5th week of notes (09/21-25/2015)
5th week of notes (09/21-25/2015) GEOL 105 ( Ken Lepper)
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This 20 page Class Notes was uploaded by Luis Blanco Seguerit on Sunday September 27, 2015. The Class Notes belongs to GEOL 105 ( Ken Lepper) at North Dakota State University taught by Ken Lepper in Fall 2015. Since its upload, it has received 93 views. For similar materials see Physical Geology in Geology at North Dakota State University.
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Date Created: 09/27/15
GEOL 105 Ken Lepper 092115 Sample Quiz Questions 0 Soils form layers from the surface downward called a Stata b Beds c Horizons d Lamination Answer is C Horizon 0 Two forms of types of weathering that breakdown the surface are Chemical and Physical What is a sedimentary rock 0 Sedimentary rocks are products of mechanical and chemical weathering of other rock at the Earth s surface 0 Rock and mineral fragments or ions in solution 0 Contain evidence of past environments 0 Often contains record of past life fossils 0 Record of past climate conditions 0 Record of sediment transport processes Examples Monument Valley 23 of the Grand Canyon Arches National Park Economic Importance of sedimentary rocks 0 Sedimentary rocks are important for economic considerations because they source of 0 Coal o Petroleum and Natural Gas 0 Source of Iron aluminum titanium manganese and REEs rare earth elements 0 Aggregate and building stones Abrasives 0 Commercial 0 Turning sediment into rock 0 Many changes occur to sediment after it is deposited o Diagenesis chemical physical and biological changes that take place after sediments are deposited o Occurs within the upper few kilometers of Earth s crust o 23 kilometers of the Earth surface are sedimentary rocks Examples of Diagenesis 0 Soil formation 0 Turbation mixing 0 Ex Bioturbation cryoturbation o Dewatering o Compaction 0 Ion Exchange with groundwater o Lithification Lust material into Solid rock Turning sediment into rock 0 Lithification Transformation of sediments into solid rock by o Compaction o Recrystallization Development of more stable minerals from less stable ones 0 Cementation Natural cements include calcite silica and Iron Oxides from groundwater Example of Recrystallization AragonitegtCalcite Different CaCO3 Polymorphs Shapes of molecules Types of sedimentary Rocks 0 Rock types are based on the manner in which the sediment was transported and deposited o Detrital sedimentary rocks sediment transported as solid particles 0 Chemical sedimentary rocks sediment that was transported in solution Textures of Sedimentary Rocks 0 Two major textures are used in the classification of sedimentary rocks 0 Clastic Discrete fragments and particles All detrital rocks have a clastic texture o Nonclastic Pattern of interlocking crystals May resemble an igneous rock Must but not all chemical sedimentary rocks have a non clastic texture Detrital sedimentary rocks 0 The chief constituents of detrital sedimentary rocks include Ex Hematite Limotite Note Highlither is to distinguish the detrital sedimentary rocks that have that feature The Colors of Detrital Sedimentary Rocks and Ironoxides 0 Iron Oxides serve another significant role in sedimentary rocks 0 They are almost entirely responsible for the COLOR or sedimentary rocks 0 Less than 12 of Feox in total rock gives it color 0 Hematite Oranges Reds Maroons o Limotite Yellows and Oranges Detrital sedimentary rocks 1 0 Common Detrital sedimentary rocks 0 Shale Clay sized lt4 um 41000 mm particles in thin layers that are commonly referred to as laminea Most common sedimentary rock Gray and black in color and can preserve fossils o Siltstone Siltsized 463 um particles generally nonlaminated Yellowish o Sandstone Composed of sand sized 63um to 2 mm particles Forms in a variety of environments I Quartz is the predominant mineral the layers can be seen Fossil preserved Note shales and Siltstones are frequently referred to as mudstones but the term is too vague Detrital sedimentary rocks 2 0 Common detrital sedimentary rocks continued 0 Conglomerate and Breccia Both are composed of glass greater than 2mm in diameter With matrix particles that are smaller in size than the clasts o Conglomerate Consist largely pf rounded gravels o Breccia If composed mainly of large angular particles Principle of Original Horizontality 0 After being transported by one or more of the mobile agents sediments are deposited in horizontal layers 0 These sedimentary layers are most commonly refer to as strata Unconformity 0 An unconformity is a break or disruption in the rock record produced by erosion andlor nondeposition