Sed Strat T1 Study

Six steps of sedimentation

1. Weathering - Phys/chem breakup 2. Erosion - Removal of particles 3. Transport - Movement of particles via wind, glacier, river, to a depositional environment 4. Deposition - Collection of particles in depositional environment 5. Burial and Compaction - Weight of overlying sediment layers 6. Cementation (Diagenesis) - Precipitation of new minerals between grains, holding grains together

Abundance of rock types

65% Ig, 27% Met, 8% Sed Of the 8% 50% Mud/shale stone, 25% Sandstone, 18% Carbonate, Many minor after.

Detrial Sedimentary Rocks Mudrocks

<63 micrometers Composed predominantly of clay minerals and quartz Most common sedimentary rock Can be rich in organic material Deposited by quiet (slow moving water): Floodplains of rivers, lakes, deep ocean, continental slope.

Detrial Sedimentary Rocks Fine-grained Sed. Rock

<63micrometers. Mud - often associated with unconsolidated Mudrock - often associated with consolidated/lithified Claystone - subdivision Mudstone - subdivision Siltstone - subdivision Shale - Laminated, fissile, often dark.

Deltas

A delta is fed by a river into a standing body of water. Similarities between Tide, River, and Wave doinated Delta types that are combined, formed by two or three of these processes. River: Several distributaries with a more pronounced outward coastline Wave: Coastal ridges due to wave action. Tide: Tidal channels that lead your currents inwards. Perpendicular to coastline which creates islands or bars.

Alluvial Fans

A fan (cone)-shaped deposit, commonly poorly sorted and with few sedimentary structures, that was formed by sediment moving from mountains and spreading out into valleys Debris-flow, Sheetflood, and Stream channel. Alluvial fans form because as drainages carrying sediment reach the mouth of the canyon, the flow spreads out, decreasing velocity of the flow, forcing sediment to be deposited

Fluid definition

A fluid (Liquid or gas) has no shear strength distinguishing it from other substances such as solids.

Oxidation

A minerals ions combine with oxygen in the air to form an oxide. EX: Iron and Manganese bearing silicate minerals, iron sulfides.| 2FeS2 + 15/2O2 + 4H2O -> Fe2O3 + 4SO4^2- + 8H^+ Pyrite + oxygen + water -> Hematite + Sulfate + hydrogen Rust (Fe2O3) very stable on earths surface

Physical Weathering

AKA Mechanical weathering Breaks larger rocks into smaller pieces of rock (Sediment) but composition stays the same. Leads to particulate residues of resistant minerals (Quartz, feldspars, rock fragments) and produce sandstone, conglomerates or mudrocks

Insolation Weathering

AKA Thermal Stress weathering Expansion and contraction of rock caused by temperature change. Differential stresses cause cracking and perhaps exfoliation Common in deserts (Large diurnal temp range)

Depositional Architechture of a meandering river

Active Channel, Point of Avulsion, Oxbow Lake, Abandonded channel, channel-fill sands, overbank deposits, floodplains

Depositional architecture of a braided river

Active Channel, abandonded channels, channel-fill sands, overbank deposits, floodplain

Glaciers (See slide 29 in lec11 for detailed zones)

Advance or retreat governed y balance of snow accumulation and loss by melting.

Combined Flow

Alternating flow from two different directions can produce a complex pattern of criss-crossing, discontinuous ripple crests. Hummocky cross stat Isolated ripples (Lenticular, flaser)

Paleosols

Ancient soils that reflect the climatic conditions during the time they formed (Rootlets, burrows oil horizons, soil structures) Important for paleoclimate reconstructions Humid (rooted) vs Arid (Caliche) soils (Caliche = a mineral deposit of gravel, sand, and nitrates, found especially in dry areas of South America.)

Varve

Annual layer of sediment or sedimentary rock. A coarse (Spring) and fine layer (later in the year) for each annual cycle

Sedimentary structure

Any structure (variation or non-variation in texture) Types of sedimentary structures Planar Bedding and Lamination,Laminated bedding, Graded bedding, Massive bedding Bedforms among the most common and most studied sedimentary structures. Bedforms are topography formed by the movement of unconsolidated sediment, commonly ripples dunes planes bedding antidunes

Unidirectional Ripples

Asymmetrical. Similar bedforms, division between ripple commonly set by size at 6cm Stoss slope (7-15degrees) lee (angle of reposte ~32) Crest (High point), bring (Break in slope) may coincide Ripple index (Length/height) For symmetrical there's an upflow and downflow. Where it follows direction. Look this up**

Four eolian dune types

Barchan dunes, Transverse dunes, linear dunes, star dunes.

Laminae and beds

Basic sedimentary units that produce stratification - difference between the two is arbitrary and placed at 1cm

Tool marks

Bounce - Tool approaches the sediment surface at LOW ANGLE and immediately bounces back into current Brush - Approaches sed surface at VERY LONG ANGLE with the axis of the tool inclined upcurrent and is then lifted away by the current producing a ridge of mud downcurrent of the mark. Prod marks - Reaches sed surface at fairly high angle and is the lifted up and away by current Roll - Tool rolls over sed surface, producing continuous roll mark Skip marks - Tool travels downcurrent with a saltating movement, hitting the sed surface at nearly regular intervals.

