TY - JOUR

T1 - Low-energy phase boundary pairs and preferred crystallographic orientations of olivines in nanometer-sized ultrapotassic fluid inclusions of Aykhal diamond

AU - Hwang, S. L.

AU - Shen, P.

AU - Yui, T. F.

AU - Chu, H. T.

AU - Logvinova, A. M.

AU - Sobolev, N. V.

N1 - Publisher Copyright: © 2018 Elsevier B.V.

PY - 2018/12/1

Y1 - 2018/12/1

N2 - The healed internal conjugated cleavages at the core of Aykhal octahedral diamond sample AH2 were decorated with {111}dia-facetted ultrapotassic fluid/melt inclusion pockets containing nanosized graphite, phlogopite and olivine (Fo92) inclusions. These olivines are either rounded in pockets with ample fluid, or facetted by the {111}dia mold in the pockets with a fluid film. Transmission electron microscopy revealed two distinct crystallographic characteristics of olivine inclusions: (1)pronounced crystallographic texture of olivines grouped in specific diamond domain, and (2)frequent parallelism or sub-parallelism of specific low-energy faces of the two phases, mainly (010)ol, {120}ol, (001)ol and {111}dia, {110}dia, {100}dia in the order of decreasing preference, forming prominent (010)ol/{111}dia, (010)ol/{110}dia, (001)ol/{110}dia, {120}ol/{111}dia, and {120}ol/{110}dialow-energy phase boundaries with thin liquid film of 1–2 nm in between. These findings not only testify to the extremely low adhesion energies of olivine-diamond boundary pairs, but also imply that, in the presence of a fluid phase, the interfacial energetics and the energetically favored crystallographic orientations of olivine inclusions in diamond can be controlled simply by the settlement/attachment of low-energy facets of olivine crystals precipitating from the parental fluid upon the low-energy {111}dia or {110}dia surfaces of diamond. Such interfacial energetics control and the resultant low-energy boundary pairs are characteristically distinct from the common topotaxy or epitaxy between oxide/silicate mineral pairs, but are in a sense like the Van der Waals heteroepitaxy in artificial systems.

AB - The healed internal conjugated cleavages at the core of Aykhal octahedral diamond sample AH2 were decorated with {111}dia-facetted ultrapotassic fluid/melt inclusion pockets containing nanosized graphite, phlogopite and olivine (Fo92) inclusions. These olivines are either rounded in pockets with ample fluid, or facetted by the {111}dia mold in the pockets with a fluid film. Transmission electron microscopy revealed two distinct crystallographic characteristics of olivine inclusions: (1)pronounced crystallographic texture of olivines grouped in specific diamond domain, and (2)frequent parallelism or sub-parallelism of specific low-energy faces of the two phases, mainly (010)ol, {120}ol, (001)ol and {111}dia, {110}dia, {100}dia in the order of decreasing preference, forming prominent (010)ol/{111}dia, (010)ol/{110}dia, (001)ol/{110}dia, {120}ol/{111}dia, and {120}ol/{110}dialow-energy phase boundaries with thin liquid film of 1–2 nm in between. These findings not only testify to the extremely low adhesion energies of olivine-diamond boundary pairs, but also imply that, in the presence of a fluid phase, the interfacial energetics and the energetically favored crystallographic orientations of olivine inclusions in diamond can be controlled simply by the settlement/attachment of low-energy facets of olivine crystals precipitating from the parental fluid upon the low-energy {111}dia or {110}dia surfaces of diamond. Such interfacial energetics control and the resultant low-energy boundary pairs are characteristically distinct from the common topotaxy or epitaxy between oxide/silicate mineral pairs, but are in a sense like the Van der Waals heteroepitaxy in artificial systems.

KW - Aykhal diamond

KW - Crystallographic orientation relationship

KW - Crystallographic texture

KW - Low-energy phase boundary pairs

KW - Olivine inclusions

KW - TEM

KW - Ultrapotassic fluid inclusions

KW - SOLID INCLUSIONS

KW - SIBERIAN DIAMONDS

KW - DER-WAALS EPITAXY

KW - GARNET

KW - MANTLE

KW - MINERAL INCLUSIONS

KW - FILMS

KW - GROWTH

KW - MICROCRACKS

KW - INSIGHTS

UR - http://www.scopus.com/inward/record.url?scp=85055899764&partnerID=8YFLogxK

U2 - 10.1016/j.lithos.2018.10.026

DO - 10.1016/j.lithos.2018.10.026

M3 - Article

AN - SCOPUS:85055899764

VL - 322

SP - 392

EP - 404

JO - Lithos

JF - Lithos

SN - 0024-4937

ER -