Hudson submarine canyon head offshore New York and New Jersey: A physical and geochemical investigation

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• 作者：Peter Rona^a ; ¹ ; ^{rona@marine.rutgers.edu" class="auth_mail" title="E-mail the corresponding author} ; Vincent Guida^b ; ^{vincent.guida@noaa.gov" class="auth_mail" title="E-mail the corresponding author} ; Mary Scranton^c ; ^{mary.scranton@stonybrook.edu" class="auth_mail" title="E-mail the corresponding author} ; Donglai Gong^d ; ^{gong@vims.edu" class="auth_mail" title="E-mail the corresponding author} ; Leonardo Macelloni^e ; ^f ; ^{lmacello@olemiss.edu" class="auth_mail" title="E-mail the corresponding author} ; Martina Pierdomenico^g ; ^{martina.pierdomenico@uniroma1.it" class="auth_mail" title="E-mail the corresponding author} ; Arne-R. Diercks^h ; ^{arne.diercks@usm.edu" class="auth_mail" title="E-mail the corresponding author} ; Vernon Asper^h ; ^{vernon.asper@usm.edu" class="auth_mail" title="E-mail the corresponding author} ; Scott Haagⁱ ; ^{smh362@drexel.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Hudson Canyon ; Seafloor mapping ; Geomorphology ; Methane ; Pockmarks ; Hydrography ; Canyon circulation
• 刊名：Deep Sea Research Part II: Topical Studies in Oceanography
• 出版年：2015
• 出版时间：November 2015
• 年：2015
• 卷：121
• 期：Complete
• 页码：213-232
• 全文大小：21159 K

文摘

Hudson Canyon is the largest shelf-sourced canyon system off the east coast of the United States, and hosts a productive ecosystem that supports key fisheries. Here we report the results of a multi-year interdisciplinary study of the geological, geochemical, and physical oceanographic features and processes in the canyon that underpin that ecosystem. High-resolution multi-beam bathymetric and backscatter data show that the contrasting morphology of the two perpendicularly oriented branches at the head of the Hudson Canyon is indicative of different states of geomorphological activity and sediment transport. Tightly spaced ridges and gullies extend perpendicularly towards the canyon axis from the canyon walls. Numerous depressions are found at the base of the canyon walls or along the canyon axis at depths from 300 m to 600 m. Elevated concentrations of dissolved methane in the water column, where the highest density of depressions occur, suggests that methane is actively venting there. The topography and reflective floors of circular depressions in canyon walls and their association with methane maxima suggest that these represent active methane gas release-collapse pockmarks with carbonate floors. Patterns of irregular, low-relief, reflective depressions on the canyon floor may also represent methane release points, either as gas release or cold-seep features. The presence of methane maxima in a region of strong advective currents suggests continuous and substantial methane supply. Hydrographic observations in the canyon show that multiple layers of distinct inter-leaved shelf (cold, fresh) and slope (warm, salty) water masses occupy the head of the canyon during the summer. Their interactions with the canyon and with each other produce shifting fronts, internal waves, and strong currents that are influenced by canyon topography. Strong tidal currents with along-canyon-axis flow shear help to drive the advection, dispersion and mixing of dissolved materials in the water column that likely help support the rich canyon ecosystem.