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101 Cards in this Set
- Front
- Back
Which of the ‘big five’ mass extinctions resulted in 2nd level ecological disruptions without significantly effecting reef ecosystems? |
Cretaceous–Paleogene extinction event (K/T) |
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On what scale do alpha, beta, and gamma diversity differ? |
A =single fossillocality or a single sample of fossils (Local)/(Habitat) B = Regional/local = True Y = Diversity of an entire landscape/oceanscape (Regional)/(Landscape) *A & Y can be measured with a species count *B = Uses A+Y to work out how strongly the habitats overlap. |
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Which type of diversity is plotted in Sepkoski curves? |
Total Diversity |
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Calculate Simpson’s evenness index for the following fossil community:(NOTE: The actual exam will contain different numbers!) brachiopod A: 1 specimens brachiopod B: 2 specimens bryozoan A: 4 specimens bryozoan B: 2 specimens crinoid A: 1 specimen |
D = 0.0476 D=1-(∑n(n-1) ------------ N(N-1) |
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How many Bambachian megaguilds are represented by the 5 species listed in the table below? |
4 1) A&B (Same Bambachian megaguild) 2) C 3) D 4) E |
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In which geological period appear the first representatives of the Modern Evolutionary Fauna? |
End-permian mass extinction lead to a rise of MFs Cambrian, rise in Triassic |
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How did the diversity of the Palaeozoic Evolutionary Fauna develop during the Mesozoic? |
stenotopic organisms |
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In the table below list the stratigraphic range (e.g. Ordovician – Permian) during which the groupslisted below were at the peak of their ecological success. 1)bivalves 2)inarticulate brachiopods 3)crinoids |
1)tria-terc 2)Cambrian 3)ord-dev |
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9. Which quantitative method results in a plot as shown below? y=N of species x=N of Samples |
Rarefaction curve |
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What is described by the Signor-Lipps effect? |
The first and last appearance of a fossil taxon is never truly known |
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Define the term convergent evolution. |
Organisms that are not closely related adapt similar characteristics, due to environmental controls. Eg. Sharks(fish), Dolphins(mammals), |
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To what substrate were crinoids with lots of arms and a long flexible stem likely attached? |
hard grounds |
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In the diagram below mark the type of survivorship curve that is typical for a population oforganisms with an r-strategy. y= N of survivors as a % x= Age of species as a % |
Type 3 Because high infant mortality rate in r-strategists, so sharp decrease in survivors in early age |
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Name two characteristics of K-strategists. |
Large body slow to mature few offspring Tendency to occupy niches in systems which are already near or at population limit Tend to occur in stable systems Low juvenile mortality |
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Name two characteristics of r-strategists. |
Fast to mature High fecundity High dispersal ratesmall body types many offspring Tend to occupy high stress/unstable environments High juvenile mortality |
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The base of which geological period is defined by the first appearance of an ichnospecies? (Burrowers) |
Base of the Cambrian period |
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If burrow A cross-cuts burrow B, which burrow formed in a shallower tier? |
B |
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What happens to burrow size as oxygen levels in the marine environment decrease? |
Decreases |
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What is the name given to the study of fossil communities? |
Palaeosynecology |
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What term is used to describe the sedimentary rock fabric caused by the activities of burrowing organisms? |
Bioturbation |
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Give two examples of trace fossils that are underground miners: (a): (b): |
Fodinichnia & Agrichnia (Possibly) or diplocraterion & rhizocordlium |
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Which ichnofacies indicates quiet, deep, muddy environments and is dominated by pascichnia andagrichnia? |
Nereites (Off shore/deep) |
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Which ichnofacies indicates mobile, sandy substrates and is dominated by vertical domichnia? |
skolithos (Shoreface) |
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What term is given to fossil taxa that temporarily disappear from the rock record, e.g. in theaftermath of extinction events? |
Lazarus taxon |
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Which large igneous province is associated with the Late Triassic mass extinction event? |
central Atlantic magmatic province |
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Name an important use of microfossils in geology? |
Dating (biostratigraphy) |
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Give an example of a method used in the preparation of sediment samples for microfossil analysis? |
Dying, washing, chemical extraction, thin section analysis |
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Name a microfossil group which has a calcareous shell? |
Foraminifera |
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Name a microfossil group which has a siliceous shell? |
Siliceoflagellate |
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Name a microfossil group which has an organic-walled shell? |
Dinoflagelattes |
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The life cycle of foraminifera is characterised by an alternation between two generations – one that reproduces sexually and one that reproduces asexually. Name these 2 generations? |
Gamont (sexual) & agamont (asexual) |
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In the classification of foraminifera, Loeblich and Tappan (1964) recognised 5 suborders. Name thesuborder of foraminifera which have imperforate, porcelaneous calcareous walls? |
Miliolina |
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In the classification of foraminifera, Loeblich and Tappan (1964) recognised 5 suborders. Name thesuborder of foraminifera which have perforate, hyaline calcareous walls? |
Rotalinia |
