Age of the Marwar Supergroup,NW India:A note on the U-Pb geochronology of Jodhpur Group felsic volcanics

• 作者: Huiru Xu Joseph G.Meert Manoj K.Pandit
• 来源期刊: 地学前缘（英文版）
• 年，卷（期）: 2022,（1）
• 所属期刊栏目: Research Paper
• 页码范围: 244-254
• 页数: 11页
• 语种: 英文

摘要

The Marwar Supergroup (NW Peninsular India) is thought to be of Ediacaran-Cambrian age,based on pre-vious paleontological and geochronological studies.However,direct constraints on the onset of sedimen-tation within the Marwar basin are still scarce.In this study,we report U-Pb zircon,LA-ICP-MS,and SIMS ages from the Chhoti Khatu felsic volcanic rocks,interlayered with the Jodhpur Group sandstones (Lower Marwar Supergroup).The cathodoluminescence images of the zircons indicate complex morphologies,and core-rim textures coupled with the wide range of ages indicate that they are likely inherited or in the case of thin poorly indurated ash-beds,detrital in origin.The age spectra of 68 zircon analyses from our sampling display a dominant 800-900 Ma age peak corresponding to the age of basement "Erinpura granite" rocks in the region.The youngest inherited zircon from a felsic ash layer yielded a U-Pb age of 651 Ma ± 18 Ma that,together with previous studies and paleontological evidence,indicates a post-Cryogenian age for the initiation of Marwar sedimentation following a ～125 Ma hiatus between the end of Malani magmatism and Marwar deposition.