Hydrothermal activities along the East Pacific Rise between 1.9°N and 6.3°S
Abstract
Studies of hydrothermal distributions, the morphology of mid-ocean ridge segments and their relationships with the underlying distribution of magmatic heat flux have predicted that the incidence of "black smoker" hydrothermal plumes detected from optical back-scatter (NTU) in the oceans is typically sparser on slow and ultraslow spreading ridges, while there is an increased incidence of such plume activity along intermediate- and fast-spreading ridge segments. However, recent studies have questioned whether there may also be an important but previously overlooked supply of hydrothermal material to the oceans which is not readily detectable from optical backscatter alone.
Here we describe a new investigation to test this hypothesis using NTU and oxidation-reduction potential (ORP) data collected from a series of cruises along the fast spreading (120-135 mm/yr) East Pacific Ridge (EPR) between 1.9°N and 6.3°S. Our analysis has identified at least 38 confirmed hydrothermal sites along this 887 km section of the EPR. Of these, 17 are inferred to be high-temperature (high-T) sites, 11 are low-temperature (low-T) sites, and 10 more are confirmed but cannot be differentiated between high-T and low-T venting. 5 further sites exhibit NTU anomalies only. Using NTU data only, between 1.9°N and 6.3°S, the hydrothermal field spatial frequency (Fs) that we calculate in this study agrees very closely with that predicted from the InterRidge database. However, if we only focus on the 1.9°N-3.8°S section of the EPR, where ORP as well as NTU data were collected, our calculated field spatial frequency (Fs) increases by a factor of 3-5 compared to what would be predicted from NTU anomalies alone. The majority of this increase can be attributed to low-T flow, suggesting that low-T on-axis hydrothermal activity accounts an important role in seafloor hydrothermal circulation, with implications for both marine mining and ocean biogeochemistry.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V33E0216C
- Keywords:
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- 0450 Hydrothermal systems;
- BIOGEOSCIENCES;
- 3616 Hydrothermal systems;
- MINERALOGY AND PETROLOGY;
- 8135 Hydrothermal systems;
- TECTONOPHYSICS;
- 8424 Hydrothermal systems;
- VOLCANOLOGY