Ultradeep Rocks and Diamonds in the Light of Advanced Scientific Technologies

Abstract

This is a review paper which summarizes recent achievements in studies of superdeep mantle rocks and diamonds from kimberlite and ultrahigh-pressure metamorphic (UHPM) terranes using advanced analytical techniques and instrumentations such as focused ion beam (FIB)-assisted transmission electron microscopy (TEM) and synchrotronassisted infrared spectroscopy. In combination, they allow characterization of geological materials formed at varying pressures, temperatures, and stresses in different chemical environments, which has enabled us to make amazing advances in understanding large-scale processes operating in the Earth through plate tectonics. Mineralogical characterisations of the ultradeep earth materials using novel techniques with high spatial and energy resolution are resulting in unexpected discoveries of new phases, thereby providing better constraints on deep mantle processes. One of such results is that the nanometric fluid inclusions in diamonds from kimberlite and UHPM terranes contain similar elements such as Cl, K, P, and S. Such similarity reflects probably the high solubility of these elements in a diamond-forming C-O-H supercritical fluid at high pressures and temperatures. The paper emphasizes the necessity of further studies of diamonds occurred within geological setting (oceanic islands, foearcs and mantle sections of ophiolites) previously

Crustal signature of δ 13C and nitrogen content in microdiamonds from Erzgebirge, Germany: Ion microprobe studies

“…Although Massonne (2003) proposed diamond crystallization from Si-rich melt, our data fit better to diamond crystallization from a supercritical C-O-H fluid. Direct observations of fluid inclusions with FIB-TEM studies (Dobrzhinetskaya et al, 2007(Dobrzhinetskaya et al, , 2003a, synchrotron assisted infrared spectroscopy (Dobrzhinetskaya and Wirth, 2010;Dobrzhinetskaya et al, 2006), and observations on microstructure of other inclusions associated with diamonds (Stöckhert et al, 2009(Stöckhert et al, , 2001 strongly suggest that the Erzgebirge diamond crystallization media was a supercritical C-O-H fluid enriched in different crustal components such as K, P, S, N, Si, Mg, Ti, Al, Ca and Pb. The innermost central part of Grt-E, for example, is characterized the lower Mg/Ca and Mg/(Mg+Fe) values (Fig.…”

First find of polycrystalline diamond in ultrahigh‐pressure metamorphic terrane of Erzgebirge, Germany

“…Dobrzhinetskaya et al. , 2003a; Wirth, 2004, 2009; Dobrzhinetskaya & Wirth, 2009; Dobrzhinetskaya, 2012). The TEM samples were prepared by cutting foils through whole diamond crystals and the host zircon in order to also investigate the diamond–zircon interface.…”