Early-concept grant for exploratory research (EAGER) proposal: Accessing the potential of clumped isotope thermometry to constrain temperatures in the Arctic during the Pliocene

这项研究的具体目标是确定碳酸盐、块状同位素？温度测量可以应用于软体动物，以准确和精确地重建北极的温度。前人的工作表明，碳酸盐矿物中出现了多次稀有同位素置换，也被称为块状。重同位素相互成键，与温度有关。这个温度指标也与水的del-18O和溶解的无机碳的del-13C无关。PI和co-PI及其合作者对生物沉淀的方解石和文石的初步研究表明，13C-18O键丰度的测量应该允许人们相对自由地确定矿物形成的温度。尽管这一新的代理看起来很有希望，但在低温(即低于15°C)下对集束同位素温度计的校准是有限的。因此，这一指标在北极气候重建中的作用尚不清楚。这个项目将决定这项技术应用于北极温度下生长的生物样本的准确性和精确度，从而决定这项技术评估极地地区古海洋温度的能力。仪器对温度的记录最多只能追溯到几百年前。为了了解当地或全球气温的自然变化，我们需要更长的记录。为了开发这样的记录，我们依赖于温度的替代测量。使用这样的代理需要假设，并且通常会在估计的温度上施加很大的误差。该项目将确定新的代理人在极地地区的用处。

The specific goal of this research is to identify whether carbonate ?clumped isotope? thermometry can be applied to mollusks to accurately and precisely reconstruct temperatures in the Arctic. Previous work has shown that the occurrence of multiple rare isotope substitutions in carbonate minerals, also referred to as the ?clumping? of heavy isotopes into bonds with each other, is temperature dependent. This temperature proxy is also independent of the del-18O of water and the del-13C of dissolved inorganic carbon. Initial studies of biologically-precipitated calcite and aragonite by the PI and co-PI and collaborators indicate that the measurements of 13C-18O bond abundance should allow one to make a relatively assumption-free determination of the temperature at which a mineral formed. Although this new proxy looks promising, calibration of the clumped isotope thermometer at low temperatures (i.e., below 15°C) is limited. Therefore the utility of this proxy for climate reconstructions in the Arctic is unclear. This project will determine the accuracy and precision of the technique when applied to biological samples grown at Arctic temperatures and, consequently, the ability of this technique to assess paleo ocean temperatures in polar regions.The instrumental record of temperature only goes back in time a few hundred years, at most. In order to understand the natural variability of temperature, either locally or globally, we require much longer records. To develop such records, we rely on proxy measurements for temperature. Use of such proxies requires assumptions and often imposes large error bars on the estimated temperature. This project will determine the usefulness of a new proxy in the polar regions.