Strýtan vent field

The oldest reports of the Strýtan vent field date back hundreds of years to fishermen using dive weights. However, the Icelandic Coast Guard did not detect the vent chimneys and declared them as non-existent in 1987.[2] Only in 1997 was the Strýtan vent field reported by divers Erlendur Bogason and Árni Halldósson and identified as a real geologic feature.[3] It was also explored by GEOMAR in 1997 using the HOV JAGO.[4]

In 2001, Strýtan was designated as a protected Icelandic preserve.[5]

Strýtan is in the vicinity of the Dalvík Lineament, which connects to the Eyjafjarðaráll Rift which extends to the Kolbeinsey Ridge.[6]

Strýtan is among the shallowest vent fields known and is among the few coastal hydrothermal systems known. Venting fluids are moderate at a temperature of ~76 °C (169 °F) and are highly alkaline at a pH of about 10.2.[7]

The vent field is composed of three primary venting sites. Big Strýtan, Arnarnesstrýtur (sometimes referred to as Little Strýtan), and Hrisey. Big Strýtan is composed prodominantly of anhydrite and saponite.[4][8] Silica, magnesium, calcium, and oxygen are abundant in venting fluids and salinity is 0.5 - 14% of that of seawater. Samples from the site indicate an extensive series of mineral phases within the mounds with firbrous, crystalline minerals establishing pore spaces for fluids to travel through.[9]

Unlike Lost City, another alkaline field to the south in the Atlantic, Strýtan is hosted on 6-12 MA basalts and most geochemistry is attributed to freshwater contributions of terrestrial origin.[10]

Sea spider grazing on a hydroid in a Norwegian fjord.

Strýtan has an abundance of mussels, bryozoans, sponges, hydroids, brittlestars, and polychete worms. Metridium anemones, nudibranchs, and sea spiders have also been reported.[11]

• Lost City Hydrothermal Field
• Hydrothermal vents