An Introduction to Deep Time Marc Hirschmann University of Minnesota

“How did early Earth become our modern world?” July 1 – August 10 CIDER Summer Program 2012 “DEEP TIME” “How did early Earth become our modern world?” July 1 – August 10 Tutorial/Workshop July 15-August 10 Application Deadline February 1st, 2012 Instructors (some additions expected) Geochemistry: Rick Carlson, Mark Harrison, Bill McDonough, Sujoy Mukhopadhyay Geodynamics: Bruce Buffett, Michael Manga, Dave Stevenson Mineral Physics: Marc Hirschmann, Jie Li, Dave Rubie Seismology: Ed Garnero, Guy Masters, Barbara Romanowicz Other Confirmed Faculty Participants: Thorsten Becker, Adam Dziewionski, Abbie Kavner, Louise Kellogg, Sarah Stewart, Kevin Zahnle

How did early Earth become our modern world? WHAT IS DEEP TIME? WHAT IS CIDER DEEP TIME? How did early Earth become our modern world?

How did early Earth become our modern world? CIDER DEEP TIME? How did early Earth become our modern world? Some Principles There were many early Earth processes that had profound influence on the subsequent evolution of our planet 2. There are many important features of Earth that arose at some early time and subsequently remained as key characteristics of the planet. These features did not arise synchronously. For each, “Deep Time” is the period before and during their origin. 4. Deep Time is broad and diverse. Attempting to cover it comprehensively goes beyond a manageable CIDER summer program. Some important and key aspects of Deep Time will not be emphasized (e.g. planetary topics, climate evolution, origin of life). A Deep Earth perspective will be emphasized.

(Giant Molecular Clouds) How far back can we go? Star Nursuries (Giant Molecular Clouds) Accretion in the solar nebula

Accretion/Core Formation/Magma Ocean(s) Energetics, geochemical differentiation, etc. Rubie et al. 2011 Wood and Halliday, 2005

Canup, 2004

The bulk composition of the Earth is a key constraint on Its modern geochemistry Righter+Drake

Antiquity of the geodynamo Usui et al. 2009 - G3

Superplumes/LLSVPs: Origin? Ancient Features? Basal Magma Ocean? Sun et al. 2010 Labrosse et al. 2007

What was and what were the effects of the Late Heavy Bombardment? Figure from Valley (2002)

Gradual “Mixing In” of PGEs from Late Veneer (?) Wolfgang et al. 2009

When did the principal mantle geochemical reservoirs arise (and how did they arise through differentiation, mixing of “primitive” and “recycled” components, stirring, etc. Tackley, 2000 Hart et al. (numerous papers))

When did plate tectonics begin? (A) Silicate inclusion initial Nd isotopic composition versus Sm-Nd age for diamonds of peridotitic (circles), lherzolitic (triangles), and eclogitic (diamonds) parageneses. Solid symbols are isochron studies for composites of garnet and clinopyroxene grains; open symbols are model age studies for composites of garnet only. Unlabeled points on convecting mantle curve are mantle extraction ages extrapolated from labeled points (11). (B) Sulfide inclusion initial Os isotopic composition versus Re-Os age. Solid symbols are isochron studies; open symbols are model age studies for single grains. For isochron studies, mantle extraction ages extrapolated from labeled points are typically <100 million years (one scale division) older than the isochron age (11). In (A) and (B), WC 1-2 denotes Wilson cycle rifting (stages 1 and 2) for the Pilbara craton (6); WC 5-6 denotes Wilson cycle continental closure (stages 5 and 6) for the Kaapvaal craton. Locality abbreviations are given in table S1. S B Shirey, S H Richardson Science 2011;333:434-436 Brown, 2006

What has been the thermal evoultion of the Earth through time? Mantle Temperature Based on basalt chemistry Thermal Evoultion of the Mantle Taking Into Account Influence of H2O Korenaga – in press Herzberg et al. 2010

What is the inventory of volatiles in the modern Earth? How much was delivered during accretion? Delivery of H2O to growing terrestrial planets Raymond et al. 2006

Zahnle et al. 2007

The NORMAL JACK HILLS WORLD Trail et al. 2011 Hopkins et al. 2008 Wilde et al. 2001 Trail et al. 2011

Origin and Stabilization of Continents And Continental Cratons Yuan and Romanowicz, 2010 Cratonic Xenolith Model Ages (Carlson et al. 2005)

Origin of Life, Evidence for Early Life Isotopically Light Carbon Nanoparticles Rosing, 1999