ES120 - STRATIGRAPHY AND SEDIMENTOLOGY
A list of terms and concepts you should be familiar for the final exam.
unconformity (angular, disconformity, paraconformity)
lateral contacts (pinch out, intertounging, progressive)
first appearance datum (first occurrence)
last appearance datum (last occurrence)
concurrent range zone
diachronous (time transgressive)
calcareous algae (coccoliths)
what are the limitations on applying biostratigraphy?
thermal remanent magnetism (curie point)
detrital remanent magnetism
chronozone, chron, sub-chron
GEOLOGIC TIME SCALE
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.
gamma ray log
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
baselap (onlap, downlap)
maximum flooding surface (MFS)
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?
Milankovitch (orbital) cycles
On what time scales (how far back in time) can cycle stratigraphy be used to evaluate relative time (as opposed to absolute time)?
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
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).