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

来自宾夕法尼亚州立大学的研究人员将测试一个假设，即“年轻”（即小于一百万年）的超微化石软泥碳酸盐的重结晶速率明显更快，地球化学代用品的改变比以前认为的要大得多。这项工作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限制海洋系统中碳酸盐的重结晶速率。这项工作将从以前测量的几个大洋钻探计划（ODP）地点扩大这种测量，大约使检查的地点数量增加一倍。目的是确定所谓的快速重结晶是否延伸到海洋的其他位置;如果是这样，快速重结晶可能被认为是一个具有全球意义的普遍现象。研究人员将收集归档的ODP样品，测量其同位素组成，并使用数值反应传输模型来解释重结晶的成岩速率，并严格评估替代假设&。rmed，拟议的工作将建立一个框架，以评估成岩蚀变在一系列的代理系统（如硼和镁），并提出了纠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，并增加我们对地球化学代理记录的不确定性的理解，以及使更准确的气候记录，以校准用于预测未来气候变化的气候模型。这项资助的研究支持了宾夕法尼亚州立大学最近完成的NSF支持的多接收器ICP-MS设施。资金还支持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产生。

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.