Constraints on Ocean Acidification Associated with Rapid and Massive Carbon Injections of the Early Paleogene: The Geological Record at Ocean Drilling Program Site 1215, Equatorial Pacific Ocean

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dc.contributor.advisorDickens, Gerald R.en_US
dc.creatorLeon-Rodriguez, Lizetteen_US
dc.date.accessioned2013-03-08T00:35:42Zen_US
dc.date.available2013-03-08T00:35:42Zen_US
dc.date.issued2012en_US
dc.description.abstractMassive amounts of 13 C-depleted carbon rapidly entered the ocean more than once during the early Paleogene, providing a geological framework for understanding future perturbations in carbon cycling, including ocean acidification. To assess the number of events and their impact on deep-sea carbonate accumulation, I have studied carbonate ooze units of the upper Paleocene-lower Eocene, which were deposited on a subsiding flank of the East Pacific Rise (ODP Site 1215). From this record several proxies were used to ascertain changes in carbonate dissolution: carbonate content, foraminiferal test fragmentation, and planktic/benthic foraminiferal ratio. Based on these analyses, 1 observe that carbonate preservation generally increased from the late Paleocene (56 Ma) through the early Eocene (51.5 Ma), after which it became poor to negligible. This trend was punctuated by four short-term intervals characterized by carbonate dissolution and pronounced negative d 18 O and d 13 C excursions. It is inferred that these were anomalously warm periods (hyperthermals) caused by massive and relative fast 13 C-depleted carbon injections. These correspond to the PETM (∼55.5 Ma), H1/ETM-2 (∼53.7 Ma), I1 (∼53.2 Ma), and K/X (∼52.5 Ma) events. I also calculated carbonate, planktic, and benthic foraminiferal mass accumulation rates for the Site 1215. These were used to comprehensively examine the history of carbonate accumulation in the equatorial Pacific Ocean throughout the early Paleogene. I deduce that in the long-term (>10 5 yr) the lysocline and calcite compensation depth (CCD) generally deepened between 55.4 and 51.5 Ma; but rapidly (≤10 5 yr) shoaled and subsequently overcompensated during and after the four intervals of massive carbon injection. Planktic foraminiferal assemblages found in the record of Site 1215 follow a predicted pattern for selective dissolution. Species of Acarinina are preferentially preserved over Morozovella, which are preferentially preserved over Subbotina, Igorina and Globanomalina. A tiny and previously overlooked species, Praetenuitella antica n.sp, is formally described in this manuscript. This species is also resistant to dissolution. The findings of this study provide firm constraints to model the short and long-term carbon cycle dynamics during the early Paleogeneen_US
dc.format.extent214 p.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.callnoTHESIS GEOL. 2012 LEON-RODRIGUEZen_US
dc.identifier.citationLeon-Rodriguez, Lizette. "Constraints on Ocean Acidification Associated with Rapid and Massive Carbon Injections of the Early Paleogene: The Geological Record at Ocean Drilling Program Site 1215, Equatorial Pacific Ocean." (2012) Diss., Rice University. <a href="https://hdl.handle.net/1911/70312">https://hdl.handle.net/1911/70312</a>.en_US
dc.identifier.digitalLeon-RodriguezLen_US
dc.identifier.urihttps://hdl.handle.net/1911/70312en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectEarth sciencesen_US
dc.subjectOcean acidificationen_US
dc.subjectCarbon injectionsen_US
dc.subjectCarbonatesen_US
dc.subjectCalcite compensation depthen_US
dc.subjectPacific oceanen_US
dc.subjectChemical oceanographyen_US
dc.subjectPaleontologyen_US
dc.subjectMarine geologyen_US
dc.titleConstraints on Ocean Acidification Associated with Rapid and Massive Carbon Injections of the Early Paleogene: The Geological Record at Ocean Drilling Program Site 1215, Equatorial Pacific Oceanen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentEarth Scienceen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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