- journal_title：Geology
- Contributor：Sarah E. Greene ; David J. Bottjer ; Frank A. Corsetti ; William M. Berelson ; John-Paul Zonneveld
- Publisher：Geological Society of America
- Date：2012-11-01
- Format：text/html
- Language：en
- Identifier：10.1130/G33205.1
- journal_abbrev：Geology
- issn：0091-7613
- volume：40
- issue：11
- firstpage：1043
- section：Articles
Triassic-Jurassic (T-J) boundary successions record a paucity of carbonate in association with the mass extinction. Here we demonstrate that three globally disparate T-J sections contain volumetrically important early diagenetic carbonate, i.e., carbonate formed soon after deposition of the sediment but commonly ignored as secondary, that contains information about the extinction and may constitute a previously unrecognized pathway in the carbon cycle. Petrographic analyses of unusual carbonate fans from three sites reveal that they grew just below the sediment-water interface, nearly concomitant with primary sediment deposition. Thus, the shallow subseafloor can be a carbonate sink of unknown size, and may be a predictable consequence of ocean acidification where carbonate precipitation first returns within the sediment before recovering in the water column.