VNIR AND TIR SPECTRA OF TERRESTRIAL KOMATIITES POSSIBLY ANALOGUES OF SOME HERMEAN TERRAIN COMPOSITIONS.

Up to date ultramafic and mafic rocks has been recognized in all the planetary surfaces of the Inner Solar System. The new MESSENGER data highlight regions proposed as possibly komatiitic lava flows in the hermean surface. The Gam-maRay and XRay spectrometers data (onboard MESSENGER mission) provide elemental abundances and show some regional variations (e.g. northern smooth plains vs. older surrounding terrain). On the other hand, VNIR spectroscopy from the MASCS data and Earth-based measurements [5] still high-lighting some surface variations, have not shown any Fe2+ characteristic absorbtion features. Comparison of Mg/Si, Ca/Si, Al/Si ratio (derived from GammaRay and XRay spectrometers) with ter-restrial rocks shows a quite good fit with the composi-tion of terrestrial komatiite and basalts. In particular, komatiite has been proposed because several sur-face’s features were interpreated to have formed em-placement in a flood-effusive style coupled with thermal erosion. This type of rocks are defined not only for the typical composition but even for the pres-ence of a particular texture, defined, by plate-like crys-tals of olivine (spinifex texture). Considering the ratios used by Weider et al. 2012 (JGR) and all the ko-matiite composition dataset from Geochemical Rock Database, we chose samples with ratios closer to the Mercury’s norther plains compositions. These samples were collected in the Carribean plateau at Gorgona’s island, which is widley known for its upper Creta-ceous ultramafic rocks sequence, (~90Ma in age) [see 7 and reference therein]. In this work we present spectra of komatiite and komatiitic basalt from Gorgona in both VNIR (reflec-tance) and TIR (emissivity) wavelength range. These are the spectral ranges that will be investigated by two different instrument (SIMBIO-SYS and MERTIS) on the joint ESA JAXA BepiColombo mission to Mercury.