http://oceans.mit.edu America/New_York America/New_York America/New_York 20171105T020000 -0400 -0500 20181104T020000 EST 20180311T020000 -0500 -0400 EDT eu60niksodc53b8umgblu9hq3s@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry http://eps.jhu.edu/directory/naomi-levin/ 20150508T100000 20150508T110000 E25-117 0 COG3 Seminar – Naomi Levin (Johns Hopkins University) eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry New Insights into Earth’s oxygenation 20150911T100000 20150911T110000 20150918T100000 20150925T100000 20151002T100000 20151009T100000 20151016T100000 20151023T100000 20151030T100000 20151106T100000 20151113T100000 20151120T100000 20151127T100000 20151204T100000 20151211T100000 20151218T100000 E25-119 FREQ=WEEKLY;COUNT=15;BYDAY=FR 0 COG3 Seminar – Noah Planavsky (Yale) 20150918T100000-eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20150918T100000 20150918T110000 E25-119 0 COG3 Seminar – Clara Blättler (Princeton) 20150925T100000-eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20150925T100000 20150925T110000 E25-119 0 COG3 Seminar – Greg Henkes (Harvard) 20151009T100000-eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry A New Perspective on the Indian Monsoon from Paleogene to Holocene 20151009T100000 20151009T110000 E25-119 0 COG3 Seminar – Livu Giosan (WHOI) 20151016T100000-eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Deglaciation to dam removal: climatic and land-use controls on New England river processes 20151016T100000 20151016T110000 E25-119 0 COG3 Seminar – Noah Snyder (Boston College) 20151030T100000-eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20151030T100000 20151030T110000 E25-119 0 COG3 Seminar – Molly McCanta (Tufts) 20151106T100000-eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20151106T100000 20151106T110000 E25-119 0 COG3 Seminar – Ben Kocar (MIT) 20151113T100000-eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Mantle pyroxenites: from asthenosphere to lithosphere 20151113T100000 20151113T110000 E25-119 0 COG3 Seminar – Veronique Le Roux (WHOI) 20151120T100000-eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Shallow Landslide Hazards in a Changing Climate. (note the change in COG3 seminar time and location this week) 20151119T100000 20151119T110000 54-915 0 COG3 Seminar – Dino Bellugi (MIT) 20151204T100000-eoscs2ep8hvtpdm2sesnj3d350@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Accelerated Late Cretaceous exhumation in the White Mountains, NH: circum-Atlantic tectonism or climate change? 20151204T100000 20151204T110000 E25-119 0 COG3 Seminar – Will Amidon (Middlebury) 2h34vavglqdue109palq439p3k@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Investigating past climate-biosphere links: Speleothem-based climate reconstructions to constrain controls on Late Holocene forest expansion in South America 20160205T100000 20160205T110000 E25-119 0 COG3 Seminar – Corinne Wong (BC) 14m4uvkacp2gos6n7mfqp63tv0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Using Thallium Isotopes to Track Sediment Transport from Slab to Surface in the Aleutian Arc 20160212T100000 20160212T110000 E25 @ 119 0 COG3 Seminar – Sune Nielsen (WHOI) pd83a411shko775gr35jaqg9fc@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry The underground economy (bioenergetics of subseafloor sedimentary life) 20160219T100000 20160219T110000 E25-119 0 COG3 Seminar – Steve D’Hondt (URI) 8t1ep6q888abq17kie34nomf4g@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry How did plate tectonics begin? 20160226T100000 20160226T110000 54 @ 915 0 COG3 Seminar – Michael Brown (University of Maryland) sc66pgbv5304ni6omomviem07g@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry The chase for 247Cm and what it reveals about the stellar environment of r-process nucleosynthesis 20160311T100000 20160311T110000 E25 @ 119 0 COG3 Seminar – Francois Tissot (MIT) 0tv6c94i72uf7g41rhopctvujk@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry The Geobiological Significance of Archaeal Tetraether Lipids: a preliminary investigation with analytical and biological constraints 20160318T100000 20160318T110000 E25 @ 119 0 COG3 Seminar – Xiaolei Liu (MIT) dcidnoocei3lhj90lagl45btgc@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20160325T100000 20160325T110000 0 No COG3 Seminar, Spring vacation 7ob465cn2h83e00ngtea7pn4r8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Variability in stable potassium isotopes in geological and biological systems 20160401T100000 20160401T110000 E25 @ 119 0 COG3 Seminar – Leah Morgan (USGS Denver) vg80snltv08i757p9eq6its0is@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Supervolcanoes and their deposits: insights into the dynamics of large magma reservoirs 