1 / 20

Investigation of geologic control on ice sheets

Investigation of geologic control on ice sheets. Beáta Csathó, Terry Wilson and Kees van der Veen Byrd Polar Research Center The Ohio State University. Objectives. Investigate the link between ice dynamics and geology to determine the effect of bedrock geology on ice dynamics, including

ita
Download Presentation

Investigation of geologic control on ice sheets

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Investigation of geologic control on ice sheets Beáta Csathó, Terry Wilson and Kees van der Veen Byrd Polar Research Center The Ohio State University

  2. Objectives • Investigate the link between ice dynamics and geology to • determine the effect of bedrock geology on ice dynamics, including • the role of topographic and lithologic-structural (geologic) control on the geometry of outlet glaciers • the role of geologic control on their dynamic behavior (surges, migration of shear zones, etc.) • infer geologic structures and lithology from ice surface features

  3. NW Greenland; Humboldt, Petermann and Ryder drainage basins • Objective: investigation of the origin of ice surface features mapped by SAR imagery. Southern Victoria Land; Dry Valleys, Skelton Neve and adjacent part of East Antarctic ice sheet (EAIS) • Objective: mapping major transfer faults under ice cover using remote sensing data.

  4. NW Greenland site:Previous knowledgeGeology • Bedrock is Paleozoic • Sedimentary basin might extend under the ice sheet • Aeromagnetics indicates a magmatic province in central and northern Greenland • Reconstructed track of Icelandic hotspot crosses the area

  5. Free air gravity (mgal) Feature on SAR imagery Feature on DEM

  6. Total magnetic fiald (ntesla) Feature on SAR imagery Feature on DEM

  7. NW Greenland:Previous knowledgeGlaciology • Southern boundary of Humboldt glacier is not controlled by topography only • Curvilinear and circular ice surface features were mapped by SAR imagery. These features are also expressed on high resolution DEM • Radio-echo sounding suggests that one of these features is related to an interconnected system of subglacial lakes or subglacial water transportation • Other surface features coincides with internal layers causing strong radar echoes. These features were interpreted as under ice hills. • A mini-surge was observed by SAR interferometry on Ryder glacier

  8. Bedrock elevation (m) Feature on SAR imagery Feature on DEM

  9. NW Greenland Description of features and interpretation • Linear features at Humboldt: Large magnetic and gravity gradient, no internal layers;normal fault separating crystalline and sedimentary rocks • Circular feature (‘loop’) between Petermann and Ryder glaciers: bedrock channel around bedrock high, circular gravity anomaly West side: internal layering in ice with strong echo - morainal debris, partial melting or bottom crevasses (shear zone??) East side: water filled bedrock channel following elongated magnetic anomaly -- increased heatflow/subglacial volcanism

  10. NW GreenlandConclusions • Notice similarities to WAIS • Possible interpretation: NW Greenland ice sheet covers a sedimentary basin characterized with high heat flow and igneous activity suggesting strong geologic control on ice dynamics • Questions: • How is the observed surge on Ryder related to the upstream hydraulic system? • Is the west side of ‘loop’ an active or abandoned shear margin? Is it really a shear margin or something else? • How were the linear features formed over the geologic boundary of Humboldt glacier?

  11. Southern Victoria LandObjective • Mapping major transverse fault zones channeling glacial drainage and possible older fluvial drainage under the EAIS • Background: • Transantarctic Mountains (TAM) is a major mountain chain developed within the Antarctic plate. • TAM segmented into blocks by major transverse zone • Major transfer faults are mapped in TAM by using a combination of satellite imagery and field observations

  12. Southern Victoria LandResults • Major transfer faults have unique surface expression and they can be traced beneath ice cover by using satellite imagery • Detailed structure of Discovery accommodation zone was mapped from a multisensor data set • The boundaries of the elongated bedrock depression can be inferred from ice surface features. These features, such as the surface undulations perpendicular to deep bedrock trough and flow lines, are related to increased ice velocity over the thicker ice.

  13. Acknowledgements • Study of geologic control on Greenland ice sheet is funded by NASA Polar Programs • Transantarctic Mountains Aerogeophysical Research Activity (TAMARA) project is funded by NSF Polar Programs • Development of GGDS (Greenland GIS Data System) GIS database is supported by NASA’s PARCA and ICESAT programs • Special thanks to Gi-Choul Ahn, Yaron Felus, Changjoo Kim (OSU) and Regine Riedel (Univ. Of Dresden) for data processing

More Related