Extensive carbonate crusts discovered forming on the slopes of seamounts in many parts of the world's oceans are providing extra stability to the volcanic edifices. These crusts are hardgrounds composed of mixtures of volcaniclastic debris and bioclastic material, in most cases cemented by calcite, in the form of isopachous coatings around grains and pore-filling spar. Such crusts, which have been collected by a remotely-operated vehicle (ROV), are described here from moderate-depth to deeper-water slopes (180–820 m) around the volcanic island of Montserrat in the Caribbean, and from the nearby Kick'em Jenny submarine volcano off Grenada. Radiogenic ⁸⁷Sr^/86Sr isotope ratios from the carbonates give an indication of age (up to 0.4 Ma years old) but they also demonstrate that some samples have been altered by hydrothermal-volcanic processes, to give ages much older than expected (14 to 18 Ma) based on the foraminifera present. Such alteration is also supported by carbon and oxygen isotope (δ¹³C and δ¹⁸O) ratios, although most samples retain typical marine values. In many cases δ¹⁸O is usually a little more positive than expected from modern Caribbean shallow-water carbonates, likely reflecting cooler water at their moderate depths of lithification. Just one sample, from Kick'em Jenny, has very negative δ¹³C (−42‰) indicating methanogenesis. Crusts are also reported here from the Mediterranean Sea, with an example described from Kolumbo submarine volcano, northeast of the Santorini volcanic complex in the Hellenic subduction zone, that are similar in many respects to those from the Caribbean. Typically, the biota of the crusts consists of calcareous red algae (commonly encrusting volcanic clasts), foraminifera (benthic, some also encrusting, and planktic), subordinate serpulids, bivalves, pteropods and heteropods, and rare deeper-water corals. Some bioclasts are derived from shallower water, others from the moderate depths of the slope itself, and planktic fallout. In addition, there is evidence for the former presence of microbes from the occurrence of calcified filaments and peloids in intragranular cavities. Several generations of sponge borings are usually present as well as calcite cement. Dissolution and calcite replacement of aragonitic bioclasts and cement, and sponge spicules (originally opaline silica), have taken place. The carbonate crusts are attributed to seawater circulating within the surficial sediment, in some cases mixing with hydrothermal fluid driven by geothermal and volcanic processes. Submarine volcanic slopes clearly provide a location for moderate-depth carbonate production and cementation, but a further significance of these hardgrounds is in stabilising seamounts, enabling their slopes to avoid frequent collapse, dissection and readjustment. However, when failure does occur, larger-scale submarine landslides involving coherent slabs are more likely.

在世界许多海域的海山坡上发现的大量碳酸盐结壳为火山大厦提供了额外的稳定性。这些地壳是硬火山岩，由火山碎屑和生物碎屑材料的混合物组成，在大多数情况下由方解石胶结而成，其形式为颗粒周围的等渗涂层和填充孔的晶石。这些地壳是由遥控车（ROV）收集的，在这里描述了加勒比海蒙特塞拉特火山岛周围以及附近基克从中深度到深水坡度（180-820 m）的情况。格林纳达附近的詹姆（Jenny）海底火山。放射源⁸⁷ Sr ^{/ 86}碳酸盐中的Sr同位素比表明年龄（最高0.4 Ma岁），但它们也表明某些样品已被热液-火山作用改变，其年龄比预期的要长得多（14至18 Ma）。有孔虫存在。这种改变也由碳和氧同位素的支持（δ ¹³ C和δ ¹⁸ O）比率，虽然大多数样品保留典型的海洋值。在许多情况下δ ¹⁸ Ø通常是一个小更积极的比现代加勒比海浅水碳酸盐预期，这可能反映了凉的水岩化作用在他们的中等深度。只是一个样本，从Kick'em珍妮，具有非常消极δ ¹³C（-42‰）表示甲烷生成。在地中海，这里也报道了地壳，例如，在希腊俯冲带圣托里尼火山群东北部的科伦博海底火山中描述了一个例子，在许多方面都与加勒比海相似。通常，地壳的生物区系由钙质红藻（通常包裹火山岩屑），有孔虫（底栖动物，有些还包裹着和浮游藻类），下属的蛇纹石，双壳类，翼足类和异足类以及稀有的深水珊瑚组成。一些生物碎屑来自浅水，另一些生物碎屑来自斜坡本身的中等深度，以及板状沉降物。另外，有证据表明以前在颗粒内的空腔中存在钙化的细丝和类胶体，从而产生了微生物。通常存在几代海绵钻孔以及方解石水泥。碎石剂和水泥的溶解和方解石置换以及海绵针（最初是不透明的二氧化硅）已经发生。碳酸盐结壳归因于表层沉积物中的海水循环，在某些情况下，它们与地热和火山作用驱动的热液混合。海底火山岩斜坡显然为中等深度的碳酸盐生产和胶结提供了场所，但是这些硬质岩层的另一个重要意义是稳定海山，使它们的斜坡避免频繁塌陷，分离和重新调整。但是，当确实发生故障时，涉及连贯平板的大型海底滑坡更有可能发生。碎石剂和水泥的溶解和方解石置换以及海绵针（最初是不透明的二氧化硅）已经发生。碳酸盐结皮归因于表层沉积物中的海水循环，在某些情况下与地热和火山作用驱动的热液混合。海底火山岩斜坡显然为中等深度的碳酸盐生产和胶结提供了场所，但是这些硬质岩层的另一个重要意义是稳定海山，使它们的斜坡避免频繁倒塌，解剖和重新调整。但是，当确实发生故障时，涉及连贯平板的更大范围的海底滑坡更有可能发生。溶解和方解石替代了碎石碎屑和水泥，以及海绵状的针头（最初是不透明的二氧化硅）。碳酸盐结壳归因于表层沉积物中的海水循环，在某些情况下，它们与地热和火山作用驱动的热液混合。海底火山岩斜坡显然为中等深度的碳酸盐生产和胶结提供了场所，但是这些硬质岩层的另一个重要意义是稳定海山，使它们的斜坡避免频繁倒塌，解剖和重新调整。但是，当确实发生故障时，涉及连贯平板的更大范围的海底滑坡更有可能发生。碳酸盐结壳归因于表层沉积物中的海水循环，在某些情况下，它们与地热和火山作用驱动的热液混合。海底火山岩斜坡显然为中等深度的碳酸盐生产和胶结提供了场所，但是这些硬质岩层的另一个重要意义是稳定海山，使它们的斜坡避免频繁塌陷，分离和重新调整。但是，当确实发生故障时，涉及连贯平板的更大范围的海底滑坡更有可能发生。碳酸盐结皮归因于表层沉积物中的海水循环，在某些情况下与地热和火山作用驱动的热液混合。海底火山岩斜坡显然为中等深度的碳酸盐生产和胶结提供了场所，但是这些硬质岩层的另一个重要意义是稳定海山，使它们的斜坡避免频繁塌陷，分离和重新调整。但是，当确实发生故障时，涉及连贯平板的更大范围的海底滑坡更有可能发生。但是这些硬地的另一个重要意义是稳定海山，使它们的斜坡避免频繁倒塌，解剖和重新调整。但是，当确实发生故障时，涉及连贯平板的更大范围的海底滑坡更有可能发生。但是这些硬地的另一个重要意义是稳定海山，使它们的斜坡避免频繁倒塌，解剖和重新调整。但是，当确实发生故障时，涉及连贯平板的大型海底滑坡更有可能发生。