Cement

Chemical precipitant within the pores of the rock formed during diagenesis Cement is a function of Sand composition Pore fluid composition: eg calcite in fluid will precipitate calcite Pore fluid flux a)Flow pathways b) permeability Pore fluid temperature Time Common types: Silicate & Carbonates Quartz, Opal, clay (kaolinite/illite) hematite - common in fine grained sediments vs Calcite (CaCO3), dolomite (Ca, Mg)(CO3)2, Aragonite (CaCO3), Siderite (FeCO3)

Chemical Weathering Processes

Chemical weathering breaks rocks into smaller pieces of rock by altering the composition of minerals and rocks mainly through chemical reactions with water. Dissolution by direct or indirect Hydrolysis Oxidation Factors: Climate/living organisms - Dependent on water, more rain promotes more chemical weathering. Similarly organisms are generally more common in wet conditions so they can greatly enhance chemical weathering Time Mineral composition - Unstable minerals weather more and faster, stable minerals weather less and slower (Think of bowens reaction series) Leads to ionic species in solutions and silicic acid (H4SiO4) that will eventually precipitate or deposit as clay minerals (shale) chert evaporites or limestone

Types of lagoons

Choked - High wave energy, significant alongshore drift, one or more long and narrow inlets, water movement by wind forcing Restricted - Two or more inlets, tidal circulation, strongly influenced by wind Leaky - Tidal currents more important than wind waves, stretch along coasts for large distances but narrow, wide tidal passes, efficient water exchange with ocean, strong tidal currents. For slides, 1st example closer to choked, 2nd possibly restricted or leaky?

Clastic vs Nonclastic

Clastic: Weathering breakdown of older rocks (Silici)-clastic sedimentary rocks (rich in silicate minirals) EX: Claystone, siltstone, sandstone, conglomerate... Non-clastic: Precipitation of minerals from water through various chemical or biochemical processes Chemical/biochemical sedimentary rocks -Different in chemistry, mineralogy, and texture from siliciclastic sed rocks Examples: Carbonates, evaporites, cherts, iron rich sed, phosphorites, carbonaceous sed rocks such as coal oil shale)

Matrix

Clay & Silt among framework grains <0.03mm How to get matrix Detrital - synchronous with deposition (eg storm deposit mixes mud and sand) Mechanical infiltration - eg point bar/flood plain Mixing of sand and clay during slumping - post depositional Mashed rock fragments, clay clasts, fecal pellets Alternation of framework grains Bioturbation

Products of chemical weathering

Clay minerals - Produced by the breakdown of feldspars and mafic minerals Metal Ores - Concentrations of metals (Al, Fe, Cu, mn, Ni, Ag) by weathering (Bauxite) Rounded boulders (chemical exfoliation) - from cracks and crevices water and chemicals react with minerals to form rounded boulders. Soils - produced by mechanical and chemical weather are the upper few meters of regolith (rock blanket)

Difference between Claystone, mudstone, and Siltstone

Claystone is 66-100% clay-sized particles <3.9micrometers or 2micrometers in engineering) Composed primarily of clay minerals Often contains micro and macro fossils Mudstone is 33-65% Clay-size particles Siltstone is 0-32% clay-sized particles and is composed primarily of quartz

Hydrologic regimes of lakes

Closed lake has no outflow, and open lake has an outflow.

Grainflow

Coesionless grains flow downhill under the force of gravity. Particles are kept apart by grain to grain collisions. Fluids Air or water) trapped between the grains act as a lubricant but unlike in stream flow doesn't propel grains. Occurrence: Slip face of Aeolian dune, steep subaqueous setting.

What do you use to describe clastic rocks?

Colour, Grain size, sorting, roundness/angularity, porosity, main cement, folk clan name (% Quartz, Feldspar, and Rock Fragments) Also shape... Kinda.

Tafoni

Combined effects of salt weathering, differential cementation, structural variation in permeability, wetting-drying, freezing-thawing cycles, variability in lithology. Also called 'honeycomb weathering'

Detrial Sedimentary Rocks Conglomerate (and breccia)

Composed of particles greater than 2mm in diameter Largely of rounded clasts if conglomerate, angular if breccia Poorly sorted Deposited by strong turbulent currents (Flooding streams, glaciers, debris flows)

Detrial Sedimentary Rocks Sandstone

Composed of sand-sized particles 1/16th - 2mm in diameter Quartz, feldspar, and polymineralic grains are most common constituents. Deposited by modest currents: Rivers, deltas, beaches, sand dunes

Conglomerates

Conglomerates contain 30% of gravel size >2mm particles. Breccias are composed of very angular, gravel size fragments(otherwise not distinguished) Clasts can be igneous, metamorphic, or sedimentary Most stable and durable clasts: quartzite, chert, vein-quartz) Unstable or metastable clasts: basalt, limestone, shale, metamorphic phyllite

