Simulation of Early Earth Hydrothermal Chimneys in a Thermal Gradient Environment

3D printing the cooling condenser allows for previously developed experimental methods to be easily modified for temperature control. The digital designs can then be easily shared, modified, and printed by any researcher with access to a 3D printer. This method could be used for simulating hydrothermal processes on earth, but could also be used for simulating hydrothermal events on Jupiter's moon Europa or Saturn's moon Enceladus.

The method we developed combines a variety of components in a unique way. Visual demonstration will allow students and researchers interested in reproducing or adapting these methods to see how to assemble and operate the experimental apparatus. Begin by placing the thermistor in a stable position on a side bench as close to the fume hood as possible.

Insert the USB side of a RS-232 adapter cable into the computer USB port and plug the cord into a power socket. Turn on the power for the thermistor and the thermistor software on the computer. Check the ribbon cables and make sure they are properly connected to the pins on the RS-232 cable pinouts.

Once connected, make sure output reads 100%in red bars. When the thermistor is flashing frequent interval measurements change the interval time to 60 seconds. In the controller options box towards the bottom, delete one second and change to 60 seconds.

Then click on the OK button. Click on the oval button next to the company logo labeled auto-scale. Note the yellow line that shows the temperature readout.

Inside the plot area, right click to adjust the plot to your liking, such as the scaling and the X and Y axes. Right click on the plot area and click on export to Excel before a new reading starts. Save the temperature and time data in the spreadsheet that has been automatically created by the program.

Place the metal thermistor probe into the glass ocean vessel within the condenser. Make sure the probe is set to the side of the glass then cover the glass with parafilm. Fill a mid-size bucket with water up to halfway, place the bucket inside a plastic pan and add ice to the water until nearly full.

Place the two plastic cutoff hoses onto either end of the water pump. Note that the vertical pump opening is where water will be poured in to begin priming, and the horizontal opening is where water is ejected. Plug the pump into a power socket, but leave the electrical connectors open.

Connect the horizontal plastic hose to the higher condenser port facing the right and make sure that the hose is long enough to reach the ice bucket. Connect another cutoff plastic hose to the left condenser port. Position this hose over the bucket of ice water into which the water will be ejected from the condenser.

Pour cold water through the hose connected to the vertical opening of the pump. When the pump is full of water, reaching all the way to condenser port, immerse the hose into the ice water bath, and immediately connect the electrical connectors. Prime the pump to start flowing water through the condenser, fill the bucket with ice, and place a thermometer in the bucket to check the temperature.

Continue adding more ice to maintain the water at a cold temperature and scooping out some of the warmer water. Wrap a pad around the sulfide syringe and firmly screw on two metal clamps around the pad. Pour one or two ocean solutions into the prefabricated chimney vessels.

Pour one ocean solution into the glass vial with a condenser and the other into the room temperature vessel with no condenser, making sure not to move the temperature probe. Start the injection and begin recording the ocean temperature on the thermistor. Once the water is circulating through the condenser, the thermistor temperature probe will begin to display the fall in temperature within the ocean.

Once the hydrothermal fluid simulant reached the ocean vial, a mineral precipitate structure began to form that grew thicker and taller for the duration of the injection. More concentrated solutions of sulfide allowed for taller and sturdier mineral precipitates. In some cases, no structure was formed only a liquid sulfide mineral soup that would eventually settle out as a sediment.

In thermal gradient chimney experiments with iron sulfide solid chimney structures generally did not coalesce as well as they did at room temperature. The chimneys in the temperature gradient were string like and tenuous in nature. Whereas the non-thermal gradient results had more semi-permanent structures.

The same was true when the hydrothermal fluid was heated. A solid iron sulfide chimney was able to form between a room temperature hydrothermal solution and cold ocean simulant at higher sulfide and iron concentrations. The effect of a thermal gradient on the growth of iron hydroxide chimneys was also tested.

While the room temperature iron hydroxide experiment produced a robust chimney precipitate, the thermal gradient experiment resulted in a smaller amount of chimney material that did not coalesce vertically. Following this procedure, a wide range of chemistry and temperature gradients can be explored to better understand the role of temperature gradients on these dynamic chemical systems.