ES120 - STRATIGRAPHY AND SEDIMENTOLOGY

A list of terms and concepts you should be familiar for the final exam.

 

LITHOSTRATIGRAPHY

lithofacies

formation

unconformity (angular, disconformity, paraconformity)

lateral contacts (pinch out, intertounging, progressive)

rhythmic sedimentation

autocyclic

allocyclic

transgression

regression

eustatic

progradation

 

BIOSTRATIGRAPHY

correlation

first appearance datum (first occurrence)

last appearance datum (last occurrence)

biozone

range zone

concurrent range zone

interval zone

lineage zone

hiatus

bioprovinciality (endemic)

index fossil

graphic correlation

diachronous (time transgressive)

isochronous

planktonic foraminifera

calcareous algae (coccoliths)

 

what are the limitations on applying biostratigraphy?

 

MAGNETOSTRATIGRAPHY

inclination, declination

thermal remanent magnetism (curie point)

detrital remanent magnetism

paleomagnetism

demagnetization

reversals

chronozone, chron, sub-chron

transition zone

polarity

 

GEOLOGIC TIME SCALE

eons

eras

periods

epochs

Paleocene-Eocene Boundary

 

CHEMOSTRATIGRAPHY

residence time

reservoirs

    Sinks

    Sources

    Feedbacks

stable isotope

isotope fractionation

oxygen isotope stratigraphy (18O/16O)

    temperature vs. ice-volume effects

    planktonic vs. benthic foraminifera

carbon isotope stratigraphy (13C/12C)

    carbon isotope gradients

    biological pump

strontium isotope stratigraphy (87Sr/86Sr)

Explain how residence time (& ocean mixing) determines which elements are suitable for chemostratigraphy.

 

LOGGING STRATIGRAPHY

well logging

resistivity logs

gamma ray log

porosity

Which mineral phases carry the most natural radioactivity (K,Th, U)?

Which sediment properties can you recognize from a natural gamma ray log? An induced gamma ray log?

 

SEISMIC & SEQUENCE STRATIGRAPHY

Reflectors

Acoustic impedeance

seismic profile

seismic sequence

erosional truncation

baselap (onlap, downlap)

highstand

lowstand

parasequence

maximum flooding surface (MFS)

system tracts

How do you distinguish a low stand system track from a transgressive system track in a seismic profile? What other information might you use to test this?

What is one distinguishing characteristic of a sequence boundary?

 

CYCLE STRATIGRAPHY

 

Milankovitch (orbital) cycles

Eccentricity

Obliquity

Precession

Ice-volume

Glacioeustatic

On what time scales (how far back in time) can cycle stratigraphy be used to evaluate relative time (as opposed to absolute time)?

 


Eart 120: Sample Questions: Stratigraphy

 

1.     Provide short definitions of the following terms and explain why they are important in stratigraphy (5 pts)

a)     Acoustic impedance

b)    Walthers law

c)     Element Residence Time

d)    Allocyclic

e)     Maximum flooding surface

 

 

2.     .  Short answer questions (5 pts each):

 

A.   What are formations. How are they defined?

 

 

 

 

B.   Which factors/processes control sediment accommodation space?

 

 

 

 

 

C.   List or describe four factors that influence the temporal and spatial distribution of fossils in the sediment record (local or global).

 

 

 

 

D.   What are the durations of the first and second-order stratigraphic cycles and what are their respective hypothesized causes?

 

 

 

 

E.   List 4 stratigraphic/sedimentary features that can indicate the possible presence of an unconformity?

 

 

3.    Answer one of the following essay questions (20 pts).

 

Explain the basic principles of oxygen isotope stratigraphy.  Include information concerning the isotopes involved, their general distribution within the ocean, primary processes that alter the mean isotopic composition of the ocean (10 pts).  Describe how the technique is used to correlate sedimentary sequences (10 pts).  Include information about the material that would be measured. Give an example.

4.      The diagram below represents a seismic profile from a passive margin. 

A) Label the following; high-stand system track (HST) (2 pts) and transgressive surface (TS)(2 pts).

B) Draw a vertical profile (curve) of depicting relative change in grain size/sea level for the section in core A in the chart below. Label the axes (4 pts).

 

 

5.      Several physical property & geochemical records (plotted vs. depth) have been generated on a deep sea core including two oxygen isotope records (right).  A) Which of the d18O records is derived from analyses of benthic foraminifera (2 pts)?  B) What are the variations in d18O indicating (4 pts)?  C) Based on what you see, how old are these sediments and what is the average sedimentation rate of this core (4 pts).