Hydrothermal sulfide accumulation along the Endeavour Segment, Juan de Fuca Ridge
Hydrothermal sulfide accumulation along the Endeavour Segment, Juan de Fuca Ridge
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DOI：
10.1016/j.epsl.2014.03.035
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发表时间：
2014-06-01
影响因子：
5.3
通讯作者：
Hannington, M. D.
中科院分区：
文献类型：
--
作者：
Jamieson, J. W.;Clague, D. A.;Hannington, M. D.
在海底形成的热液硫化物矿床的位置往往是通过探测水柱中的热液羽流来确定的，然后是用深拖摄像机、侧扫声纳成像进行勘探，最后是用遥控潜水器或有人潜水器进行目视勘测。然而，热液羽流探测对于寻找热液不活跃的硫化物矿床是无效的，即使在热液活跃的环境中，硫化物矿床也可能占海底硫化物累积总量的很大一部分。在这里，我们目前的结果，从最近的高分辨率，自主水下航行器为基础的热液活动的努力段的胡安·德富卡海岭，在东北太平洋的映射。通过对海脊水深测量的分析，确定了沿着24公里海脊的581个硫化物矿床的位置。热液矿床根据其表面形态特征，如形状和倾角，与火山和构造地貌相区别。对每个存款的体积计算得出，热液硫化物-硫酸盐-二氧化硅材料的总体积为372 500立方米，相当于海脊轴谷内海底120万吨热液材料的质量，假设密度为3.1克/厘米3。这一总量的大部分来自主要活跃喷口区以外以前没有记录的非活跃矿床。根据硫化物沉积的最小年龄，矿床的最大积累速度约为400吨/年，沉积效率（海底积累的热液物质与热液动员和输送到海底的总量的比例）约为5%。计算出的硫化物吨数比以前对奋进段硫化物的估计增加了四倍，以前的估计主要是基于活跃油田内的积累。这些结果表明，最近的全球海底硫化物资源估计主要是根据热液活动矿床的大小和分布，可能同样低估了沿着全球海底新火山区的硫化物数量。(C)2014爱思唯尔有限公司版权所有。
Hydrothermal sulfide deposits that form on the seafloor are often located by the detection of hydrothermal plumes in the water column, followed by exploration with deep-towed cameras, side-scan sonar imaging, and finally by visual surveys using remotely-operated vehicle or occupied submersible. Hydrothermal plume detection, however, is ineffective for finding hydrothermally-inactive sulfide deposits, which may represent a significant amount of the total sulfide accumulation on the seafloor, even in hydrothermally active settings. Here, we present results from recent high-resolution, autonomous underwater vehicle-based mapping of the hydrothermally-active Endeavour Segment of the Juan de Fuca Ridge, in the Northeast Pacific Ocean. Analysis of the ridge bathymetry resulted in the location of 581 individual sulfide deposits along 24 km of ridge length. Hydrothermal deposits were distinguished from volcanic and tectonic features based on the characteristics of their surface morphology, such as shape and slope angles. Volume calculations for each deposit results in a total volume of 372,500 m(3) of hydrothermal sulfide-sulfate-silica material, for an equivalent mass of similar to 1.2 Mt of hydrothermal material on the seafloor within the ridge's axial valley, assuming a density of 3.1 g/cm(3.). Much of this total volume is from previously undocumented inactive deposits outside the main active vent fields. Based on minimum ages of sulfide deposition, the deposits accumulated at a maximum rate of similar to 400 t/yr, with a depositional efficiency (proportion of hydrothermal material that accumulates on the seafloor to the total amount hydrothermally mobilized and transported to the seafloor) of similar to 5%. The calculated sulfide tonnage represents a four-fold increase over previous sulfide estimates for the Endeavour Segment that were based largely on accumulations from within the active fields. These results suggest that recent global seafloor sulfide resource estimates, which were based mostly on the sizes and distribution of hydrothermally-active deposits, may be similarly underestimating the amount of sulfide along the global submarine neovolcanic zones. (C) 2014 Elsevier B.V. All rights reserved.