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In the classification of foraminifera, Loeblich and Tappan (1964) recognised 5 suborders. Name thesuborder of foraminifera that use foreign particles to make their tests and cement them together witheither organic or calcareous cements? |
Textulinia |
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In the morphology of foraminifera, what term is used for the chamber arrangement where chambers are coiled in a helical spire? |
Trochospiral |
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Name an abiotic environmental factor that controls the distribution and abundance of benthic foraminifera? |
Salinity Temperature Dissolved O2 |
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Name an important biotic environmental factor that controls the distribution and abundance ofbenthic foraminifera? |
Space food competiton |
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In the study of modern foraminifera, what is the name of the non-vital stain that is commonly usedto differentiate ‘live’ from ‘dead’ individuals? |
Rose-bengal |
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The proportions of three wall structures of foraminifera are commonly plotted on ternary diagramsto differentiate particularly shallow-water environments. Name these 3 wall structures? |
Hyaline porcelaneous agglutinated |
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Name a diversity index that is commonly used in the study of benthic foraminifera? |
Fisher alpha index |
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Larger foraminifera are said to be adapted to nutrient deficient conditions. What term is used fornutrient deficient conditions? |
Oligotrophic |
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Give the name of a genus of larger foraminifera? |
Nummulite zenehesis |
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Name an area on Earth where the environment is described as ‘hypersaline’? |
Arabian gulf |
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Name a genus of benthic formaninifera that is typical of lagoon environments? |
Quincoequelina |
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What morphological features are typically associated with benthic foraminifera that occupy an epifaunal microhabitat? |
Rounded trochospiral Milioline biconvex |
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Name two key morphological features of planktic foraminifera? |
Globular chambers & open appiture |
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Name an important ecological factor that controls the distribution and abundance of planktic foraminifera? |
Temperature |
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It is known that planktic foraminifera occupy different depths within the water column. Typically,what are the morphological characteristics of species that occupy surface waters? |
Smaller thinner walled Symbiont bearing |
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It is known that planktic foraminifera occupy different depths within the water column. Typically,what are the morphological characteristics of species that occupy deeper waters? |
Keeled non spinose thicker walled |
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The coiling direction of the planktic foraminifera Neogloboquadrina is commonly used forreconstructing past water temperatures. Name the species that coils in an anticlockwise direction(left/sinistral) and dominates in colder waters? |
Neoglobquadrina pachyderma |
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Cemented beach sands are common in which diagenetic environment? |
Marine Vadose |
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Cements in modern beach rocks typically consist of which carbonate mineral? |
Aragonite or High-Mg calcite |
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The formation of cemented beach sands typically occurs how far below the surface? |
10's of cm |
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Microbial micritisation is common in which diagenetic environment? |
Marine phreatic (Quieterwater-low energy areas- back reef lagoons) |
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Formation of grapestones and aggregates is common in which diagenetic environment? |
Meteoric Vadose |
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Carbonate dissolution commonly occurs in which diagenetic environment? |
Meteoric |
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What is the defining feature of isopachous cements? |
Equal all the way around the grain |
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As rainwater is undersaturated with respect to CaCO3, this leads to which process? |
Dissolution |
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As water moves downwards through the meteoric vadose zone via diffuse or conduit flow it become saturated in CaCO3 so that cementation occurs. These cements are typically what type of carbonate? |
Low mg-calcite |
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Name a carbonate mineral that is highly susceptible to dissolution? |
Aragonite |
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In arid settings what is the typical rate of alteration? |
Slow |
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Ferroan cements contains elevated concentrations of which element? |
Iron (Fe+) |
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Name an environment in which cementation takes place where CaCO3 enriched waters result from evaporation? |
Meteoric Vadose (Cave systems, desert wadi) |
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With respect to carbonate diagenesis principle cements types include aragonite; high-Mg calcite;low-Mg calcite and dolomite. Name a less common cement type associated with carbonate diagenesis? |
Quartz Kaolinite Gypsum Halite (Salt) |
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Slow and continuous cementation processes in the meteoric phreatic diagenetic environment leadto what type of cement morphologies? |
Large blocky spar |
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Increasing ambient Mg/Ca supply combined with increasing carbonate ion supply typically leads to which cement morphology? |
Accicular |
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In which latitudes is seawater supersaturated with respect to CaCO3 today? |
Tropics +/- 25 degrees |
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What is the surname of the geologist who devised the Facies code system for fluvial deposits? |
Miall (1977) |
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What does a sedimentary facies allow the interpretation of? |
Allows a sedimentary process to be established, based upon key descriptive attributes. I.e. - Fluid (Air or water) or Gravitational deposition - Planar Cross laminations etc. - Coarsening/ fining up cycles |