20160407T100000 20160407T110000 54-915 0 COG3 Seminar – Olivier Bachmann (ETH Zurich) rlvogkvcd5qun4u56asglevkts@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Landscape evolution of the Channeled Scablands, eastern Washington 20160415T100000 20160415T110000 E25 @ 119 0 COG3 Seminar – Isaac Larsen (UMass) ptd2h63hnhj0ql1hbcn99957ek@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Climate and Tectonics of the southern Central Andes, NW Argentina 20160422T100000 20160422T110000 E25 @ 119 0 COG3 Seminar – Alexander Rohrmann (Oregon State University) a5dfrcep1oi350iejd3gmjtuks@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Strain controls on olivine crystallographic texture: a record from mantle xenoliths, West Marie Byrd Land, Antarctica 20160429T100000 20160429T110000 E25 @ 119 0 COG3 Seminar – Seth Kruckenberg (BC) g7md7ulk3eourmg52pjl54te0g@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry When did the continents grow? 20160506T100000 20160506T110000 E25 @ 119 0 COG3 Seminar – Stephen Parman (Brown) 1l7rbp8gscpdmu2724b07a3g00@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Correlative microscopy, geochronology, and atom probe tomography of metamorphosed zircon 20160513T100000 20160513T110000 E25 @ 119 0 COG3 Seminar – Emily Peterman (Bowdoin) 7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20160909T150000 20160909T160000 20160923T150000 20161014T150000 20161021T150000 20161104T150000 20161111T150000 20161118T150000 20161209T150000 Building E25, Room 117 FREQ=WEEKLY;UNTIL=20161209T200000Z;BYDAY=FR 0 COG3 Seminar – TBD 20160909T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20160909T150000 20160909T160000 Building E25, Room 117 0 NO COG3 Seminar 20160916T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry The role of magmatism during continental rifting 20160916T150000 20160916T160000 Building E25, Room 117 0 COG3 Seminar – Sara Mana (Salem State University) 20160923T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20160923T150000 20160923T160000 Building E25, Room 117 0 NO COG3 Seminar – Student Holiday 20160930T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Using gut molecular markers to reveal our ancestors' gut microbiome 20160930T150000 20160930T160000 Building E25, Room 117 0 COG3 Seminar – Ainara Sistiaga (MIT) 20161007T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20161007T150000 20161007T160000 Building E25, Room 117 0 NO COG3 Seminar 20161014T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry A view of the Hadean Earth: petrogenesis of the oldest rocks within the Acasta Gneiss Complex 20161014T150000 20161014T160000 Building E25, Room 117 0 COG3 Seminar – Jesse Reimink (Carnegie) 20161021T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Megeagravel on the move: storm, waves, boulder transport, and the erosion of rocky coasts 20161021T150000 20161021T160000 Building E25, Room 117 0 COG3 Seminar – Rónadh Cox (Williams College) 20161028T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Understanding microbial ecology in the deep terrestrial biosphere: a geochemical and metagenomic approach 20161028T150000 20161028T160000 Building E25, Room 117 0 COG3 Seminar – Lily Momper (MIT) 20161104T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20161104T150000 20161104T160000 Building E25, Room 117 0 NO COG3 Seminar 20161111T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20161111T150000 20161111T160000 Building E25, Room 117 0 NO COG3 Seminar – Veteran’s Day 20161118T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Chemical Controls on Calcite Dissolution Kinetics in Seawater 20161118T150000 20161118T160000 Building E25, Room 117 0 COG3 Seminar – Adam Subhas (Caltech) 20161125T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20161125T150000 20161125T160000 Building E25, Room 117 0 NO COG3 Seminar – Thanksgiving Vacation 20161202T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20161202T150000 20161202T160000 Building E25, Room 117 0 No COG3 Seminar 20161209T150000-7r1v9apia8c9p6k3dqpf2bq0u8@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20161209T150000 20161209T160000 Building E25, Room 117 0 NO COG3 Seminar enootj7h0g9qv4m68l1dpcr708@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20161216T150000 20161216T160000 Building E25, Room 117 0 NO COG3 Seminar – Finals Week/AGU 20170210T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Linking fault-zone geology, fluid flow and seismicity at oceanic transform faults 20170210T100000 20170210T110000 Building E25, Room 119 0 COG3 Seminar – Jessica Warren (University of Delaware) n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20170210T100000 20170210T110000 20170210T100000 20170217T100000 20170224T100000 