Tidal Fluctuation of Diffuse Vent Fluid Flow
When you think hydrothermal vents, what typically comes to mind are towering seafloor structures billowing black, mineral-rich fluid at high temperatures of 300oC. In addition to these high-temperature vents, however, there are diffuse vents from which lower temperature (<100oC) sub-seafloor fluids seep into the surrounding waters. For example, sensors deployed at the ASHES Vent Field site on the OOI Cabled Axial Seamount Array collect data surrounding the 4 meter tall actively venting sulfide chimney called “Mushroom” as well as a diffuse vent site adjacent to its base.
One of the interesting dynamics of diffuse vent sites is the correspondence between vent fluid flow and the semi-diurnal tidal cycle. To examine vent fluid flow, water temperature close to the seafloor over the vent area is examined; seawater temperatures increase as warm, sub-seafloor water emerges from the vent. Tidal cycle is examined by looking at fluctuations in the bottom pressure and tilt sensor. Looking at these two datasets, the pattern emerges that during times of high pressure on the seafloor (high tide) temperature in the seawater around the vent increases, it appears that the increased pressure on the seafloor from high tide is “squeezing” more hot fluid from the diffuse vent.
Vent fluid flow at Cabled ASHES Vent Field fluctuates with the tidal signal captured by the Bottom Pressure and Tilt instrument. Flow rates can be inferred from changes in water temperature close to the vent, as measured by thermistor 01 at the bottom center of the 3-D temperature array (according to the Data Product Specification sheet).
Access the Data
Disclaimer: data used in this example and provided in the .csv file were downloaded from the OOI on November 7, 2019. The file format and/or contents could have changed if downloaded directly from OOI Net after this date.
Access from OOI Net:
Pull Data Using Python Code. Code demonstrates how to to download Vent Fluid Temperature and Bottom Pressure and Tilt data from the OOI system using the Machine-to-Machine (M2M) interface, downsample the dataset, and export as a .csv file.
Data Review Pages:
Diffuse Vent Fluid 3-D Temperature Array
Bottom Pressure and Tilt Sensor
Cabled Axial Seamount ASHES Vent Field (RS03ASHS)
Location: Ashes vent field on the Axial Seamount caldera on the Juan de Fuca plate in the NE Pacific
Lat/Lon: 45.9337°N, 130.0139°W
Water Column Depth: 1,552m
Platform: Medium-Power Junction Box (MJ03B)
Instruments: Both instruments are connected to the Medium Power Junction Box through extension cables
Diffuse Vent Fluid 3-D Temperature Array (TMPSF-A)
Bottom Pressure and Tilt Sensor (BOTPT-A)
Graphics Credit: OOI Cabled Array program & the Center for Environmental Visualization, University of Washington
Essentials of Oceanography Textbook Sections
3.4 What features exist along the mid-ocean ridge?
15.4 What communities exist on the deep-ocean floor?
For more details, check out the full “Textbook Crosswalk”
Next Gen Science Standard Connections
HS-PS3-4. Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (second law of thermodynamics). As hot vent fluid enters the ocean it mixes with the cooler seawater and increases the surrounding water temperature.
NOAA NeMO Explorer – “Diffuse Vents”
National Geographic Resource Library – “Ocean Vent”
Woods Hole Oceanographic Institution Dive and Discover Expeditions to the Seafloor – “Vent Basics”
NOAA National Ocean Service – “What is a hydrothermal vent?”
OOI Science Theme
Fluid-Rock Interactions and the Sub-seafloor Biosphere
Mitteldstaedt, E., et al. 2016. Diffuse venting at the ASHES hydrothermal field: Heat flux and tidally modulated flow variability derived from in situ time‐series measurements. Geochemistry, Geophysics, Geosystems 17(4):1435-1453. https://doi.org/10.1002/2015GC006144.
Bemis, K., et al. 2015. Diffuse Flow On and Around Hydrothermal Vents at Mid-Ocean Ridges. Oceanography 25:182-191. https://doi.org/10.5670/oceanog.2012.16.
Barreyre, T., et al. 2014. Temporal variability and tidal modulation of hydrothermal exit‐fluid temperatures at the Lucky Strike deep‐sea vent field, Mid‐Atlantic Ridge. Journal of Geophysical Research: Solid Earth 119:2543-2566. https://doi.org/10.1002/2013JB010478.
Tivey, M.K., et al. 2002. Insights into tide-related variability at seafloor hydrothermal vents from time-series temperature measurements. Earth and Planetary Science Letters 202:693-707. https://doi.org/10.1016/S0012-821X(02)00801-4.