Holocene Geomagnetic Field Variations and Their Constraints on Dating and Climate Events

Paleomagnetism reconstructs the ancient geomagnetic field structure and evolution through the remanent magnetization of geological materials. When applied the palaeomagnetic principles and methods to baked archaeological materials such as bricks, pottery, and metallurgical slag, it is referred to as archaeomagnetism, which mainly focuses on the fine-scale geomagnetic field variations during the Holocene. The geomagnetic field varies continuously through time, and a series of time-varying regional reference curves and global models have been constructed with the accumulation of archaeomagnetic data. In addition to providing insights into the dynamic processes of the internal Earth over the past millennia, these models and curves also have significant applications in stratigraphy. On the one hand, similar to the radiocarbon calibration curve, the geomagnetic reference curves can serve as a complementary dating method for archaeological materials known as archaeomagnetic dating. This method allows direct dating of baked archaeological materials and has advantages during radiocarbon calibration plateaus as well as at sites where no suitable dating samples are available. On the other hand, an increasing number of studies have reported that the geomagnetic field variations are synchronous with climate changes across multiple timescales, thus proposing that the geomagnetic field is one of the factors influencing climate change. One of the most widely discussed mechanisms involves geomagnetic modulation of galactic cosmic ray flux, which may influence cloud nucleation and, consequently, climate variability. There were multiple abrupt climate change events during the Holocene, offering us the opportunities to examine the potential coupling between geomagnetic and climate change at centennial to millennial scales. However, such investigations rely heavily on the accuracy and resolution of the geomagnetic reference curves and models, the same for archaeomagnetism dating. Europe has led global research into those two fields, given that its archaeomagnetism research started the earliest in 1830s and it has the highest proportion of global archaeomagnetic datasets. In China, a large amount of high-quality data has been published over the past two decades, enabling us to make preliminary attempts at both archaeomagnetic dating and geomagnetic-climate studies. Nevertheless, the temporal distribution of the existing data remains uneven, with almost no modern data available before 4000 BCE. Therefore, the acquisition of high-quality data is essential for improving regional geomagnetic reference curves, enhancing chronological frameworks, and better assessing the potential role of geomagnetic variability in Holocene climate events.