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ESS Department - April 18th, 2024
Constraining the age of collision between the Kohistan-Ladakh arc (KLA), an intra-oceanic arc remnant, and Eurasia along the Shyok suture zone is critical to understand the development of the India-Eurasia orogenic system. Estimates of the timing of KLA-Eurasia collision span 100 – 40 Ma, permitting conflicting tectonic scenarios in which the KLA either collided first with Eurasia or first with India. Each of these scenarios has very different implications for how India-Eurasia convergence was accomodated and the linkages between Himalayan orogenesis and global climate change in the Cenozoic. In this talk I will present field observations, structural analyses, and U/Pb zircon ages that constrain the tectonostratigraphy and structural development of the Shyok suture zone in Ladakh, NW India. These results support multi-stage arc-continent accretion models for the India-Eurasia collision because they show that KLA-Karakoram collision likely...
ESS Department - April 11th, 2024
Ice-infiltrated sediment, or frozen fringe, is responsible for phenomena such as frost heave, ice lenses and meters of debris-rich ice under glaciers. Understanding frozen fringes is important as frost heave is responsible for damaging infrastructure at high latitudes and sediment freeze-on at the base of glaciers can modulate subglacial friction, influencing the rate of global sea level rise. Here we describe the thermomechanics of liquid water flow and freezing in ice-saturated sediments, focusing on the conditions relevant for subglacial environments. The force balance that governs the frozen fringe thickness depends on the weight of the overlying material, the thermomolecular force between ice and sediments across liquid premelted films and the water pressure required by Darcy flow. We combine this mechanical model with an enthalpy method that conserves energy across phase change interfaces on a fixed computational grid. The force balance...
ESS Department - April 9th, 2024
Can the culture of STEM help reproduce inequality? The professional cultures of STEM, which give each discipline its particular “feel” and unite discipline members under a taken-for-granted system of meanings and values, are not benign. Drawing from several NSF-funded studies, articles, and my recent book, Misconceiving Merit, I argue that these professional cultures can have built within them intersectional inequalities along gender, race/ethnicity, and LGBTQ+ status. I discuss the role of three particular cultural ideologies—the Schema of Scientific Excellence, Depoliticization, and the Meritocratic Ideology—in producing these disadvantages. I end by explaining why decisions (e.g. hiring, promotion) that partially rely on assessments of individuals’ “fit” with professional cultures are particularly important to critically examine for their potential to contribute to inequality.