of rocks unit Types of unconformities o Angular unconformity tilted rocks are overlain by flatlying rock 0 Disconformity Strata on either side of the unconformity are parallel 0 Generally indicates Erosional Service 0 Non conformity metamorphic or igneous rocks in contact with sedimentary strata f UHCH farmftfes Mmmn nmiity ngnuilarr Mnmnfurmiity iis n mity U mn fannitfas in the Gran CE y n Sedimentary Facies I xtreme Mountairi streams breccias 39 simpification iFoothills conglomerates Rivers sandstones amp Shorelines deltas Off shore a sandstories siltstories Deep ocean basins shales i Timeequivalent strata I Sedimentary rocks deposited at the same time in the past can have different grainsizes i be different rock types i Represents transportation distance and energy Rock Symbols Table of Lithologic Symbols SYMBOL tI li HDLDGTt39 SYMEDL lJTHOLDGV39 Breeds Limestone Conglomerate Dolostone Sandstone v Volcanic rocks galEm 1 Plutonis rocks Shale i Platonic Coal Meta morphi rocks 092315 POP Sample Quiz Questions The physical chemical and biological changes that take place in sediments after deposition are called Dialysis Diagenesis Diagonalization Disapparition Answer is B Diagenesis PPPT Which of the following detrital sedimentary rocks is most likely to exhibit fine laminations A Shale B Siltstone C Sandstone D Conglomerate Answer is A Shale rocks Chemical Sedimentary rocks Consist of Precipitates material that was once in solution Precipitation of chemical sedimentary occurs 0 Predominantly by organic processes biochemically facilitated Creatures that live in water helps 0 But also by Inorganic processes under certain conditions BiochemicalBiogenetic Limestone Numerous aquatic organisms synthesize CaCO3 for their tests Shells from ions dissolved in water form in association with coral reefs 0 Minerals Calcite or Aragonite Same chemical formula Different arrangement of atoms in space 0 Limestones formed from these shells or tests are called biochemical or biogenetic Chemical Sedimentary Rocks Limestones Dolostones Origen gtgt alteration from limestones Evaporite Chen 5 Coal Chemical Sedimentary Rocks 0 Common chemical sedimentary rocks 0 1 Limestone Most abundant chemical sedimentary rock Composed primarily of the mineral calcite Marine biogenetic limestones form in association with coral reefs or shoals and include the rock types 0 Fossiliferous limestone o Coquina broken shells o Chalk microscopic organism tests 0 The white cliffs of Dover England Inorganic Limestone 0 Under some conditions Ca2 and C03 2 can precipitate directly from water forming calcite inorganically 0 Usually associated with Sudden changes in water temperature Mixing of waters with very different C03 2 concentrations 0 Inorganic limestones include Oolitic limestone Bahamas Banks with spherical form and Travertine Yellowstone Chemical Sedimentary Rocks 0 Common chemical sedimentary rocks 0 2 Dolostonesl Dolomite Product of alteration of limestones Diagenetic interaction of brines rich in Mg with calcareous sedimentslimestones Calcite Dolomite 2CaC03 Mg2 CaMgC032 Ca Acid Reactivity o Calcite Immediate I vigorous with acid 0 Dolomite Must be prepared to react with acic o 3 Evaporites Transported as ions Usually highly soluble but Evaporation of water containing the ions triggers deposition of chemical precipitates Examples include Rock salt and rock gypsum o 4 Chert Composed of microcrystalline quartz Transported as colloidal silica Varieties include flint jasper Branded iron formation and chalcedony banded form is called agate Opal microscopic spheres of microcrystalline quartz o 5 Coal Different from other biogenetic chemical sedimentary rocks because it is composed of organic material not just originating from biological processes Stages of Coal Peat swap environment Lignite Bituminous CoalCompaction AnthraciteMetamorphism Stages in coal formation in order of increasing burial pressure and heat 0 Plant material 0 Peat o Lignite o Bituminous o Anthracite Metamorphic Revie Sample Test Question 0 Rock gypsum is a A Biogenetic Limestone B Inorganic Limestone C Biogenetic Evaporite D Inorganic Evaporite Answer is D Inorganic Evaporite 0 Which of the following rocks is a form of inorganic limestone A Coquina B Fossiliferous limestone C Travertine D Chalk Answer is C Travertine 0 Which of the following is not a form of microcrystalline sedimentary quartz A Opal B Oolite C Agate D Jasper Answer is B Oolite 092515 Sedimentary Environments o A Geographic setting where sediment is accumulated o Is linked to the characteristics of the sediments that accumulate mineral content grain size grain shape etc 0 Types of sedimentary environments 1 