Glacier Abrasion

Covered in detail later

Crossstratification

Cross bedding Ripple cross-lamination Flaser and lenticular bedding Hummocky cross-stratification Forms by migration of ripples and dunes in water or air. Trough by sinusoidal Planar by straight crested ripples

Debris vs Sheetflood vs streamchannel sed logs

Debris flow dominated fan. Matrix=supported, poorly sorted, conglomerate beds, no sedimentary structures. Sheet flood deposits. Horizontally stratified conglomerate and sandstone Stream channel fans. Channel-fill units of conglomerates and sandstones in fining successions (Braided river deposits)

What are the different subenvironments of a delta

Delta Top: Delta top/plain, interdistributary bays Delta Front: Subaqueous (sandy gravelly) mouth bar, delta slope, prodelta Delta slope is between mouthbar and prodelta. Prodelta - material that gets carried the farthest away.

River dominated delta

Delta plain with little finger like landmasses with sediment leaking out at the end of those land penensulas. Avulsions such as from Mississippi. Individual delta lobes that move along and change with the avulsions.

Marginal Marine Depositional Environments

Deltas and Lagoons

Lacustrine Delta

Deltas form anywhere that running water enters a standing body of water

Debris flow

Dense, viscous mixture of sediment and water with the volume and mass of sediment exceeding that of water. Low Reynolds laminar flow. Produces structureless (Chaotic fabric), very poorly sorted deposits. Material of any size from clay to large boulders may be present Occurence: Arid environments on land (alluvial fans), submarine environments (continental slopes), coarse-grained delta slopes Despoits on land are typically matrix supported conglomerates, but clast supported is possible.

Modern gilbert type coarse grained delta

Density of water systems can change, Topset foreset and bottomset - Easy to make them out because of this migration. Foresets are inclined like a dune. Bottomset are sandy turbidites interbedded with mudstone Foreset beds - Clast supported and matrix supported conglomerate, steeply inclined at 30 degrees to the horizontal Topsets - pebbly and sandy braided river deposits Mouthbar deposit coarsens UP

Facies Models

Depositional/sedimentary facies - Rocks from similar depositional environments ie fluvial facies. This is interpretive and comes after intensive study of the rocks themselves. Lithofacies - Similar rock types - sandstone facies; mudstone facies Biofacies - similar biota/fossil assemblages -bivalve facies Chemofacies - Similar chemical composition

Roundness/ angularity

Describes the smoothness of the grains corners, reflects hardness, duration, and strength of abrasion agent. General Rules: For the same clast type (quartz, feldspar, etc) gravel rounds faster than sand. Silt and clay do not round by abrasion. Aoelian (wind) abrasion is the most effective at rounding - more than aqueous (water). Beach more effective than river.

Lagoon and Tidal summary

Different types depending on shape and number of inlets Protected by beach barrier bars or islands Quiet waters Alternating bioturbated muds and wave rippled washover sands Tidal flats Generally fining landward ( decrease energy) Subtidal (Bellow water) Tidal channel herring bone cross strat sandstones Intertidal (Exposed to air once or twice a day) flaser, wavy, lenticular bedding Supratidal (exposed to air) salt marshes and mucracks

Turbidity Current

Diluted mixture of water and sediment with concentrations up to 1% by weight, distinguished between low-, medium-, and high-density turbidity currents. High Reynolds # -> Turbulent flow. Range from gravel to sand to mud may be present. Occurence: Deep lakes, continental shelves, deep marine environments (most abundant) 1) Earthquakes trigger slumps or other mass wasting events. These kick sediments up into the water column 2) The resulting mixture of water and sediment is much denser than plain water, and goes roaring downsloap. The turbidity current has a life of its own, separate from the landslide that started it; they are capable of carving canyons in unconsolidated sediments. 3) After flowing downhill into the continental rise - perhaps 100s of kilometers, the heavier clasts start to settle out reducing density contrast and causing current to slow down, followed by lighter ones and finally including clay particles - producing a turbidite. BOUMA SEQUENCE

Delta Definition

Discrete shoreline protuberance formed at a point where a river enters the ocean or any other body of standing water.

Bring big grey or blue scantron.

Don't need to know equations.

Upper (stage) plane bed (USPB)

Dynamic, mobile sheet of streaks of grains in transport High energy flow Planar stratification Parting lineation (paleocurrent indicator) Shallow or rapid (high velocity) subaqueous flow Bed load and suspended load Typically of beach swash Zone

Bernoulli Equation

Energy must be conserved by can change forms. Equation expresses inverse relationship between low pressure gradients at the top of hills and high wind speeds. Among other applications, this relationship is important for understanding river meanders and how grains are lifted from the ground in air and water.

Shape

Equant and disc shaped clasts are most common.

Shorelines/Coastlines types

Erosional: Steep gradients where energy is reflected back to sea (Reflective coasts) - Typical of active margins eg California Depositional: Shallow gradient and wave energy is dissipated in shallow water - must be a supply of sediment to be depositional, - passive margins, eg gulf coast, east coast.

Delta cycles

Facies succession preserved depends on location of vertical profile relative to the depositional lobe of a delta. Significant for where you would want to be drilling.

