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Date: June 13, 2018
Speaker: Chao Liu, Carnegie Institution for Science
Topic: Dynamics of The Supercontinent Rodinia
Time and Location: 1:00 p.m., with Q&A to follow in 1st floor conference room B at the American Center for Physics (www.acp.org), 1 Physics Ellipse, College Park, MD - off River Rd., between Kenilworth Ave. and Paint Branch Parkway.
Introduction: Many people have heard of Pangaea, the supercontinent that included all continents on Earth and began to break up about 175 million years ago. But before Pangaea, Earth’s landmasses ripped apart and smashed back together to form supercontinents repeatedly. This cycle has been going on for at least the last 3.0 billion years of Earth’s history, regulating our planet’s geography, climate, and carbon cycles. Rodinia, is such a super continent.
Abstract: The mineralogy and geochemistry associated with Rodinian assembly (~1.3–0.9 Ga) are significantly different from those of other supercontinents. Compared to other supercontinents, relatively more Nb-bearing minerals, Y-bearing minerals, and zircons formed during Rodinian assembly, with corresponding enrichments of Nb, Y, and Zr concentrations in igneous rocks. By contrast, minerals bearing many other elements (e.g., Ni, Co, Au, Se, and platinum group elements) are significantly less abundant, without corresponding depletion of Ni and Co concentrations in igneous rocks. Here we suggest that the Nb, Y, and Zr enrichments in igneous rocks and relatively more occurrences of corresponding Nb-bearing minerals, Y-bearing minerals, and zircons result from significant non-arc magmatism during the mid-Proterozoic, while fewer occurrences of many other minerals suggest enhanced erosion of Rodinian volcanic arcs and orogens. The prolonged, extrovert assembly of Rodinia from thickened mid-Proterozoic continental crust via two-sided subduction can account for both the prevalence of non-arc magmatism and the enhanced erosion.
Biography: Chao Liu got his PhD in geoscience from Yale University in 2015. Now he is a postdoctoral associate working with Prof. Robert Hazen at Carnegie Institution for Science. His study is focused on geochemistry, mineralogy and data science; including prediction of the population of undiscovered mineral species by statistical modeling, mining of mineral locality and age data, and statistical analysis of geochemical data to understand how Earth's evolution in the past.