The taphonomic signature of a brine seep and the potential for Burgess Shale style preservation

Title:
The taphonomic signature of a brine seep and the potential for Burgess Shale style preservation
Authors:
Parsons-Hubbard, Karla; Powell, Eric N.; Raymond, Anne L.; Walker, Sally E.; Brett, Carlton E.; Ashton-Alcox, Kathryn A.; Shepard, Rebekah N.; Krause, Richard A.; Deline, Bradley
Abstract:
Unusually fine preservation of soft anatomy in the fossil record, often referred to as Lagerstätte deposits, has led to great advances in understanding the evolution of life. An understanding of the potential environments of deposition that might lead to exquisite preservation may help to reconstruct the effects of the taphonomic filter and thereby better interpret the completeness of fossil Lagerstätten. Seafloor brines are potential environments leading to exceptional preservation. The Shelf and Slope Experimental Taphonomy Initiative (SSETI) placed mollusc shells, decapod crustaceans, sea urchins, and wood into a Gulf of Mexico seafloor brine pool environment to study the rates and modes of skeletal and soft tissue decay. We found that skeletons, soft tissue, and wood placed directly in the sulfidic anoxic brine were essentially not degraded or discolored over nearly a decade. Where the brine mixed with overlying seawater in a brine stream, the taphonomic signature was quite different. Calcium-carbonate shell and urchin tests underwent severe dissolution, whereas terrestrial plant remains were unaltered. Farther from the brine, shell and urchin carbonate was only slightly dissolved, wood was completely consumed by xylophagus animals, and decapods were reduced to claw parts only. From these experiments, we conclude that the taphonomic signature of a brine seep can be recognized by a unique juxtaposition of preservation styles that varies across phyla. The central area of the anoxic brine would promote exquisite preservation of carbonate, soft-animal tissue, and cellulose. The central area would be ringed by a zone of near total loss of shell carbonate, but paradoxically would promote the preservation of organic tissue such as shell periostracum and ligament, wood, nuts, and cones. Where seawater salinity is normal, the taphonomic signature would return to a seafloor assemblage appropriate to the depth and depositional environment. Brine seep systems may provide a mechanism for maintaining unaltered organism remains at the sediment-water interface long enough to become buried with soft anatomy intact and undisturbed. The very important fossil deposit known as the Burgess Shale exhibits preservation styles and patterns that might be explained by presence of brine. Our experimental work in a modern brine system may shed some light on the taphonomic conditions that led to preservation known as the “Burgess Shale type.”
Citation:
Parsons-Hubbard, Karla, E. N. Powell, A. Raymond, S. E. Walker, et al. 2008. "The taphonomic signature of a brine seep and the potential for Burgess Shale style preservation." Journal Of Shellfish Research 27(1): 227-239.
Publisher:
National Shellfisheries Association
DATE ISSUED:
2008
Department:
Geology
Type:
article
PUBLISHED VERSION:
10.2983/0730-8000(2008)27[227:TTSOAB]2.0.CO;2
PERMANENT LINK:
http://hdl.handle.net/11282/309519

Full metadata record

DC FieldValue Language
dc.contributor.authorParsons-Hubbard, Karlaen_US
dc.contributor.authorPowell, Eric N.en_US
dc.contributor.authorRaymond, Anne L.en_US
dc.contributor.authorWalker, Sally E.en_US
dc.contributor.authorBrett, Carlton E.en_US
dc.contributor.authorAshton-Alcox, Kathryn A.en_US
dc.contributor.authorShepard, Rebekah N.en_US
dc.contributor.authorKrause, Richard A.en_US
dc.contributor.authorDeline, Bradleyen_US
dc.date.accessioned2013-12-23T16:11:20Zen
dc.date.available2013-12-23T16:11:20Zen
dc.date.issued2008en
dc.identifier.citationParsons-Hubbard, Karla, E. N. Powell, A. Raymond, S. E. Walker, et al. 2008. "The taphonomic signature of a brine seep and the potential for Burgess Shale style preservation." Journal Of Shellfish Research 27(1): 227-239.en_US
dc.identifier.issn0730-8000en_US
dc.identifier.urihttp://hdl.handle.net/11282/309519en
dc.description.abstractUnusually fine preservation of soft anatomy in the fossil record, often referred to as Lagerstätte deposits, has led to great advances in understanding the evolution of life. An understanding of the potential environments of deposition that might lead to exquisite preservation may help to reconstruct the effects of the taphonomic filter and thereby better interpret the completeness of fossil Lagerstätten. Seafloor brines are potential environments leading to exceptional preservation. The Shelf and Slope Experimental Taphonomy Initiative (SSETI) placed mollusc shells, decapod crustaceans, sea urchins, and wood into a Gulf of Mexico seafloor brine pool environment to study the rates and modes of skeletal and soft tissue decay. We found that skeletons, soft tissue, and wood placed directly in the sulfidic anoxic brine were essentially not degraded or discolored over nearly a decade. Where the brine mixed with overlying seawater in a brine stream, the taphonomic signature was quite different. Calcium-carbonate shell and urchin tests underwent severe dissolution, whereas terrestrial plant remains were unaltered. Farther from the brine, shell and urchin carbonate was only slightly dissolved, wood was completely consumed by xylophagus animals, and decapods were reduced to claw parts only. From these experiments, we conclude that the taphonomic signature of a brine seep can be recognized by a unique juxtaposition of preservation styles that varies across phyla. The central area of the anoxic brine would promote exquisite preservation of carbonate, soft-animal tissue, and cellulose. The central area would be ringed by a zone of near total loss of shell carbonate, but paradoxically would promote the preservation of organic tissue such as shell periostracum and ligament, wood, nuts, and cones. Where seawater salinity is normal, the taphonomic signature would return to a seafloor assemblage appropriate to the depth and depositional environment. Brine seep systems may provide a mechanism for maintaining unaltered organism remains at the sediment-water interface long enough to become buried with soft anatomy intact and undisturbed. The very important fossil deposit known as the Burgess Shale exhibits preservation styles and patterns that might be explained by presence of brine. Our experimental work in a modern brine system may shed some light on the taphonomic conditions that led to preservation known as the “Burgess Shale type.”en_US
dc.publisherNational Shellfisheries Associationen_US
dc.identifier.doi10.2983/0730-8000(2008)27[227:TTSOAB]2.0.CO;2en
dc.subject.departmentGeologyen_US
dc.titleThe taphonomic signature of a brine seep and the potential for Burgess Shale style preservationen_US
dc.typearticleen_US
dc.identifier.journalJournal Of Shellfish Researchen_US
dc.subject.keywordTaphonomyen_US
dc.subject.keywordLagerstatteen_US
dc.subject.keywordBrine seepen_US
dc.subject.keywordExceptional preservationen_US
dc.subject.keywordBurgess shaleen_US
dc.identifier.volume27en_US
dc.identifier.issue1en_US
dc.identifier.startpage227en_US
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