Diamondites: evidence for a distinct tectono-thermal diamond-forming event beneath the Kaapvaal craton.

ABSTRACT: The petrogenesis and relationship of diamondite to well-studied monocrystalline and fibrous diamonds are poorly understood yet would potentially reveal new aspects of how diamond-forming fluids are transported through the lithosphere and equilibrate with surrounding silicates. Of 22 silicate- and oxide-bearing diamondites investigated, most yielded garnet intergrowths (n = 15) with major element geochemistry (i.e. Ca-Cr) classifying these samples as low-Ca websteritic or eclogitic. The garnet REE patterns fit an equilibrium model suggesting the diamond-forming fluid shares an affinity with high-density fluids (HDF) observed in fibrous diamonds, specifically on the join between the saline-carbonate end-members. The δ¹³C values for the diamonds range from - 5.27 to - 22.48‰

SUBMITTER: Mikhail S 

PROVIDER: S-EPMC6713314 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature