Fig. 1.

Comparison of the strontium and neodymium isotopic compositions of basaltic volcanic rocks at the time of their crystallization (i = initial crystallization time) from Mars and Earth. Terrestrial basalts include ocean island basalts (green field), mid-ocean ridge basalts (MORB; gray field), Hawaiian Main Shield (Mauna Loa, Mauna Kea; blue field), and Hawaiian Rejuvenated Volcanism (Honolulu volcanics, North Arch, Niihau, Kaula; orange field). Approximate terrestrial “HIMU” (high²³⁸U/²⁰⁴Pb), EMI and EMII (enriched mantle I and II) geochemical reservoirs are shown. ε¹⁴³Nd_i = ([(¹⁴³Nd/¹⁴⁴Nd_i)_sample/(¹⁴³Nd/¹⁴⁴Nd_i)_chondritic]−1) × 10⁴. Data sources are given in the Methods section and error bars are smaller than symbols unless shown