Sasquatch Field of the Endeavour Segment, Juan de Fuca Ridge
One of the reasons the Sasquatch field of the Endeavour Segment is so interesting, is that it was only recently discovered in the year 2000. Its characteristics are not typical for a hydrothermal vent site at Endeavour and thus it is an oddity to scientists. The reasons for these severe differences are unknown but questions have been asked and expeditions have been led to this curious site in search of answers.
It has been proposed that Sasquatch is a formerly extinct field due to its small active chimneys and extensive deposits of extinct sulfide. Scientists at the University of Washington believe that it is a rejuvenated field with periodic reactivation through eruptive or diking activity. Recent diking events (1999-2000 and 2005) at the Endeavour Segment could have provided the physical mechanism needed to rejunvenate the field (Glickson et al, paper in preparation).
Sasquatch is located 6 km north of the Main Endeavour Field (MEF) in the center of axial valley. It comprises >1 m tall, diffusely venting sulfide chimneys, within a tectonized geologic terrain containing basaltic pillow ridges. There are extinct sulfide deposits and heavy hydrothermal sediments extending outward from the active chimneys (Glickson et al, paper in preparation).
There are three notable vent sites in Sasquatch: Pico, Marker C, and Christmas Tree. The Pico Vent site is composed of three active sulfide chimneys and one extinct structure. Diffusively venting fluids are expelled from both sides of the pillow ridge, and while the western side supports macrofaunal communities, the eastern side sustains patchy bacterial mats. The vents tend to be very fragile and have been knocked over after sampling due to this characteristic. There is one isolated chimney to the north with abundant diffuse hydorthermal flow that supports lush bacterial mats of blue ciliates, white bacterial mats, limpets, scale worms, and small tube worms. Marker C vent site is composed of one single isolated chimney with a broad base southwest of Pico. It sits upon mixed sulfide and basalt surrounded by truncated pillow basalt ridges. A bacterial mat coats the sediment for about one meter around the chimney. The Christmas Tree vent site is northewest of Marker C and is composed of a composite chimney with two active spires, and "beehive" chimneys that host healthy tube worm patchs, uncommon features within Sasquatch. There are patchy bacterial mats surrounding the structures atop the hydrothermal sediment (Glickson et al, paper in preparation).
Based on bulk chemistry of three extinct sulfide samples, the Sasquatch chimneys are composed of approximately equal amounts of zinc sulfide and pyrite, with small amounts of chalcopyrite. The high Zn weight percent is comparable to active and extinct chimneys at High Rise, and is also comparable to higher than normal values reported for active and extinct chimneys at MEF (Glickson et al, paper in preparation).
Geologic setting, field extent, number of structures and chimney size separate Sasquatch from the other fields in the Endeavour Segment. Sasquatch is most comparable to High Rise 3.5 km to the south, however it is composed of broken sheet and lobate flows with isolated pillow basalts. Sasquatch, on the other hand, is extensively tectonized with truncated pillow ridges and appears to be dwarfed in size in comparison to the other ridges. It is about the size of one sulfide cluster in Mothra. It is also the only field to have such widespread extinct sulfide deposits in comparison to active fields. These characteristics set Sasquatch apart from the other ridges in Endeavour (Glickson et al, paper in preparation).
