![]() Malgré l’importance des nutriments pour ces cycles, on connaı̂t peu de chose sur leur variabilité temporelle car les données disponibles sont souvent insuffisantes à l’échelle du bassin. A l’échelle climatologique, le bassin est dominé par un régime subtropical, à l’exception de certaines zones spécifiques, qui présentent une dynamique typique des régions tempérées. Equilibration temperatures calculated for the above rocks indicate that the studied samples represent typical mantle peridotites formed within the spinel stability field.La Méditerranée est caractérisée par des concentrations en nutriments parmi les plus faibles au monde, et qui montrent des valeurs décroissantes d’ouest en est. The Spontang peridotites have olivine, clinopyroxene and orthopyroxene compositions similar to those from both abyssal and fore-arc peridotites and display spoon shaped REE profiles characteristic of interaction between LREE-enriched melt, derived from the subducting slab and LREE-depleted mantle residues. ![]() Mineral and whole-rock chemistry of the Spontang peridotites is characterized by interaction between depleted magma and pre-existing oceanic lithosphere, typical of supra-subduction zone settings. ![]() Variations in Cr-spinel Cr# and Mg# observed in the investigated peridotites may have resulted from a wide range of degrees of mantle melting during their evolution. Cr# in the studied spinels are characterized by a small decrease in TiO 2 for a larger increase in Cr# consistent with observations for spinels aligned along the Luobusa trend of the Yarlung Zangpo Suture Zone (YZSZ) ophiolites. Chrome spinels are characterized by low TiO 2 and high Cr 2 O 3 indicative of their depleted nature. Spinel occurs as blebs and vermicular exsolutions within orthopyroxene to spherical inclusions within olivine, characteristic of which is the elongate holly leaf shape. Chromian spinel is brown to reddish, and its morphology and textural relationship with coexisting silicates varies with strain. The mantle suite of rocks is represented by minor lherzolites, harzburgites and dunites. The complex consists of a well-preserved ophiolite sequence dominated by peridotites, gabbros and ultramafic cumulates along with highly tectonized sheeted dykes and pillow lavas. ![]() The complex lying south of the ITSZ forms the highest tec-tonic thrust slice above the Mesozoic-Early Tertiary continental margin in the Ladakh-Zanskar Himalaya. ![]() The Spontang ophiolite complex exposed along the Indus Tsangpo Suture Zone (ITSZ) represents a fragment of oce-anic lithosphere emplaced after the closure of the Neo-Tethyan Ocean. ![]()
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