Wednesday Seminar

today is Wednesday, January 17th, 2018

Wednesday, January 17th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“Re-evaluating fault zone evolution, geometry, and slip rate along the restraining bend of the southern San Andreas Fault”

      – by Dr. Kim Blisniuk, Geology Department, San Jose State University

This study presents new multi-proxy data to provide an alternative interpretation of the late –to–mid Quaternary evolution, geometry, and slip rate of the southern San Andreas fault, comprising of the Garnet Hill, Banning, and Mission Creek strands, along its restraining bend near the San Bernardino Mountains and San Gorgonio Pass. Present geologic and geomorphic studies in the region indicate that as the Mission Creek and Banning strands diverge from one another in the southern Indio Hills, the Banning strand accommodates the majority of lateral displacement across the San Andreas Fault. In this currently favored kinematic model of the southern San Andreas Fault, slip along the Mission Creek Strand decreases significantly northwestward toward the San Gorgonio Pass. Along this restraining bend, the Mission Creek Fault Strand is considered to be inactive since the late –to–mid Quaternary (~500-150 kya) due to the transfer of plate boundary strain westward to the Banning and Garnet Hills strands, the Jacinto Fault, and northeastward, to the Eastern California Shear Zone. Here, we present a revised geomorphic interpretation of fault displacement, initial 36Cl/10Be burial ages, sediment provenance data, and detrital geochronology from modern catchments and displaced Quaternary deposits that improve across-fault correlations. We hypothesize that continuous large–scale translation of this structure has occurred throughout its history into the present. Accordingly, the Mission Creek Strand is active and likely a primary plate boundary fault at this latitude.

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Wednesday, January 24th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“The influence of melting on the thermo-chemical evolution of rocky planets' interiors”

      – by Dr. Diogo Lourenço

Melting has always been present throughout the history of the Earth, and especially early in its evolution. However, many unknowns still remain regarding its role in the dynamics of our planet. In this presentation I will show results that contribute to the developing understanding of the effects of melting on the thermo-chemical evolution of rocky bodies, with a special focus on the history of Earth, from its molten early days (magma ocean stage) to the present solid-state convection and plate tectonics. To achieve this, I performed numerical simulations of global mantle convection, and combine the numerical results with insights from scaling analysis to explore some fundamental aspects of the effects of melting on the thermo-chemical evolution of terrestrial bodies. I applied the models to investigate (i) how does melting-induced crustal production affects the interior state and surface behaviour of an Earth-like planet, (ii) the effects of intrusive versus extrusive magmatism on the surface tectonics and mantle cooling of a terrestrial planet, and (iii) the evolution of the Earth from a molten initial state to present-day solid-state convection and plate tectonics.
Results show that (i) melting-induced crustal production helps plate tectonics on Earth-like planets by strongly enhancing the mobility of the lid, replacing a stagnant lid with an episodic lid, or greatly extending the time in which a smoothly evolving mobile lid is present; (ii) high intrusion efficiencies (i.e. dominance of intrusion versus extrusion) lead to a new tectonic regime, named “plutonic-squishy lid”characterised by a set of strong plates separated by warm and weak regions generated by plutonism, and can cool the mantle more efficiently than volcanic eruptions for planets with no subduction in their history; (iii) for the early evolution of the Earth, results show rapid cooling and crystallisation until the rheological transition (transition to a solid-dominated regime with completely different properties and dynamics) then much slower crystallisation, large-scale overturn well before full solidification, and the formation and subduction of an early crust while a partially-molten upper mantle is still present. Then, the planet transitions to a mostly-solid-state long-term mantle convection and plate tectonics or an episodic-lid regime.

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Wednesday, January 31st, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“Paleocene-Eocene Thermal Maximum meets the North Atlantic Igneous Province: Coincidence or global environmental conspiracy?”

      – by Dr. Andy Ridgwell, Department of Earth Sciences, UC Riverside

The Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma), with its multiple lines of
attendant evidence for massive greenhouse gas release and global-scale warming, is
regarded as a highly plausible future analogue. However, because the onset of the PETM
likely took place at a rate at least one, if not two, orders of magnitude slower than current
century-scale anthropogenic warming, it is uncertain what we can learn e.g. re. biotic
sensitivities, except perhaps to place a lower limit on potential future disruption. Instead,
focus has often been on what the PETM might reveal regarding the sensitivity of surficial,
reduced carbon stores (e.g. vegetation and soil carbon, permafrost, marine hydrates) to
warming, and hence the strength of positive feedbacks between atmospheric CO2 and
climate change. Indeed, almost all explanations to date for the PETM have relied either
solely, or dominantly, on one or more of these carbon sources and feedbacks. Yet one of the
largest igneous provinces (the North Atlantic Igneous Province — ‘NAIP’) recorded in the
geological record was being emplaced exactly at this time and its role to date, almost entirely,
overlooked.
Here I present a revised view of the PETM as one predominantly the product of massive
volcanism, making it rather unexpectedly more like the end Permian in character. Feedbacks
with climate and involving reservoirs of reduced organic carbon likely only play a more minor
role, reducing the event’s future relevance. I come to these conclusions on the basis of new
paired records of boron and carbon isotope changes, assimilating these data in an Earth
system model to reconstruct the unfolding carbon cycle dynamics across the event. Model
results indicate >10,000 PgC with an average isotopically heavier than -17‰ is required to
account for the observations, leading to the identification of volcanism associated with the
NAIP as the main driver of the PETM.

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Wednesday, February 7th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Geerat Vermeij

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Wednesday, February 21st, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Rob Campbell

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Wednesday, February 28th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Aodhan Butler

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Wednesday, March 7th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Mitch Mihalynuk

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Wednesday, March 14th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Zach Sharp

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Wednesday, April 25th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Nita Sahai

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Wednesday, May 2nd, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Caroline Strömberg, Department of Biology, University of Washington

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Wednesday, May 9th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Susannah Dorfman, COMPRES Distinguished Lecturer, Department of Earth and Environmental Sciences, Michigan State University

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Wednesday, May 16th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Ravi Kanda

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Wednesday, May 30th, 2018, Wednesday Seminar

4:10 PM, 55 Roessler
Tea and cookies at 3:45 in the aviary - (2110 EPS)

“TBA”

      – by Dr. Bradley Hacker

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