Raman spectroscopic identification of continuity of a channel olivine in a peridotite specimen

Abstract

In the Horoman peridotite complex, the peridotite containing olivine-filled channels is known to exist. To examine the distribution pattern of the channel olivine, we performed non-destructive microanalyses of Raman spectra at 51 points of the olivine with 5 mm intervals along the channel. Compared with the Raman spectra of a reference euhedral olivine, for which the crystallographic orientation is known, there is no abrupt change in the crystallographic orientation in the 250 mm line analysis region of the channel. Moreover, Mg/Fe ratios of the channel olivine show gradual change over the entire measured area. If the channel olivine is an aggregate of olivine grains crystallized from magma infiltrating into the channel, then there should be olivine grains with both uneven crystallographic orientation and a homogeneous Mg/Fe ratio. Therefore, the olivine in the channel is regarded as a single crystal with slight growth zoning. The peridotite with the channel had been a part of mantle that was uplifted by the collision of plates. Therefore, the channel is a trace of magma migrating in the mantle. Magma migration in mantle drives the material-thermal circulation system connecting the Earth's interior and surface. Furthermore, the size of the mineral in mantle reflects its stress field. Therefore, the magma channel involving such a large olivine is a unique specimen that reveals the particular characteristics of magmatism occurring in the Earth's interior.

Unlocking ultimate precision of intensity and area ratio measurements in Raman spectroscopy: Insights from simulation, experimentation, and theory and implications for isotope ratio analysis

“…The black line was computed for various 13 I þ F:D: conditions using Equation (15). The cross symbols are the σ all noise αI =σ shot αI of the intensity and area ratios obtained while varying 13 I þ F:D:,e=s and n read to achieve 13 I þ F:D: = 80,951 e À .…”

“…Raman spectroscopy, a versatile technique for nondestructive analysis and high spatial resolution, is especially valuable for inclusion studies and high-temperature and high-pressure experiments. Because the intensity ratio (α I ) and area ratio (α A ) of Raman spectra are indicators of various physical properties, they are used in widely various fields to estimate, for example, volatile compositions of fluid inclusions, [1][2][3][4][5] viscosities of silicate melts, 6 composition and structural properties of silicate glasses, [7][8][9] H 2 O and OH contents in silicate glasses or minerals, [10][11][12][13] crystallographic orientations, [14][15][16][17] and chemical compositions of minerals. 18,19 Obtaining the most accurate estimates of α I and α A is a crucially important goal for all these applications, for which the highest probable precision is desirable.…”

“…only take values between 0.8 and 1.0. Actually, Equation(15) shows that σ all noiseα I =σ shot α I is primarily dependent on I e À =times w when σ D and σ R are held constant. It is noteworthy that the maximum value of I e À =times w is limited by the bit depth of an A/D converter.…”