Insights Into the Source of Relative Depletion and Enrichment of HFSE in Arc Lavas From High-Nb Basalts From the Sulu Arc (southern Philippines)

火山弧熔岩的标志性地球化学特征之一是相对于其他微量元素，其高场强元素（HFSE，如Nb、Ta和Zr）的浓度减少。本研究的主要目的是测试在苏禄弧模型，已提出解释这种地球化学特征，如熔融或脱水的俯冲玄武岩地壳加上上覆沉积物和存在的洋岛玄武岩源组件在弧下的地幔楔。苏鲁弧系统提供了一个独特的机会，以限制弧熔岩中HFSE耗尽的起源，因为它包含具有可变Nb和其他HFSE浓度的玄武岩（即，从典型的贫Nb弧玄武岩到稀有的高Nb玄武岩）和俯冲到弧系之下的洋壳。调查将使用各种地球化学和同位素示踪剂（例如，REE、Nb/Ta、Ba/La、Pb/Ce、87 Sr/86 Sr、143 Nd/144 Nd、206 Pb/204 Pb、18 O/16 O），以识别多种微量元素，特别是HFSE在弧熔岩形成过程中的行为。研究结果也将有助于对全球弧系熔岩源物质的全面认识。

EAR-0001212CastilloOne of the hallmark geochemical features of volcanic arc lavas is the depletion of their concentrations of high field strength elements (HFSE such as Nb, Ta, and Zr) relative to those of other trace elements. The main objective of this study is to test in the Sulu Arc models that have been proposed to explain this geochemical feature such as melting or dehydration of the subducted basaltic crust plus overlying sediments and presence of ocean island basalt source component in the mantle wedge beneath the arc. The Sulu Arc system offers a unique opportunity to constrain the origin of HFSE depletion in arc lavas because it contains basalts with variable Nb and other HFSE concentrations (i.e., from typical Nb-depleted arc basalts to rare high-Nb basalts) and the oceanic crust subducting beneath the arc system has been sampled by the Ocean Drilling Program. The investigation will employ various geochemical and isotopic tracers (e.g., REE, Nb/Ta, Ba/La, Pb/Ce, 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, 18O/16O) in order to fingerprint the behavior of many trace elements, particularly the HFSE, during the generation of arc lavas. Results of the study will also be useful for a general understanding of the source materials of lavas in the global arc system.