EXPERIMENTAL INVESTIGATION OF MANTLE HETEROGENEITY USING PARTITIONING OF FIRST-ROW TRANSITION ELEMENTS BETWEEN CLINOPYROXENE AND MELT WITH VARYING JADEITE COMPONENTS

Earth’s mantle is generally thought to be composed of peridotite, but subducted oceanic crust may be present as lithological heterogeneities in the mantle. These lithological heterogeneities may contribute to the diversity of magmas generated in the upper mantle, such as the chemical differences between ocean island basalts and mid ocean ridge basalts [1]. First-row transition elements (FRTE) have been used for identifying basalts formed from partial melting with a component of recycled crust [2,3,4]. FRTE are distributed differently between crystals and melt depending on the composition of the minerals in the melting source [4]; therefore, to accurately model FRTE concentrations in melts derived from different lithologies requires constraints on the compositional effects on partitioning of those elements. To better understand how FRTE partitioning is affected by differing mineral compositions I performed experiments focusing on the partitioning of FRTE between clinopyroxene and silicate melt as a possible indicator of mantle heterogeneities. Five parent compositions with variable Na concentrations were created and used in piston cylinder experiments. I performed experiments at a pressure of 2 GPa and temperatures between 1000-1100°C. The data presented will be SEM imaging, electron microprobe analysis, and laser ablation inductively coupled plasma mass spectrometry. These data sets will demonstrate how increasing Na concentrations in clinopyroxene effets the partitioning of FRTE. This will improve modeling of the compositions of melts derived from heterogeneous mantle sources in future work.

[1] Zindler & Hart 1986, Ann. Rev. Earth Planet. Sci.; [2] Humayun et al. 2004, Science; [3] Le Roux et al. 2011, Earth Planet. Sci. Lett.; [4] Davis et al. 2013, Geochim. Cosmochim. Acta.