - In Metasomatism: Water brings ions from outside the rock, and they are added to the rock during metamorphism. Other may be dissolved and removed. - In hydrothermal: Water passes through cracks or pore rocks spaces in rock and precipitates minerals on the walls of cracks and within spaces. -Water at convergent boundaries: Water that percolate(渗出) from the surface into the ground becomes groundwater. -Groundwater seeps downwards through pores and fractures in rocks. -Metasomatism(交代变质):It’s metamorphism coupled with the introduction of ions from an external sources. -Hornfels(⻆角⻚页岩): A very fine-graind, morfoliated, metamorphic rock whose parent rock is either shale or basalt. -Foliated rocks(层状岩⽯石) from lower-grade to higher-grade: -Slate(板岩): Very fine-grained rock that splits easily along flat, parallel planes. (chalk board, pool table, roof) -Phyllite(千枚岩,硬绿泥泥⽯石): A rock in which the newly formed micas(云⺟母) are larger than the platy minerals in slate but still cannot be seen with the naked eyes. -Schist: It’s characterized by megascopically visible, approximately parallel oriented minerals. Platy or elongate minerals that crystallized from the parent rocks that are clearly visible to the naked eye. -Gneiss: A rock consisting of light and dark mineral layers or lenses. The highest temperatures and pressures have changed the rocks so that minerals have separated into layers. Temperature conditions under which a gneiss develops approach those at which granite solidifies. -Marble(⼤大理理⽯石): A coarse-grained rock composed of interlocking calcite crystals, form when limestone recrystallizes during metamorphism. -If the parent rock is dolomite(⽩白云⽯石), then the recrystallized rock is a dolomite-marble. -It is highly susceptible to chemical weathering. -Differential stress: The fore on a body defer in different directions. It tends to deform objects into oblong(椭圆形) or flattened forms. -Shearing(变形): Caused by differential stress, which is, parts of a body more or slide relative to one another across a plane. The shearing often takes places perpendicular to, or nearly perpendicular to, the direction of compressive stress. - Three very different textures (from lowest to highest degree of metamorphism) are variations of foliation and important to classify metamorphic rocks. -1). If the rocks splits easily along nearly flat and parallel planes, indicating that pre- existing, microscopic, platy minerals were pushed into alignment during metamorphism — The rock is slaty or it possesses slaty cleavage(板岩劈理理,板状劈理理). -2). If visible platy or needle-shaped minerals have grown essentially parallel to a pane due to differential stress, the rock is schistose(⽚片岩的). -3). If the rock became very ductile and the new minerals separated into distinct (light and dark) layers and lenses, the rock has a layered or gneissic texture(⽚片麻岩材质). Chapter 11: Geological Structure -Structure Geology: The branch of geology concerned with the shapes, arrangements, and interrelationships of bed rock units and the forces that cause them. -Strain: The change in size(volume) or shape, or both, in response to stress. -Compressive stress(压应⼒力力, 抗压应⼒力力): If the rocks are pushed together or squeezed from opposite directions, we say the stress is compressive. -Tensional stress(张⼒力力,张应⼒力力): Caused by forces pulling away from one another in opposite directions. -Tensional stress results in a stretching or extension of material. -Shear stress: When stresses act parallel to a plane, shear stress is produced. -A shear stress results in a shear strain parallel to the direction of the stress. Shear stress occur along actively moving faults. -Elastically Rocks behaviour: If a deformed body recovers, its original shape after the stress is reduced or removed, the behaviour is elastic. -Ductile(plastic) manner: A rock that behaves in a ductile or plastic manner will bend while under stress and does not return to its original shape after relaxation of the stress. -Brittle(破碎) behaviour: A rock exhibiting brittle behaviour will fracture at stresses higher than its elastic, or once the stress are greater than the strength of the rock. -Rocks typically exhibit brittle behaviour at or near the earth’s surface where