Alluvial Fans - Keypoints

Fan (Cone)- shaped deposit Moves sediment from mountains to valleys Steep gradient Proximity to source Erosive base Usually coarse grained, clast supported, imbricated Normal grading from unhindered settling of grains in turbulent flow.

Going out to in of a tidal flat

Farthest out - Herring Bone looks like fish bone. Imagine Japanese hiragana ku over and over with a line in the center. (Reactivation surface, creating asymmetric tidal cycle causes erosion of ripple crests and production of reactivation surfaces. Forming same bedforms over old ones. See slide.) Intertidal environment - Flaser, Wavy, and Lenticular bedding. Wavy and Lenticular have more shale than Flaser.

Framework Feldspar

Feldspar Orthoclase KAlSi3O8 Plagioclase NaAlSi3O8-CaAl2Si2O8 Abrasion: High survivability common in Aeolian wind blown sands Weathering stability at surface:Low in humid, ortho stronger than plagio, high in arid. Hand sample: pink (K), White (Na) Thin section: .. Finish later

Turbidite

Fining upward sequence that can grade from conglomerate to mud. Turbidites can be up to 10m thick, however most are much smaller. They oftentimes show sedimentary structures indicating current direction, such as sole marks and flute casts.

BOUMA SEQUENCE (SEE IMAGE)

Five units. Unit a massive granules to sand, rapid deposition Unit b

Types of estuaries

Fjord, Ria, Bar built, and Delta front, see slide there are more.

Irregular Stratifications

Flame structures Convolute Laminae Dish and Pillar Ball and pillow structures Synsedimentary folds Erosion structures - channels

Flaser bedding in tidal-flat sediments

Flaser bedding is a type of ripple bedding: Thin streaks of mud occur between sets of cross-laminated or ripple-laminated sandy or sily sediment (mostly in troughs) -> Fluctuating hydraulic conditions Deposition and preservation of sand more favorable. Form in tidal flats, subtidal environments, and marine delta-front environments Sand > Mud

Morphological features of a meandering River

Floodplain Cut bank Levee Lateral Accretion Pointbar Crevasse Splay Overbank deposit Channel deposit

Morphological features of a braided river

Floodplain Mid-channel bars Vegetated former bars Bar surfaces Overbank deposits Channel deposits Mobile rivers with no fixed channel margins. Channels migrate and avulse frequently due to unstable substrate - high bedload.

Flow regime summary

Flow regime (FR)/Bedforms/Sed structures No grain movement - Flat beds - Parallel bedding Lower-lower FR/Ripples/Cross laminations Lower FR/Sandwaves (2d)/Planar-tabular x-beds Upper-Lower FR/Dunes(3d)/Trough x-beds Lower-upper FR/Plane bed/Planar bedding Upper FR/Antidunes/Up-current dipping laminations

Non-marine/continental/terrestrial depositional Environments

Fluvial systems - Alluvial fans and Rivers

Antidunes

Fr # > 1, Super critical flow Fast shallow flows Form beneath standing waves Antidune bedforms are destroyed during decreased flow, thus, cross bedding is not preserved

Components of clastic rocks

Framework, Matrix, Cement, Porosity. FMCP = 100%

Rockfall

Free fall of blocks or clasts from cliffs or steep slopes

Facies

Fundamental building blocks of a sedimentary succession. May be descriptive (mudstone facies) or interpretive (fluvial facies) Facies Combine observations of internal rock characteristics and spatial relationships that allow comparison between areas.

Depositional Environment

Geographic area in which sed is deposited. Characterized by a combination of geological process and environmental conditions.

Gravity mass Movements

Gravity flows occur in subaerial(air) and subaqueous (underwater) Memorize chart? Don't worry about slump or glide? Slowest (Creep) to faster (Slumps, flows and slides) to fastest (Avalanche & Falls) Velocity (steepness of slope and water content) Can start as one kind and change into another.

Hydrolosis

H+ or OH- ion displace other ions in a mineral structure to produce a new mineral. EX: SIlicate minerals (Feldspars -> Clay) 2KAlSi3O8 + 2H2CO3 + 9H2O -> Al2Si2O5(OH)4 + 4H4SiO4 + 2K+ + 2HCO3- Orthoclase + carbonid acid + water -> Kaolinite + Silicic acid in soln + potassium and bicarbonate ions in soln. 2NaAlSi3O8 + 2H2CO3 + 9H2O -> Al2Si2O5(OH)4 + 4H4SiO4 + 2Na+ + 2HCO3- In the example of a plant soil forming processes plant roots exchange hydrogen ions with other positively charged ions. Plants use the ions and the minerals become clays.

Hard vs firm ground fossils

Hard is borings, Firm is burrows

Depositional settings in a wave dominated estuary

Has a beach barrier with an inlet. Small delta may be at the bay head with a central lagoon attached. Wash over deposits may be on the beach barrier on the lagoon side.

Colour

Highly variable Depends upon original mineral colour, weathered mineral colour, and percent of organic material.

