@article {238,
	title = {Asphalt volcanoes as a potential source of methane to late Pleistocene coastal waters},
	journal = {Nature Geoscience},
	volume = {3},
	year = {2010},
	note = {id: 1866; Sp. Iss. SI 589XW Times Cited:0 Cited References Count:28; YY},
	pages = {345-348},
	abstract = {Every year, natural petroleum seepage emits 0.2-2 Tg of oil to the ocean(1). Significant oil seepage can build large underwater mounds, consisting of tar deposits with morphologies similar to volcanic lava flows, known as asphalt volcanoes(2,3). Such events are typically accompanied by large fluxes of the greenhouse gas methane(4,5). Marine sediments from the Santa Barbara basin, California, contain a record of elevated methane concentrations(6), anoxia and tar deposition(7) during the Pleistocene epoch that had been attributed to dissolution of methane hydrates. However, the region is known to have exhibited oil seepage in the past(7). Here, we document the discovery of seven extinct asphalt volcanoes off the coast of southern California. The morphology of the deposits and geochemistry of samples taken from the two largest structures supports their classification as asphalt volcanoes, derived from a common source. We estimate that the two structures resulted from seepage of 0.07-0.4 Tg of oil, accompanied by the emission of 0.35-1.8 Tg of methane. Radiocarbon dating of carbonate deposits entrained with the asphalt indicates formation of the volcanoes between 44 and 31 kyr ago. The timing and volume of erupted hydrocarbons from the asphalt structures can explain some or all of the documented methane release and tar accumulation in the Santa Barbara basin during the Pleistocene.},
	issn = {1752-0894},
	doi = {10.1038/Ngeo848},
	author = {Valentine, D. L. and Reddy, C. M. and Farwell, C. and Hill, T. M. and Pizarro, O. and Yoerger, D. R. and Camilli, R. and Nelson, R. K. and Peacock, E. E. and Bagby, S. C. and Clarke, B. A. and Roman, C. N. and Soloway, M.}
}
@article {1962,
	title = {Biogeochemical investigations of marine methane seeps, Hydrate Ridge, Oregon},
	journal = {Journal of Geophysical Research-Biogeosciences},
	volume = {110},
	year = {2005},
	note = {090wnTimes Cited:19
Cited References Count:72
},
	month = {Nov 10},
	pages = {1-17},
	abstract = {[1] A series of biogeochemical studies were conducted at the southern summit of Hydrate Ridge, offshore Oregon. Using the submersible DSV Alvin, sediment push cores were collected from two distinct seep environments characterized by the presence of clam fields (CF) or microbial mats (MM) at the sediment-water interface; samples were also collected from a nearby reference site characterized by a barren surface at the sediment-water interface. Sediment samples from each setting were analyzed for the depth distributions of total organic carbon (concentrations, delta C-13 and Delta C-14), total sedimentary nitrogen, and microbial abundance. Pore fluids were extracted and analyzed for sulfate, alkalinity, sulfide, organic carbon, and volatile organic acids. These depth distributions clearly indicate the presence of three distinctive biogeochemical settings in the surface sediments of Hydrate Ridge, and provide the basis for a comparative biogeochemical analysis. Both CF and MM sites display properties indicating enhanced microbial activity in the subsurface, compared with the reference site. MM sites display evidence of net biomass production in the subsurface; however, a loss of sediment nitrogen relative to the reference site indicates that mineralization is also enhanced. Calculations based on the removal of nitrogen indicate that greater than 30\% of autochthonous organic material is lost to enhanced mineralization in the top 23 cm of one MM site. An isotope mass balance of sediment-bound organic carbon indicates a mixed source, including methane and allochthonous organic carbon dissolved in the seep fluids. The concentrations of organic carbon dissolved in seep fluids reach values of 22 mM and provide a first indication that advective transport of dissolved organic carbon from great depth may supply an important source of energy and carbon to "methane seep{\textquoteright}{\textquoteright} communities.},
	keywords = {anaerobic oxidation, authigenic carbonates, cascadia convergent margin, community structure, dissolved organic-carbon, fluid-flow, ne pacific, odp site 892b, phylogenetic analysis, sulfate-reducing bacteria},
	isbn = {0148-0227},
	doi = {10.1029/2005JG000025},
	url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&amp;SrcAuth=Alerting\&amp;SrcApp=Alerting\&amp;DestApp=WOS\&amp;DestLinkType=FullRecord;UT=WOS:000240984200001},
	author = {Valentine, D. L. and Kastner, M. and Wardlaw, G. D. and Wang, X. C. and Purdy, A. and Bartlett, D. H.}
}