temperatures and pressure are low. -Geologic map: Uses standardized symbols and patterns to represent rock types and geologic structures, is typically produced from the field maps for a given area. -Strike: The compass direction of a line formed by the intersection of an inclined plane with a horizontal plane. -Angle of dip: Measured downward from the horizontal plane to the bedding plane (an inclined plane). -Direction of dip: The compass direction in which the angle of dip is measured, if you could roll a ball down a bedding surface, the compass direction in which the ball rolled would be the direction of dip. -Geologic cross section: Represents a vertical slice through a portion of the Earth. -Folds: Bends or wave like features in layered rock. -The fact that the rock is folded or bent shows that it behaved as a ductile material. -Anticline(背斜层): An upward-arching fold. -Usually the rock layers dip away form the hinge line (or axis). -Syncline(向斜,向斜层): The downward-arching counterpart of an anticline, a thought-like fold. -The layered rock usually dip toward the syncline’s hinge line. -Limb(翼): Each anticline and adjacent syncline share a limb. -Axial plane: An imaginary plane containing all of the hinge lines of a fold. Each of these planes is and axial plane. -Plunging folds: Folds in which the hinge lines are not horizontal. -On a surface levelled by erosion, the patterns of exposed strata (beds) resemble V- shape or horseshoes. -Structural dome: A structure in which the beds dip away from a central point -In cross-section, a dome resembles an anticline and is sometimes called a doubly plunging anticline. -Structural basin: The bed dip toward a central point. -In cross-section, it is comparable to a syncline (doubly plunging syncline). -A structural basin is like a set of nested bowls. If the set of bowls is turned upside down, it is analogous(类似于) to a structural dome. - 4 types of common Folds: -1). Open folds: It has limbs that dip gently. -All other factors being equal, the more open the fold, the less it has been trained by shortening. -2). Isoclinal fold(等斜褶皱): One in which limbs are parallel to one another, implies larger shortening strain or shear strain. -Asymmetric: Where the axial plane of a fold is not vertical, but is inclined or tripped over. -3). Overturned fold(倒转褶皱): The axial plane is inclined to such degree that the fold limbs dip in the same direction. -4). Recumbent fold: Overturned to such an extent that the limbs are essentially horizontal. -Joint(节理理): A fracture or crack in bedrock with no displacement occurs. -Fault fracture: The rock on either side of a fracture moves parallel to the fracture surface. -Columnar joint: In which hexagonal columns form as the result of tension and contraction of a cooling, solidified lava flow. -Sheet jointing: A type of jointing due to expansion is caused by pressure release due to the removal of overlying rock and has the effect of creating tensional stress perpendicular to the land surface. -Joint set: Joints are oriented approximately parallel to one another. -Faults(断层): Fractures in bedrock along which sliding has taken place. -Dip-slip fault: Parallel movement to the dip of the fault surface. -Strike-slip fault: Horizontal motion parallel to the strike of the fault surface. -Oblique-slip fault: Has both strike-slip and dip-slip component. -Hanging wall: The side of the fault above the inclined fault surface. -Foot wall: The side below the fault. -Two most common types of dip-slip faults: -1). Normal faults: The hanging wall block has moved downward relative to the footwall block. -A normal fault results in extension or lengthening of the crest. -2). Reserve faults: The hanging wall block has moved up relatively to the footwall block. -Thrust fault: A reserve fault in which the dip of the fault plane is at a low angle (<30 degrees) or even horizontal. -There are Two common types of strike-slip faults: -1). Right-lateral fault: When look across the faults and see the displaced stream to the right. -2). Left-lateral fault: A stream or other displaced feature would appear to the left across the fault. Chapter 15: Groundwater -Groundwater: The water that is lying beneath ground surface, filling the