Provenance

Humid : Active chemical weathering and breakdown of feldspars and lithic fragments Arid: Limited chemical weathering. Metamorphic source terrains in human climate -> Weathered quartz-rich sandstone Plutonic igneous source terrains in humid climate - Feldspar-rich sandstones Arid climates preserve the lithic fragments produced from metamorphic terrains and both feldspar and lithics produced from plutonic terrains.

Hummocky cross stratification

Hummocky cross stratification forms during storm events with combined wave and current activity in shallow seas and is the result of aggradation of mounds and swales. Normally seen in fine to medium sand.

Hummock vs Swales

Hummocky is up turned while swales are down facing.

Famous dimensionless number - Reynolds Number

Inertial forces vs viscous forces Low under 500 = laminar, 2000+ = turbulent Inertial Force vs gravitational forces >1 supercritical can't go upstream 1 critical <1 subcritical, upstream

Continental Shelf

Inner, middle, and outer shelf. Shelf break is where it begins continental slope. Slope becomes continental rise. Landward is on backside Backward is shore side

Lacustrine Systems

Lakes Lakes are standing bodies of water formed on land and as such they contain many of the same features that form along shorelines. (Deltas, turbidites, slumps)

Laminar vs turbulent

Laminar - All molecules within the fluid move parallel to eachother in the direction of transport - almost no mixing. Turbulent - Molecules in the flow move in all directions, but with a new movement in transport direction near complete mixing.

Flow types

Laminar and Turbulent Laminar is all moving down stream linearly

Planar bedding and lamination

Laminated bedding Graded bedding Massive bedding

Dunes

Larger bedforms (Greater than 6cm) with spacing or wavelength ranging from under 1m to over 1km Similar to ripples Form at higher velocities Grain size ranges from fine sand to gravel. Can grow to about 1/4 of the flow depth in a river.

Stratigraphy & Its branches

Larger scale vertical/horizontal relation between units of sedimentary rocks. Allows for environmental and temporal synthesis along with sediment composition, texture, structure, and other features in order to interpret Earth's history. Lithostratigraphy - Uses well logs Biostratigraphy - Fossil content Chronostratigraphy - Age Sequence stratigraphy - Concept of packages of strata bound by unconformities Seismic stratigraphy - Interpreted by seismic data Magnetostratigraphy - Magnetic properties Event stratigraphy - Based on marker beds or event horizons Cyclostratigraphy - Short period high frequency sedimentary cycles Chemostratigraphy - Correlation based on stable isoptopes such as O, C, Sr

Lenticular bedding in tidal flats

Lenticular bedding is formed by interbedded mud and ripple cross-laminated sand. Ripples or sand lenses are discontinuous. Deposition and preservation of mud more favorable Form in tidal flats, subtidal environments, and marine delta-front environments. Mud > Sand

Laminae

Less than 1 cm

Lib tide vs spring tide

Libb? Nibb? tide is at right angle weaker Spring tide when sun and moon in line every 15 or so days, stronger.

Liquefied flows

Liquefaction of sediment fill recognizable through fluid escape "pipes" and "sand volcanoes". Dish structures in sedimentary rocks.

Barrier island facies

Marsh, Tidal flat, flood tidal delta, secondary tidal channel, main tidal channel (inlet, washover, dunes, beach, ebb tidal delta.

Sole marks

May be on exam! Sole marks are erosional sedimentary structures on a bed surface (bottom) that have been preserved by subsequent burial Preserved particularly well on underside of coarse grained sedimentary rocks (sandstones) that overlie mudstone beds Often show direction features and indicator of paleocurrent 2 stage process Erosion of cohesive fine grained material (Mud) Depostion of coarser (Sand)

Influenced by wave and tidal processes

Microtidal barrier islands - Long and skinny above 4m Mesotidal barrier islands - Short and stubby 2-4m Macrotidal - No barrier islands below 2m Beach barriers with inlets between that are flood-tidal deposit. Mudflats on outer lagoon exterior. Ebb tidal deposits on sea side. Tidal currents make the ebb and flood-tidal These don't exist on wave dominated Slide 19 Lec 13

Mode vs Median vs Mean

Mode - Most frequently occuring particle size Median - Midpoint of average grain distribution (50th percentile on cumulative curve) Mean - Arithmetic average of all particle sizes (Approximated by using distinct percentiles from cumulative curve and mathematical expressions

Dune type based on sand and wind amount

Much sand with variable wind is Star, little sand with variable wind is linear, sand and moderately uniform wind is transverse, little sand with uniform wind is barchan.

Subaqueous shrinkage cracks and mudcracks

Mudcracked caused by subaerial dessication of mud Subaqueous shrinkage cracks- shrinkage of sed without dessication. Mudcracks look like Vs in a cross section

Tide dominated delta

Multiple channels and fingering due to the tidal currents going in and out. In between the tidal channels are the tidal sand bards. No longer have a continuous coastline

Conservation of momentum

Navier-stokes equations. Rate of change of momentum of a fluid particle is equal to the new forces acting upon it. momentum per unit volume, ρu Among many applications, solving this equation is the primary means by which flow fields in both air (wind) and water (Rivers, oceans) are quantified)

Newtonian fluids

Newtonian fluids: Air and Water Shear thinning: Blood, lava, non-drip paint Shear thickening: Cornstarch + water

Clastic

Often called Siliciclastic rocks - composed mostly of silicate minerals (Quartz, Feldspar) Physically transported fragments produced by weathering of pre-existing rocks. Transported and deposited by wind, water, or ice.

