GES 206: Antarctic Marine Geology Winter Quarter, 2007 Introductions and contacts Class meetings: lectures and lab – Lectures: Tues & Thurs at 11:00 am.

GES 206: Antarctic Marine GeologyWinter Quarter, 2007

• Introductions and contacts• Class meetings: lectures and lab

– Lectures: Tues & Thurs at 11:00 am - 12:15 pm– Alan: geologic framework and seismic stratigraphy– Rob: ice, ocean and geochemistry– Guests: various general topics – Labs: 3 to 4, times TBA (seismic, biostratigraphy, C14, student talks)

Leaders: Rob Dunbar and Alan Cooper TAs: Matt Long, Christina Riesselman

Website: http://pangea.stanford.edu/research/Oceans/GES206/

• Class text and resources– Text: Antarctic Marine Geology by John Anderson

– Resources: GES library, online, “Class” library, other

• Assignments: (readings, exercises, and project)– Readings: from the text (for general background) and sometimes a

“paper of the day” or a “hot topic” document.

– Exercises: 5 to 6, commonly as group efforts.

– Project: research project: oral presentation and written report.

• Exams and grading– No final exam, but a late-term take-home exam.

– Exercises, quizes and group discussions (35%)

– Late-term exam (35%)

– Research project: oral presentation (10%) and written report (25%)

• Opportunities and “changes as needed” – After completion of the class, there may be opportunities for

– Participation in Antarctic field operation (ship, on the ice).

– Presentation of research projects at the 10th International Symposium on Antarctic Earth Sciences, Santa Barbara, Aug/Sept 2007.

– Final class structure will likely be changed to best meet learning needs.

Important questions and topics YOU will learn about about (or will wish to learn about):

Two general categories:

* Paleoclimate (historic, ancient, Cenozoic)

* Geologic and oceanographic processes of polar margins

Why study Antarctic marine geology?

What are the important questions?

What do we need to know to answer the questions and “solve” the problems?

Can we use the geologicpaleoclimate record topredict future climates?

I. Paleoclimate:Important Questions Part of the knowledge needed

1. Mechanics of glaciers and floating ice – how ice moves (P/T conditions)   2. Factors that affect ice stability:  Morphology (shape) of the bed and adjacent areas;  Geologic factors affecting the bed (tectonics: faulting, flexure, volcanism);  Geology at the bed (rock, sediment, sediment condition (I.e., frozen, unconsolidated));  Oceanographic factors affecting ice shelves: ocean currents, temps, changing sea levels;  Meteorologic factors affecting ice-mass balance.

The record is in sediments:  Methods used to map, characterize, and infer sediment type (seismic) and methods to collect/analyze them (coring and drilling);  Processes by which sediments are transported to the ocean (rivers, ice, wind, etc.) and distributed in the ocean (currents, mass flow, ice, wind, etc.); Processes by which biogenic microorganisms (that hold the direct record) are created (ocean productivity), distributed and deposited (ocean currents and gravity); Geochemistry of the ocean sediment and how to decipher the paleoclimate record.

How stable is theAntarctic Ice Sheet?

II. Polar geologic and oceanographic processes:Important Questions Part of the knowledge needed

How do different tectonic segments of the Antarctic margin control ice-sheet history?

  Geologic history of present and paleo-continental margin areas around Antarctica;  Geophysical methods by which key geologic and climatic events are noted in the sedimentary record (I.e., via seismic); Processes by which tectonics, temperature, CO2, etc, control ice-sheet evolution on different margin segments; Processes by which margin evolution, sea-level changes, and ice-sheet development have created the present margin morphology.

  Methods for analyzing the physical, geochemical and biologic properties of sedimentary rocks;   Processes by which sediments are eroded, distributed, and deposited onshore and in the ocean by water and ice;  Paleooceangraphy of the Southern Ocean and sediment distribution;  Microfossil paleontology and paleobotany of sediments;  Method for characterizing paleoenvironments from seismic facies and lithostratigraphic facies.

How do sediments evolve in the Antarctic and give a record of paleoenvironments?

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Glacial diamictite Interglacial diatomite

Drill core data

Unraveling Cenozoic ice-sheet history

Here is an example of how we acquire some of the knowledge needed ….

Seismic reflection data

SDLS (2007)

Water depth Sediment thickness

Cooper et al. 1995

“The holy grail has always been considered …..getting the time when Antarctica went from being this green, warmish, vegetated continent to having an ice sheet,…… The Cape Roberts Drilling Project [CRP; predecessor to ANDRILL] didn’t ultimately answer that question, but the cores did provide evidence that East Antarctica had a cool, temperate climate with low woodland vegetation from 34 to 24 million years ago. CRP also found that the Transantarctic Mountains had achieved most of their present height by 34 m.y. ago.” Tim Naish, Co-chief scientist on ANDRILL

http://antarcticsun.usap.gov/2006-2007/documents/11-26-2006_antarcticsun.pdf

Some basic skills you’ll acquire

• Reading maps (projections and scales) and learning Antarctic geography and geopolitics

(Assignment #1);• Using the polar “geologic language”;• Learning the “geotools of the trade”;• Avoiding the “house of cards” pitfall; and

• Appreciating Antarctica as a beautiful place to be preserved and carefully studied by all.

Some key concepts related to Antarctica

What are the topics to be be emphasized to illustrate these concepts?

Important role of short-term processes (k.y.), long-term processes (m.y.), “thresholds” and transitions in controlling ice-sheet history

significant role of tectonics and prior geologic structures on erosion and geomorphology;

key role of ocean currents in shaping continental margins, and in the Antarctic especially since Eocene time;

key role of water in movement of glaciers;

key role of isostacy in the evolution of Antarctica’s geomorphology onshore and offshore;

Many geologic features observed in seismic and drilling data from the Antarctic continental margin are similar, but WHY?

Topics to be emphasized…. (see website syllabus)

 Evolution of Antarctica’s margins, to include structural framework and sedimentary processes Seismic data analysis The types of sedimentary rocks to be found beneath the Antarctic margin. Evolution and paleoceanography of the Southern Ocean, from geologic and physical oceanographic perspectives Glacier, iceberg, and sea-ice processes Glacial sedimentation processes

 Antarctic Ice Sheet History 

30 Ma

When you have questions, then…..

…ask them…and express your ideas!

Assignment #1: Geography and Geology of the Antarctic Region

Objectives: 1. Learn where key features are located; 2. Preview the class textbook: Antarctic Marine Geology by John Anderson; 3. Preview the geology of Antarctica that will be discussed in the next lecture.

Exercise 1: Geography of the Antarctic Region – see attached sheet (due in class next Tuesday – Jan. 16)

Reading (for next class): 1. Look through the Anderson textbook to get a feel for the topics it covers; 2. For Chapter 2 (Geologic History of Antarctica), our emphasis will be on the last 175 m.y. (I.e., since initial Gondwana breakup). Look at the figures and briefly read p.34 (bottom) to p. 43 (middle) and p.53 (bottom) thru p.57.

End of Lecture 1