How Glaciation Changes Sediment Dispersal To The Sea

Authored by Sandra Passchier, Montclair State University
Author Profile
Initial Publication Date: June 8, 2018

Summary

High-latitude continental margins are spectacular sites to study the effects of climate change on continental shelf and slope sediments because of the prominent effects of glaciation on sediment delivery to the sea. This lesson aims to teach students how glaciation affects sediment supply from the drainage basin (the source) to deposition in the ocean (the sink). We will investigate 1) how climate in the drainage basin affects sediment composition via chemical vs. physical weathering; 2) how rivers transport sediment to the ocean in contrast to glaciers; and 3) how these different sedimentary systems affect the yield (volume), particle size and chemical composition of the sediments supplied. Our aim is to apply these concepts to an interpretation of the sedimentary record in Prydz Bay, Antarctica in the second part of the module.


Learning Goals

  • Geosystems thinking: Understanding the effects of climate (weathering, glacial vs. fluvial erosion) on the volume and composition of sediment generated in catchment areas
  • Data acquisition and analysis: The composition of continental margin sediments and source area characteristics
  • Time-space analysis: Interpreting continental margin stratigraphy as an archive of past Earth surface processes
  • Earth Systems thinking: Role of Antarctic glaciation in the Earth System

Context for Use

This module is designed for use in upper level undergraduate or lower level graduate geoscience courses, such as Sedimentology, Stratigraphy, or Marine Geology. Students should be familiar with the basics of Earth Surface Processes, Marine Science, and Sedimentary Geology, as generally taught in entry-level Earth Science courses. Students should understand the concepts of weathering, erosion, and sedimentation and be familiar with the source-to-sink approach to studying sedimentary systems on passive continental margins. Students should be familiar with sediment classifications, and lithological terms such as diamicton, and glacial rock flour. Students should have been introduced to the principles of biostratigraphy. The collection and interpretation of multichannel seismic data should also be explained. The powerpoint with this module includes a summary of relevant concepts and terminology.

The first part of the module is meant to provoke interest in Antarctica's changing environments and the effects of climate change. A text is available for free via PDF download that discusses the basics of Antarctica's changing environments from greenhouse world to icehouse world: https://www.nap.edu/catalog/12168/antarctica-a-keystone-in-a-changing-world. Links to the key note papers in this volume are also available at the USGS: https://pubs.usgs.gov/of/2007/1047/ Hand samples of (Antarctic) igneous rocks, for example a granite and a gabbro, thin sections, as well as hand samples of poorly sorted glacial rocks and well-sorted fluvial and deltaic rocks are also needed for the first part of the module. MS Excel and GeoMapApp (http://www.GeoMapApp.org) are needed for the second part, as well as example slides of microfossils, specifically calcareous nannofossils, palynomorphs, and diatoms. If an ICP lab is available on site, the instructor could arrange a tour of the lab with the students. How fast the students complete the module depends on the level of preparation of the students, the course requirements implemented by the individual instructor, and the level of technical assistance needed in using MS Excel and GeoMapApp. The two parts of the module are intended for two ~120 minute instructional sessions.

Description and Teaching Materials

In the first part of the module the students are introduced to the Greenhouse to Icehouse transition in Antarctica. Students are asked to read the materials before class and a powerpoint presentation will be provided to summarize and illustrate the content of those documents. Antarctica is known as "the frozen continent". Its warm past with river basins and vegetated fluvial and coastal plains, and higher plants such as palm and baobab, is bound to pique student interest. A connection of the project to the effects of greenhouse gases on climate change will allow students to further engage in the problem.

Students are then introduced to the process of chemical weathering in the source area. Students will be asked to look up chemical formulas of feldspars and clay minerals, and to make a prediction of enrichments or depletions of major elements in the regolith during the chemical weathering process. Students will be shown examples of sandstones, mudrocks and diamictites, and will be asked to classify rock samples into those that are compositionally mature or immature.

In the second part of the module, students will link what they have learned about modern source-to-sink systems with the sedimentary rock record. Students will be shown a video of the deep-sea drilling process on research vessels of the International Ocean Discovery Program. Students will examine seismic profiles, hand samples, thin sections, and images of a variety of sedimentary rocks to determine how different sedimentary lithologies offshore may have been eroded transported and deposited. Students will analyze major element data collected on drillcore samples and determine mudrock maturity. Further, students will synthesize data from the drillcores and interpret the stratigraphic record. Finally, students will use critical thinking skills to assess Antarctica's role in the Earth System.