20170303T100000 20170324T100000 20170331T100000 20170414T100000 20170421T100000 20170505T100000 20170512T100000 Building E25, Room 119 FREQ=WEEKLY;UNTIL=20170512T140000Z;BYDAY=FR 0 COG3 Seminar – Speaker () 20170217T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Life under ice: Exploring the microbial landscape of Antarctic lakes 20170217T100000 20170217T110000 Building E25, Room 119 0 COG3 Seminar – Tyler Mackey (MIT) 20170224T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry The Mars Mantle: Insights from Rover Missions and Terrestrial Analogues Basaltic igneous rocks represent samples of a planet’s interior and give insight to the degree of heterogeneity or homogeneity of the interior. This talk will focus on the origins of geochemical diversity and estimates of oxygen fugacity among igneous and least altered sedimentary rocks measured by rover missions. Relative influences of partial melting, fractional crystallization, and mantle metasomatism will be explored. Terrestrial mantle xenoliths from alkaline provinces are considered as analogues to the Martian mantle, including cumulate xenoliths from post-shield Hawaiian volcanoes and metasomatized xenoliths from Mount Taylor Volcanic Field (New Mexico). Such a comparison is worthwhile because the Martian upper mantle is likely a mixture of primary, residual, metasomatized, and cumulate mantle. 20170224T100000 20170224T110000 Building E25, Room 119 0 COG3 Seminar – Mariek Schmidt (Brock University) 20170303T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Dust in the Wind: Investigating Past and Present Dust Deposition in the Uinta Mountains, Utah Eolian delivery of mineral dust impacts soil development, contributes to soil fertility, influences surface water chemistry, and alters snowpack albedo in high mountain ecosystems. This study focuses on past and present deposition of mineral dust in the alpine zone of the Uinta Mountains in northeastern Utah. Alpine soil profiles in the Uintas feature a ubiquitous layer of silt ~20 cm thick, indicating that dust deposition has been a significant long-term process in this environment. Four passive dust collectors were deployed in June, 2011, and an additional four were deployed in October, 2015. These collectors document an average dust flux of ~4 g/m2/yr, similar to values measured from snowpack samples in the Wind River (Wyoming) and San Juan (Colorado) Mountains. XRD analysis reveals that the dust is dominated by quartz, potassium feldspar, plagioclase, and illite. Some samples contain amphibole and chlorite. The dust is very well-sorted, with a median size of 8 μm. Geochemical records from lacustrine sediment cores reveal that the flux and properties of dust arriving in the Uinta Mountains have varied over the post-glacial period, likely in response to regional changes in aridity. A specially designed active sampler deployed at an elevation of 3700 m collects separate samples of NNW and SSE provenance. Differences in grain size distribution, mineralogy, and geochemistry of samples from contrasting wind directions indicate the importance of regional dust sources. 20170303T100000 20170303T110000 Building 54, Room 915 0 COG3 Seminar – Jeff Munroe (Middlebury College) 20170310T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Generation of Arc Crust Requires Oxidation of the Mantle Continental crust forms uniquely on Earth. High water and oxygen activities lead to the generation of continental crust, but the location, mechanism, and pathway by which oxygen activity increases remains elusive. I¹ll present recent work mapping oxygen activity in space and time during subduction zone initiation in the Western Pacific, a story told by basalts and forearc peridotites. 20170310T100000 20170310T110000 Building E25, Room 119 0 COG3 Seminar – Elizabeth Cottrell (Smithsonian Institution National Museum of Natural History) 20170317T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Seeing Through the Haze: Using Sulfur-Isotope Systematics to Probe the Composition of Earth's Early Atmosphere Reconstructing the evolution of atmospheric chemistry has long been the focus of geochemical research; however, the utility of our geochemical toolbox is rarely without inference. Introducing quadruple S-isotope systematics, we’ll take a ramble through the Archean sulfur-isotope record and take a glimpse at the evolution of our atmosphere. Focusing on newer, high-resolution, approaches I will present recent and [maybe] emerging data that constrains the first irreversible rise in atmospheric oxygen—The Great Oxidation Event—as well as a mechanism that may have expedited the accumulation of oxygen and the biological innovations that followed. 