Investigations of Hydrothermal Activity on the Gorda Ridge using ALVIN

作为对加利福尼亚州海湾(瓜伊马斯盆地)开始的覆盖沉积物的脊轴上热液活动调查的继续，为前往东北太平洋戈尔达岭的潜水探险提供了支持。这个缓慢扩张的海脊的南端(埃斯卡纳巴海槽；半速率(12毫米/年))埋藏在数百米厚的浊流沉积物之下，这些沉积物来自太平洋西北部的山区海岸。沉积物成分是变质和花岗岩成因的未成熟砂，与瓜伊马斯遇到的安山岩和生物成因碎屑的混合物形成鲜明对比。因此，热液系统是一个极端的端元，只有三种成分：海水、拉斑玄武岩、浊积岩，因此，沉积物对热液流体化学的贡献将很容易辨别出来。这一点尤其正确，因为山脊北部缺乏沉积物，也可以进行研究。通过对这两个系统的比较研究，将有可能确定与纯碎屑沉积物的反应在定位矿藏和控制其化学方面的有效性。

As a continuation of the investigations of hydrothermal activity on sediment covered ridge axes begun in the Gulf of California (Guaymas Basin), support is provided for a diving expedition to the Gorda Ridge in the Northeast Pacific. The southern end of this slow spreading ridge (Escanaba Trough; half- rate (12 mm/yr) is buried under several hundred meters of turbidite sediments derived from the mountainous coasts of the Pacific Northwest. The sediment composition, immature sands of metamorphic and granitic origin, contrasts sharply with the mixture of andesitic and biogenic debris encountered in Guaymas. The hydrothermal system is thus an extreme end-member with only three components: seawater, tholeiites, turbidites and as a result, the contribution of the sediment to the chemistry of the hydrothermal fluids will be easy to discern. This is especially true since the sediment- starved northern part of the Ridge is also available for study. In a comparative study of these two systems it will be possible to establish the effectiveness of reactions with purely detrital sediments in localizing ore deposits and in controlling their chemistry.//