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Seafloor Sediment workshop ppt
1. Seafloor Sediments Investigation (Ch 2 p. 27)
Goal: To explores marine sediments using cores,
photos, and smear slide data.
Objectives: After this exercise, you (your students)
should be able to:
•Describe the physical characteristics of sediment cores.
•Identify major sediment components and their origin.
•Make smear slides, and use composition and texture data
from smear slide samples to determine the lithologic
names of the marine sediments.
•Make a map showing the distribution of the primary
sediment lithologies of the Pacific and North Atlantic
Oceans.
•Explain the distribution of marine sediments on their map.
•Predict what the sediment lithologies are at other
locations on the sea floor (e.g., in the Indian Ocean).
3. Part 2.1. Predict (individually and then in your
team):
1. What kinds of materials might you expect to find onWhat kinds of materials might you expect to find on
the seafloor?the seafloor?
2.2. Is there any geographic pattern to the distribution ofIs there any geographic pattern to the distribution of
these materials?these materials?
You will investigate these questions using empirical data and
teamwork. And then hypothesize why the sediments are
distributed the way they are.
Goal for you to learn both WHAT we know about seafloor
sediments and HOW we know it.
p. 27
4. Initial Inquiry into Seafloor Sediments:
Core Observation
Part 2.2 Q1: Find your team’s assigned cores in:
• Core Photos (p.60-79; or access high resolution photos at:
http://iodp.tamu.edu/database/coreimages.html)
• Table 2.1 (p. 28-29)
• On the base map (p. 32-33).
Make a list of observations and questions.
[Follow with whole group discussion.]
p. 28-33
5. Scientific ocean drilling site locations, from:
http://iodp.tamu.edu/scienceops/maps.html
Assigning Unique Identification Codes to Scientific Samples
6. Example of sample nomenclature and core photo.
The standard labeling for ocean drilling samples.
From ODP Leg [i.e., Expedition] 199 Initial Reports Volume, Explanatory Notes:
http://www-odp.tamu.edu/publications/199_IR/chap_02/chap_02.htm)
7. TO DO in your group:
Q2 (p.30): Design a way to
organize and record your visual
observations that could be used
by all of the students in the class
for all of the cores. [Follow with
whole group discussion.]
Q3 (p. 31): Using the agreed
upon approach, describe your
core. [Follow with group
presentations of cores.]
Q4 (p. 34): Explain why a
systematic, complete, and
consistent method of recording
observations is important.
8. Sediment Composition (think back to your predictions)
• Composition (minerals & microfossils) and texture are the primary
data used to “name” the sediment:
TO DO:
Part 2.3 Q1 (p. 37): Match smear
slide data for your core’s samples
listed Table 2.2 (p. 42-51) to mineral
and fossil images in Fig 2.3.
p. 35-51
Extension Lab: Make a sample request from IODP (http://iodp.tamu.edu/curation/samples.html)
and make your own smear slides. Try to identify the components, using the following
resources:
•Images in Fig 2.3, p. 35-36.
•http://www.noc.soton.ac.uk/gg/BOSCORF/curatorial/grain_id.html
•Rothwell, Minerals and Mineraloids in the Marine Sediments.
9. Sediment Classification….Name that Sediment!
TO DO: Q2, (p. 37) For your assigned core(s), determine the
dominant sediment types in the samples.
HOW?
–Use the smear slide data (Table 2.2, p. 42-51).
–Look at the core photos p. 60-79, or access high res digital
core photos at
http://iodp.tamu.edu/database/coreimages.html)
–Use the Decision Tree p. 38-41.
–Record your sediment names in Table 2.2 AND (Part 2.4,
Q1, p. 52) plot on your map AND on “class” map using
colors on p. 52.
Do example together
10. Important information about using the Decision Tree (p.38-41):
The decision tree aims to capture the most distinctive (i.e., end-member, dominant)
sediment types:
• Calcareous ooze: biogenic sediments composed of calcareous nannofossils and/or
foraminifers.
• Siliceous ooze: biogenic sediments composed of diatoms, radiolarians, sponge
spicules, and/or silicoflagellates.
• Red clays: very fine terrigenous sediment that often contains siliceous microfossils,
fish teeth, Mn-Fe micronodules, and/or volcanic glass.
• Terrigenous sediment: siliclastics; sediment from the weathering of continents or
volcanic islands.
• Glaciomarine sediment: sediment containing terrigenous sand, pebbles, or cobbles
transported to the sea by icebergs.
Note, while the above 5 sediment types are the most distinctive sediment types, mixed
sediment types are common. In addition, the sediment type can also change within a
core. For example the sediment could alternate between two or more sediment types or
gradually change from one to another.
In any of the sediment types, but especially in biogenic oozes and deep sea red clays,
layers of volcanic ash may be distinguishable.
11. TO DO: Q2 & Q3 (p. 52-54). Analyze class map. Develop
hypotheses for what controls the distribution of each of the
primary sediment types in the modern ocean.
12. How does this distribution compare to your initial predictions?
13. Distribution of the primary sediment types on the seafloor (from Davies and Gorsline, 1976; Rothwell, 1989)
Distribution of Marine Sediments– there is a rhyme and reason!
