Hydrothermal vents and their impact on paleoenvironmental proxies

• Main Author: Veresh, Alison
• Other Authors: Riedinger, Natasch, Quan, Tracy, Burkett, Ashley
• Format: Thesis
• Language: English
• Published: 2022
• Subjects: Antarctic; Scotia Sea; The Antarctic; Antarc*
• Online Access: https://shareok.org/handle/11244/338815

Trace metals such as cobalt, copper, molybdenum, and uranium have been used as redox and productivity proxies to interpret paleoenvironments. However, the presence of a hydrothermal vent could potentially alter the interpretations if metal-rich fluids from these vents serve as another source for these specific trace metals into the sediment. To date, there are no published studies on the impact of hydrothermal vent deposits on paleoproxies. In this thesis the impact of hydrothermal vents on trace metal deposition in the surrounding sediments was investigated. Two cores were compared for their elemental composition applying a multi-acid total digestion and inductively coupled plasma mass spectrometry analysis. The comparison was carried out on samples collected during the RV Polarstern Expedition PS119 in the Scotia Sea, on a core collected on the east side of an ocean ridge containing a hydrothermal vent field and another core from the west side of the ridge. The direction of the Antarctic Circumpolar Current is from west to east in the Scotia Sea. Thus, only the site on the east side of the hydrothermal vent could potentially receive hydrothermal vent plume deposits. Concentrations of the proxies, specifically molybdenum, copper, and cobalt are higher in the core on the east side of the hydrothermal vent field than the core on the west side. While there are a few potential sources of the enrichment, the most likely cause is hydrothermal vent input. Other sources of metal enriched layers include volcanic ash deposits or diagenetic alteration. The findings of this study highlight that hydrothermal vent deposits need to be regarded in the interpretation of paleo-redox and productivity proxies in the ancient rocks deposited near active ocean ridges.