Hells Bells - microbially generated underwater speleothems from Yucatán, Mexico

在我们对保存在尤卡坦水下洞穴系统的考古和生态地质档案的持续研究中，我们最近在墨西哥Yucatán半岛莫雷洛斯州港以西的水下El Zapote和其他天坑（天然井）中发现了一种未知类型的米大小的垂坠洞穴。这些圆锥形，地幔状向下扩展和分叉的钙质结构，这里被称为地狱钟，其特征是钟形或喇叭形的纵向和圆形，椭圆形或马蹄形的水平横截面。根据我们的初步分析，“地狱之铃”生长在29-35米深的盐跃层或以上无光、缺氧、富含h2s的水下环境中。我们假设这些结构的生长是由微生物方解石沉淀引起的，这种沉淀优先发生在锥体的底表面，正如结构的向心尖径向向下发散和水平层压的内部纹理所暗示的那样。我们在此建议对这些结构进行更详细的研究，以提供关于它们的形成、年龄和区域分布的答案。我们还将开始研究可能形成这些独特洞穴的微生物群落。

During our on-going research on the archaeological and ecological geoarchives preserved in the submerged Yucatan cave system, we recently discovered a yet unknown type of meter-sized pendant speleothem from the submerged El Zapote and other sinkholes (cenotes) west of Puerto Morelos on the Mexican Yucatán Peninsula. These conical, mantle-shaped downward expanding and diverging calcareous structures, here termed Hells Bells, are characterized by bell- or trumpet shaped longitudinal and circular, elliptical or horse-shoe-like horizontal cross-sections. According to our initial analysis, Hells Bells grow in a lightless oxygen-depleted and H2S-rich subaqueous environment at or above the halocline at water depths of 29-35 meters. We hypothesize that the growth of these structures is caused by microbial calcite precipitation, which preferentially takes place on the bottom surface of the cones, as is implied by excentric apicoradial downward divergence of the structures and by the horizontally laminated internal texture. We here propose to investigate these structures in greater detail to provide answers on their formation, age, and regional distribution. We will also initiate research on the microbial communities that may have formed these unique speleothems.