A Seismic Tomography, Gravity, and Flexure Study of the Crust and Upper Mantle Structure Across the Hawaiian Ridge: 2. Ka'ena
A Seismic Tomography, Gravity, and Flexure Study of the Crust and Upper Mantle Structure Across the Hawaiian Ridge: 2. Ka'ena
复制标题
DOI：
10.1029/2023jb028118
复制
发表时间：
2024-02
期刊：
影响因子：
--
通讯作者：
R. Dunn;A. Watts;C. Xu;D. J. Shillington;AL Dunn
中科院分区：
文献类型：
--
作者：
R. Dunn;A. Watts;C. Xu;D. J. Shillington;AL Dunn
夏威夷海脊是中太平洋典型的板内火山链，由于其起源、喷发模式和对岩石圈变形的影响，长期以来一直吸引着研究者。被认为是由地幔柱内的压力释放熔融引起的，其质量引起的地球表面变形取决于载荷分布和岩石圈特性，包括弹性厚度（Te）。为了调查这些特征，2018年在夏威夷海岭开展了一项海洋地球物理活动。在奥廷加岛的向西，一幅经重力数据验证的地震层析成像图像显示，大量火山物质侵位在洋壳上，两侧是火山碎屑裙，填充着板块挠曲形成的护城河。海脊为先前存在的16公里厚的洋壳增加了17公里的物质。一个高速和高密度的核心位于火山建筑物内，被交替的熔岩流和大量浪费物质覆盖。在该构造带之下，上地幔的速度略高于周围地幔的速度，并且没有证据表明地壳存在广泛的岩浆底侵作用。沉积物-地壳和地壳-地幔边界由于火山负荷的弯曲而向下偏转了1.35公里。在Ka'ena Ridge，火山建筑物的高度和横截面积不超过夏威夷岛的一半。总之，这些研究证实，夏威夷西部的火山负荷在很大程度上是由弯曲补偿的。与皇帝海山链相比，夏威夷海岭的岩石圈硬度相对较强。
The Hawaiian Ridge, a classic intraplate volcanic chain in the Central Pacific Ocean, has long attracted researchers due to its origin, eruption patterns, and impact on lithospheric deformation. Thought to arise from pressure‐release melting within a mantle plume, its mass‐induced deformation of Earth's surface depends on load distribution and lithospheric properties, including elastic thickness (Te). To investigate these features, a marine geophysical campaign was carried out across the Hawaiian Ridge in 2018. Westward of the island of O'ahu, a seismic tomographic image, validated by gravity data, reveals a large mass of volcanic material emplaced on the oceanic crust, flanked by an apron of volcaniclastic material filling the moat created by plate flexure. The ridge adds ∼7 km of material to pre‐existing ∼6‐km‐thick oceanic crust. A high‐velocity and high‐density core resides within the volcanic edifice, draped by alternating lava flows and mass wasting material. Beneath the edifice, upper mantle velocities are slightly higher than that of the surrounding mantle, and there is no evidence of extensive magmatic underplating of the crust. There is ∼3.5 km of downward deflection of the sediment‐crust and crust‐mantle boundaries due to flexure in response to the volcanic load. At Ka'ena Ridge, the volcanic edifice's height and cross‐sectional area are no more than half as large as those determined at Hawai'i Island. Together, these studies confirm that volcanic loads to the west of Hawai'i are largely compensated by flexure. Comparisons to the Emperor Seamount Chain confirm the Hawaiian Ridge's relatively stronger lithospheric rigidity.