Module 3 Flashcards
Types of Weathering
Mechanical weathering
Chemical weathering
In situ soils
Transported soils
Soil Horizons
Picture in Folder
O-Organic: Dead roots, leaves, worms
A-Rock with leeching: This layer receives dissolved minerals and nutrients and other soluble substances from the O layer, delivered mostly be precipitation
B
C
Eluviation
Also called leaching, is a process where precipitation dissolves and carries soluble minerals and nutrients down into deeper horizons.
Illuviation
A process where deposited solubles form a layer in a deeper soil horizon
Erosion/Transport types
Mass wasting- gravity gently moves soil particles
Fluvial-water, rivers, rain
Aeolian-wind (sand dunes)
Glacial
Diagenesis, types
Indludes process through which sediment becomes a sedimentary rock, prior to weathering or metamorphism. This can include physical, chemical and biochemical processes such as compaction, cementation, solution and recrystallization from water leaching in.
Lithification is just compaction and cementation.
Sedimentary environment types
Continental, Transitional, and Marine
Continental environments-Short Systems
Alluvial fans- Flowing water carries sediment from a high altitude onto a flatter, open plain. Has a fan shape
Short streams
Continental environments-Long Systems
Alluvial Fans
Meandering Streams
Braided Streams
Flood Plains
Continental environments-Desert
Sand Dunes
Playa Lakes and evaporite faults
Loess
Continental environments-Glacier
Ground moraine
Lateral moraine
Periglacial-adjacent to glaciers
Subglacial-under glaciers
Continental environments-Transitional
This is between continental and Marine environments
Sand Dune fields
Beaches
Coastal lagoons-water body parallel to ocean, separated by sand bar or reef
Barrier Islands-possibly left over sand dune fields from previous facies
Estuaries-High tide version of delta, water goes in and out
Tidal straits and tidal flats- tides periodically wet and dry this area on a daily basis
Prodelta
Foredelta
Delta plain
Estuary vs Delta
Estuary is a water body where river meets ocean. Occurs when river is met with high tide, high sea level.
Delta is a land form where river meets ocean. River is met with low tide, low sea level.
Both are shaped like a funnel or triangle
Delta components, name and basic explanation
Prodelta-Silt and clay distributed, water slowed down. This is the area outside the immediate deposition zone of the delta into the ocean.
Foredelta-sand and gravel is distributed, immediate area in ocean where coarse sediments are deposited. Also includes distributary channels above sea level.
Delta Plain-gently sloping plain flanking the river where water rises to at high tides.
Continental environments-Shallow Marine Clastic Systems
Standard Pattern of Shallow Shelf Deposition, super common
Sand-> Silt-> Clay-> Limestone deposits
Continental environments-Shallow Marine Carbonate Systems
Coastal Lagoon/backreef->Reef (that seperates lagoon from ocean)->Forereef (ocean breaks reef into fragments that spread out)
Carbonate Platform (Florida, Yukatan peninsula)-shallow, extensive carbonates
Continental environments-Deep Marine
Continental Rise Turbidites-turbidites that are inactive, as they have emerged from the ocean
Abyss deposits-Deep ocean fine clays and chert
Grain maturity index
Low maturity to high maturity is defined by Size, Sorting and Rounding.
Rounded, uniform clast size sand is high distance travelled, high maturity. Varying clast size, including fist size, angular shape indicates low maturity
Sed Rock Textures
Clastic (Low-high maturity)
Nonclastic-Biogenic(you can see fossils)
Crystalline (limestone has calcite crystals)-might have a clastic texture
Clastic rock mineralogy-Importance
Gives source rock clues
Primary Structures-Primary; What does primary mean, list and def
Picture provided in folder
Primary means they were formed as sediment was deposited , physics causes it
Bedding
Lamination-thin bedding
cross bedding-tidal environment
Ripple marks-Water flows through rivers, streams or marine area. Steep side indicates direction of waterflow
Mudcrack-Floodplains, deltaplain, NOT ocean. Sed deposit dried
Load cast-Sand deposited on soft clay
Flute casts-teardrop or whale shaped grooves where water flowed in direction of tapered end.
Tool Marks-Large clasts transported by water cut a groove in mud. Water flow was parallel to the marks.