20170317T100000 20170317T110000 Building E25, Room 119 0 COG3 Seminar – Gareth Izon (MIT) 20170324T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Cave records from Southeast Asia: Windows to past hydroclimate variability Despite significant advances in our understanding of tropical Australasian monsoon climate variability over the past decade(s), we still know very little about the range and mechanisms of rainfall variability in Southeast Asia on orbital (~100,000-year) to millennial (~1000-year) timescales. As a result, state-of-the-art general circulation models have little data with which to validate simulations of past climate, thereby placing much uncertainty on future projections of monsoon variability. Given the large population of SE Asia who rely on the monsoon rains for agriculture and economic development, it is critical that we gain a better understanding on the factors that influence the monsoon climate. Over the past decade, my colleagues and I have explored a host of cave systems in remote regions of SE Asia installing data-loggers and collecting stalagmites, with the overarching goals being to: i) better constrain modern processes controlling speleothem growth, and in particular, how they preserve above-cave climate changes; and ii) to build high-resolution and long records of past monsoon behavior from the geochemical signals preserved in these deposits. In this talk, I will discuss the utility of speleothems to accurately preserve past changes in regional SE Asian hydroclimate, and their strong potential in addressing current uncertainties in tropical climate variability over a range of timescales (i.e. glacial-interglacial to millennial), particularly with respect to how the Asian monsoon responded to past changes in Earth’s boundary conditions. 20170324T100000 20170324T110000 Building E25, Room 119 0 COG3 Seminar – Michael Griffiths (William Paterson University) 20170331T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20170331T100000 20170331T110000 Building E25, Room 119 0 No COG3 Seminar – Spring Break 20170407T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Biostratigraphy and Glaciations in the Neoproterozoic: Updates from Re-Os geochronology Sedimentary strata from the Neoproterozoic Era (1000-541 Ma) host evidence for widespread glaciations, major fluctuations in geochemical proxy records, and numerous biological innovations associated with the diversification of eukaryotes that culminated with the emergence of Metazoans. Understanding the drivers and rates of change through this critical transition has been limited by the lack of a robust chronology. Here I will present multiple new Re-Os and U-Pb geochronology data from Neoproterozoic strata in an attempt to refine global correlation schemes and further constrain this critical interval of Earth history. 20170407T100000 20170407T110000 Building E25, Room 119 0 COG3 Seminar – Alan Rooney (Yale) 20170414T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry The What, When, Where, and Why of Supereruptions Supereruptions are gigantic volcanic eruptions (�450 km^3 of magma) the likes of which we have never witnessed. Yet, this does not mean that we will never experience one. Such enormous eruptions have the potential to wreak havoc on life, infrastructure, travel, and the environment. Consequently, it is critical that we study past supereruptions to understand how, when, where, and why one might happen in the future. In addition, supereruption deposits are evidence that large volumes of magma existed in the crust multiple times in Earth’s history; thus, studying these systems can inform on the magmatic construction of Earth’s crust. In this talk, I will address several outstanding and strongly debated questions regarding supereruptive systems: Where in the crust do these magmas reside? What shape do they take? How long do they persist in the crust before erupting? When, why, and over what timescales does the eruptive process occur? How are the giant volumes of crystal-poor high-silica rhyolite magma involved in supereruptions generated? Answering these questions is important both for practical reasons (e.g., hazards preparation and mitigation) and intellectual ones (e.g., understanding crustal processes). To address these questions, I combine information from multiple scales and perspectives (field studies, geochemistry, textural relations of crystals in rocks and melt inclusions in crystals, geochronology, geobarometry, phase-equilibria modeling, and diffusion modeling). Results from this work suggest that we can make some broad generalizations about supereruptive systems, but these systems have notable variability as well (e.g., their shape in the crust). This work also illustrates the power in using a multi-faceted, multi-disciplinary approach to addressing questions in the Earth Sciences. 