Abstract:Xiarihamu eclogites occur as lenses in the Proterozoic Jinshuikou Group at the western part of East Kunlun. The eclogites have SiO2 content varying from 474% to 5078% and Mg# values from 40 to 62, implying that protoliths of the eclogites were highly fractionated mafic rocks and suggesting that they belong to tholeiite series. This study divides the Xiarihamu eclogites into two groups in the light of Nb contents, Nbenriched eclogites (Nb>7×10-6) and normal eclogites (Nb<7×10-6). The Nbenriched eclogites are characterized by low SiO2, MgO, Al2O3 and high FeOt, TiO2. The chondritenormalized REE patterns of the Nbenriched eclogites display OIB patterns consistent with Paleozoic Nbenriched basalts (NEB) and Seki island arc basalts. In additional, the primitive mantlenormalized trace elements spider diagrams have weakly negative anomalies of Nb, Ta, Ti, consistent with Paleozoic Nbenriched basalts (NEB). The normal eclogites (Nb<7×10-6) are characterized by low FeOt, TiO2 and high SiO2, MgO, Al2O3. The REE patterns of normal eclogites display EMORB patterns; the spider diagrams show weakly negative anomalies of Nb, Ta, P and positive anomalies of U, Sr, consistent with continental back arc basin basalt (BABB) like Okinawa BABB. εNd(0) and εNd(t=571Ma) isotopic contents of the Nbenriched eclogites are 0~455 and -088~726 and those of the normal eclogites are 22~519, 317~622, both plotted into the field of HPUHP belts of Caledonian orogeny and SuluDabie orogeny. Trace element diagrams also show that the samples have been assimilated and contaminated. Therefore, the protoliths of the Xiarihamu eclogites could be interpreted to be derived from intracontinental BABB with the origin reconstructed by subductionrelated crust and assimilationcontamination during magmatism. According to the published age data, it can be concluded that highpressure metamorphic event in the North Kunlun terrane occurred in the Late OrdovicianSilurian and the Xiarihamu eclogite is probably the result of metamorphism owing to an arccontinent collision during closure of the backarc basin.