pore space between grains in bodies of sediment and clastic sedimentary rock, and filling cracks and crevice in all types of rock. -Porosity(多孔性): The percentage of rock or sediment that consist of voids or openings is a measurement of a rock’s ability to hold water. -Permeability(渗透性): The capacity of a rock to transmit a fluid such as water or patrolmen through pores and fractures. -Porous: A rock that holds much water. -Permeable: A rock that allows water to flow easily through it. -Impermeable rock: A rock that does not allow water flow through it easily. -Saturated zone(饱和层): The subsurface zone in which all rock openings are filled with water. -Water table(⽔水位): The upper surface that has been marked by the water level inside the well. -Unsaturated zone(不不饱和带,通⽓气层): A zone above the water level that is generally unsaturated. -Capillary fringe(⽑毛细上升区): A transition zone with high moisture content at the base of the vadose zone(包⽓气带) just above the water table. -Perched water table: The top of a body of groundwater separated from the main water table beneath it by a zone that is not saturated. -Hydraulic head(⽔水位差,⽔水势) = elevation(仰⻆角,海海拔) + pressure -Hydraulic gradient(⽔水⼒力力梯度) = difference in head / distance = change in h / L -Groundwater velocity = permeability / porosity * hydraulic gradient V = k / n * change in h / L -Aquifer(蓄⽔水层): A body of saturated rock or sediment through which water can move easily. -Aquifers are both highly permeable and saturated with water. -Unconfined Aquifer(⽆无压含⽔水层,⾮非承压含⽔水层): Partly filled with water. -Confined aquifer(承压含⽔水层,⾃自流含⽔水层): Completely filled with water. -Cone of depression: When water is pumped from a well, the water table is typically drown down around the well into a depression shape like an inverted corn. -Artesian well(⾃自流井): In confined aquifers, the water is under pressure and rises in wells to a level above the top of the aquifer. -Spring: A plane where the water flows naturally from rocks into the land surface. -Gaining stream(潜⽔水补给流): The streams that receive water from the saturate zone (In rainy region). -Losing stream: Rivers are losing water to the saturate zone(In dry region). -Groundwater quality: A measurement of the suitability of groundwater for certain purpose. -The pH, salinity, hardness -Caves(Caverns): Naturally formed underground chambers. -Dripstone(speleothems)(洞洞⽳穴堆积物): Deposits of calcite(rarely other minerals) built up in caves by dripping water. -Stalactites(钟乳⽯石): Icicle-like pendants of dripstone hanging from cave ceiling. -Stalagmites(⽯石笋): Cone shaped masses of dripstones formed on cave floor, generally directly below stalactites. -Sinkholes(dolines)(天坑,灰岩坑,落⽔水洞洞): closed depressions formed on land surfaces underlain by limestone. -Formed either by the collapse of a cave roof or by solution as descending water enlarges a crack in limestone. -Karst topography: An area with many sinkholes and with cave systems beneath the land surface. -Petrified wood(硅化⽊木): Fossils develops when porous buried wood is either filled in or replaced by inorganic silica carried in by groundwater. -Concretion(结⽯石): A hard rounded mass developed when a considerable amount of ce,emting material precipitates locally in a rock. -Typically around an organic nucleus such as leaf, tooth, or other fossil. -Geodes(晶洞洞⽟玉⽯石,晶洞洞): Partly hollow, globe shaped bodies found in volcanic rocks, some limestones, and locally in other rocks. -Hot spring: Springs in which water is warmer than human body temperature. -Geyser(间歇喷泉): A type of hot spring that periodically erupts hot water and stream. -Mudpot: A special type of hot spring that contains thick boiling mud. Chapter 20: Geological History in Canada -Acasta Geniss(4000 million years): North-America territories, which forms part of the Slave Province of the Canadian Shield. -North America was essentially complete by 65 million years ago. -Late ice sheet: 12000 years ago left southern part of the country, 10000 years finally melted in Labrador. -Baffin Island(巴芬岛): Remnants of this vast ice sheet still survive on Baffin Island as Penny and Barnes Ice Caps. -Craton(稳定地块): The ancient core of North America, composed
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