Extending sea loch sedimentary records: OSL dating of shallow marine systems

我们对陆地表面的地质学理解大部分是由于应用了定年技术，这些技术限制了陆地表面如何随着时间的推移而演变。海洋洛克斯（峡湾）的独特之处在于，它们能有效地捕获沉积物，从而捕捉陆地和海洋（陆地-海洋系统）的相互作用，以及这些相互作用如何因气候波动而随时间变化。该项目将证明，发光测年技术可用于测定古代海洋洛赫沉积物的年代，该技术可作为14 C（或其他适用于海洋沉积物的技术）的补充工具。发光测年技术比放射性碳测年技术更有优势，因为它的年龄范围比放射性碳（5万年）更长（石英的年龄范围从几十年到超过20万年），并且它可以应用于几乎所有的沉积物。这使我们能够扩展海洋洛赫年代学，在那里有机物保存得很差，而在保存的地方，沉积物的年龄超过50,000年。这两个方面都允许记录、确定日期和调查陆地与海洋的相互作用。近20 ka来陆地系统对冰川剥蚀的响应速率是一个活跃的研究领域，当有机质对14 C的响应很少时，发光测年法有可能提供这一时期陆地表面响应的海洋洛赫年代学。由于发光测年也反映了沉积物的迁移历史，因此可以使用这种技术解决额外的沉积信息。我们的项目包括3个部分：首先，我们将比较一个已发表的放射性碳年代学从沉积物中收集的核心洛赫Sunart的一个新的发光年代学开发作为本项目的一部分。我们将扩展发光年代学记录在过去的20万年的冰川剥蚀沉积物，以证明这种技术有可能被用来定年沉积物超出放射性碳的限制。第二部分的研究将涉及影响发光测年的一些基本特征的实验，即沉积物的敏感性和迁移过程中的漂白。这些实验将在从苏纳特洛赫收集的现代沉积物上进行。研究的最后一部分是沉积物的环境辐射剂量率，这是发光测年所需的测量。我们将探讨铀不平衡是如何受到不同的沉积物岩性和海水洛赫环境中的水含量，以及需要什么样的调整，以纠正这些影响剂量率随着时间的推移。 随着海洋数据集数量和分辨率的增加，我们需要建立海岸线周围积累的沉积物档案的编年史，以了解海岸变化的速率，并促进我们对因海平面变化而被淹没的丰富考古记录的了解。晚第四纪。此外，随着海洋可再生能源产业的发展，需要沉积物测年技术来确定淹没考古遗址的年代，并限制近海沙系统的运动速率。定年是了解变化速率的必要条件，光释光定年的优点是可以广泛应用于几乎所有的沉积物和沉积物，不依赖于有机物质的可用性，并且有可能确定200-400 ka（石英）或100万年（长石）的沉积物的年代。

Much of our geological understanding of the land surface is due to the application of dating techniques that constrain how the land surface has evolved through time. Sea lochs (fiords) are unique in that they trap sediments efficiently and therefore capture the interactions of land and sea (the land-ocean system), and how those interactions change through time due to climatic fluctuations. This project will demonstrate that luminescence dating techniques can be applied to date ancient sea loch sediments, and that the technique can be a complementary tool to 14C (or other techniques applied to marine sediments). Luminescence dating techniques have advantages over radiocarbon dating, because the age range is longer (from decades to greater than 200,000 years for quartz) than radiocarbon (50,000 years) and it can be applied to almost all sediments. This permits us to extend the sea loch chronology where organic matter is poorly preserved, and where preserved, sediments that are older than 50,000 years in age. Both of these aspects permit land-ocean interactions to be recorded, dated and investigated. The response rates of the land system to deglacation over the last ~ 20 ka is an active area of research, and luminescence dating has the potential to provide a sea loch chronology of the land surface response over that tme period when little orgnic matter is available for 14C. Since luminescence dating also reflects the sediment's transport history, there is additional sedimentary information that can be resolved using this technique. Our project comprises of 3 parts: we will first compare a published radiocarbon chronology from sediment cores collected in Loch Sunart to a new luminescence chronology developed as part of this project. We will extend the luminescence chronology to sediments recording deglacation over the last 20 ka, to demonstrate that this technqiue has the potential to be used to date sediments beyond the limits of radiocarbon. The second part of our research will involve some fundamental experiments on characterisitics that affect luminescnece dating, namely sediment sensitivity and bleaching during transport. These experiments will be conducted on modern sediments collected from Loch Sunart. The final part of the research involves the environmental radiation dose rate of sediments which is required measurement for luminecence dating. We will explore how uranium disequilibium is affected by different sediment lithologies and water contents in sea loch environments, and what adjustments are required to correct for these influences on dose rate over time. As marine datasets grow in number and resolution, we need to build chronologies of the sediment archive accumulating around our coastline in order to understand rates of coastal change, and to advance our understanding of the rich archaeological record that has been drowned by changing sea levels during the Late Quaternary. In addition, with the marine renewables industries growth sediment dating techniques are required to date drowned archaeological sites, and constrain the rates of movement of offshore sand systems. Dating is an imperative for understanding rates of change and OSL dating has the advantage of being widely applied to almost all sediments and environmments, is not reliant on the availability of organic matter, and has the potential to date sediments as old as 200-400 ka (quartz) or a million years (feldspar).