Earth and Planetary Science Letters 392 (2014) 154–165 Contents lists available at ScienceDirect Earth and Planetary Science Letters www.elsevier.com/locate/epsl A geochemical evaluation of potential magma ocean dynamics using a parameterized model for perovskite crystallization Colin R.M. Jackson a,∗ , Leah B. Ziegler b , Hongluo Zhang c , Matthew G. Jackson d , Dave R. Stegman e a Geological Sciences, Brown University, Providence, RI, USA b CEOAS, Oregon State University, Corvallis, OR, USA c Department of Earth Sciences, University of Minnesota, Minneapolis, MN, USA d Department of Earth Sciences, UCSB, Santa Barbara, CA, USA e Scripps Institution of Oceanography, UCSD, San Diego, CA, USA article info abstract Article history: Received 14 August 2013 Received in revised form 26 December 2013 Accepted 17 January 2014 Available online 4 March 2014 Editor: L. Stixrude Keywords: early Earth magma ocean crystallization basal magma ocean perovskite Magnesium perovskite (MgPv) is likely the first phase to crystallize from a deep magma ocean. Consequently, MgPv crystallization has a strong control on the dynamics and chemical evolution associated with the earliest stages of silicate Earth differentiation. In order to better understand the chemical evolution associated with MgPv crystallization during a magma ocean, a parameterized model for major and trace element partitioning by MgPv has been developed. The parameterization is based on a compilation of published experimental data and is applied to batch and near-fractional crystallization scenarios of ultramafic liquids, allowing for a more complete analysis of the geochemical implications for magma ocean crystallization. The chemical signatures associated with modeled MgPv fractionation are evaluated in the context of possible dynamical outcomes to a magma ocean (e.g. basal magma ocean (BMO) or crystal settling). It is shown that fractionating MgPv from ultramafic liquids imparts diagnostic signatures (e.g. Ca/Al, HFSE anomalies, ε 176 Hf–ε 143 Nd) in both the liquid and solid phases. These signatures are not currently observed in the accessible Earth, suggesting that either early-fractionating MgPv was subsequently homogenized or crystal suspension was dominant during the earliest stages of magma ocean crystallization. A BMO that fractionates CaPv and MgPv is also considered and shown to mute many of unobserved geochemical effects associated with a MgPv-only fractionation, offering an alternative possibility for the evolution of a BMO depleted in heat producing elements.  2014 Elsevier B.V. All rights reserved. 1. Introduction The accretion of Earth marked a period of rapid change, which ultimately set the initial conditions for subsequent geologic evo- lution. Our understanding of the earliest stages of Earth’s history, however, remains largely incomplete and based on a limited set of observations. Accretionary scenarios posit Earth’s formation pro- ceeded with increasingly energetic collisions, and the last stages of accretion were likely energetic enough to melt large volumes of the mantle. These scenarios are supported by several indepen- dent lines of reasoning including the high pressure of core for- mation needed to explain abundance of moderately siderophile elements in the mantle (e.g. Li and Agee, 1996; Righter et al., 1997), evidence for a global magma ocean on the moon (e.g. Wood et al., 1970), and dynamical models of accretion (e.g. Chambers and Wetherill, 1998; Wetherill, 1985). Experimental and theoret- * Corresponding author. Tel.: +1 858 531 8544; fax: +1 401 863 2058. E-mail address: colin_jackson@brown.edu (C.R.M. Jackson). ical results suggest crystallization of liquids with compositions close to that of bulk silicate Earth (BSE) under lower mantle pressures begins with magnesium perovskite (MgPv) as the liq- uidus phase, which is followed at lower temperatures by ferroper- iclase (fP) and calcium perovskite (CaPv) (Andrault et al., 2011, 2012; de Koker et al., 2013; Fiquet et al., 2010; Ito et al., 2004; Liebske and Frost, 2012; Nomura et al., 2011; Presnall et al., 1998; Tronnes and Frost, 2002; Zhang and Herzberg, 1994). As such, MgPv likely dominated the chemical characteristics of the earli- est forming solids following the putative terrestrial magma ocean. The chemical characteristics of this early-forming reservoir strongly influence the dynamics associated with, and immediately follow- ing, the crystallization of a deep magma ocean, which we consider here to be a complete or nearly complete melting of silicate Earth (e.g. Canup, 2004). Indeed, the distribution of major elements in- fluences the density contrast between liquid and solid phases, and radioactive elements, such as U + Th, control the heat produc- tion within a particular phase. Moreover, fractionation of MgPv from a silicate liquid has consequences for the major and trace element composition and isotopic evolution that are implicit in 0012-821X/$ – see front matter  2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.epsl.2014.01.028