Calcium and strontium isotopes as indicators of recrystallization rates in marine carbonates: Implications for geochemical proxies

宾夕法尼亚州立大学的研究人员将验证一个假设，即“年轻”（即不到100万年）的纳米化石软泥碳酸盐的再结晶速度要快得多，地球化学指标的变化也比之前认为的要大得多。本研究将对海洋碳酸盐和孔隙流体进行钙和锶同位素测量，并使用数值成岩模型来约束海洋系统中的碳酸盐再结晶速率。这项工作将在之前测量的几个海洋钻探计划（ODP）地点的基础上扩展这些测量，大约使检查的地点数量增加了一倍。目的是确定所谓的快速再结晶是否会延伸到海洋的其他地方；如果是这样，则可以认为快速再结晶是一种普遍存在的现象。具有全球意义的问题。研究人员将收集存档的ODP样品，测量它们的同位素组成，并使用数值反应输运模型来解释再结晶的成岩速率，并批判性地评估其他假设。如果快速再结晶是con&amp；#64257；因此，这项工作将创建一个框架，用于评估一系列代理系统（如硼和镁）的成岩变化，并提出校正用于研究地球气候和地球化学演化的记录的方法。这项工作有可能产生更准确的代理记录，增加我们对地球化学代理记录的不确定性的理解，以及实现更准确的气候记录，以校准用于预测未来气候变化的气候模型。该研究资助了最近在宾夕法尼亚州立大学完成的nsf支持的多收集器ICP-MS设备。资金还用于研究生的教育和培训，本科生的研究经验，以及在宾夕法尼亚州立大学地球和矿物科学博物馆展出的宣传材料的生成。

Researchers from Penn State University will test the hypothesis that recrystallization rates in "young" (i.e, less that one million years old) nannofossil ooze carbonates are significantly faster, and alteration of geochemical proxies much greater, than previously thought. This work will conduct calcium and strontium isotope measurements on marine carbonates and pore fluids and use a numerical diagenetic model to constrain carbonate recrystallization rates in marine systems. The work will extend such measurements from a few Ocean Drilling Program (ODP) sites previously measured, approximately doubling the number of sites examined. The goal is to ascertain if so-called rapid recrystallization extends to other locations in the ocean; if it does, rapid recrystallization may be considered to be a widespread effect of global significance. Researchers will collect archived ODP samples, measure their isotopic composition, and use numerical reactive transport models to interpret diagenetic rates of recrystallization and, critically, evaluate alternate hypotheses.If rapid recrystallization is confirmed, the proposed work will create a framework for evaluating diagenetic alteration in a range of proxy systems (such as boron and magnesium), and suggest methods for correcting records used to study climate and geochemical evolution on Earth. This work has the potential to produce more accurate proxy records and increase our understanding of the uncertainty of geochemical proxy records, as well as to enable more accurate climate records with which to calibrate climate models used to predict future climate change. The funded research supports a recently-completed NSF-supported multiple-collector ICP-MS facility at Penn State University. Funding also supports education and training of a graduate student, research experiences for undergraduates, and the generation of outreach materials to be displayed at the Penn State Earth and Minerals Sciences Museum.