Category Archives: UMD

University of Maryland geology department

UMD: Hopkins’ Holder on metamorphism and plate tectonics

2019 Geology Colloquium Series

Friday, April 26th 2019 at 3:10 pm
in PLS 1140

Watch live at https://www.geol.umd.edu/youtube

Robert Holder
Johns Hopkins University

Metamorphism and the Evolution of Plate Tectonics

At present, Earth’s mantle convection, which facilitates planetary heat loss, is expressed at the surface as plate tectonics. When plate tectonics emerged and how it has evolved through time are two of the most fundamental and provocative questions outstanding in Earth science. Metamorphic rocks, those that have experienced solid-state mineral transformations due to changes in pressure (P) and temperature (T), record periods of burial/exhumation and heating/cooling that reflect the tectonic environments in which they formed. Changes in the global distribution of metamorphic P–T conditions in the continental crust through time reflect secular evolution of Earth’s tectonic processes at convergent plate boundaries. On modern Earth, convergent plate margins are characterized by metamorphic rocks that record a bimodal distribution of apparent thermal gradients (change in temperature with depth, parameterized in this talk as metamorphi! c T/P), in the form of paired metamorphic belts, which is attributed to metamorphism near to (low T/P) and away from (high T/P) subduction zones. In this talk, I will evaluate the emergence of bimodal metamorphism as a proxy for secular change in plate tectonics using a statistical evaluation of the distributions of metamorphic T/P through time. I will argue that Earth’s modern plate tectonic regime developed gradually since the Neoarchaean Era in conjunction with secular cooling of the mantle and associated changes in the thickness, buoyancy and rheology of oceanic lithosphere, resulting in an evolution in the styles of both subduction and collisional orogenesis.

UMD: Kurz on OIB noble gases

2019 Geology Colloquium Series

Friday, April 5th 2019 at 3:10 pm
in PLS 1140,
University of Maryland, College Park

Watch live at https://www.geol.umd.edu/youtube

Mark Kurz
Woods Hole Oceanographic Institution

Noble gases from the deep earth: evidence from ocean island volcanoes

UMD: Meredith Townsend on modeling magma chamber evolution

University of Maryland geology department 2019 Geology Colloquium Series

Friday, March 29th 2019 at 3:00 pm
in PLS 1140

Watch live at https://www.geol.umd.edu/youtube

Meredith Townsend
Brown University

How do magma chambers grow? Insights from thermo-mechanical modeling with applications to large silicic caldera systems

Magma chambers in Earth’s crust can grow to be hundreds to thousands of cubic kilometers, potentially feeding catastrophic caldera‐forming eruptions. Smaller‐volume chambers are expected to erupt frequently and freeze quickly; a major outstanding question is how magma chambers ever grow to the sizes required to sustain the largest eruptions on Earth. I will present recent results from Townsend et al. 2019 G-cubed, which uses a thermo‐mechanical model to investigate the primary factors that govern the extrusive:intrusive ratio in a chamber, and how this relates to eruption frequency, eruption size, and long‐term chamber growth. The model consists of three fundamental timescales: the magma injection timescale τin, the cooling timescale τcool, and the timescale for viscous relaxation of the crust τrelax. We estimate these timescales using geologic and geophysical data from four volcanoes (Laguna del Maule, Cam! pi Flegrei, Santorini, Aso) to compare them with the model. In each of these systems, τin is much shorter than τcool and slightly shorter than τrelax, conditions that in the model are associated with efficient chamber growth and simultaneous eruption. In addition, the model suggests that the magma chambers underlying these volcanoes are growing at rates between ~10‐4‐10‐2 km3/yr, speeding up over time as the chamber volume increases. We find scaling relationships for eruption frequency and size that suggest that as chambers grow and volatiles exsolve, eruption frequency decreases but eruption size increases. These scaling relationships provide a good match to the eruptive history from the natural systems, suggesting the relationships can be used to constrain chamber growth rates and volatile saturation state from the eruptive history alone.

