Moytirra: Discovery of the first known deep‐sea hydrothermal vent field on the slow‐spreading Mid‐Atlantic Ridge north of the Azores

Abstract

[1] Geological, biological, morphological, and hydrochemical data are presented for the newly discovered Moytirra vent field at 45 o N. This is the only high temperature hydrothermal vent known between the Azores and Iceland, in the North Atlantic and is located on a slow to ultraslowspreading mid-ocean ridge uniquely situated on the 300 m high fault scarp of the eastern axial wall, 3.5 km from the axial volcanic ridge crest. Furthermore, the Moytirra vent field is, unusually for tectonically controlled hydrothermal vents systems, basalt hosted and perched midway up on the median valley wall and presumably heated by an off-axis magma chamber. The Moytirra vent field consists of an alignment of four sites of venting, three actively emitting ''black smoke,'' producing a complex of chimneys and beehive diffusers. The largest chimney is 18 m tall and vigorously venting. The vent fauna described here are the only ones documented for the North Atlantic (Azores to Reykjanes Ridge) and significantly expands our knowledge of North Atlantic biodiversity. The surfaces of the vent chimneys are occupied by aggregations of gastropods (Peltospira sp.) and populations of alvinocaridid shrimp (Mirocaris sp. with Rimicaris sp. also present). Other fauna present include bythograeid crabs (Segonzacia sp.) and zoarcid fish (Pachycara sp.), but bathymodiolin mussels and actinostolid anemones were not observed in the vent field. The discovery of the Moytirra vent field therefore expands the known latitudinal distributions of several ventendemic genera in the north Atlantic, and reveals faunal affinities with vents south of the Azores rather than north of Iceland.Components: 8,953 words, 11 figures, 2 tables.

Rheology and the Fe3+–chlorine reaction in basaltic melts

“…Crystal-free basaltic glass samples were obtained by an ROV (remotely operated vehicle) from the flat topped volcano located at 2993 m water depth (Station V24: 45° 28.7'N/27° 51.0'W) during the VENTuRE expedition aboard the national research vessel RV Celtic Explorer (Wheeler et al, 2011a;2011b;2013). The composition of the glass has been determined by electron microprobe, and is listed in Table 1.…”

Hydrothermal assemblages associated with different foundation species on the East Pacific Rise and Mid‐Atlantic Ridge, with a special focus on mytilids

“…Metal content of hydrothermal fluids also may affect the recently discovered hydrothermal vent area Moytirra, located between the Azores and Iceland (depth 2095 m), which is devoid of mytilid assemblages (Wheeler et al . ).…”

“…, ; Wheeler et al . ). Environmental factors specific to a field may also explain the substantial differences seen among some fields on the MAR (Copley et al .…”

“…Depth has been suggested as the main factor determining the distribution pattern on the MAR (Mironov et al 2002;Gebruk & Mironov 2006;Fabri et al 2011). Another point of view is that changes in abiotic factors mediated by changes in depth play the main role (Desbruy eres et al 2000(Desbruy eres et al , 2001Wheeler et al 2013). Environmental factors specific to a field may also explain the substantial differences seen among some fields on the MAR (Copley et al 2007;Fabri et al 2011).…”

A new method for ecological surveying of the abyss using autonomous underwater vehicle photography

“…Remotely operated vehicles (ROVs) and human occupied vehicles (HOVs) have also been used to collect photographic and video data, allowing topographically complex habitats to be studied, including deep-sea vent and cold-water coral sites (Morris et al 2012(Morris et al , 2013Wheeler et al 2013). These vehicles may also permit the collection of voucher specimens for identification.…”