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What does a facies association allow the interpretation of? |
Assign all sediments to an environment ( Look for facies patterns in a log) |
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Name a sedimentary process that is typical of alluvial fan environments? |
1) Debris Flow 2) Sheet Flood 3) Stream Channel |
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In stratigraphy, what is the name of the law that describes the arrangement of sedimentary facies in space and time? |
Walther's Law - The principle that facies occur in conformable vertical successions of starta, also occur in laterally adjacent environments |
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Name an environmental controlling factor that can result in the development of a coarsening or fining upwards facies sequence? |
Reduction in energy from a channel caused by warming of climate (Less precipitation) will cause a fining up sequence in river beds. Vise versa Repeated fault movements caused by tectonics increasing gradients causes coarsening upwards in alluvial fans. |
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An alluvial fan with a low surface slope and a large catchment area will be dominated by what kind of sedimentary process? |
Sheet flood Higher water supply Low angle |
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Name a facies model for an alluvial fan setting? |
The Trollheim Facies Model or Conceptual alluvial fan facies model by Miall (1977) |
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An alluvial fan with a steep surface slope and a small catchment area will be dominated by what kind of sedimentary process? |
Debris flow Low water supply Steep slopes |
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Meandering river channels can often undergo avulsion. Name a cut off process that results inavulsion? |
Neck cut-off |
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Palaeosols in floodplain deposits that show grey mottling indicate what kind of climatic setting? |
Humid Climate -Reduction mottling - Gleys? |
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What is a lake setting characterised by evaportic sediments called? |
Playa Lake |
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The development of evaporitic minerals on a lake floor will result in the formation of what kind of surface cracks? |
Desiccation cracks |
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What kind of basin fill geometry is formed within a symmetrical rift basin? |
Graben |
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What kind of sedimentary environment characterises the footwall setting of a terrestrial rift basin? |
Alluvial fan |
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The axis of an externally drained rift basin is dominated by what kind of sedimentary environment? |
Rivering environment (Fluvial) Axial drainage channel |
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What is the collective name of the sedimentary facies that develops within the underfilled stage offoreland basin development? |
Flysch (Fine) |
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What is the collective name of the sedimentary facies that develops within the overfilled stage offoreland basin development? |
Molasse (Coarse) |
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What are the main deltaic-sub environments? |
1) Delta Plain (Interdistributary bays & Distributary channels) 2) Delta Front (Proximal and Distal) 3) Prodelta |
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What are the main sub-environments in a delta plain? |
Interdistributary bays (muds) & Distributary channels (Sands) |
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What are names of the two processes which deliver sediment from distributary channels to interdistributaryareas? |
Overbank flooding & crevassing |
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What kind of facies successions typify minor mouth bar progradation? |
Progradation = Coarsening Up successions |
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What kind of dense flows deliver coarse sediment to the distal delta front and prodelta? |
Hyperpycnal (Turbidity currents) - Effluent denser than basin waters |
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Hypopycnal conditions are occur when? |
When effluent is less dense than basin water density, leading to effluence floating above basin water creating a salt wedge |
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What is the key difference between failure-induced turbidites and hyperpycnal turbidites on deltafronts? |
Hyperpycnal is caused by denser effluent from channel entering a less dense basin. Failure-induced is from slumping & slides along basal sheare zone, caused by tectonics, gas hydrate escape |
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Normal regression in deltas generates what kind of facies succession? |
Progradation so coarsening up successions |
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What sedimentary features are typical of delta front successions which are not found in offshoreshelf deposits? |
1) heterolithic Clinoforms <2°? 2) Higher Sand:Mud ratio Coarse deposited at mouth) 3) Wave reworked (offshore below mean storm wave base) |
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Which type of sedimentary structure is unique to the offshore-transition zone? |
Storm-generated sand beds of laminated hummocky cross-stratification |
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Palaeocurrent distributions from trough cross bedding deposited in the upper shoreface are likely toshow what kind of distribution? |
Parallel to palaeo shoreline |
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The thickest successions in near-shore facies are likely to be deposited during what kind of genetic behaviour? |
Progradation |
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What flow regime does parting lineation develop in? |
lower part of the upper flow regime |
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What kind of genetic behaviour occurs when sediment supply rate in the nearshore zone is greaterthan the rate of relative sea-level rise? |
Normal Regression - Progradation |
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How can erosion surfaces generated by regression and transgression be differentiated in nearshoresuccessions? |
Forced regression - Out-of-sequence shallowing & surface offorced regression *Offlap w/ downstepping Transgression - Ravinements (transgressive surfaces of erosion) *Retrogradation w/ backstepping |
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Forced Regression = Sea level fall (forced progradation) Retrogradational = Sed. deficit & formation of barrier islands, estuaries ( *Flooding) |
Not a question |