Accomplishment Based Renewal: Evolution of the Lau Basin-A Reappraisal

基于成就的更新：劳盆地的演变-重新评估

• 批准号: 0727138
• 负责人: Fernando Martinez
• 金额: $ 19.89万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0727138&HistoricalAwards=false
• 关键词: Accomplishment; Based; Renewal; Evolution; Lau

ABSTRACTOCE-0727138Intellectual Merit. This Accomplishment Based Renewal of the investigator's ongoing studies of Lau Basin will make use of gravity data, magnetic data and bathymetry to model the variations in thickness of the ocean crust for the Western Lau Spreading Center in the western Pacific. The project will also include efforts to identify lineations in seafloor magnetization, and to use these as well as the gravity and magnetics models to study the early evolution of Lau Basin. The Western Lau Spreading Center is older than Central and Eastern Lau Spreading Centers, and existing models suggest that it formed through tectonic rifting prior to the inception of active seafloor spreading. The central emphasis of this project is to question this origin for WLSC, pointing out that bathymetric data indicates that western basin morphologies are similar to those of the active Central and Eastern Lau Spreading Centers. At these newer centers, current understanding suggests that bathymetry and rock chemistry is determined strongly by proximity to the back-arc. CLSC is furthest from the back-arc, and is most mid-ocean ridge-like, whereas ELSC is nearest the arc and shows a gradient in rock types, ranging from basaltic to the north at points furthest from the back-arc, to andesitic to the south at points closest to the arc. Seafloor bathymetry also transitions along this transect, from deeper Mid Ocean Ridge-like (3000 m) to shallower (~1600m). There is also a preponderance of seismic magma lens reflectors as one moves closer to the arc and crustal thicknesses increase, whereas these are largely absent to the north. Given this backdrop, the question arises: Did the Western Lau basin morphology arise as the basin formed by changes in magmatic productivity of spreading centers as they migrated over a mantle wedge of variable composition? This is in contrast to the existing view of a purely tectonic rifting model for the formation of the Western Lau basin. The question may also be inverted to address the issue of how changes in crustal composition and other characteristics might provide information on the spatial patterns and the nature of the compositional variations in the mantle wedge. For instance, the release of volatiles and water into the mantle through subduction-related transport lowers mantle solidus temperatures, and should lead to production of a greater quantity of melt than expected for a dehydrated mantle. Broader impacts. Broader Impacts include research and training experiences for a graduate student, and fundamental insights into crustal formation processes of wider interest both to Ridge 2000 and Margins communities.

ABSTRACTOCE-0727138智力价值。研究者对劳盆地正在进行的研究的基于成果的更新将利用重力数据、磁力数据和测深数据来模拟西太平洋西劳扩散中心的洋壳厚度变化。该项目还将包括识别海底磁化线的工作，并利用这些线以及重力和磁力模型来研究劳盆地的早期演化。西刘扩张中心比中刘扩张中心和东刘扩张中心更古老，现有模型表明它是在活跃的海底扩张开始之前通过构造裂谷形成的。该项目的重点是质疑 WLSC 的起源，指出测深数据表明西部盆地形态与活跃的中部和东部刘扩散中心相似。在这些较新的中心，目前的理解表明，测深和岩石化学很大程度上取决于弧后的接近程度。 CLSC 距离弧后最远，并且最像洋中脊，而 ELSC 距离弧最近，并且显示出岩石类型的梯度，从玄武岩到北部距离弧后最远的点，再到安山岩在最靠近弧线的点向南。海底测深也沿着该横断面从较深的中洋海脊状 (3000 m) 过渡到较浅的 (~1600 m)。随着靠近弧线和地壳厚度增加，地震岩浆透镜反射体也占优势，而在北部则基本上不存在。在这种背景下，问题出现了：西劳盆地的形态是否是由于扩张中心的岩浆生产力在成分可变的地幔楔上迁移时发生变化而形成的盆地？这与现有关于西劳盆地形成的纯构造裂谷模型的观点形成鲜明对比。这个问题也可以反过来解决地壳成分和其他特征的变化如何提供有关地幔楔的成分变化的空间模式和性质的信息。例如，通过俯冲相关的运输将挥发物和水释放到地幔中，降低了地幔固相线温度，并且应该导致产生比脱水地幔预期数量更多的熔体。更广泛的影响。更广泛的影响包括研究生的研究和培训经验，以及对 Ridge 2000 和 Margins 社区更广泛感兴趣的地壳形成过程的基本见解。