Grains in motion

Once in motion stay in motion Transport paths Traction & saltation are bedloads Traction (Grains rolling or sliding across bottom, impact and creep) Saltation (Grains hop/bounce along bottom) Suspended load (Grains carried w/o settling) upward forces > downward forces, particles uplifted stay aloft through turbulent eddies. Clays and silts usually, can be larger (sand in floods) Washload (Claysized particles travel in continuous suspension; in rivers, from upstream source area or erosion of banks) Grains can shift pathway depending on conditions

Estruaries

Opposite of a delta. Forms where a river enters an ocean but the tidal/wave action is STRONGER than the river discharge. Mix of fresh and sea water. Fluvial and Marine system interface Estuaries form during transgressive cycles

Morphological features of a beach. Break this one up, actually multiple

Parallel Laminae typically dip 2-3 degrees. Strand Plain - Beach attached to coastal plain) Chenier ridges (Former beach ridges) Coastal Plain Wave Dominated? Inlets Longshore drifts Wash over deposits, only on Wave Dominated. Spits - Little protrusions due to swash waves.

Factors influencing soil formation

Parent material, topography, vegetation, time, climate Bedrock controls many soil forming processes.

Stokes law

Particles have different terminal velocities depending on size, shape, density, and fluid properties. Must have correct units! Only for very fine grain.

Weathering

Physical Weathering - Glaciers, crushing, grinding, freeze-thaw cycles, abrasion by fluvial processes Chemical Weathering - Breakdown of unstable minerals on earth's surface (Feldspars -> clays)

Frost Wedging

Physically weathers rock by changing water in pores/cracks to ice. Water enters cracks, expands as ice, intervening rock then dislodged.

Framework Rockfragments

Pieces of ancient rock that were not physically or chemically weathered Highly variable in composition, thus, stability at surface and appearance in hand same and thin section Most important for determining provenance of the sediment or rock. VRF - Volcanic rock fragments MRF - Meta rock frags SRF - Sed rock frags CRF - Carbonate rock frags Chert - Microcrystalline Quartz

Dropstone

Pops out of the bottom of an aquatic glacier on the bottom of the waters.

Porosity

Pore space between grains. 0% means no porosity. Rock can contain air, water, oil, gas in pore space.

Trace Fossils - Biogenic structures

Preserved remains of the activity and behavioral patterns of organisms. Naming trace fossils -> Naming shapes not biological species Reason: One animal can make different kinds of traces, one trace fossil can be made by different organisms Ichnology - Study of trace fossils.

Mechanical Exfoliation

Pressure release aka unloading Overlying material removed by erosion causing underlying rocks to expand and fracture parallel to surface

Framework Quartz

Quartz, Formula SiO2, most common mineral in siliciclastic rocks Abrasion: High survivability Weathering stability at surface: High (See bowens reaction series) Hand sample: Clear, translucent, milky grains Thin section: Colourless, undulose or straight extinction, lacks cleavage, gray, white or pale interference colours in cross polars. Types of Quartz: Monocrystalline, polycrystalline, microcrystalline, cryptocrystalline

Flow Factor

Ratio of driving stress to resisting strength determines flow behavior... This seems complicated, ask if it'll be on test.

Sorting

Reflects strength, duration, and uniformity of wave or current action that deposited the sediment.

Rock avalanche

Relatively DRY, extremely rapid movement of debris Can travel enormous distances with little elevation difference Travels on a cushion of air

Till deposit

Result of accumulation of debris

Bioturbation & Bioturbation index

Reworking of seds by microrganisms or plants Bioturbation can occur on the surface or deep waters. Index tells you how much bioturbation occurred. Trace fossils indicate depositional environments on siliciclastic shelves.

Grain and Rock Descriptions

Rocks and grains making up a rock are the record of 1. Provenance - source region of the rock 2. Abrasion History - Transport history of grains 3. Evolution or porosity - Burial and diagenesis

Salt Crystal Growth

Salt crystallization causes disintegration of rocks when saline fluids seep into cracks and joints and then evaporate leaving salt crystals behind. Salt expands in heat and puts pressure on the rock Common in arid climates with lots of evaporation and along coasts.

Mangroves along margin of muddy lagoon, why?

Salt tolerant trees, complex root system. Many trees and plants don't like salt water, but their root system allows them to grow in salty/brackish water.

Three aspects of the dune triangle

Sand, Wind, and vegetation. See slide 19 on Lec11

Form of a depositional coast line is determined by

Sediment supply - high moderate low Wave energy - high moderate low Tidal range - micro meso macro Climate - arid temperate tropical Tectonics - active, passive, volcanic Source mineralogy clastic vs carbonate.