UMD: Gunderson on ethics & harassment

2019 Geology Colloquium Series

Friday, March 1st 2019 at 3:10 pm
in PLS 1140

Watch live at https://www.geol.umd.edu/youtube

Linda Gundersen
USGS

Scientific Integrity, Ethics, Diversity, and Sexual Harassment: Why Should You Care?

Understanding the values each person brings to the table is key to understanding how ethics, integrity, diversity, and  harassment are connected. Values are critical, they determine decisions we make such as falsifying data or consciously discriminating to out-compete someone. Values also determine our implicit and explicit biases, both scientific and personal. Through these biases we may systematically exclude ideas, people, and practices; weakening the very framework of science. This presentation explores these concepts interactively with the audience through learning, scenarios, and discussion.

UMD Geology: Kring on Chixculub crater discovery

2019 Geology Colloquium Series

Friday, February 22nd 2019 at 3:00 pm
in PLS 1140

David Kring
USRA – Lunar and Planetary Institute

The Discovery of the Chicxulub Crater and Recent Insights from IODP-ICDP Expedition 364

The discovery of the Chicxulub impact crater added tremendous credibility to the impact-mass extinction hypothesis.  That discovery led, in turn, to detailed studies of the impact’s environmental effects.  More recently, deep subsurface drilling by IODP and ICDP provided an opportunity to study the formation of the extraordinary ~180 km diameter basin, which shattered the Yucatan Peninsula, causing once immobile granite to flow in excess of a hundred kilometers an hour.  The heat of the impact spawned a vast hydrothermal system that persisted for about a million years.  That hydrothermal system is currently being used as a proxy for Hadean Earth systems that may have hosted Earth’s earliest life.

UMD: Woods Hole’s Fauria on submarine volcanism

2018 University of Maryland Geology Colloquium Series

Friday, November 2nd 2018 at 3:00 pm
in PLS 1130, UMD College Park

Kristen Fauria
Woods Hole Oceanographic Institution

Submarine volcanic eruptions: why some rocks float and others sink

The 2012 eruption of Havre submarine volcano was the largest submarine pyroclast-producing eruption in modern history. Most of the material from the eruption formed a > 1.2 km3 pumice raft that floated across the South Pacific for more than a year. Rafts of floating pumice spread volcanic material far from its source and are important for the dispersal of marine organisms. Here we explore how pumice get to the surface from deep submarine eruptions, why some – but not all – pumice stay afloat in rafts, and how high porosities and phase changes lead to complex behaviors. By understanding the clast-scale dynamics of pumice in water, we can better interpret deposits and understand the fate of volcanic material in the ocean.

Gene Likens: inaugural Helz lecture

The University of Maryland’s Department of Geology hosts its inaugural Helz Lecture on October 18th, and we hope that you can join us.  The Helz Lecture is a new lecture series graciously supported by Drs. George and Rosalind Helz.
Our first speaker will be Dr. Gene Likens.  Dr. Likens and his team were the first to discover the regional effects of acid rain in North America.  The title of the talk will be:  “Acid Rain:  A long and unfinished journey from discovery to political action.”  Dr. Likens is a member of the National Academy of Science and is a recipient of the National Medal of Science among many other honors.  In addition to his research, he also currently teaches a course in science ethics at the University of Connecticut and enjoys interacting with students.
There will be a catered reception prior to the Helz Lecture at 5 pm in the new Edward St. John Learning and Teaching Center, 2nd Floor Lounge.  The lecture will begin at 5:30 pm in Edward St. John Learning and Teaching Center Room 2204.  A link providing further details can be found at: https://life.umd.edu/communications/cmns/helz.html
Everyone is invited to the inaugural Helz Lecture, and it is open to the public.  It should be interesting and fun.  Please feel free to share widely with your students, classes, colleagues, and friends.