Geochemistry of Axial Lavas from Intra-Transform Spreading Centers of the Valdivia F.Z. System, Chile Ridge

这一联合计划将对智利北部山脊和瓦尔迪亚断裂带的变形内扩张中心进行详细的地球物理和地球化学研究。一项为期40天的野外计划将使用SeaBeam 2000、磁学和重力绘制出布鲁内斯-松山磁性反转边界的轴线区域的详细地貌。新火山带将通过疏浚和蜡取芯在约125个地点取样，回收的熔岩将通过电子探针、电感耦合等离子体质谱(ICPMS)、差示扫描量热法(DCP)和质谱仪进行常量元素、微量元素和铅-钕-锶同位素特征的分析。智利北部山脊的综合数据集将被用来研究轴向深度、地壳结构和熔岩成分与大偏移距转换断层相关的热效应的关系。Valdia F.Z.数据集将用于进一步调查以前对智利南部海脊进行的研究中发现的东南太平洋异常地球化学特征的范围和变异性(即DUPAL同位素特征和具有俯冲带微量元素特征的MORB)，并将正在进行的太平洋中洋脊玄武岩化学和轴向深度之间的关系研究扩展到更深的海脊段。

This combined program will conduct a detailed geophysical and geochemical study of the Northern Chile Ridge and Valdivia Fracture Zone intra-transform spreading centers. A 40-day field program will use SeaBeam 2000, magnetics, and gravity to map the detailed geomorphology of the axial region out to the Brunhes-Matuyama magnetic reversal boundary. The neo-volcanic zone will be sampled at ~125 sites by dredging and wax coring; lavas recovered will be analyzed by electron microprobe, ICP-MS, DCP, and mass spectrometry for major element, trace element, and Pb-Nd-Sr isotopic characteristics. The combined data set for the Northern Chile Ridge will be used to investigate the relationship of axial depth, crustal structure and lava composition with thermal effects associated with large- offset transform faults. The Valdivia F.Z. data set will be used to further investigate the extent and variability of anomalous geochemical features of the Southeast Pacific discovered in previous studies of the Southern Chile Ridge (i.e., DUPAL isotopic signatures and MORB with subduction zone trace element characteristics) and to extend on-going studies of relationships between Pacific mid-ocean ridge basalt chemistry and axial depth to deeper ridge segments.