20170414T100000 20170414T110000 Building E25, Room 119 0 COG3 Seminar – Ayla Pamucku (Princeton) 20170421T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry The role of grain size on the seismic structure of the oceanic upper mantle and melt migration beneath midocean ridges Grain size is a key microstructural property of the Earth's mantle, because it influences rheology, deformation mode (e.g., diffusion vs. dislocation creep), seismic attenuation and wave-speeds, electrical conductivity, and the permeability of the mantle to melt migration. In this talk I will discuss models for grain size evolution in the oceanic upper that combine composite grain-size dependent rheology with the Wattmeter [Austin & Evans, 2007] model for how grain size changes in response to the evolving deformation field. These results will be interpreted in the context of the seismic low velocity zone beneath the ocean basins and the origin of the lithosphere asthenosphere boundary. Finally, I will discuss the implications of grain size variability on the patterns of melt migration beneath mid-ocean ridges and subduction zones and show the results of preliminary two-phase flow models that couple melt migration with the predicted grain-size field. 20170421T100000 20170421T110000 Building E25, Room 119 0 COG3 Seminar – Mark Behn (WHOI) 20170428T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Why magma stall in the Earth’s crust? The emplacement depth of magmas plays a key role in determining the chemical stratification of the crust, and on the probability of magma to reach the surface to feed volcanic eruptions. While mechanical discontinuities within the crust have been shown to lead to the arrest of propagating dykes, in a section of a volcanic island arc in Kohistan, the depth of emplacement of granitoids does not seem to correspond to any particular mechanical discontinuity. I will focus on the evolution of crystallinity and temperature as function of magma chemistry and depth to show how magma chemistry can strongly affect the depth at which magma stall in the crust to form magma reservoirs. 20170427T100000 20170427T110000 Building 54, Room 915 0 COG3 Seminar – Luca Caricchi (University of Geneva) 20170505T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20170505T100000 20170505T110000 Building E25, Room 119 0 COG3 Seminar – No Seminar 20170512T100000-n91e8qdrst0dg1c0kqh59dudk0@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry Identifying Traces of Primitive Life in Ancient Rocks The early life fossil record is based upon a limited number of often controversial graphitic microfossils. The main complication resides in the poor preservation of organic biosignatures in the (meta)sedimentary rock record. Biodegradation and fossilization processes, as well as the increase of temperature and pressure conditions during diagenesis and metamorphism inevitably alter the original biochemical signatures of organic molecules. Thus, at a certain stage, biogenic and abiotic organics may become very difficult to distinguish. During this talk, I will show how combining characterization of natural samples using advanced spectroscopic techniques (STXM-based XANES & Raman microspectroscopies) and simulation of fossilization processes in the laboratory sheds new light on the potential preservation of microorganism molecular biosignatures in ancient rocks. 20170512T100000 20170512T110000 Building E25, Room 119 0 COG3 Seminar – Julien Alleon (MIT) flstovv4lnrvgo4mdv6gd931qg@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry The origin of the eukaryote cell Eukaryotes have a fundamentally different cell structure from bacteria and archaea, and possibly evolved from the latter. This possibility: an archaeal origin of eukaryotes has been a bit of a distraction in that it has led to models that try and explain eukaryote origins from modern archaea lacking any eukaryotic features. In this talk I will summarise what we know about eukaryote origins, and argue that ways of thinking now more common in palaeontology can help us to understand eukaryote origins. By focusing on known biological processes, and ecological drivers, key events in the origin of eukaryotes can be understood without needing to appeal to special or rare events. 20170516T100000 20170516T110000 Building 54, Room 915 0 COG3 Seminar – Anthony Poole (The University of Auckland) fk5ja28aab6c21d6k2igk755nk@google.com 20180503T092946Z MIT Seminar | PAOC Chemical Oceanography and Biogeochemistry 20170518T100000 20170518T110000 Building 54, Room 915 0 COG3 Seminar – Cathy Busby (UCSB)