Graded Bedding-Suggests turbiditic deposition, gravity pulls sediment laden water down a marine slow, and progressively larger clasts settle as the water slows down.
Burrows-Animals dig down until they hit hard rock.
Fossils
Primary Structures-Secondary; What does secondary mean, list and def
Pic in folder
Cementation-Large nodules of minerals that precipitated from pore fluids around a nucleus or seed that could have been a fossile or rock.
Septarian nodules-Cementations dry and form cracks. New minerals crystallize within these cracks.
Stylolites-irregular, serrated marks in rocks like limestone where a mineral dissolved due to pressure. Indicates tectonic activity applied the pressure that dissolved a mineral.
Soft sediment deformation- mud slumps down due to gravity, swirling effect
Hierarchy of rock grouping (area where rock is present is called)
Member(Rock)/Zone(Fossil)->Formation->Group
Stratigraphic Facies; what is it
When the charecteristics of a rock unit change laterally, it is called stratigraphic facies. A channel deposit is being deposited laterally to a flood plain deposit. Facies= Adjacent and simulataneous
Walther’s Law
Assuming no unconformities, two rock units that are in concordant vertical contact must represent adjacent sedimentary environments. This can be extended to lateral changes.
In this context, concordant means the bedding and strata are parallel. Vertical means the units are adjacent to each other laterally.
Marine Facies (List laterally adjacent rock units as you walk across)
Alluvial Fan gravels->Fluvial sand->Estuary Silts->Beach sands->Barrier Island Sand->Clay-Lime mud
Note because it is an estuary, high tide makes it so energy decreases as you go inland. Thus, silts are inland from beach sands and island sand.
Fluvial Facies (List laterally adjacent rock units as you walk across)
Terrace Sand and Gravels->Flood Plain Sand->Fine sand levees->coarse sand point bars->Gravel Channel deposits->coarse sand point bars->Fine sand levees->Flood Plain Sand->Terrace Sand and Gravels
Note Point bars are the inner wall of the meandering river, collecting finer material as water is slowing down on the curve. Levees are the outer wall that gets built up by returning sediment when the river floods.
What does sea level transgression and regression look like in the rock record.
Using facies, you can determine sea level change by seeing if facies move inland or offshore. You might see lime mud get pushed out, indicated sea level decrease. Or you might see lime mud dominate more space, meaning higher sea levels.
regression=ocean go away, shore moves away from continent
transgression=ocean come up, shore moves inland
USA Index fossils by geologic time
Cenozoic Mammal: Deer
Mesozoic Reptile: Dinosaur
Paleozoic invertebrate: Trilobite
Ordered based on time, where you would find it in rock record.
Mexico Index fossils by geologic time
Cenozoic Mammal: Horse
Mesozoic Reptile: Marine reptile
Paleozoic invertebrate: Brachipod
Ordered based on time, where you would find it in rock record.
Europe Index fossils by geologic time
Cenozoic Mammal: Pig
Mesozoic Reptile: Primitive Bird
Paleozoic invertebrate: Crinoid
Ordered based on time, where you would find it in rock record.
Africa Index fossils by geologic time
Cenozoic Mammal: Horse
Mesozoic Reptile: Dinosaur
Paleozoic invertebrate: Trilobite
Ordered based on time, where you would find it in rock record.
Are index fossils typically marine or continental
Marine, less weathering
Cenozoic Index Fossils
Gastropods, mollusks, foraminifera, diatoms
Mesozoic Index Fossils
Ammonites, diatoms
Upper Paleozoic Fossils
Crinoids, fusilinids, radiolaria
Middle Paleozoic Fossils
Brachiopods, conodonts
Lower Paleozoic Fossils
Trilobites, graptolites
Residual vs Transported soils
Residual soils are soil that was eroded from the immediate bedrock, and formed horizons in situ.
Transported soils are soil that was eroded and either later or immediately got transported by water, wind, gravity or glaciers. The horizons get jumbled up and the soil horizon process restarts. The soil is not in situ.
Soil Formation Factors
Climate
(Heavy rainfaill+hot temps=laterite, high in iron oxide, reddish soil) ( Topography (Steep=thin soil) Source rock (Serpentinite Mg is poisonous, Till crumbles up and forms soil horizons quickly) Time