Sed log of braided river deposits

See lecture 9 slid 67

Sediment processes in lakes

See slide 14 in lecture 10. Low siliciclastic input through rivers - Chemical, biochemical and siliciclastic deposits High siliciclastic input through rivers - Dominantly siliciclastic sediments

Facies distribution in a clastic freshwater lake & sed column

See slide 15 in lecture 10 Shallow lake deposits, beach or lake delta sands on top Shallow lake deposits, mud and wave ripple sands Deeper lake deposits. Laminated dark shales and thin turbiditic sands and silts.

Rates of subsidence and frequency of avulsion

See slide 57 lecture 9.

Thermal stratification in a freshwater lake

See slide, 13 in lecture 10.

Characteristics of a storm-dominated shelf environment

See slide. Storm wave base vs fair weather wave base. depth is 1/2 the wavelength. Deeper in storm wave since storm waves are stronger. See slide on sed log. Has 'wave dominated' which a tide normally wouldn't due to occilation.

Sandwaves, sand ridges, sand ribbons in shallow tidal

See slides Lecture 14?

Udden-Wentworth grain-size scale for clastic sediments.

Semi-quantitative terms, no relative terms like 'large/big, etc'

Lagoon

Shallow body of water separated from large body of water by barrier islands or reefs.

Kurtosis

Sharpness or flatness of a curve peak

Texture

Size, Shape and Sorting. Depends on Mineralogy of source rock Distance Traveled Method of transport (water wind or ice)

Soft sediment deformation structures

Slump structures (on slopes) Dewatering structures (Upward escape of water, commonly due to loading) Load structures (Density contrasts between sand and underlying wet mud; can in extreme cases cause mud diapirs)

Abrasion

Small Particles that are being carried in an agent such as wind water or a glacier, grind a larger rock down and smoothen sharp edges.

Scour and Fill

Small depression scoured by currents into underlying sand, then filled with sand/gravel

Soils

Soil profiles - The vertical succession of soil horizons at one location Soil horizons are distinct units in the soil based on composition and internal characteristics Commonly follows this pattern O Organic-rich A Inorganic material + humus E - Eluviated (materials removed by dissolution) commonly light coloured B - Illuviated (Materials from above settle here) C - Weathered parent material Bedrock - Unaltered rock

Walther's law of facies

States that facies found superimposed on one another and not separated by an unconformity must have been deposited adjacent to eachother at a given point of time.

Angle of repose

Steepest angle at which granular material will accumulate in a stable configuration Grain shape, moisture, electrostatic forces

Submarine Channel-levee systems

Step 1) Erosion by turbidity currents in blue unit Step 2) Levees form and grow as channel deepens in blue unit Step 3) Toe thrusts while blue unit rotatoes Step 4) Channel then gets filled

Wave dominated delta

Still a river but the waves and wind are so strong that their actions are dominated, still have river channel and muddy delta plain with sandy mouthbars. But whats new is the yellow coastal sands. These form parallel to your coast and which direction the wave fronts are coming in. ec

Straight vs Sinuous vs isolated (linguoid)

Straight is straight (duh) Sinuous is curving slightly or significantly Isolated (linguoid) - Broken, separate crescents

Types of rivers

Straight, Sinuous (Meandering), Single Channel, Multiple Channel-anastomosing, Without channel bars, with channel bars braided

Midterm exam stuff

Study canyon lake field trip fossils/rocks. She may give result, such as 'have a stone turned red, is this physical or chemical and which process?' Lecture 2: Chemical - Leads to Ions. Paleosols - Important. Lecture 3: Silica or Calcite are cements. Don't memorize numbers for standard deviation. Mudrock has highest porosity without compaction, but with compaction sandstone will. (Because grains are smaller) As depth increases porosity goes down.

Tidal Flats and their zones

Subtidal zone - SAND Intertidal between sub and supra tidal - SAND AND MUD Supratidal zone - Only flooded maybe twice a month during spring tide or a huge storm event. Dry environment. Salt marshes. MUD

Unidirectional Bedforms

Succession of bedforms during unidirectional flow of sandy sediment om shallow waters Lower (Stage) plane bed (LSBP) - Coarse sands and gravel Flow conditions similar to those generating current ripples in finer sand Low rates of sediment transport Shallow scours in the sediment surface Unidirectional ripples and dunes - Similar bedforms, division between ripple commonly set by size at 6cm Stoss slope at 7-15 degrees with less slope about 32 degrees. Crest (highpoint) brink (Break in slope) may coincide. Ripple index (Length/height)

Explain the equilibrium line in a glacier

The elevation at which accumulation and melting (ablation) of glacier ice are equal is known as the equilibrium line.

Factors of Delta

Three main river tide and wave dominated Different factors on morphology such as grainsize, water depth, slope, process controls Subenvironments. Delta top/plain and inderdistributary bays Delta front mouth bar and delta front, prodelta. 'prograting features'

Conservation of mass - Continuity equation

Total mass or volume of the system equal what goes in (influx) plus what goes out (outflix) plus what is stored or lost from the system. Called sediment conservation or sediment continuity equation when applied to sediments This is how sed deposits form at all scales - from accumulation of grains to accumulation of sedimentary basins Mass in - Mass out = Increase -> Deposition Decrease -> Erosion Steady-state -> Steady state

Deposition of facies in transgression and regression sea patterns.

