Geochemical Constrains on MORB Composition and Magma Sources at East Pacific Rise Between 1°S and 2°S

作者：ZHANG; Wei; ZENG; Zhigang; CUI; Lukai;...eastpacificriseeprmidoceanridgebasalts

摘要：The East Pacific Rise(EPR)is a typical fast spreading ridge.To gain a better understanding of the magmatism under ridges,Mid Ocean Ridge Basalts(MORBs)with remarkably heterogeneous compositions are obtained from(EPR)1°–2°S and multielement geochemical and radioisotope analyses are conducted.Results show that these MORBs have wide variation ranges in trace element concentrations and isotopic ratios.Sample 07 has low concentrations of incompatible elements,and very low 87Sr/86Sr,and high 143Nd/144Nd from 0.70213 to 0.702289 and 0.513234 to 0.513289,respectively.However,other samples show enrichment in incompatible elements to varying degrees,and medium values of 87Sr/86Sr and 143Nd/144Nd from 0.702440 to 0.702680 and 0.513086 to 0.513200,respectively.This study proposes that one depleted source and two enriched sources contribute to the formation of MORBs from EPR 1°–2°S.Samples 02 and 10 are formed by mixing between one enriched source and one depleted source,while sample 07 is crystallized from the depleted source with no mixing process involved.However,the formation of samples 06 and 11 are different,and thus further research is required to determine genesis.

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