An alternative explanation for the Hf-Nd mantle array

• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2017,（14）
• 页码范围: 974-975
• 页数: 2页
• 语种: 英文

摘要

The 176Hf/177Hf and 143Nd/144Nd of mid-ocean ridge basalts (MORB) and ocean island basalts (OIB) are significantly correlated and form the so-called Hf-Nd mantle array [1,2] (Fig.1a).Model calculations show that the association of OIB with the array is inconsistent with the distinctive Hf and Nd isotopic compositions of their purported ancient sediment sources in the mantle [1].A current consensus for the origin of the array is that the Lu/Hf and Sm/Nd of recycled sediments nullify each other due to thorough mixing or averaging of sediments during subduction [1,3].This model,however,is incompatible with the heterogeneous Sr-Nd-Pb and noble gas isotope as well as trace element composition of oceanic basalts that clearly requires distinct mantle sources.Thus,the origin of the Hf-Nd mantle array is still not fully understood.Here I show that in addition to the significant correlation between Hfand Nd isotopes,a systematic relationship also exists among the Hf-Nd-Sr-Pb isotopes of oceanic basalts.These systemic,coherent isotopic features of oceanic basalts require a unified explanation.