Open AccessFossil clams from a serpentinite‐hosted sedimented vent field near the active smoker complex Rainbow, MAR, 36°13′N: Insight into the biogeography of vent fauna
Author(s) -
Lartaud Franck,
de Rafelis Marc,
Oliver Graham,
Krylova Elena,
Dyment Jérôme,
Ildefonse Benoît,
Thibaud Remy,
Gente Pascal,
Hoisé Eva,
Meistertzheim AnneLeïla,
Fouquet Yves,
Gaill Françoise,
Le Bris Nadine
Publication year - 2010
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2010gc003079
Subject(s) - hydrothermal vent , chemosynthesis , geology , mid atlantic ridge , paleontology , oceanography , cold seep , petroleum seep , ultramafic rock , abyssal plain , ridge , continental margin , fauna , hydrothermal circulation , geochemistry , ecology , sediment , biology , methane , tectonics
Hydrothermal circulation at ultramafic‐hosted sites supports a large variety of high‐ and low‐temperature hydrothermal vents and associated ecosystems. The discovery of abundant fossil vesicomyid and thyasirid shell accumulations at the ridge crest, approximately 2.5 km east of the active Rainbow vent field on the Mid‐Atlantic Ridge (MAR, 36°13′N), increased our knowledge regarding the diversity of vent communities at slow spreading ridges. Bivalve molluscs of the family Vesicomyidae were represented by the genus Phreagena . Here we present the first record of this genus in the Atlantic Ocean. This second vesicomyid species known from the MAR, Phreagena sp., was found to be associated with a Thyasira species that is affiliated with T. southwardae (at the Logatchev vent field on the MAR) and with T. vulcolutre (in the Gulf of Cadiz). These two clams have close relationships with seep taxa along the continental margin, and were likely associated with sedimented vent fields. δ 18 O and δ 13 C analyses of the shells suggested that the burrowing bivalve Thyasira could incorporate isotopically light carbon, derived from the oxidation of methane in the sediment, while the signature of Phreagena sp. shells denoted a different carbonate source. 14 C dating of the shells denoted that the hydrothermal activity in the Rainbow area began at least ∼25.5 kyr BP, which is similar to the model of the hydrothermal vent field distribution that was proposed for the Logatchev hydrothermal site. The results provide new insight regarding the diversity of chemosynthetic fauna on the MAR over geologic time. Ultramafic‐hosted, on‐axis sedimented vent fields extend the range of habitats for chemosynthetic communities, underlying the need to further explore the geology of these types of environments on slow‐spreading ridges and to determine their role in the ecology of deep‐sea vent communities.