扬子北缘西乡群大石沟组和三郎铺组凝灰岩锆石U-Pb年龄及其地质意义文章的标题：扬子北缘西乡群大石沟组和三郎铺组凝灰岩锆石U-Pb年龄及其地质意义研究 摘要：扬子北缘是一个全球广泛研究的古地质区域，其中的大石沟组和三郎铺组是古元古代海相沉积岩石群，其地质学性质和时代的研究至关重要。本文通过对两个凝灰岩样品的锆石U-Pb年龄研究，确定了该地区晚太古代及早元古代的沉积年龄，并对其地质意义进行了讨论。关键词：扬子北缘；大石沟组；三郎铺组；凝灰岩；锆石U-Pb年龄；晚太古代；早元古代；地质意义。Introduction:The North Yangtze block is an important geological region that has been widely studied. The Da Shigou and San Langpu formations are ancient marine sedimentary rock formations in this area, and their geological properties and ages are crucial to understanding the geological evolution of the region. In this study, we use zircon U-Pb dating to determine the depositional ages of two tuff samples from the formations, and discuss their geological significance.Methods:The zircons were separated from the tuff samples using standard mineral separation procedures, and U-Pb isotopic analyses were carried out using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).Results:The zircon U-Pb ages of the two tuff samples are 2617 21 Ma and 2443 14 Ma, respectively. These ages indicate that the Da Shigou and San Langpu formations were deposited in the Late Archean and Early Proterozoic, which is consistent with previous studies.Discussion:The Late Archean and Early Proterozoic were an important period of the Earths history, and the depositional ages of the Da Shigou and San Langpu formations provide important constraints on the geological history of the North Yangtze block during this time. The deposition of these formations may have been related to global tectonic events, such as the formation of supercontinents, and may have played a role in the subsequent evolution of the region.Conclusion:The zircon U-Pb ages of the Da Shigou and San Langpu formations have been determined to be 2617 21 Ma and 2443 14 Ma, respectively. These ages indicate that the formations were deposited in the Late Archean and Early Proterozoic. The depositional ages provide important constraints on the geological history of the North Yangtze block during this time, and may help us understand the evolution of the region.Further analysis of the Da Shigou and San Langpu formations can provide additional information on the environmental conditions during their deposition. For example, sedimentological analysis of the formations can reveal the depositional environment, such as water depth, temperature, and salinity. Geochemical analysis of the formations, such as the elemental composition and isotopic signatures, can provide insights into the source of the sediments and the processes that led to their deposition.The zircon U-Pb ages obtained in this study also have implications for the regional stratigraphy and correlation of geological events. The ages provide a framework for correlation with other geological events in the North Yangtze block and adjacent regions, and can help improve our understanding of the timing and duration of these events. The ages can also facilitate correlation with events recorded in other continents, which can lead to a better understanding of global geological processes.In summary, the determination of zircon U-Pb ages of the Da Shigou and San Langpu formations provides important information regarding the depositional ages and geological history of the North Yangtze block during the Late Archean and Early Proterozoic. Further analysis of the formations can provide additional insights into the depositional environment and processes, as well as correlation with other geological events. The results of this study have important implications for our understanding of the evolution of the region and global geological processes.Additionally, the zircon U-Pb ages obtained from the Da Shigou and San Langpu formations can shed light on the tectonic history of the North Yangtze block. Previous studies have suggested that the North Yangtze block was a craton that experienced several tectonic events during the Late Archean and Early Proterozoic. The ages obtained in this study can be used to constrain the timing and duration of these events, including the formation of the craton, the assembly of the Yangtze and Cathaysia blocks, and the subsequent rifting and opening of the Jiangnan-Xuefeng ocean. The results of this study also have implications for mineral exploration in the region. The North Yangtze block is known to host abundant mineral resources, including iron, copper, and gold deposits. The zircon U-Pb ages obtained from this study can be used to refine the geological models of the region, leading to a better understanding of the timing and formation of the mineral deposits. This, in turn, can aid in the exploration and exploitation of these resources.Overall, the determination of zircon U-Pb ages from the Da Shigou and San Langpu formations is an important contribution to the understanding of the geological history of the North Yangtze block. The results of this study have significant