1. By Bruno Tremblay (Lamont-Doherty Earth Observatory, Columbia University)

    This lecture is part of the The Earth Science Colloquium video series. The Earth Science Colloquium Series is sponsored by the Lamont-Doherty Earth Observatory and the Columbia University Department of Earth and Environmental Sciences (DEES). This series provides a lively forum for discussing a wide variety of topics within the earth sciences and related fields. Colloquia are attended by the full range of scientific and technical staff at LDEO.

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  2. Lynn Sykes (Dept. Earth and Environmental Sciences, Lamont-Doherty Earth Observatory, Columbia University)

    This lecture is part of the The Earth Science Colloquium video series. The Earth Science Colloquium Series is sponsored by the Lamont-Doherty Earth Observatory and the Columbia University Department of Earth and Environmental Sciences (DEES). This series provides a lively forum for discussing a wide variety of topics within the earth sciences and related fields. Colloquia are attended by the full range of scientific and technical staff at LDEO.

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  3. By Carol Raymond (NASA, Jet Propulsion Laboratory, California Institute of Technology) "Exploring Protoplanets from the Beginning of the Solar System: Dawn at Vesta"

    Abstract: The Dawn spacecraft reached Vesta, the second most massive asteroid in the main belt, in July of 2011, and has since returned a wealth of remarkable scientific findings. These have included the confirmation of Vesta as the parent body of a common class of meteorites (the Howardite-Eucrite-Diogenites), evidence for a substantial iron core, an impact record consistent with recent dynamical models driven by giant planet migration, and intriguing brightness and compositional variations. Vesta's nature is transitional between an asteroid (planetesimal) and a planet, and represents one of the oldest intact planetary building blocks from the beginning of the solar system. Dawn's novel ion-propulsion system allows the spacecraft to travel further and orbit the dwarf planet Ceres in 2015.

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  4. By: Aaron Putnam (Lamont-Doherty Earth Observatory) "Climate Battles Between the Hemispheres During and since the Last Ice Age: Palaeoclimate Insights from the Record of Earth’s Mountain Glaciers and Drylands"

    Abstract: Developing precise and accurate records of mountain-glacier variations between the hemispheres can help to discriminate among hypothesized drivers of ice-age climate, glacial terminations, and sub-millennial interglacial climate oscillations. Such records are important for placing industrial-age global warming and glacier recession into a meaningful palaeoclimatic context. Here, I present records of mountain glacier behavior and climate change at middle latitudes of the polar hemispheres spanning the past ~30,000 yrs in order to examine interhemispheric phasing of snowline variations during and since the last ice age on orbital, millennial, and sub-millennial timescales. These new records were constructed by employing important advances in 10Be surface-exposure dating techniques, detailed glacial geomorphologic mapping, and glacier snowline modeling. Key conclusions are as follows. (1) There is close correspondence at northern and southern middle latitudes in timing and magnitude of snowline-inferred temperature depression during the last glacial maximum (LGM), suggesting that ice age cooling was synchronous in both polar hemispheres. One possibility is that lower atmospheric CO2, coupled with the effects of polar-ocean stratification, produced global cooling during the LGM. (2) Rapid rise of Southern Hemisphere glacier snowlines beginning about 18,000 yrs ago was coeval with the northern Heinrich Stadial-1, implicating a bipolar seesaw mechanism for initiating the southern termination. (3) Southern mid-latitude glaciers registered the Antarctic Cold Reversal in antiphase with the northern Bølling-Allerød interstadial, suggesting that a bipolar seesaw mechanism operated in the south over a large geographical footprint. (4) Asynchronous Holocene glacier behavior in the Southern and European Alps reflects southward migration of Earth’s thermal equator on orbital and submillennial timescales. (5) Such persistent climate asynchrony since the end of the last ice age implies that globally synchronous warming and glacier recession during the past century is anomalous in the context of detected post-glacial climate changes, and corresponds with the rise of fossil CO2 in the atmosphere since the beginning of the industrial age.

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  5. By: Heather Savage and Pratigya Polissar (Lamont-Doherty Earth Observatory) "Biomarkers Heat Up During Earthquakes: New Geological Evidence of Earthquake Slip in the Rock Record"

    Why do faults fail where they do, when they do? The rock record can provide details about the rupture process that are unavailable to other methods, such as seismology. In particular the fault frictional strength during slip is an important unknown parameter that is needed for a complete understanding of earthquake dynamics, and a crucial ingredient in predictive failure models. Because faults get hot during rapid slip due to friction, thermal signatures in the rock record can provide evidence of earthquakes. The most widely accepted thermal signature is frictional melt (pseudotachylyte), but these rocks are rare and cannot provide information when faults are heated to temperatures below melting. We have developed a new thermometer that utilizes the thermal alteration of organic biomarkers that apply to any fault hosted in sedimentary rock with sufficient organic material. We present results from field examples, including the fault that potentially hosted the 2011 Tohoku-Oki earthquake, and explore the implications of these results for earthquake processes.

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