Résumé
The In Teria district (N-Hoggar, SE Algeria) is located along a high heat flow (100-120 mW.m-2). In Teria area is composed of melilite pipe, which contains xenolith of spinel and garnet peridotite, pyroxenite, mega-crystals of amphibole. This study provides constraints on reaction/percolation processes recorded by the mantle and allow to tracking melt sources.Garnet and spinel peridotites record percolation of alkali silicated magmas allowing phlogopite and/or amphibole formation. The spinel peridotites record carbonatitic metasomatism producing melt pocket with clinopyroxene (cpx), olivine, feldspath. The garnet peridotite expresses a deep deformation corresponding to a slip (010) [001] system. The spinel peridotites display gliding along [001] maxima axe and epitaxy underline by amphibole and cpx crystallization. Trace element pattern of clinopyroxene in garnet peridotite and pyroxenite are quite similar. Primary cpx from spinel peridotite are depleted in LREE and secondary cpx from melt pocket are enriched in LREE. Nd, Pb and Sr isotope analyses of all lithologies highlight two distinct domains in the 207Pb/204Pb- 206Pb/204Pb. A first one carried by spinel peridotites and pyroxenites shows a clear himu affinity. The second domain contains the garnet peridotite (± spinel peridotites) and is close to the EM1 pole. Mantle sequence beneath In Teria and particularly below the small area study (<35 km²) represents a large window from 2.5-2.7 GPa (garnet peridotite) to 1.6-1.9 GPa (spinel peridotite). The mantle is heterogeneous and records several melting processes. The results indicate interaction between reservoirs via melting and metasomatism reactions and an isotopic stratification of the lithosphere. The IníTeria peridotites sample provide a complex sequence related to melilite volcanic rocks, which are commonly related to rifting context, associated with carbonate, or related to initialization of thermic anomaly in the lithosphere.