Establishing a new palaeothermometer from the speleothem archive of phosphate-oxygen isotopes

利用磷酸氧同位素洞穴档案建立新的古温度计

• 批准号: NE/X011968/1
• 负责人: Andrew Smith
• 金额: $ 2.59万
• 依托单位: British Geological Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX011968%2F1
• 关键词: Establishing; new; palaeothermometer; speleothem; archive

Temperature records are critical for understanding past and future climate. However, reconstructing past temperature dynamics is incredibly difficult. Of the currently available terrestrial archives of past temperature, these are often spatially limited, suffer from ambiguity around calibration, or require large sample sizes. These issues have prevented the development of a high resolution, high density network of terrestrial temperature records. This is now often considered the single most significant gap in the palaeoclimate archive. Here, we seek to provide a breakthrough in the field of temperature reconstruction by developing a new palaeothermometer. For this, we use speleothems (cave stalagmites). Speleothems grow in layers, which can be dated like the rings in a tree. The chemistry in each layer offers an unprecedented resolution of environmental information, constrained by an absolute age model over 500,000 years. At the Lancaster Environment centre, we have recently developed a technique which allows phosphate to be extracted from the stalagmite layers. This is a critically important advance in the research field, as phosphate-oxygen isotopes are known to be controlled by temperature dynamics. Our first measurements of the phosphate-oxygen isotope composition in cave drip waters and modern cave calcite provide clear evidence that the cave temperature signal can be captured and stored within the speleothem record. As the internal temperature of shallow cave systems are known to reflect the external average air temperature (plus or minus localised effects), this provides an exciting opportunity through which a truly independent terrestrial temperature record may be built. This research aims to build and test a modern-day calibration between cave temperature and speleothem phosphate-oxygen isotopes. This will enable a platform from which precisely dated, well preserved, independent temperature records can be confidently obtained from the global archive of speleothems at a spatial and temporal scale hitherto unprecedented.

温度记录对于理解过去和将来的气候至关重要。但是，重建过去的温度动态非常困难。在过去温度的当前可用陆地档案中，这些档案通常在空间上受到限制，校准周围含糊不清或需要大量样本量。这些问题阻止了高分辨率，高密度的陆地温度记录网络的发展。现在，这通常被认为是古气候档案中最重要的差距。在这里，我们试图通过开发新的古热计，在温度重建领域提供突破。为此，我们使用speleothems（洞穴石匠）。斑点分层生长，可以像树上的戒指一样贴上日期。每一层的化学反应提供了前所未有的环境信息解决方案，受到超过500，000年的绝对年龄模型的约束。在兰开斯特环境中心，我们最近开发了一种技术，该技术允许从石岩层中提取磷酸盐。这是研究领域中至关重要的进步，因为已知磷酸盐 - 氧同位素受温度动力学控制。我们对洞穴滴水水和现代洞穴方解石中磷酸盐 - 氧同位素组成的首次测量提供了明确的证据，表明可以在Speleothem记录中捕获并存储洞穴温度信号。由于已知浅洞系统的内部温度反映了外部平均空气温度（另外或减去局部效果），因此可以通过该温度建立一个令人兴奋的机会，可以通过该温度建立真正独立的陆地温度记录。这项研究旨在建立和测试洞穴温度和斑壳磷酸氧同位素之间的现代校准。这将使一个平台能够从该平台上从空间和时间表上的全球speleothems的全球档案中自信地从迄今为止始终前所未有的空间和时间表中获得确切的保存完好的独立温度记录。