Materials needed

Part I:

  • hand samples of (Antarctic) igneous rocks, for example, granite and gabbro
  • thin sections and hand samples of poorly sorted glacial sedimentary rocks, and well-sorted fluvio-deltaic rocks
A rock box with Antarctic samples can be borrowed for free from the Polar Rock Repository: http://research.bpcrc.osu.edu/rr/rock_box/

Part II:
  • Laptops or a computer lab
  • GeoMapApp installed on computers: http://www.geomapapp.org/
Literature to be assigned:
  • Francis et al. (2008): https://pubs.usgs.gov/of/2007/1047/kp/kp03/of2007-1047kp03.pdf
  • Jamieson & Sugden (2008): https://pubs.usgs.gov/of/2007/1047/kp/kp05/of2007-1047kp05.pdf
  • Miller et al. (2008): https://pubs.usgs.gov/of/2007/1047/kp/kp06/of2007-1047kp06.pdf
Presentation files and handouts:
  • Glaciated Margins (PowerPoint 2007 (.pptx) 8.1MB July31 17)
  • Jamstec Video deep-sea drilling; https://youtu.be/yuu0QcnOVbo?t=456
  • Glaciated Margins - Student Version (Microsoft Word 2007 (.docx) 308kB July27 17)
  • Glaciated Margins -Notes to Instructor (Microsoft Word 2007 (.docx) 731kB Aug4 17)

Excel data sheets

Teaching Notes and Tips

The GeoMapp App section can be left out. The seismic profiles have multiples, which may confuse students.

Assessment

How well students have achieved the learning goals can be assessed by their answers to the questions in the module. Student participation in group discussions, how students help each other to complete tasks, and the level of questions asked of the instructor(s) can also be used as part of the assessment.

References and Resources

Cooper, A.K., Barrett, P.J., Hinz, K., Traube, V., Leitchenkov, G., Stagg, H. M.J., 1991 Cenozoic prograding sequences of the Antarctic continental margin: a record of glacio-eustatic and tectonic events, Marine Geology, v. 102, i. 1–4, p. 175-213, DOI:10.1016/0025-3227(91)90008-R.

Gulick, S.P., Jaeger, J.M., Mix, A.C., Asahi, H., Bahlburg, H., Belanger, C.L., Berbel, G.B., Childress, L., Cowan, E., Drab, L. and Forwick, M., 2015, Mid-Pleistocene climate transition drives net mass loss from rapidly uplifting St. Elias Mountains, Alaska: Proceedings of the National Academy of Sciences, v. 112, no. 49, p.15042-15047.

Passchier, S., Ciarletta, D.J., Miriagos, T.E., Bijl, P.K., Bohaty, S.M., 2017. An Antarctic stratigraphic record of stepwise ice growth through the Eocene-Oligocene transition. GSA Bulletin, v. 129, i. 3-4, p. 318-330, DOI: 10.1130/B31482.1

Pross, J., Contreras, L., Bijl, P.K., Greenwood, D.R., Bohaty, S.M., Schouten, S., Bendle, J.A., Röhl, U., Tauxe, L., Raine, J.I., Huck, C.E., van de Flierdt, T., Jamieson, S.S., Stickley, C.E., van de Schootbrugge, B., Escutia, C., Brinkhuis, H., and Integrated Ocean Drilling Program Expedition 318 Scientists, 2012. Persistent near tropical warmth on the Antarctic continent during the early Eocene Epoch: Nature, v. 488, no. 7409, p. 73–77, doi: 10 .1038 /nature11300

Ryan, W.B.F., S.M. Carbotte, J.O. Coplan, S. O'Hara, A. Melkonian, R. Arko, R.A. Weissel, V. Ferrini, A. Goodwillie, F. Nitsche, J. Bonczkowski, and R. Zemsky, 2009. Global Multi-Resolution Topography synthesis, Geochem. Geophys. Geosyst., 10, Q03014, doi:10.1029/2008GC002332

Jamstec Video deep-sea drilling; https://youtu.be/yuu0QcnOVbo?t=456

Acknowledgement
This module was developed with support from the National Science Foundation award number ANT 1245283