The NE Lau Basin: Widespread and Abundant Hydrothermal Venting in the Back-Arc Region Behind a Superfast Subduction Zone
The NE Lau Basin: Widespread and Abundant Hydrothermal Venting in the Back-Arc Region Behind a Superfast Subduction Zone
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DOI：
10.3389/fmars.2019.00382
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发表时间：
2019-07-09
影响因子：
3.7
通讯作者：
Rasing, Joseph A.
中科院分区：
文献类型：
--
作者：
Baker, Edward T.;Walker, Sharon L.;Rasing, Joseph A.
热液喷发的分布揭示了海底环境中存在岩浆的重要线索。西南太平洋东北-刘盆地是一个复杂的弧后区域，具有广泛的热液活动。它包括扩张山脊、弧形火山和板内火山，这些火山为研究热液活动和岩浆来源之间的相互作用提供了可能是独特的实验室。自2004年以来，已有多艘邮轮对东北刘盆地的水柱进行了勘探。在这里，我们使用这些数据，通过光学、温度和化学示踪剂在每个地点排放的羽流中识别和表征43个活跃的热液地点。20座突出的火山建筑中有17座分布在托夫亚弧形、扩张的山脊和板块内部，其中有17座是活跃的热液遗址。14个明显释放高温流体，包括板内火山W Mata多年的海底喷发。430公里的扩张山脊容纳了31个活跃地点，其中一个是2008年的喷发事件。我们的数据表明，东北刘盆地的场地空间密度(站点/100公里脊峰)与脊线扩展速率(8-42 mm/年)之间的关系遵循与之前建立的刘盆地中部较快扩展(40-90 mm/年)脊线相同的线性趋势。东北刘盆地的场地密度比刘南部低，这与最近的板块重建一致，这些板块重建将东北刘盆地类似50-100毫米/年的扩张速度估计降低了一半以上。来自整个刘弧后盆地扩张海脊的综合数据表明，根据现有的大洋中脊数据，按扩张速度归一化的热液地点类似于10倍于预期的热液地点。这一增长证明，与传统技术相比，使用浊度和化学传感器进行细致勘探的能力，可以更全面地描述扩张海脊的真实热液种群。它进一步揭示了刘弧后盆地同时受益于山脊和弧形岩浆来源，支持了异常高的山脊和板内热液地点。
The distribution of hydrothermal venting reveals important clues about the presence of magma in submarine settings. The NE Lau Basin in the southwest Pacific Ocean is a complex back-arc region of widespread hydrothermal activity. It includes spreading ridges, arc volcanoes, and intra-plate volcanoes that provide a perhaps unique laboratory for studying interactions between hydrothermal activity and magma sources. Since 2004, multiple cruises have explored the water column of the NE Lau Basin. Here, we use these data to identify and characterize 43 active hydrothermal sites by means of optical, temperature, and chemical tracers in plumes discharged by each site. Seventeen of 20 prominent volcanic edifices dispersed among the Tofua arc, spreading ridges, and plate interiors host active hydrothermal sites. Fourteen apparently discharge high-temperature fluids, including a multi-year submarine eruption at the intraplate volcano W Mata. The 430 km of spreading ridges host 31 active sites, one an eruption event in 2008. Our data show that the relationship between site spatial density (sites/100 km of ridge crest) and ridge spreading rate (8-42 mm/year) in the NE Lau Basin follows the same linear trend as previously established for the faster-spreading (40-90 mm/year) ridges in the central Lau Basin. The lower site density in the NE Lau Basin compared to the southern Lau is consistent with recent plate reconstructions that more than halved earlier estimates of similar to 50-100 mm/year spreading rates in the NE Lau Basin. Combined data from the spreading ridges throughout the entire Lau back-arc basin demonstrates that hydrothermal sites, normalized to spreading rate, are similar to 10x more common than expected based on existing mid-ocean ridge data. This increase documents the ability of meticulous exploration, using both turbidity and chemical sensors, to more fully describe the true hydrothermal population of a spreading ridge, compared to conventional techniques. It further reveals that the Lau back-arc basin, benefiting from both ridge and arc magma sources, supports an exceptionally high population of ridge and intra-plate hydrothermal sites.