Fluid conduits formed along burrows of giant bivalves at a cold seep site, southern Taiwan

Blouet, Jean-Philippe and Wetzel, Andreas and Ho, Sutieng. (2021) Fluid conduits formed along burrows of giant bivalves at a cold seep site, southern Taiwan. Marine and Petroleum Geology, 131. p. 105123.

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At a Pliocene methane seep site in Taiwan characterized by nume rous tubular carbonate bodies and bivalves, a half meter-long dolomitic concretion con taining a lucinid bivalve Anodontia goliath reveals the impact of chemosymbiotic bivalves on fluid migratio n through shallow sediments. The concretion consists of a cortex encasing a central channel filled with sparite and varying amounts of brecciated material derived from the channel walls. The studied bivalve is preserved with the hinge upward. When restor ed to life position, the central channel is connected to the anterior side of the bivalve. In th e lower longer segment, the channel is connected to the posterior sector of the bivalve. Th e channels are interpreted as the anterior tube for supply of res piration water and the posterior tube for mining sulphide generated in the sulfate-methane transition zone of the sedimen t. The dolomitic cortex surrounding the central channe l is characterized by δ13C values as low as -29‰ VPDB, indicating that the rate of an aerobic oxidation of methane was enhanced around the conduit. At the base of the central channe l, upward soft sediment deform ation structures likely resulted from the dragging effect when flui d migrated out of the sedimen t and entered the channel. Brecciation of the channel walls indicates pulsating seepage du ring the incipient stages of cementation. The burrow, thus, acted as a highly permeable cond uit channeling upstreaming methane-charged fluid for a substantial period of time. Therefo re, burrows can be efficient in pre-determining the formation of fluid conduits at seep sites, having potentially a large impact on fluid mixing and diagenetic reaction rates in sediments, and ultimately the amount of methane released. The reported bivalve with its conserved burro w fossilized as seep carbonate concretion provides direct evide nce that fluid conduits form al ong animal burrows.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Ehemalige Einheiten Umweltwissenschaften > Sedimentology (Wetzel)
UniBasel Contributors:Wetzel, Andreas
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:01 Oct 2023 01:30
Deposited On:26 Aug 2021 14:40

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