Oceanic and super-deep continental diamonds share a transition zone origin and mantle plume transportation.

Rare oceanic diamonds are believed to have a mantle transition zone origin like super-deep continental diamonds. However, oceanic diamonds have a homogeneous and organic-like light carbon isotope signature (δC - 28 to - 20‰) instead of the extremely variable organic to lithospheric mantle signature of super-deep continental diamonds (δC - 25‰ to + 3.5‰).

Geochemical evidence for a widespread mantle re-enrichment 3.2 billion years ago: implications for global-scale plate tectonics.

Progressive mantle melting during the Earth's earliest evolution led to the formation of a depleted mantle and a continental crust enriched in highly incompatible elements. Re-enrichment of Earth's mantle can occur when continental crustal materials begin to founder into the mantle by either subduction or, to a lesser degree, by delamination processes, profoundly affecting the mantle's trace element and volatile compositions. Deciphering when mantle re-enrichment/refertilization became a global-scale process would reveal the onset of efficient mass transfer of crust to the mantle and potentially when plate tectonic processes became operative on a global-scale.

Author Correction: Global geochemical fingerprinting of plume intensity suggests coupling with the supercontinent cycle.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Global geochemical fingerprinting of plume intensity suggests coupling with the supercontinent cycle.

Plate tectonics and mantle plumes are two of the most fundamental solid-Earth processes that have operated through much of Earth history. For the past 300 million years, mantle plumes are known to derive mostly from two large low shear velocity provinces (LLSVPs) above the core-mantle boundary, referred to as the African and Pacific superplumes, but their possible connection with plate tectonics is debated. Here, we demonstrate that transition elements (Ni, Cr, and Fe/Mn) in basaltic rocks can be used to trace plume-related magmatism through Earth history.

Cr-spinel records metasomatism not petrogenesis of mantle rocks.

Mantle melts provide a window on processes related to global plate tectonics. The composition of chromian spinel (Cr-spinel) from mafic-ultramafic rocks has been widely used for tracing the geotectonic environments, the degree of mantle melting and the rate of mid-ocean ridge spreading. The assumption is that Cr-spinel's core composition (Cr# = Cr/(Cr + Al)) is homogenous, insensitive to post-formation modification and therefore a robust petrogenetic indicator.

Origin of arc magmatic signature: A temperature-dependent process for trace element (re)-mobilization in subduction zones.

Serpentinite is a major carrier of fluid-mobile elements in subduction zones, which influences the geochemical signature of arc magmatism (e.g. high abundances of Li, Ba, Sr, B, As, Mo and Pb).