Faunal and stable isotopic analyses of benthic foraminifera from the Southeast Seep on Kimki Ridge offshore southern California, USA

摘要: Abstract We investigated the benthic foraminiferal faunal and stable carbon oxygen isotopic composition of a 15-cm push core (NA075-092b) obtained on Telepresence-Enabled cruise to Southeast Seep Kimki Ridge offshore southern California. The seep was taken at depth 973 m in vicinity Beggiatoa bacterial mat vesicomyid clams (Calyptogena) compared previously published data living assemblages from ~ 714 m, four reference cores 1030 m, another one 739 m. All sites are also Inner Continental Borderland but with no evidence methane seepage. No endemic species were found site most taxa recovered there have been reported other or low environments. Q- R-mode cluster analyses clearly illustrated differences non-seep sites. assemblage characterized by abundant Takayanagia delicata, Cassidulina translucens, Spiroplectammina biformis, whereas San Pedro Basin comprised primarily Chilostomella oolina Globobulimina pacifica. Density richness lower site, reflecting harsher conditions there. dead dominated Gyroidina turgida translucens 1030 m Pseudoparrella pacifica, delicata 739 m site. three times than comparable water 30% higher. Stable values considerably depleted samples samples, progression lightest heaviest average δ13C evident microhabitat preference vital effect: deep infaunal Globobulimina, shallow Uvigerina peregrina, epifaunal Cibicidoides wuellerstorfi, aragonite-shelled Hoeglundina elegans. downcore among each indicates ongoing fluid seepage through least last 3800 cal yr B.P. Seep. Besides continual local seepage, planktic foraminifera suggest two pulses (at 3000 3700 cal yr B.P.) released that large enough influence much column. Paired isotope records provide paleoenvironmental changes such as increased bottom-water temperature bottom pore waters during this 3800-year record induce releases. Instead, appears be result faulting providing pathways for flow seafloor fault stepover transpressional bend regional strike-slip system.