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Growth, Chamber Formation, and Microscale Heterogeneity in Planktic Foraminifera: Implications for Paleoclimate Proxies
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Growth, Chamber Formation, and Microscale Heterogeneity in Planktic Foraminifera: Implications for Paleoclimate Proxies. |
| 개인저자 | Bonnin, Elisa Angeles. |
| 단체저자명 | University of Washington. Oceanography. |
| 발행사항 | [S.l.]: University of Washington., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 293 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781088364123 |
| 학위논문주기 | Thesis (Ph.D.)--University of Washington, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Gagnon, Alexander C. |
| 이용제한사항 | This item must not be sold to any third party vendors.This item must not be added to any third party search indexes. |
| 요약 | The calcite tests of planktic foraminifera contain a number of geochemical proxies, which are often used to determine past ocean conditions. However, the incorporation of these proxies into the test is often affected by growth and biomineralization processes, which cause biogenic calcite to behave differently from inorganic calcite. These are often called 'vital effects'. The examination of foraminiferal tests at the microscale, using novel imaging and isotope labeling techniques, can further our understanding of the underlying mechanisms behind the incorporation of these proxies into calcite, reducing the impact of individual variability and aiding accurate paleoclimate reconstructions. This work examines three aspects of growth that may affect metal-to-calcium (Me/Ca) proxies in planktic foraminifera: (1) the incorporation of organic matrices into the test during chamber formation, (2) systematic diurnal heterogeneity throughout the test, and (3) gametogenic calcification, where an extra layer of calcite is precipitated at the end of the organism's life. Using time-of-flight secondary ion mass spectrometry (ToF-SIMS), an imaging technique with a resolution of ~300 nm, we observe that Na and Mg are both high at the location of the primary organic sheet (POS) in Orbulina universa, and that during chamber formation, a new POS is laid down over all existing chambers in that species. We also observe Na banding throughout the test of O. universa, which may be linked to previously observed heterogeneity in Mg/Ca (Chapter 2). By making use of a novel, multi-isotope labeling technique and ICP-MS analyses to examine diurnal heterogeneity, we observe high Sr/Ca during the night, following a similar pattern as Mg/Ca heterogeneity. Sr/Ca and Mg/Ca also appear positively correlated during the night, a relationship consistent with Sr/Ca and Mg/Ca in inorganic calcite and other biominerals. This indicates that this positive relationship is due to a mineralogical property of calcite, and any shift away from this relationship is due to other processes, such as kinetics or Rayleigh fractionation (Chapter 3). Finally, by using the same isotope labeling technique to examine gametogenic calcite, we observe that gametogenic calcite is high in Mg/Ca and Sr/Ca, and has a similar chemical composition and mechanism as night calcification (Chapter 4). |
| 일반주제명 | Chemical oceanography. Paleoclimate science. |
| 언어 | 영어 |
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