The Zannone Giant Pockmark (ZGP) is a shallow-water (< −150 m) giant depression located on the shelf off Zannone Island (Pontine Archipelago, central Tyrrhenian Sea, Italy), hosting active hydrothermal vents. The ZGP seabed displays different fluid-venting morphologies (pockmarks, lithified pavements, mounds, and cone-shaped structures) and widespread bacterial communities. In this study, we analyzed ROV (Remote Operated Vehicle) images to gain information on seabed geology and the textural, mineralogical, and geochemical composition of authigenic crusts and gravel-sized clasts sampled close to active emissions. ROV images show authigenic dome-shaped crusts composed of native sulfur associated with barite, gypsum, amorphous silica, and secondary hydrothermal minerals (illite–montmorillonite). The gravel-sized clasts are mostly rhyolites strongly affected by hydrothermal alteration (Alteration Index > 88; depletion of some mobile elements and enrichment of some base metals), causing feldspar-destruction, silicification, formation of hydrothermal phyllosilicates, and precipitation of disseminated pyrite. More intense alteration implying the complete obliteration of the primary mineralogy or fabric is represented by quartz-pyrite samples. ZGP seabed morphology and petro-geochemical features of deposits point to the possible occurrence of a sulfide system linked to the degassing of magma similar to that feeding the Pleistocene products of Ponza Island.

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Zannone巨型麻子（Zannone热液场，第勒尼安海）的蚀变和矿化产物

Zannone巨型麻点（ZGP）是位于Zannone岛（意大利第勒尼安海中部的庞廷群岛）外架子上的浅水（<-150 m）巨型洼地，拥有活跃的热液喷口。ZGP海床展现出不同的通气形态（麻点，石化路面，土墩和锥形结构）和广泛的细菌群落。在这项研究中，我们分析了遥控车辆（ROV）图像，以获取有关海床地质以及接近活动排放而取样的自生地壳和砾石大小碎屑的质地，矿物学和地球化学组成的信息。ROV图像显示了由天然硫组成的自生圆顶状地壳，其与重晶石，石膏，无定形硅石和二次热液矿物（伊利石—蒙脱石）有关。砾石大小的碎屑主要是受热液蚀变影响的流纹岩（蚀变指数> 88;一些活动元素的耗竭和某些贱金属的富集），造成长石破坏，硅化，水热页硅酸盐的形成以及散布的黄铁矿沉淀。石英黄铁矿样品代表着强烈的蚀变，意味着主要矿物学或织物被完全消灭。ZGP的海床形态和沉积物的岩石地球化学特征表明，可能存在与岩浆脱气有关的硫化物系统，类似于供应Ponza岛的更新世产物的系统。热液层状硅酸盐的形成，以及散布的黄铁矿的沉淀。石英黄铁矿样品代表更强烈的蚀变，意味着主要矿物学或织物被完全消灭。ZGP的海床形态和沉积物的岩石地球化学特征表明，可能存在与岩浆脱气有关的硫化物系统，类似于供应Ponza岛的更新世产物的系统。热液层状硅酸盐的形成，以及散布的黄铁矿的沉淀。石英黄铁矿样品代表着强烈的蚀变，意味着主要矿物学或织物被完全消灭。ZGP的海床形态和沉积物的岩石地球化学特征表明，可能存在与岩浆脱气有关的硫化物系统，类似于供应Ponza岛的更新世产物的系统。