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Earth sciences overview. Chris Paola [email protected] 4-8025 SAFL & Pills 30b. Plan for next two weeks. Today: overview of earth sciences Friday: Nonlinearity and nonequilibrium case examples Monday: paleoclimate (with Emi Ito) Friday: ESci connections to other fields.

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Earth sciences overview l.jpg

Earth sciences overview

Chris Paola

[email protected]

4-8025

SAFL & Pills 30b


Plan for next two weeks l.jpg
Plan for next two weeks

  • Today: overview of earth sciences

  • Friday: Nonlinearity and nonequilibrium case examples

  • Monday: paleoclimate (with Emi Ito)

  • Friday: ESci connections to other fields


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Journals and societies

  • American Geophysical Union (Eos, Journal of Geophysical Research, Water Resources Research)

    • Nearly all areas of earth science: atmosphere, oceans, surface (inc. hydrology), geobiology, lithosphere, deep earth)

  • Geological Society of America (Geology, GSA Today, GSA Bulletin)

    • All areas of geology, geobiology, and geochemistry

  • European Geophysical Union

  • Terra Nova


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The Ancient Kingdoms

  • Mineralogy & petrology

  • Structural geology

  • Paleontology

  • Igneous, metamorphic, sedimentary geology

  • Surficial and Quaternary geology

  • Geophysics

  • Geochemistry

  • Geobiology


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Research threads

  • Observation and inference on planetary scales: atmosphere, ocean, deep interior

  • Mechanical properties & materials

  • Extreme conditions (e.g. heat, pressure)

  • Extreme events (e.g. meteorite impact)

  • Co-evolution of Earth and life

  • Spatial structure through time: surface

  • Spatial structure through time: lithosphere

  • Comparative planetology


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Major intellectual contributions

  • Uniformitarianism: present as key to past

  • Deep time, evolution, age of Earth

  • Plate tectonics

  • “Mechanism”: application of physical laws over planetary scales

  • Neocatastrophism

  • Alternative earths and planetary history: past as key to (possible) futures







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Plate tectonics: a simple estimation problem

  • Plate horizontal motion rates: of the order of cm/year

  • Relation of vertical to horizontal rates: order 0.1

  • What (order of magnitude) should be the concentration of sediment in river water?


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Mechanism: how plates bend

The theory describing plate deflection is identical to that used for beams in structural engineering!


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Alternative Earth: Mesozoic greenhouse

  • Warm, ice-free poles

  • High CO2

  • Weak oceanic, atmospheric circulation

  • Oceanic anoxic events

  • Land initially assembled as one ‘supercontinent’


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The Earth in equilibrium

  • Atmospheric temperature

  • Steady state erosion

  • Steady state deposition


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Non equilibrium – the variability around the mean

  • It’s hard to think of examples of geologic systems that don’t fluctuate:

    • Stream flow

    • Plate motion (earthquakes)

    • Sedimentation

    • Heat flow (volcanoes)

    • Erosion rates

  • One basic question is: what is the distribution of fluctuation energy over time and/or space scales?


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Example: earthquake distribution follows Gutenberg-Richter law

An example of a “power law” – a common distribution



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Nonlinearity: Earth sciences have provided the type examples for three major classes of new nonlinear phenomena of C20

  • Fractals: coastline of Britain (contour line)

  • Chaos: simplified atmospheric model

  • Self-organized criticality: sand pile (a few minor problems…)


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Non-linearity: self-organization & pattern formation for three major classes of new nonlinear phenomena of C20

  • Plate tectonics

  • Fault systems

  • Banding in minerals

  • River networks

  • Bedforms and bars

Canyonlands, UT

Rio Salado, NM


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Trends and culture for three major classes of new nonlinear phenomena of C20

  • Dominant influence of finding resources

    • Minerals

    • Fossil fuels: coal, hydrocarbons

    • water

  • From story-telling to advanced mathematics

    • Wavelet analysis invented in geophysics

    • Historical tradition – we like a ‘good story’

    • Induction vs deduction – detectives vs theorists

    • Central role of field work

    • Is prediction possible? How to test models in historical sciences


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Trends and culture for three major classes of new nonlinear phenomena of C20

  • Research trends:

    • Crossing disciplines, e.g. emergence of geobiology

    • Quantification & theory

    • New methods

    • Major limitations:

      • Access to information

      • Age control


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New methods for three major classes of new nonlinear phenomena of C20

New research made possible by new measurement techniques

LIDAR


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New methods for three major classes of new nonlinear phenomena of C20

High-res bathymetry


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New methods for three major classes of new nonlinear phenomena of C20

Dating methods for surface materials and short time scales

Cosmogenic radionuclides (CRN)


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New methods for three major classes of new nonlinear phenomena of C20

Geomicrobiology


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New methods for three major classes of new nonlinear phenomena of C20

High res 3D seismic reflection


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Research frontiers for three major classes of new nonlinear phenomena of C20

  • Complexity, natural variability, and predictability

    • Natural variability in surface morphology

    • Can we forecast earthquakes? Floods?

    • Big problem seems to be systems that are too random to simulate directly, too ordered to use only statistics

  • Long-range connections (“teleconnections”) in the Earth system

    • Ocean/atmosphere coupling

    • Deep earth/surface earth coupling – does erosion cause mountain belts?

  • Role of microbes


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Research frontiers for three major classes of new nonlinear phenomena of C20

  • Drivers and history of plate tectonics

    • Role of life?

  • Atmospheric history and regulation

    • Role of life?

  • Origin of life


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Connections for three major classes of new nonlinear phenomena of C20

  • Civil engineering: hydrology, geomorphology, structural geology, rock mechanics

  • Ecology: geobiology, paleoecology

  • Computer science: data bases and data mining; numerical earth modeling


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Milankovitch orbital cycles for three major classes of new nonlinear phenomena of C20

1. Eccentricity

Circular orbit, no eccentricity.

Orbit with 0.5 eccentricity

Periods: 413,000, 95,000, and 136,000 years. Overall dominant ~ 100,000 year cycle

Range: -0.03 to +0.02).

Present value: 0.017.


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Milankovitch orbital cycles for three major classes of new nonlinear phenomena of C20

2. Axial tilt (obliquity)

Period: 40,000 years

Range: 2.4 degrees

Present value: 23.44 degrees


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Milankovitch orbital cycles for three major classes of new nonlinear phenomena of C20

3. Precession

Period: 20,000 years

Range: entire orbit

Present value: perihelion during SH summer, aphelion during NH summer



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Milankovitch orbital cycles: linear superposition but nonlinear Earth response

Vostok ice core data


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