Transgression are retrogradational stacking patterns. Regression sea results in progradational stacking patterns.

Fluvial (alluvial) river systems

Transporting agent - river currents Sediments - sand, mud, & gravel Ripples, cross-bedding, mudcracks common Coarse-grained channels surrounded by mud (floodplain deposits) Climate - arid to humid Organic processes - organic matter in muddy flood deposits Mississsippi drains 41% of USA. May be very long lasting on continent, e.g. Mississippi 40-60mio.years old. Erosian via rivers occurs directly after uplift Fluvial deposits are good aquifers and oil and gas reservoirs.

Eolian/Desert depositional environment

Transporting agent - wind. Sediments - sand and dust (loess) Sand dunes are large features with steep faces ripples, cross bedding formed from migrating sand dunes. Well sorted, quartz rich sands Mudcracks in wet area between sand dunes. Climate - Arid Organic processes - little organic activity, mainly surface tracks and trails.

Biological

Tree roots gradually grow into and open up joins in the rock, during the decay of organic material, organic acids are also released resulting in chelation.

Methods of analyzing sediment grain sizes

Unconsolidated Sediment & disaggregated sedimentary rock Boulders Cobbles and Pebbles - Manual measurement of individual clasts Granules, sand, some silt - Sieving, settling-tube analysis, image analysis Some silts and Clays - Pipette analysis, sedimentation balances, photohydrometer, sedigraph, laser diffractometer, electroresistance (coulter counter) Lithified sed rock Boulders, Cobbles, Pebbles - Manual measurement of individual clasts. Granules, sand, some silt - Thin-section measurement, image analysis Some silt and clay - Electron microscope

Normal grading

Upward decrease in grain size within a single lamina or bed (typically indicates a decrease in flow velocity) reverse grading is the opposite

Sorting, their depositional environments and the standard deviation

Very well sorted, <0.35, coastal dunes, some beaches, shelf sands. Well sorted, 0.35 - 0.50, most beaches, inland dunes, shelf Moderately well sorted, 0.5 - 0.71, Inland dunes, rivers, lagoons Moderately sorted, 0.71-1.0, glaciofluvial, fluvial Poorly to very poorly sorted, 1.0 - 2.0 and >2.0, glacial, glaciofluvial, alluvial fans.

Mass flows

Water mixes with regolith to create a slurry that moves downslope. Just mud - Mudflow Mud mixed with larger rock fragments - debris flow Lahar - Mix of volcanic ash from current eruption or previous eruptions and water (from snow and ice that melts in a volcanos heat or from heavy rainfall)

Flows

Water or air mix with material to create a slurry that moves downslope. Moves as a viscous fluid with little resistance to deformation Velocity is a function of (Slope angle and water content) The higher the angle and the more water/air -> The faster the flow Can carry large rocks, houses, cars, trees 4 major types Mud and debris Grain Liquefied Turbidity currents Other gravity flows: Snow/rock avalanches, pyroclastic flows

Dissolution

Water removes ions or ion groups from a mineral or rock without leaving a visible trace. Direct Dissolution - Soluble minerals are being dissolved in water. (Natural solubility) EX: Quartz, highly soluble SiO2 + 2H2O -> H4SiO4. Direct dissolution of halite or gypsum leaves brecciated zones. Indirect dissolution - Water reacts with another compound to form acid Rainwater combines with CO2 in atmosphere or soil to make weak carbonic acid that percolates downward and will begin to dissolve away limestone, leaving pits in the rock. Acid rain occurs when gasses such as sulfur dioxide and nitrogen oxides are present in atmosphere. EX: CARBONATES. H2O + CO2 -> H2CO3 CaCO3 + H2CO3 -> Ca(HCO3)2 Leaving voids, pits, caves. Dissolved ions commonly precipitate as scale on pipes or cement in other rocks.

Wave vs current ripples

Wave ripples are formed in relatively shallow water conditions in the absence of strong currents. In plain view, wave ripples have long straight to sinuous crests In lateral view wave ripples are symmetrical with cross laminae dipping in both directions either side of the crest (unique exception for climbing ripples)

What are the different factors that control delta morphology?

Wave/Tide/River dominated. Sediment (Whether coarse or fine) Water depth Slope

Oscillatory Bedforms

Wind driven waves. Circular particle motion Greatest motion at surface Decreasing amplitude with depth Described by their wavelength, height, period (Time required for one wavelength to pass a fixed point), and base (which is 1/2 wavelength below surface) Only really in shallow water. Low energy = sharp, high energy = rounded crests

Causes of dune types

Wind strength, vegetation, wind direction, amount of sediment

Anastomosing rivers See terms on slide 71 lecture 9

composed of multiple stable and active, but moderate sinuosity channels separated by stable islands (largely stabilized by vegetation)