A glacial upper limit to mountain range elevation

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    Beskrivelse

     

    A number of previous studies have indicated that long term glacial erosion efficiently can limit mountain height and control the overall morphology of mountain ranges. This "glacial buzzsaw" mechanism effectively prevents significant mass transport to elevations above the local snowline, which hereby serves as a first order control on mountain height. As a result of this glacial buzzsaw, topographic surface area will accumulate in an elevation interval in the vicinity of the local snowline. This appears as a local maximum in the hypsometric distribution.

     

    Through quantitative analysis of the entire SRTM3 data base (Shuttle Radar Topography Mission data with 3 arc-sec resolution), we have investigated the glacial buzzsaw mechanism on a global scale (between 60N and 56S), hereby including most of the Earths mountain ranges in one study. The global analysis of topography shows that variations in maximum mountain height correlate closely with climate-controlled gradients in snowline altitudes across mountain ranges of different orogenic ages and tectonic styles.

     

    The close correlation of these independent data sets corroborate that climate, when expressed as glacial activity, serves as an overall control of mountain height and morphology. That the correlation extends across tectonic ages and styles as well as lithologies, implies that glacial erosion has the capacity of keeping pace with even the highest present-day tectonic rock uplift rates.

     

    We use a computational glacial landscape evolution model to show how the hypsometric signature of the glacial buzzsaw mechanism can be produced. The combined effects of glacial erosion of surface topography above the snowline and flexural isostatic uplift that affects the entire landscape, including unglaciated hill slopes below the snowline, produces the local maximum in the hypsometric distribution just below the snowline, in accordance with existing ideas regarding the glacial buzzsaw denudation mechanism.

    Periode16 dec. 2009
    BegivenhedstitelAmerican Geophysical Union fall meeting
    BegivenhedstypeKonference
    ArrangørAmerican Geophysical Union
    PlaceringSan Francisco, USAVis på kort