9526609 Salters The research will investigate which of the two processes that explains the high 176Hf/177Hf at Salt Lake Crater, Hawaii, is the most plausible. In addition to the Hf and Nd isotope analyses, the P.I. will analyze the mineral phases of the peridotites for their trace element content. The P.I. intends to either use existing data or otherwise obtain full major and trace element analyses on all the xenoliths. The specific peridotite samples that are proposed to be analyzed include: set of Hawaiian anhydrous spinel lherzolites, including LREE depleted xenoliths; continental peridotites from Kilbourne Hole, Potrillo Maar, San Carlos, and the Colorado Plateau; the P.I. will also try to initiate a study on the peridotites from the southern part of the Siberian Plateau, Vitim and Bartoy localities; in collaboration with E. Hauri and J. Natland the P.I> will analyze peridotites from the Austral Island and the Marquesas. In Addition the P.I. will analyze a limited number of MORB for either Pb or Hf to determine whether a correlation exist between Hf and Pb isotopes in MORB. Obtaining the above analyses should increase our knowledge of the space and time relationships between the different components within the mantle.