Geology Seminar Series: Dr. Jesse R. Reimink: Evaluation of Continental Freeboard in the Neoarchean Using Detrital Zircons

Wed., Apr. 7, 2021 4:00 p.m.

Location: https://uregina-ca.zoom.us/j/92337163072?pwd=b2xnMFpVYXRUQnlRYnZaWEF2WDlnUT09

Title: Evaluation of Continental Freeboard in the Neoarchean Using Detrital Zircons

Speaker: Dr. Jesse R. Reimink, The Pennsylvania State University

Abstract:

Determining when continental masses emerged above the global ocean is crucial to understanding secular changes in crustal and Earth-surface processes. The emergence of continents above sea level provided important sinks for atmospheric CO₂, a source of bioavailable P₂O₅, and initiated the erosional component of the rock cycle. Previous estimates for continental emergence vary widely and depended on complex geochemical proxies. Here we formulate a simple testable hypothesis for the behavior of sedimentary systems in a world with flooded vs. emergent continents and employ a sample-based analysis of the global detrital-zircon record. We contend that watersheds with sizes relative to their host continents similar to modern ones became common ~2.8 billion years ago, and that punctuated continental growth and consistent recycling occurred at least since the Neoarchean. Our analysis therefore provides a novel and reliable chronometer to track the emergence, growth, and recycling of continental-crust throughout Earth’s history.

I will also end with a discussion of a science outreach project involving my former high school teacher, a nationally-lauded educator from Michigan, Chris Bolhuis. Our geoscience podcast, PlanetGeo, is an evolving collaborative project that currently is aimed at providing entertaining and concise information about the importance of geoscience to society at large.