Continental I Terrigenous o Stream deposition fluvial system c Alluvial fans 0 Deposition in lakes lacustrine o Evaporite basins playas I salt flats I pluvial lakes o Sediment deposited from the action of ice glacial 0 Wind transport Eolian 2 Marine 0 Shallow to about 200 meters depth 0 Continental shelves 0 Deep 0 Continental slope o Abyssal plain 3 Transitional shorelinenear shore o Beaches Tidal flats Lagoons back bays bayous Deltas Stream I Fluvial Environments Streams from tributary systems or drainage networks to collect and distribute the water on the surface There are braided Stream systems and Meandering stream systems There are some evidences of possible tributary systems on Mars An Example of Fluvial Environments is the flood plain of the lower Mississippi river An Example of meandering stream system is the Mississippi river L bangle Mississippi River Meandering stream Alluvial Fan Environment Conglomerate Alluvial form where streams and debris flows discharge from mountains onto valley floor leaving a triangular or wedgeshaped deposit of sands and gravel typically the larger clast are more abundant closer to their sources Alluvial Fan forming at the mouth of a canyon Glacial Environments Collectively known as drift Depostied through processes like till or outwash Till most common Glacial Deposit o Deposited directly by the melting ice along the glacial margin and consists of all sediment that has been picked up by the glacier as it scraped across the surface of the Earth 0 Mixed Grain size 0 Once it is lithified till is classified as a conglomerate Glacial really produce numerous lands Lithified till or Tillite is a type of conglomerate that can be found on Gowganda Tillite Ontario Canada Gowganda Conglomerate Periglacial Environments those that are in a cold climate typically near glaciered regions cold climate frequently marginal to the glacial environment and is characteristically subject to intense cycles of freezing and thawing of superficial sediments Peat bog Coal Eolian Environments Great Sand Dunes National Park Mon CO Eolian amp Pluvial Environment Sand dunes Gypsum dunes White Sands National Monument in New Mexico Shallow Marine Environments gtgt Limestones Great Barrier Reef from space Australia Guadalupe Mountains Ancient reefs NM Deep Marine Environments Modern clay deposition Rock record Shale Turbidities formation on the ocean Important petroleum environments Transitional Environments Beach Tidal flats and evaporitic basins o Racetrack Playa Death Vally CA 7 7 ill 39 Hanaquot Deltas o Nile River Delta exhibit distributary channel systems o Lena river Delta Lagoons Back bays Bayus I H n n 5 L Bayou Come in Louisiana Sedimentary Structures 0 Provide information useful in the interpretation of o Sedimentary Environments o Sedimentary structures 0 Types of sedimentary structures 0 Strata the characteristic layering of most sedimentary rocks Also called beds or sedimentary layers Personal notes Sedimentary structures 0 Ripple Marks Wave ripples 1 Symmetric Profile 2 Asymmetric ripples can be used to determine flow direction Bottom 5 symmetrical ripple marks E asymmetrizal ripple mar o Crossbedding in rock 1 Can be used to determine flow 2 High angle crossbeds Fluvial stream Deposit more than 25 3 Low angle crossbeds Eolian wind deposit 10 up to 25 7 i Crossbedding of sandstone near Mt Carmel roadZion Canyon indicating wind action and sanddune formation had occurred prior to formation of the rock 0 Modern mud cracks 0 Ancient mud crack 6 j m Ancient mud cracks preserved on the base of a bed of sandstone Fossil raindrop impressions on the top of a waverippled sandstone from the Horton Bluff Formation near Avonport Nova Scotia 0 Tools Marks gtgt Glacial Striations Sandstone with preserved too marks o Concretions gtgt chemical sedimentary rocks formed secondary within detrital sedimentary rocks 1 SD Badlands same rocksioutro o Septarian concretions gtgt tertiary chemical sedimentary within a secondary chemical sedimentary rock Sedimentary rocks 0 Types of sedimentary structures continued Crossbedding Graded beds Ripple Mark Mud Cracks Raindrop Marks Tool Marks Concretions Fossils 9 19791P9 NT Sample Test Questions Tributary channel systems are characteristic of which sedimentary environment Fluvial Lacustrine Alluvial Deltaic 9003 Answer is A Fluvial o Evaporite minerals are most likely to form in which sedimentary environment A Glacial B Fluvial C Deep Marine D Pluvial Answer is D Pluvial o The most common unconsolidated glacial sediment deposit is A Soil B Till C Conglomerate D Breccia Answer is B Till Note Conglomerate is when it gets solid
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