Hells Bells - microbially generated underwater speleothems from Yucatán, Mexico

点击翻译按钮获取中文摘要

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.