Dataset: In-situ temperature profiles

Thermal profiles were measured in surficial sediments using Alvin’s 50 cm heat flow probe in Guaymas Basin, Gulf of California (111W 27N) in November 2018. Alvin dive numbers 4991-5001.

A Heatflow probe manufactured by the Woods Hole Oceanographic Institution (WHOI) was used to measure temperature profiles. This is a 0.6 m titanium tube containing a linear heater and five thermistors (type 44032, Omega Engineering, Inc.) at 10 cm intervals along the length of the tube (personal communication with Lane J. Abrams, WHOI). The thermistors have a tolerance of +/- 0.2 up to 40C, and +/- 1 C up to 200C.

The probe has thermal sensors every 10 cm, starting 5 cm under the attached plastic disk (the “puck”) that limits probe penetration and rests on the seafloor once the probe is inserted. After approx. 3 to 5 minutes, temperature readings stabilize and are recorded. The heat flow probe shorted at the beginning of Alvin dive 5000; instead, the thermosensor within the tip of the suction intake was inserted into the sediment at approx. 5 cm, 10 cm and 20 cm depth, and the temperature was recorded immediately.

The probe is considered fully inserted when a disk at the base reaches the sediment surface, and takes temperature readings at 0, 10, 20, 30 and 40 cmbsf. For additional resolution, 5 cm depth resolution was achieved by first inserting the probe 5 cm less than complete insertion and recording one profile, and then inserting the probe the rest of the way and recording a second profile, 5 cm offset from the first. Temperatures were recorded after the readings had stabilized for each of the five depths, usually after 3 to 5 minutes.