Analysis of bubble plume distributions to evaluate methane hydrate decomposition on the continental slope
Analysis of bubble plume distributions to evaluate methane hydrate decomposition on the continental slope
复制标题
DOI：
10.1002/2015gc005955
复制
发表时间：
2015-11-01
影响因子：
3.5
通讯作者：
Solomon, Evan A.
中科院分区：
文献类型：
--
作者：
Johnson, H. Paul;Miller, Una K.;Solomon, Evan A.
卡斯卡迪亚边缘沉积物含有来自陆地输入和海面生产力的丰富的碳库。这种碳的一部分以固体气体水合物的形式存在于沉积物孔隙空间中，先前的研究表明，在卡斯卡迪亚边缘的温哥华岛和俄勒冈州部分，这些孔隙空间是相当大的甲烷储层。Cascadia边缘的多道地震反射剖面显示沉积柱内广泛存在底部模拟反射体（BSRs），表明天然气水合物储层从3000 m深度的变形前缘延伸到500 m水深附近的天然气水合物稳定性上限。在这项研究中，我们编制了一份清单的甲烷气泡羽流网站卡斯卡迪亚保证金进行了一系列跨学科的目标，也包括商业渔民自愿的网站调查确定。高烟羽密度异常与东北太平洋的大陆架（< 180 m）和甲烷水合物稳定深度上限（MHSD）的深度（500 m附近）有关。在卡斯卡迪亚斜坡上观察到的异常可能是由于中间深度的海水变暖，这表明现代气候变化已经开始破坏卡斯卡迪亚边缘沉积物内气候敏感的水合物储层的稳定性。对北美大西洋斜坡上类似羽流图像的再分析表明，在大部分纬度范围内，观测到的羽流深度与MHSD之间缺乏相关性。
Cascadia margin sediments contain a rich reservoir of carbon derived both from terrestrial input and sea surface productivity. A portion of this carbon exists as solid gas hydrate within sediment pore spaces which previous studies have shown to be a methane reservoir of substantial size on both the Vancouver Island and Oregon portions of the Cascadia margin. Multichannel seismic reflection profiles on the Cascadia margin show the widespread presence of Bottom Simulating Reflectors (BSRs) within the sediment column, indicating the gas hydrate reservoir extends from the deformation front at 3000 m depth to the upper limit of gas hydrate stability near 500 m water depth. In this study, we compile an inventory of methane bubble plume sites on the Cascadia margin identified in investigations carried out for a range of interdisciplinary goals that also include sites volunteered by commercial fishermen. High plume density anomalies are associated with both the continental shelf (< 180 m) and the depth of the upper limit of methane hydrate stability depth (MHSD) that occurs near 500 m in the NE Pacific. The observed anomalies on the Cascadia slope may be due to the warming of seawater at intermediate depths, suggesting that modern climate change has begun to destabilize the climate-sensitive hydrate reservoir within the Cascadia margin sediments. Reanalysis of similar plume images on the North American Atlantic slope suggests a lack of correlation between observed plume depths and the MHSD for much of the latitudinal range.