Cold-Seep Carbonates of the Louisiana Continental Slope-to-Basin Floor

1993 ◽  
pp. 95-104 ◽  
Author(s):  
Harry H. Roberts ◽  
Paul Aharon ◽  
Maud M. Walsh
Keyword(s):  
Continental Slope ◽  
Cold Seep ◽  
Basin Floor

scholarly journals Time averaging and temporal persistence in chemoautotrophic molluscan-dominated death assemblages on the Louisiana continental slope

1992 ◽  
Vol 6 ◽  
pp. 49-49
Author(s):  
W. Russell Callender ◽  
Eric N. Powell
Keyword(s):  
Continental Slope ◽  
Amino Acid Content ◽  
Local Variation ◽  
Cold Seep ◽  
Time Averaging ◽  
Time Since Death ◽  
Sample Collection ◽  
Death Assemblages ◽  
Mussel Shells ◽  
Petroleum Seep

Petroleum seeps on the Louisiana continental slope produce luxurious communities based on chemoautotrophic symbiotic bacteria. Petroleum seeps are typical cold seep communities and generate classic autochthonous death assemblages. Fossil cold seep communities are well-known, common and widespread. Most fossil analogues are dominated by lucinids, but petroleum seeps are not. A combination of sample collection and in situ experimentation has been used to determine rates of taphonomy and time averaging in petroleum seep assemblages.Cores were obtained and sectioned from seep sites in Green Canyon lease blocks 272, 234, and 184 and Garden Banks lease block 386. Lucinids and thyasirids were selected for dating time-since-death to determine the importance of time averaging in these assemblages. Dating was accomplished by measuring the free amino acid content of the shells. Time-since-death became progressively older with depth; accordingly little time averaging had occurred in these autochthonous assemblages. Lucind and mussel shells were placed on the sea floor and recovered 3 yr later. Comparison of each species to the controls left on a laboratory shelf for 3 yr shows that taphonomic alteration was rapid. Mussels were more severely altered than lucinids. Mussels were more heavily dissolved, had more altered edges, were more prone to fragmentation and exhibited greater weight loss than lucinids. The rapid taphonomic loss of the mussels suggests that the preponderance of lucinids in the fossil record is an artifact of preservation. Taphofacies analysis suggests the same; thus verifying an important assumption of taphofacies analysis that taphonomic signatures record biases in preservation by identifying inter-species differences in the rates of important taphonomic processes. Significant variability in taphonomic rates exists between shells from locations 10 m apart indicating significant local variation in the taphonomic process. Local variability in taphonomic and community attributes is characteristic of many autochthonous assemblages.

Cold-seep carbonates of the middle and lower continental slope, northern Gulf of Mexico

2010 ◽  
Vol 57 (21-23) ◽  
pp. 2040-2054 ◽  
Author(s):  
Harry H. Roberts ◽  
Dong Feng ◽  
Samantha B. Joye
Keyword(s):  
Gulf Of Mexico ◽  
Continental Slope ◽  
Cold Seep ◽  
Northern Gulf Of Mexico

scholarly journals Preliminary video-spatial analysis of cold seep bivalve beds at the base of the continental slope of Israel (Palmahim Disturbance)

2020 ◽  
Vol 171 ◽  
pp. 104664 ◽  
Author(s):  
V. Beccari ◽  
D. Basso ◽  
S. Spezzaferri ◽  
A. Rüggeberg ◽  
A. Neuman ◽  
...  
Keyword(s):  
Spatial Analysis ◽  
Continental Slope ◽  
Cold Seep

Growth and size-structure of Stegophiura sp. (Echinodermata: Ophiuroidea) on the continental slope off central Chile: a comparison between cold seep and non-seep sites

2009 ◽  
Vol 89 (2) ◽  
pp. 421-428 ◽  
Author(s):  
Eduardo Quiroga ◽  
Javier Sellanes
Keyword(s):  
Continental Slope ◽  
Size Structure ◽  
Growth Models ◽  
Benthic Fauna ◽  
Cold Seep ◽  
Central Chile ◽  
Disc Diameter ◽  
Preferred Habitat ◽  
Growth Bands ◽  
Size At Age

The growth and size-structure of the bathyal ophiuroid brittle star, Stegophiura sp., were analysed from skeletal growth bands and disc diameter frequencies. Specimens were collected in trawl samples taken on the continental slope off central Chile (~36°S) at two sites within the recently discovered Concepción Methane Seep Area (CMSA) and at two control non-seep sites. Growth bands were measured as radii of vertebral ossicles from scanning electron microscope (SEM) micrographs and used to provide size-at-age data. The von Bertalanffy and the Gompertz growth models provided good fit to size-at-age data. The size-structure distributions observed in the study area suggest that small-bodied (<10 mm disc diameter) individuals of Stegophiura sp. are more abundant near seep sites, probably attracted there by the presence of methane-derived authigenic carbonates, which provide a preferred habitat for ophiuroids and benthic fauna in general. Furthermore, size-at-age data from measurements of the ossicle growth bands indicate relatively rapid growth of Stegophiura sp. populations at seep sites. Assuming that the growth rings are annual, the maximum Stegophiura sp. age was estimated to be 15 years. The growth performance of this species falls within the range of values reported for sub-Antarctic and bathyal species.

Two new species of flatworms (Platyhelminthes: Polycladida) from the continental slope of the Gulf of Mexico

2008 ◽  
Vol 88 (7) ◽  
pp. 1363-1370 ◽  
Author(s):  
Sigmer Y. Quiroga ◽  
D. Marcela Bolaños ◽  
Marian K. Litvaitis
Keyword(s):  
New Species ◽  
Natural History ◽  
Gulf Of Mexico ◽  
Continental Slope ◽  
Cold Seep ◽  
Field Museum ◽  
Two New Species ◽  
Glandular Cells ◽  
Natural Wood ◽  
The Brain

Two new species of polyclads are described from the continental slope of the Gulf of Mexico. Specimens ofDidangia carneyisp. nov. andOligocladus bathymodiensissp. nov. were collected from the Louisiana slope at 610 m and 650 m, respectively.Didangia carneyisp. nov. was collected from a natural wood fall, and is characterized by the presence of tentacular and cerebral eyes, an interpolated prostatic vesicle provided with two muscular accessory prostatic vesicles, and large glandular cells that surround the male atrium.Oligocladus bathymodiensissp. nov. has a mouth anterior to the brain, a few cerebral and pseudotentacular eyes, four pairs of intestinal branches, and a ventral anal pore. Specimens of this species were collected on the margin of a hypersaline cold seep in association with mussels ofBathymodiolus childressi. All type material is deposited at the Field Museum of Natural History, Chicago, Illinois, USA.

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