YOU derived this sediment type map from core data!
Q4 (p.54): How does your map compare to this one?
14. Idea for extension: Interpret the rest of map (draw boundaries between
different primary sediment types)
15. Follow-Up Exercise with Lecture
on Marine Sediments
Terrigenous Sediment
• derived from the weathering
& erosion of rocks on land:
sand & mud
• accumulates along
continental margins
• masks other sediment types
because of high
sedimentation rates
Glaciomarine Sediment
• Terrigenous – but a special
type that indicate glacial
conditions on land.
• Can accumulate far from
land via iceberg rafting.
• Best recognized by
dropstones in cores.
16. What are the requirements
for biogenic ooze to
accumulate ?
Biogenic Rich Sediment = Ooze
1. Productivity in the surface waters
2. Preservation (i.e., not dissolved) as
settle through the water column
3. High relative abundance (i.e.,
avoid dilution by other sediment
types)
17. Key points for Lecture on Marine
Sediments
Calcareous Ooze
• composed of carbonate
shells of plankton (CaCO3)
• accumulates on
bathymetric highs (above
CCD) & beyond the
continental margins
Siliceous Ooze
• composed of the siliceous
shells of plankton (SiO2)
• accumulates under areas of
high productivity
18. Follow-Up Exercise with Lecture
on Marine Sediments
Deep Sea Red Clay
• wind-blown dust & current
transported clays
• accumulates on the abyssal
plains (deep broad sea
floor)
• mixed with minerals that
precipitate on the sea floor
and some siliceous
microfossils
• very slow sedimentation
rates
19. Exploring Further:
Q5b (p. 55): Is calcareous ooze in the N Atlantic found at the same depth, shallower
depths, or deeper depths than in the N. Pacific? Why?
Q6 (p. 55): The map you constructed represents the modern distribution of sediment
types in the Pacific Ocean. Do you think this map would also represent sediment type
distribution in the geologic past and in the geologic future? What factors might vary (in
the past and in the future) that could change the distribution of sediment types?
20. Exploring The Instructor Guide See handout for
most of the
instructor guide;
For full guide go
to DROPBOX.
21. Exploring Scientific Data Collected from Marine Expeditions
To Do: See Scientific Ocean Drilling Initial Results Volume(s) (online:
http://www.iodp.org/scientific-publications/ or get a hard copy). Explore
Initial Results Vol overall.
Idea for extension: Write (type, single spaced) a 1-page summary of the
types of scientific data collected from cores, how it is reported and
organized, and your comments and questions on it.
22. Ideas for Extension: Refine Your Core Description
and Sediment Classification
• Find the core description online (IR volumes) for your core.
Compare your core description to the published description.
Write a reflection on: the strengths and weakness of your
description, how you would modify your approach in the future.
• Refine based on Explanatory Notes section of an Initial Results
(IR) volume:
-methodologies and symbols used in descriptions
http://publications.iodp.org/proceedings/320_321/102/102_f8.htm
http://publications.iodp.org/proceedings/320_321/102/102_3.htm
- lithostratigraphy: naming the sediments (and then defining
lithostratigraphic units)
-http://publications.iodp.org/proceedings/320_321/102/102_f9.htm
Editor's Notes
Think-pair-share…Address these questions via our exercise (Ch2)….SO shift in course to me lecturing way less and them constructing their own knowledge with my guidence…experiential learning…so they build skills important towards transition from novice to expert
I won’t assign the cores, rather we will use 3 poster-size examples. The following 3 cores would be good choices to show the variety of sediment types and lithologic features: 130-807A-2H [we have 8H in poster size], 145-887C-2H, [we have section 6H in poster size], and 206-1256B-2H. Won’t describe the cores for workshop (Q2.2 2-3)
for any type of data collection need to keep samples organized – need a unique ID.
Gets at developing expert skills – deciding on what is important to focus on and what isn’t. Complext pattern recognition and developing ways of organizing Developing skills in organization of data and evaluation of data: complex pattern recognition – sorting out what is important and what are part of what it means to become an expert. I am helping them transition from novice to expert Option to then give them access to the scientists’ core description and write a reflection on how their desc and the shipboard scientists desc compare. Strengths and weakness of their own work. How would they modify their work…and what was distinctly different in the data available to them vs shipboard scientists For 1 section – desc color, sharp boundaries, gradational, compo, texture (from smear slide data), any anomolies, patterns, color – using muncell color charts, sed structures, degree of coring desturbance and degree of bioturbation….use of symbols for these… This means you need to come up with categories (e.g., color) for your observations and also a means of recording them (i.e., all observations written, all observations sketched, some combination of the two?).
For workshop – they can simply pick a core of interest to them.
So just likes minerals, rocks, and fossils have names, so does sediment. Do 1 example, What if more than 1 dominent sediment type? Plot as pie chart
Note naming goes beyond… can have a nannofossil mud etc…see suggested extensions at end of ppt.
After they have completed their core description. The goal with this is to show them what they want to work towards.. The expert approach.